網絡請求] Okhttp: 網絡請求框架

序

準備改造一套數據源連接框架，需要借助OkHttp，故記錄之。

本文主要是轉載第1篇參考文獻。

概述：Okhttp

Android中的網絡請求框架，基本是okhttp和Retrofit一統天下，而Retrofit又是以okhttp為基礎。

所以，系統學習okhttp的使用和原理就很有必要了。

okhttp是由square公司開發，Android中公認最好用的網絡請求框架，在接口封裝上做的簡單易用，
它有以下默認特性：

支持HTTP/2，允許所有同一個主機地址的請求共享同一個socket連接

使用連接池減少請求延時

透明的GZIP壓縮減少響應數據的大小

緩存響應內容，避免一些完全重復的請求

當網絡出現問題的時候OkHttp 會自動恢復一般的連接問題，如果你的服務有多個IP地址，當第一個IP請求失敗時，OkHttp會交替嘗試你配置的其他IP。

安裝指南

Maven依賴

implementation 'com.squareup.okhttp3:okhttp:3.14.9'
implementation 'com.squareup.okio:okio:1.17.5'

其中Okio庫是對Java.io和java.nio的補充，以便能夠更加方便，快速的訪問、存儲和處理你的數據。
OkHttp的底層使用該庫作為支持。
另外，如果是在Android上運行，別忘了申請網絡請求權限，如果還使用網絡請求的緩存功能，那么還要申請讀寫外存的權限:

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

使用指南

get請求

get方式中又可以分為2種情況:同步請求和異步請求；
同步請求在進行請求的時候，當前線程會被阻塞住，直到得到服務器的響應后，后面的代碼才會執行；
而異步請求不會阻塞當前線程，它采用了回調的方式，請求是在另一個線程中執行的，不會影響當前的線程。
以百度主頁為例，進行Get請求：

同步請求

import okhttp3.Request;
import okhttp3.Call;
import okhttp3.OkHttpClient;

public void getSync() {
	//同步請求
	OkHttpClient httpClient = new OkHttpClient();
	String url = "https://www.baidu.com/";
	Request getRequest = new Request.Builder()
			.url(url)
			.get()
			.build();
	//準備好請求的Call對象
	Call call = httpClient.newCall(getRequest);//只是配置請求，不會觸發網絡操作 (需確保每個 Call 對象只執行一次，避免重復使用)
	try {
		Response response = call.execute();//必須調用 execute() 或 enqueue() 才會真正發起請求
		Log.i(TAG, "okHttpGet run: response:"+ response.body().string());
	} catch (IOException e) {
		e.printStackTrace();
	}
}

首先，創建了OkHttpClient實例，接著用Request.Builder構建了Request實例、并傳入了百度主頁的url

然后，httpClient.newCall方法傳入Request實例生成call，最后在子線程調用call.execute()執行請求獲得結果response。

使用OkHttp進行get請求，是比較簡單的，只要在構建Request實例時更換url就可以了。

異步請求

call.execute()是同步方法。
想要在主線程直接使用可以嘛？當然可以，使用call.enqueue(callback)即可

public void getAsync() {
	//異步請求
	OkHttpClient httpClient = new OkHttpClient();
	String url = "https://www.baidu.com/";
	Request getRequest = new Request.Builder()
			.url(url)
			.get()
			.build();
	//準備好請求的Call對象
	Call call = httpClient.newCall(getRequest);
	call.enqueue(new Callback() {
		@Override
		public void onFailure(Call call, IOException e) {
		}

		@Override
		public void onResponse(Call call, Response response) throws IOException {
			Log.i(TAG, "okHttpGet enqueue: onResponse:" + response.body().string());
			ResponseBody body = response.body();
			String string = body.string();
			byte[] bytes = body.bytes();
			InputStream inputStream = body.byteStream();
		}
	});
}

call.enqueue會異步執行，需要注意的是，2個回調方法onFailure、onResponse是執行在子線程的

所以，如果想要執行UI操作，需要使用Handler或其他方式切換到UI線程。

取消請求

每一個Call對象只能執行一次。

如果想要取消正在執行的請求，可以使用call.cancel()，通常在離開頁面時都要取消執行的請求的。

結果處理

請求回調的兩個方法是指傳輸層的失敗和成功。

onFailure通常是connection連接失敗或讀寫超時；

onResponse是指成功得從服務器獲取到了結果，但是這個結果的響應碼可能是404、500等，也可能就是200（response.code()的取值）。

如果response.code()是200，表示應用層請求成功了。

此時我們可以獲取Response的ResponseBody，這是響應體。
從面看到，可以從ResponseBody獲取string、byte[ ]、InputStream，這樣就可以對結果進行很多操作了。
比如UI上展示string（要用Handler切換到UI線程）、通過InputStream寫入文件等等。

上面異步請求執行后結果打印如下：

okHttpGet run: response:<!DOCTYPE html> <!--STATUS OK--><html> <head><meta http-equiv=content-type content=text/html;charset=utf-8><meta http-equiv=X-UA-Compatible content=IE=Edge><meta content=always name=referrer><link rel=stylesheet type=text/css 
href=https://ss1.bdstatic.com/5eN1bjq8AAUYm2zgoY3K/r/www/cache/bdorz/baidu.min.css><title>百度一下，你就知道</title></head> <body link=#0000cc> <div id=wrapper> <div id=head> <div class=head_wrapper> <div class=s_form> <div class=s_form_wrapper> <div id=lg> 
<img hidefocus=true src=//www.baidu.com/img/bd_logo1.png width=270 height=129> </div> <form id=form name=f action=//www.baidu.com/s class=fm> <input type=hidden name=bdorz_come value=1> <input type=hidden name=ie value=utf-8> <input type=hidden name=f value=8> <input type=hidden name=rsv_bp value=1> <input type=hidden name=rsv_idx value=1> <input type=hidden name=tn value=baidu><span class="bg s_ipt_wr"><input id=kw name=wd class=s_ipt value maxlength=255 autocomplete=off autofocus=autofocus></span><span class="bg s_btn_wr"><input type=submit id=su value=百度一下 class="bg s_btn" autofocus></span> </form> </div> </div> <div id=u1> <a href=http://news.baidu.com name=tj_trnews class=mnav>新聞</a> <a href=https://www.hao123.com name=tj_trhao123 class=mnav>hao123</a> <a href=http://map.baidu.com name=tj_trmap class=mnav>地圖</a> <a href=http://v.baidu.com name=tj_trvideo class=mnav>視頻</a> <a href=http://tieba.baidu.com name=tj_trtieba class=mnav>貼吧</a> <noscript> <a href=http://www.baidu.com/bdorz/login.gif?login&amp;tpl=mn&amp;u=http%3A%2F%2Fwww.baidu.com%2f%3fbdorz_come%3d1 name=tj_login class=lb>登錄</a> </noscript> <script>document.write('<a + encodeURIComponent(window.location.href+ (window.location.search === "" ? "?" : "&")+ "bdorz_come=1")+ '" name="tj_login" class="lb">登錄</a>');                                                                                                                   </script> <a href=//www.baidu.com/more/ name=tj_briicon class=bri style="display: block;">更多產品</a> </div> </div> </div> <div id=ftCon> <div id=ftConw> <p id=lh> <a href=http://home.baidu.com>關于百度</a> <a href=http://ir.baidu.com>About Baidu</a> </p> <p id=cp>&copy;2017&nbsp;Baidu&nbsp;<a href=http://www.baidu.com/duty/>使用百度前必讀</a>&nbsp; <a href=http://jianyi.baidu.com/ class=cp-feedback>意見反饋</a>&nbsp;京ICP證030173號&nbsp; <img src=//www.baidu.com/img/gs.gif> </p> </div> </div> </div> </body> </html>

post請求

POST請求將參數放在請求的主體中，不會直接顯示在URL中。Post請求也分為同步和異步方式，和get方式用法相同

同步POST

public void postSync(){//同步請求
	new Thread(new Runnable() {
		@Override
		public void run() {
			OkHttpClient okHttpClient = new OkHttpClient();
			FormBody formBody = new FormBody.Builder()
					.add("a","1")
					.add("b","2")
					.build();
			Request request=new Request.Builder()
					.post(formBody)
					.url("https://www.httpbin.org/post")
					.build();
			//準備好請求的Call對象
			Call call = okHttpClient.newCall(request);
			try {
				Response response = call.execute();
				Log.i("postSync",response.body().string());
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}).start();
}

異步POST

public void postAsync(){//異步請求
	OkHttpClient okHttpClient=new OkHttpClient();
	FormBody formBody=new FormBody.Builder() //okhttp3.FormBody extends RequestBody
			.add("a","1")
			.add("b","2")
			.build();
	Request request=new Request.Builder()
			.post(formBody)
			.url("https://www.httpbin.org/post")
			.build();
	//準備好請求的Call對象
	Call call = okHttpClient.newCall(request);
	call.enqueue(new Callback() {
		@Override
		public void onFailure(@NonNull Call call, @NonNull IOException e) {

		}

		@Override
		public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {
			if(response.isSuccessful()){
				Log.i("postAsync",response.body().string());
			}
		}
	});
}

post請求提交多種 MediaType 格式

`text/x-markdown` : String、文件

post請求與get請求的區別是在構造Request對象時，需要多構造一個RequestBody對象，用它來攜帶我們要提交的數據，其他都是一樣的。

示例如下：

import okhttp3.MediaType;
import okhttp3.RequestBody;

OkHttpClient httpClient = new OkHttpClient();

MediaType contentType = MediaType.parse("text/x-markdown; charset=utf-8");
String content = "hello!";
RequestBody body = RequestBody.create(contentType, content);

Request getRequest = new Request.Builder()
	.url("https://api.github.com/markdown/raw")
	.post(body)
	.build();

Call call = httpClient.newCall(getRequest);

call.enqueue(new Callback() {
	@Override
	public void onFailure(Call call, IOException e) {
	}

	@Override
	public void onResponse(Call call, Response response) throws IOException {
		Log.i(TAG, "okHttpPost enqueue: \n onResponse:"+ response.toString() +"\n body:" +response.body().string());
	}
});

對比get請求，把構建Request時的get()改成post(body)，并傳入RequestBody實例。

RequestBody實例是通過create方法創建，需要指定請求體內容類型、請求體內容。
這里是傳入了一個指定為markdown格式的文本。

`application/json` : json

傳入RequestBody的 MediaType 還可以是其他類型，如客戶端要給后臺發送json字符串、發送一張圖片，那么可以定義為：

demo1

// RequestBody:jsonBody，json字符串
String json = "jsonString";
RequestBody jsonBody = RequestBody.create(MediaType.parse("application/json; charset=utf-8"), json);

//RequestBody:fileBody, 上傳文件
File file = new File(Environment.getExternalStorageDirectory(), "1.png");
RequestBody fileBody = RequestBody.create(MediaType.parse("image/png"), file);

demo2

if(esUrl.endsWith("/_search")){//dsl語法
	JSONObject jsonObject = JSON.parseObject(sql);
	jsonStr = JSON.toJSONString(jsonObject);
} else {//es opendistro 插件的SQL語法
	json.put("query", sql);
	jsonStr = JSON.toJSONString(json);
}

OkHttpClient okHttpClient = SpringContextUtil.getBean(OkHttpClient.class);

String credential = Credentials.basic( username, password);// base64({user}:{password})
Request request = new Request.Builder()
		.header("Authorization", credential)
		.method("POST", RequestBody.create(MediaType.get("application/json"), jsonStr))
		.url(esUrl)
		.build();

MediaType
Call newCall = okHttpClient.newCall(request);//只是配置請求，不會觸發網絡操作 (需確保每個 Call 對象只執行一次，避免重復使用)
Response response = newCall.execute();//必須調用 execute() 或 enqueue() 才會真正發起請求

if (!response.isSuccessful()) {
	ObjectMapper mapper = new ObjectMapper();
	String body = new String(response.body().bytes());

	logger.error("code:{},message:{},body:{}", response.code(), response.message(), body);

	ErrorMessage errorMessage = mapper.readValue(body, ErrorMessage.class);
	if (null != errorMessage && errorMessage.getError() != null && errorMessage.getError().getType() != null) {
		throw new RuntimeException(ErrorCodeEnum.QUERY_ES_FAIL.getCode(), ErrorCodeEnum.QUERY_ES_FAIL.getMsg() + ", cause that : " + errorMessage.getError().getType());
	}
}

`application/x-www-form-urlencoded` : 提交表單

構建RequestBody除了上面的方式，還有它的子類FormBody，FormBody用于提交表單鍵值對，這種能滿足平常開發大部分的需求。

//RequestBody:FormBody，表單鍵值對
RequestBody formBody = new FormBody.Builder()
	.add("username", "henry")
	.add("password", "666")
	.build();

FormBody是通過FormBody.Builder用構建者模式創建，add鍵值對即可。它的contentType在內部已經指定了。

public final class FormBody extends RequestBody {
  private static final MediaType CONTENT_TYPE = MediaType.get("application/x-www-form-urlencoded");
  ...
}

`multipart/*` : 提交復雜請求體

RequestBody另一個子類MultipartBody，用于post請求提交復雜類型的請求體。

復雜請求體可以同時包含多種類型的的請求體數據。

上面介紹的 post請求 string、文件、表單，只有單一類型。
考慮一種場景–注冊場景，用戶填寫完姓名、電話，同時要上傳頭像圖片，這時注冊接口的請求體就需要接受表單鍵值對以及文件了，那么前面講的的post就無法滿足了。
那么就要用到MultipartBody了。

源碼


/** An <a >RFC 2387</a>-compliant request body. */
public final class MultipartBody extends RequestBody {
  /**
   * The "mixed" subtype of "multipart" is intended for use when the body parts are independent and
   * need to be bundled in a particular order. Any "multipart" subtypes that an implementation does
   * not recognize must be treated as being of subtype "mixed".
   */
  public static final MediaType MIXED = MediaType.get("multipart/mixed");

  /**
   * The "multipart/alternative" type is syntactically identical to "multipart/mixed", but the
   * semantics are different. In particular, each of the body parts is an "alternative" version of
   * the same information.
   */
  public static final MediaType ALTERNATIVE = MediaType.get("multipart/alternative");

  /**
   * This type is syntactically identical to "multipart/mixed", but the semantics are different. In
   * particular, in a digest, the default {@code Content-Type} value for a body part is changed from
   * "text/plain" to "message/rfc822".
   */
  public static final MediaType DIGEST = MediaType.get("multipart/digest");

  /**
   * This type is syntactically identical to "multipart/mixed", but the semantics are different. In
   * particular, in a parallel entity, the order of body parts is not significant.
   */
  public static final MediaType PARALLEL = MediaType.get("multipart/parallel");

  /**
   * The media-type multipart/form-data follows the rules of all multipart MIME data streams as
   * outlined in RFC 2046. In forms, there are a series of fields to be supplied by the user who
   * fills out the form. Each field has a name. Within a given form, the names are unique.
   */
  public static final MediaType FORM = MediaType.get("multipart/form-data");

  ...

demo

OkHttpClient httpClient = new OkHttpClient();

// MediaType contentType = MediaType.parse("text/x-markdown; charset=utf-8");
// String content = "hello!";
// RequestBody body = RequestBody.create(contentType, content);

//RequestBody:fileBody,上傳文件
File file = drawableToFile(this, R.mipmap.bigpic, new File("00.jpg"));
RequestBody fileBody = RequestBody.create(MediaType.parse("image/jpg"), file);


//RequestBody:multipartBody, 多類型 （用戶名、密碼、頭像）
MultipartBody multipartBody = new MultipartBody.Builder()
		.setType(MultipartBody.FORM)
		.addFormDataPart("username", "hufeiyang")
		.addFormDataPart("phone", "123456")
		.addFormDataPart("touxiang", "00.png", fileBody)
		.build();


Request getRequest = new Request.Builder()
		.url("http://yun918.cn/study/public/file_upload.php")
		.post(multipartBody)
		.build();

Call call = httpClient.newCall(getRequest);

call.enqueue(new Callback() {
	@Override
	public void onFailure(Call call, IOException e) {

		Log.i(TAG, "okHttpPost enqueue: \n onFailure:"+ call.request().toString() +"\n body:" +call.request().body().contentType()
		+"\n IOException:"+e.getMessage());
	}

	@Override
	public void onResponse(Call call, Response response) throws IOException {
		Log.i(TAG, "okHttpPost enqueue: \n onResponse:"+ response.toString() +"\n body:" +response.body().string());
	}
});

請求配置項

前置問題

如何全局設置超時時長?

緩存位置、最大緩存大小呢？

考慮有這樣一個需求，我要監控App通過 OkHttp 發出的所有原始請求，以及整個請求所耗費的時間，如何做？

這些問題，在OkHttp這里很簡單。把OkHttpClient實例的創建，換成以下方式即可：

OkHttpClient client = new OkHttpClient.Builder()
  .connectTimeout(15, TimeUnit.SECONDS)
  .readTimeout(10, TimeUnit.SECONDS)
  .writeTimeout(10, TimeUnit.SECONDS)
  .cache(new Cache(getExternalCacheDir(),500 * 1024 * 1024))
  .addInterceptor(new Interceptor() {
      @Override
      public Response intercept(Chain chain) throws IOException {
          Request request = chain.request();
          String url = request.url().toString();
          Log.i(TAG, "intercept: proceed start: url"+ url+ ", at " + System.currentTimeMillis());
          Response response = chain.proceed(request);
          ResponseBody body = response.body();
          Log.i(TAG, "intercept: proceed end: url"+ url+ ", at " + System.currentTimeMillis());
          return response;
      }
  })
  .build();

這里通過OkHttpClient.Builder通過構建者模式設置了連接、讀取、寫入的超時時長，用cache()方法傳入了由緩存目錄、緩存大小構成的Cache實例，這樣就解決了前兩個問題。

使用addInterceptor()方法添加了Interceptor實例，且重寫了intercept方法。

Interceptor意為攔截器，intercept()方法會在開始執行請求時調用。
其中chain.proceed(request)內部是真正請求的過程，是阻塞操作，執行完后會就會得到請求結果ResponseBody
所以chain.proceed(request)的前后取當前時間，那么就知道整個請求所耗費的時間。上面chain.proceed(request)的前后分別打印的日志和時間，這樣第三個問題也解決了。

具體Interceptor是如何工作，后面介紹。

另外，通常OkHttpClient實例是全局唯一的，這樣這些基本配置就是統一，且內部維護的連接池也可以有效復用（后面介紹）。

全局配置的有了，單個請求的也可以有一些單獨的配置。

Request getRequest = new Request.Builder()
  .url("http://yun918.cn/study/public/file_upload.php")
  .post(multipartBody)
  .addHeader("key","value")
  .cacheControl(CacheControl.FORCE_NETWORK)
  .build();

使用addHeader()方法添加了請求頭。

使用cacheControl(CacheControl.FORCE_NETWORK)設置此次請求是能使用網絡，不用緩存。（還可以設置只用緩存FORCE_CACHE）

最佳實踐: MyOkHttpClientConfig

pom.xml

  <dependency>
    <groupId>com.squareup.okhttp3</groupId>
    <artifactId>okhttp</artifactId>
    <version>4.9.1 or 3.14.9[推薦]</version>
  </dependency>

MyOkHttpClientConfig

import lombok.extern.slf4j.Slf4j;
import okhttp3.ConnectionPool;
import okhttp3.OkHttpClient;
import okhttp3.internal.connection.Transmitter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.annotation.Nullable;
import java.util.Map;
import java.util.concurrent.TimeUnit;

@Configuration
@Slf4j
public class OkHttpClientConfig {

    //Socket.setSoTimeout(int timeout)
    public final static String OKHTTP_CONNECTTIMEOUT_PARAM = "OKHTTP_CONNECTTIMEOUT";
    public final static String OKHTTP_CONNECTTIMEOUT_DEFAULT = "1000";

    public final static String OKHTTP_CALLTIMEOUT_PARAM = "OKHTTP_CALLTIMEOUT";
    public final static String OKHTTP_CALLTIMEOUT_DEFAULT = "3000";

    public final static String OKHTTP_READTIMEOUT_PARAM = "OKHTTP_READTIMEOUT";
    public final static String OKHTTP_READTIMEOUT_DEFAULT = "1000";

    public final static String OKHTTP_CONNECTIONPOOL_MAXIDLE_PARAM = "OKHTTP_CONNECTIONPOOL_MAXIDLE";
    public final static String OKHTTP_CONNECTIONPOOL_MAXIDLE_DEFAULT = "100";

    public final static String OKHTTP_CONNECTIONPOOL_KEPPALIVCEDURATION_PARAM = "OKHTTP_CONNECTIONPOOL_KEPPALIVCEDURATION";
    public final static String OKHTTP_CONNECTIONPOOL_KEPPALIVCEDURATION_DEFAULT = "30000";

    @Bean(name = "okHttpClient")
    public OkHttpClient okHttpClient() {
        OkHttpClient okHttpClient = buildOkHttpClient( OkHttpClient.class.getSimpleName() + "SpringBean(okHttpClient)");
        return okHttpClient;
    }

    /**
     * 構建 OkHttpClient 連接池
     * @param caller 可選參數，標明調用方
     * @return
     */
    public static OkHttpClient buildOkHttpClient(@Nullable String caller){
//        MyOkHttpRetryInterceptor.Builder builder = new MyOkHttpRetryInterceptor.Builder()
//            .retryInterval(500)
//            .executionCount(3);

        Map<String, String> env = System.getenv();

        long connectTimeout = Long.valueOf( env.getOrDefault(OKHTTP_CONNECTTIMEOUT_PARAM, OKHTTP_CONNECTTIMEOUT_DEFAULT) );
        long callTimeout = Long.valueOf( env.getOrDefault(OKHTTP_CALLTIMEOUT_PARAM, OKHTTP_CALLTIMEOUT_DEFAULT) );
        long readTimeout = Long.valueOf( env.getOrDefault(OKHTTP_READTIMEOUT_PARAM, OKHTTP_READTIMEOUT_DEFAULT) );
        int maxIdleConnections = Integer.valueOf( env.getOrDefault( OKHTTP_CONNECTIONPOOL_MAXIDLE_PARAM, OKHTTP_CONNECTIONPOOL_MAXIDLE_DEFAULT ) );
        long keepAliveDuration = Long.valueOf( env.getOrDefault( OKHTTP_CONNECTIONPOOL_KEPPALIVCEDURATION_PARAM, OKHTTP_CONNECTIONPOOL_KEPPALIVCEDURATION_DEFAULT ) );

        log.info("config({}) | connectTimeout:{}, callTimeout:{}, readTimeout:{}, maxIdleConnections:{}, keepAliveDuration:{}"
            , caller==null?"":caller
            , connectTimeout, callTimeout, readTimeout, maxIdleConnections, keepAliveDuration
        );
        return new OkHttpClient().newBuilder()
            .connectTimeout(connectTimeout, TimeUnit.MILLISECONDS)
            .callTimeout(callTimeout, TimeUnit.MILLISECONDS)
            .readTimeout(readTimeout, TimeUnit.MILLISECONDS)
            .retryOnConnectionFailure(true) //開啟 okhttp 自帶的 重試阻攔器
            .followRedirects(true)//重定向
            //.addInterceptor( new MyOkHttpRetryInterceptor(builder) )//本重置攔截器，尚不可靠
            .connectionPool(new ConnectionPool(maxIdleConnections, keepAliveDuration, TimeUnit.MILLISECONDS))
            .build();
    }

    public static OkHttpClient buildOkHttpClient(){
        return buildOkHttpClient(null);
    }
}

攔截器的使用

OkHttp的攔截器（Interceptors）提供了強大的自定義和修改HTTP請求和響應的能力。
攔截器允許在發送請求前、收到響應后以及其他階段對HTTP流量進行攔截和處理。

例如：攔截器可以修改請求的URL、請求方法、請求頭部、請求體等。
這對于添加身份驗證頭、設置緩存控制頭等場景很有用。
用法如下：

public void interceptor(){
    OkHttpClient okHttpClient=new OkHttpClient.Builder()//添加攔截器的使用OkHttpClient的內部類Builder
      .addInterceptor(new Interceptor() {//使用攔截器可以對所有的請求進行統一處理，而不必每個request單獨去處理
          @NonNull
          @Override
          public Response intercept(@NonNull Chain chain) throws IOException {
              //前置處理，以proceed方法為分割線：提交請求前
              Request request = chain.request().newBuilder()
                      .addHeader("id", "first request")
                      .build();
              Response response = chain.proceed(request);
              //后置處理：收到響應后
              return response;
          }
      })
      .addNetworkInterceptor(new Interceptor() {//這個在Interceptor的后面執行，無論添加順序如何
          @NonNull
          @Override
          public Response intercept(@NonNull Chain chain) throws IOException {
              Log.i("id",chain.request().header("id"));
              return chain.proceed(chain.request());
          }
      })
      .cache(new Cache(new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM).getAbsolutePath()+"/cache"),1024*1024))//添加緩存
      .build();

    Request request=new Request.Builder()
      .url("https://www.httpbin.org/get?a=1&b=2")
      .build();

    //準備好請求的Call對象
    Call call = okHttpClient.newCall(request);
    //異步請求
    call.enqueue(new Callback() {
        @Override
        public void onFailure(@NonNull Call call, @NonNull IOException e) {

        }

        @Override
        public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {
            if(response.isSuccessful()){
                Log.i("interceptor",response.body().string());
            }
        }
    });
}

Cookie的使用

大家應該有這樣的經歷，就是有些網站的好多功能都需要用戶登錄之后才能訪問，而這個功能可以用cookie實現:

首先，在客戶端登錄之后，服務器給客戶端發送一個cookie，由客戶端保存；

然后，客戶端在訪問需要登錄之后才能訪問的功能時，只要攜帶這個cookie，服務器就可以識別該用戶是否登錄。

用法如下

public void cookie(){
    Map<String,List<Cookie>> cookies = new HashMap<>();

    new Thread(new Runnable() {
        @Override
        public void run() {
            OkHttpClient okHttpClient = new OkHttpClient.Builder()
                .cookieJar(new CookieJar() {
                    @Override
                    public void saveFromResponse(@NonNull HttpUrl httpUrl, @NonNull List<Cookie> list) {//保存服務器發送過來的cookie
                        cookies.put("cookies",list);
                    }

                    @NonNull
                    @Override
                    public List<Cookie> loadForRequest(@NonNull HttpUrl httpUrl) {//請求的時候攜帶cookie
                        if(httpUrl.equals("www.wanandroid.com")){
                            return cookies.get("cookies");
                        }
                        return new ArrayList<>();
                    }
                })
                .build();

            FormBody formBody = new FormBody.Builder()
                    .add("username","ibiubiubiu")
                    .add("password","Lhh823924.")
                    .build();

            Request request = new Request.Builder()  //模擬登錄
                    .url("https://wanandroid.com/user/lg")
                    .post(formBody)
                    .build();

            //準備好請求的Call對象
            Call call = okHttpClient.newCall(request);
            try {
                Response response = call.execute();
                Log.i("login",response.body().string());
            } catch (IOException e) {
                e.printStackTrace();
            }

            //請求收藏頁面，必須登錄之后才能訪問到
            request=new Request.Builder()
                    .url("https://wanandroid.com/lg/collect")
                    .build();

            //準備好請求的Call對象
            call = okHttpClient.newCall(request);
            try {
                Response response = call.execute();
                Log.i("collect",response.body().string());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    })
    .start();
}

連接池 : OkHttp ConnectionPool

基礎概念

OkHttp ConnectionPool 是 OkHttp 庫中的一個關鍵組件，用于管理 HTTP 連接的復用。
OkHttp ConnectionPool 是一個連接池，用于存儲和管理 HTTP 連接。

它允許在多個請求之間復用連接，從而提高網絡請求的效率。
連接池中的連接可以被多個線程共享，并且會根據配置的策略（如最大空閑連接數、連接超時時間等）來管理連接的生命周期。

優勢

提高性能：通過復用連接，減少了每次請求時的握手和連接建立時間。
減少資源消耗：避免頻繁地創建和銷毀連接，節省了系統資源。
支持并發：允許多個線程同時使用同一個連接，提高了并發處理能力。

參數項

OkHttp ConnectionPool 主要有以下幾種配置參數：

maxIdleConnections：池中最大空閑連接數。
keepAliveDuration：連接保持活躍的時間。
timeUnit：keepAliveDuration 的時間單位。

應用場景

Web 服務器和客戶端之間的通信：在高并發場景下，使用連接池可以顯著提高響應速度。
移動應用網絡請求：在移動應用中，頻繁的網絡請求可以通過連接池優化性能。
微服務架構中的服務間調用：在微服務架構中，服務之間的調用可以通過連接池提高效率。

常用方法

//連接數 : Returns total number of connections in the pool.
int : okHttpClient.connectionPool().connectionCount();

//空閑連接數 : Returns the number of idle connections in the pool.
int : okHttpClient.connectionPool().idleConnectionCount()

//關閉所有連接 : Close and remove all idle connections in the pool.
void : okHttpClient.connectionPool().evictAll();

okhttp3.ConnectionPool的底層實現類： okhttp3.internal.connection.RealConnectionPool

借助連接池可解決的常見問題

Q: 連接池中的連接超時 / 配置連接池

原因：可能是由于網絡不穩定或服務器響應慢導致的。
解決方法

import okhttp3.ConnectionPool;

ConnectionPool pool = new ConnectionPool(5, 5, TimeUnit.MINUTES);
OkHttpClient client = new OkHttpClient.Builder()
    .connectionPool(pool)
    .readTimeout(30, TimeUnit.SECONDS)
    .writeTimeout(30, TimeUnit.SECONDS)
    .connectTimeout(30, TimeUnit.SECONDS)
    .build();

Q: 連接池的默認配置

連接池默認配置：

每個地址的空閑連接數為 5個，每個空閑連接的存活時間為 5分鐘

package okhttp3;

public ConnectionPool() {
    this(5, 5, TimeUnit.MINUTES);
}

public ConnectionPool(int maxIdleConnections, long keepAliveDuration, TimeUnit timeUnit) {
    this.maxIdleConnections = maxIdleConnections;
    this.keepAliveDurationNs = timeUnit.toNanos(keepAliveDuration);

    if (keepAliveDuration <= 0) {
        throw new IllegalArgumentException("keepAliveDuration <= 0: " + keepAliveDuration);
    }
}

Q: 過期連接的處理策略？

連接池每次添加一個新的連接時，都會先清理當前連接池中過期的連接，通過清理線程池executor 執行清理任務cleanupRunnable。

Q: 連接池中的連接數過多

原因：可能是由于客戶端請求過于頻繁，導致連接池中的連接數超過了設定的最大值。
解決方案：

ConnectionPool pool = new ConnectionPool(100, 5, TimeUnit.MINUTES);
OkHttpClient client = new OkHttpClient.Builder()
    .connectionPool(pool)
    .build();

Q: 連接池中的連接無法釋放

原因：可能是由于某些請求未正確關閉連接導致的。
解決方案：

確保每次請求后都正確關閉響應體：

Response response = client.newCall(request).execute();
try {
    // 處理響應
} finally {
    response.close();
}

綜合案例

import okhttp3.ConnectionPool;
import okhttp3.OkHttpClient;
import java.util.concurrent.TimeUnit;

public class OkHttpExample {
    public static void main(String[] args) {
        ConnectionPool pool = new ConnectionPool(100, 5, TimeUnit.MINUTES);
        OkHttpClient client = new OkHttpClient.Builder()
            .connectionPool(pool)
            .readTimeout(30, TimeUnit.SECONDS)
            .writeTimeout(30, TimeUnit.SECONDS)
            .connectTimeout(30, TimeUnit.SECONDS)
            .build();

        // 使用 client 進行網絡請求
    }
}

通過合理配置和使用 OkHttp ConnectionPool，可以有效提升網絡請求的性能和穩定性。

綜合應用

案例1：封裝OkHttp單例模式 : OkHttpUtils(自定義)

public class OkHttpUtils {
    /**
     * 單例模式
     */
    private static OkHttpUtils okHttpUtils = null;
 
    private OkHttpUtils() {
    }
 
    public static OkHttpUtils getInstance() {
        //雙層判斷，同步鎖
        if (okHttpUtils == null) {
            synchronized (OkHttpUtils.class) {
                if(okHttpUtils == null){
                    okHttpUtils = new OkHttpUtils();
                }
            }
        }
        return okHttpUtils;
    }
 
    /**
     * 單例模式
     * 封裝OkhHttp
     * synchronized同步方法
     */
    private static OkHttpClient okHttpClient = null;
 
    private static synchronized OkHttpClient getOkHttpClient() {
        if (okHttpClient == null) {
            //攔截器
            HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor(new HttpLoggingInterceptor.Logger() {
                @Override
                public void log(String message) {
                    //攔截日志消息
                    Log.i("henry", "log: " + message);
                }
            });
            //設置日志攔截器模式
            interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
 
            okHttpClient = new OkHttpClient.Builder()
                //日志攔截器
                .addInterceptor(interceptor)
                //應用攔截器
                .addInterceptor(new Interceptor() {
                    @Override
                    public Response intercept(Chain chain) throws IOException {
                        Request request = chain.request()
                                .newBuilder()
                                .addHeader("source", "android")
                                .build();
 
                        return chain.proceed(request);
                    }
                })
                .build();
        }
        return okHttpClient;
    }
 
    /**
     * doGet
     */
    public void doGet(String url, Callback callback) {
        //創建okhttp
        OkHttpClient okHttpClient = getOkHttpClient();
        Request request = new Request.Builder()
                .url(url)
                .build();
        okHttpClient.newCall(request).enqueue(callback);
    }
 
    /**
     * doPost
     */
    public void doPost(String url, Map<String, String> params, Callback callback) {
        OkHttpClient okHttpClient = getOkHttpClient();
        //請求體
        FormBody.Builder formBody = new FormBody.Builder();
        for (String key : params.keySet()) {
            //遍歷map集合
            formBody.add(key, params.get(key));
        }
        Request request = new Request.Builder()
                .url(url)
                .post(formBody.build())
                .build();
        okHttpClient.newCall(request).enqueue(callback);
    }
}

實現了單例模式來確保 OkHttpUtils 和 OkHttpClient 實例的唯一性

案例2：配置https的自簽證書和信任所有證書

HTTPS / SSL 證書

HTTPS協議是由SSL+HTTP協議構建的可進行加密傳輸、身份認證的網絡協議，要比http協議安全。

一般支持https的網站，都是CA(Certificate Authority)機構頒發的證書，但是一般該機構頒發的證書需要提供費用且有使用時間的限制，到期需要續費。
否則，默認該鏈接是不信任的，通過okHttp無法直接訪問。

但是我們可以使用自簽的方式，通過JDK自帶的keytool.exe 生成一個自己的證書，然后使用該證書內容。
雖然也是會出現提示“不安全”，但是我們可以通過okhttp訪問鏈接。

使用自簽證書

將證書文件放置在assets目錄（也可以放置在其他目錄下，只要能正確讀取到該文件），在創建OkhttpClient對象時sslSocketFactory()將該證書信息添加。

private SSLContext getSLLContext() {
        SSLContext sslContext = null;
        try {
            CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");
            InputStream certificate = mContext.getAssets().open("gdroot-g2.crt");
            KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
            keyStore.load(null);
            String certificateAlias = Integer.toString(0);
            keyStore.setCertificateEntry(certificateAlias, certificateFactory.generateCertificate(certificate));
            sslContext = SSLContext.getInstance("TLS");
            final TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
            trustManagerFactory.init(keyStore);
            sslContext.init(null, trustManagerFactory.getTrustManagers(), new SecureRandom());
        } catch (CertificateException e) {
            e.printStackTrace();
        } catch (KeyStoreException e) {
            e.printStackTrace();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (KeyManagementException e) {
            e.printStackTrace();
        }
        return sslContext;
    }

信任所有證書

通過添加證書的形式，可以實現客戶端訪問Https服務端的功能，但是如果服務端更換證書內容，那么客戶端需要相應的更換https證書，否則無法正常交互獲取不到數據，我們可以通過自定義X509TrustManager的形式實現來規避所有的證書檢測，實現信任所有證書的目的。

 private OkHttpClient getHttpsClient() {
        OkHttpClient.Builder okhttpClient = new OkHttpClient().newBuilder();
        //信任所有服務器地址
        okhttpClient.hostnameVerifier(new HostnameVerifier() {
            @Override
            public boolean verify(String s, SSLSession sslSession) {
                //設置為true
                return true;
            }
        });
        //創建管理器
        TrustManager[] trustAllCerts = new TrustManager[] { new X509TrustManager() {
            @Override
            public void checkClientTrusted(
                    java.security.cert.X509Certificate[] x509Certificates,
                    String s) throws java.security.cert.CertificateException {
            }

            @Override
            public void checkServerTrusted(
                    java.security.cert.X509Certificate[] x509Certificates,
                    String s) throws java.security.cert.CertificateException {
            }

            @Override
            public java.security.cert.X509Certificate[] getAcceptedIssuers() {
                return new java.security.cert.X509Certificate[] {};
            }
        } };
        try {
            SSLContext sslContext = SSLContext.getInstance("TLS");
            sslContext.init(null, trustAllCerts, new java.security.SecureRandom());

            //為OkHttpClient設置sslSocketFactory
            okhttpClient.sslSocketFactory(sslContext.getSocketFactory());

        } catch (Exception e) {
            e.printStackTrace();
        }

        return okhttpClient.build();
    }

創建X509TrustManager對象，并實現其中的方法。由于X509TrustManager是通用證書格式，只需要拿到該格式就行。最后init該安全協議，將其放入okhttp的sslSocketFactory中。

由于Retrofit只是對Okhttp網絡接口的封裝。因此實際使用中，該方法同樣適用于Retrofit中。

原理與架構

okhttp 請求過程

FAQ for okhttp

面試可能會問到的問題:

簡單說一下okhttp
okhttp的核心類有哪些？
okhttp對于網絡請求做了哪些優化，如何實現的？
okhttp架構中用到了哪些設計模式？
okhttp攔截器的執行順序

Q: OkHttp3 超時設置(callTimeout/connectTimeout/readTimeout)?

okhttp:3.14.9

場景導入: Socket closed , SocketTimeoutException

假設應用程序使用okhttp3框架時，報如下錯誤，考慮下如何解決？

[TID: xxx.100.xxxx01] [ds-service] [system] [2025/03/13 09:56:44.512] [DEBUG] [http-nio-9527-exec-6] [AbstractQuery] logDatabaseQuerySQL:113 ElasticSearchQuery | database final query sql: select xxx from xxx #other-info# [pageSql]
[TID: xxx.100.xxxx01] [ds-service] [system] [2025/03/13 09:56:45.515] [ERROR] [http-nio-9527-exec-6] [ElasticSearchConnector] post:387 Fail to execute for send post request cause that the exception!url:http://127.0.0.1:9200/_opendistro/_sql?format=json, requestJson:`select xxx from xxx`,exception:
java.net.SocketTimeoutException: timeout
	at okio.Okio$4.newTimeoutException(Okio.java:232) ~[okio-1.17.2.jar!/:?]
	at okio.AsyncTimeout.exit(AsyncTimeout.java:286) ~[okio-1.17.2.jar!/:?]
	at okio.AsyncTimeout$2.read(AsyncTimeout.java:241) ~[okio-1.17.2.jar!/:?]
	at okio.RealBufferedSource.indexOf(RealBufferedSource.java:358) ~[okio-1.17.2.jar!/:?]
	at okio.RealBufferedSource.readUtf8LineStrict(RealBufferedSource.java:230) ~[okio-1.17.2.jar!/:?]
	at okhttp3.internal.http1.Http1ExchangeCodec.readHeaderLine(Http1ExchangeCodec.java:242) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.internal.http1.Http1ExchangeCodec.readResponseHeaders(Http1ExchangeCodec.java:213) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.internal.connection.Exchange.readResponseHeaders(Exchange.java:115) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.internal.http.CallServerInterceptor.intercept(CallServerInterceptor.java:94) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.internal.connection.ConnectInterceptor.intercept(ConnectInterceptor.java:43) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:117) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.internal.cache.CacheInterceptor.intercept(CacheInterceptor.java:94) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:117) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.internal.http.BridgeInterceptor.intercept(BridgeInterceptor.java:93) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.internal.http.RetryAndFollowUpInterceptor.intercept(RetryAndFollowUpInterceptor.java:88) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:142) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:117) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.RealCall.getResponseWithInterceptorChain$original$BnZzvgYR(RealCall.java:229) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.RealCall.getResponseWithInterceptorChain$original$BnZzvgYR$accessor$VWw5Xe8t(RealCall.java) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.RealCall$auxiliary$aiLFzmy0.call(Unknown Source) ~[okhttp-3.14.9.jar!/:?]
	at org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstMethodsInter.intercept(InstMethodsInter.java:86) ~[skywalking-agent.jar:8.9.0]
	at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.RealCall.execute$original$BnZzvgYR(RealCall.java:81) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.RealCall.execute$original$BnZzvgYR$accessor$VWw5Xe8t(RealCall.java) ~[okhttp-3.14.9.jar!/:?]
	at okhttp3.RealCall$auxiliary$JZ7wpldV.call(Unknown Source) ~[okhttp-3.14.9.jar!/:?]
	at org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstMethodsInter.intercept(InstMethodsInter.java:86) ~[skywalking-agent.jar:8.9.0]
	at okhttp3.RealCall.execute(RealCall.java) ~[okhttp-3.14.9.jar!/:?]
	at com.xxx.common.connector.elasticsearch.ElasticSearchConnector.post(ElasticSearchConnector.java:385) [ds-service-common-1.1.24-SNAPSHOT.jar!/:?]
	at com.xxx.common.connector.elasticsearch.ElasticSearchConnector.post(ElasticSearchConnector.java:328) [ds-service-common-1.1.24-SNAPSHOT.jar!/:?]
	at com.xxx.common.query.ElasticSearchQuery.post(ElasticSearchQuery.java:116) [ds-service-common-1.1.24-SNAPSHOT.jar!/:?]
	at com.xxx.common.query.ElasticSearchQuery.autoPagingQuery(ElasticSearchQuery.java:101) [ds-service-common-1.1.24-SNAPSHOT.jar!/:?]
	at com.xxx.common.query.QueryFactory.query(QueryFactory.java:88) [ds-service-common-1.1.24-SNAPSHOT.jar!/:?]
	at com.xxx.biz.ds.service.impl.CommonSearchBizServiceImpl.queryDatasourceData(CommonSearchBizServiceImpl.java:398) [classes!/:?]
	at com.xxx.biz.ds.service.impl.CommonSearchBizServiceImpl.executeQuery(CommonSearchBizServiceImpl.java:160) [classes!/:?]
	at com.xxx.biz.ds.service.impl.CommonSearchBizServiceImpl.executeQuery(CommonSearchBizServiceImpl.java:337) [classes!/:?]
	at com.xxx.biz.ds.controller.v2.DataSearchController.datasetQuery$original$Ezz0kp0w(DataSearchController.java:158) [classes!/:?]
	at com.xxx.biz.ds.controller.v2.DataSearchController.datasetQuery$original$Ezz0kp0w$accessor$8fPZVSws(DataSearchController.java) [classes!/:?]
	at com.xxx.biz.ds.controller.v2.DataSearchController$auxiliary$XARzqMqE.call(Unknown Source) [classes!/:?]
	at org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstMethodsInter.intercept(InstMethodsInter.java:86) [skywalking-agent.jar:8.9.0]
	at com.xxx.biz.ds.controller.v2.DataSearchController.datasetQuery(DataSearchController.java) [classes!/:?]
	at com.xxx.biz.ds.controller.v2.DataSearchController$$FastClassBySpringCGLIB$$6bfcdaf9.invoke(<generated>) [classes!/:?]
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) [spring-core-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:779) [spring-aop-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) [spring-aop-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:750) [spring-aop-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.validation.beanvalidation.MethodValidationInterceptor.invoke(MethodValidationInterceptor.java:119) [spring-context-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) [spring-aop-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:750) [spring-aop-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:692) [spring-aop-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at com.xxx.biz.ds.controller.v2.DataSearchController$$EnhancerBySpringCGLIB$$957c5021.datasetQuery(<generated>) [classes!/:?]
	at sun.reflect.GeneratedMethodAccessor257.invoke(Unknown Source) ~[?:?]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_422]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_422]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) [spring-web-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) [spring-web-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) [spring-webmvc-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878) [spring-webmvc-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792) [spring-webmvc-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) [spring-webmvc-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) [spring-webmvc-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) [spring-webmvc-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) [spring-webmvc-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909) [spring-webmvc-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:665) [javax.servlet-api-4.0.1.jar!/:4.0.1]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) [spring-webmvc-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:750) [javax.servlet-api-4.0.1.jar!/:4.0.1]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) [tomcat-embed-websocket-9.0.46.jar!/:?]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.skywalking.apm.agent.core.context.TraceMdcWebFilter.doFilter(TraceMdcWebFilter.java:58) [classes!/:8.9.0]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.46.jar!/:?]
	at com.xxx.biz.common.filter.AccessPathWebFilter.doFilter(AccessPathWebFilter.java:92) [classes!/:?]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) [spring-web-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) [spring-web-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:97) [spring-boot-actuator-2.3.12.RELEASE.jar!/:2.3.12.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) [spring-web-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.2.15.RELEASE.jar!/:5.2.15.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.core.StandardHostValve.invoke$original$q8sTk9iR(StandardHostValve.java:143) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.core.StandardHostValve.invoke$original$q8sTk9iR$accessor$N646g7Eq(StandardHostValve.java) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.core.StandardHostValve$auxiliary$MLBge40B.call(Unknown Source) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstMethodsInter.intercept(InstMethodsInter.java:86) [skywalking-agent.jar:8.9.0]
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.valves.RemoteIpValve.invoke(RemoteIpValve.java:764) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1707) [tomcat-embed-core-9.0.46.jar!/:?]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.46.jar!/:?]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_422]
		at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_422]
		at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.46.jar!/:?]
		at java.lang.Thread.run(Thread.java:750) [?:1.8.0_422]
	Caused by: java.net.SocketException: Socket closed
		at java.net.SocketInputStream.read(SocketInputStream.java:204) ~[?:1.8.0_422]
		at java.net.SocketInputStream.read(SocketInputStream.java:141) ~[?:1.8.0_422]
		at okio.Okio$2.read(Okio.java:140) ~[okio-1.17.2.jar!/:?]
		at okio.AsyncTimeout$2.read(AsyncTimeout.java:237) ~[okio-1.17.2.jar!/:?]
		... 115 more

OkHttpClient 配置解釋

OkHttpClient httpClient = new OkHttpClient.Builder()
	.callTimeout(CALL_TIMEOUT, TimeUnit.MILLISECONDS)
	.connectTimeout(CONNECT_TIMEOUT, TimeUnit.SECONDS) //連接超時
	.readTimeout(READ_TIMEOUT, TimeUnit.SECONDS) //讀取超時
	.writeTimeout(WRITE_TIMEOUT, TimeUnit.SECONDS) //寫超時
    //.pingInterval(1000, TimeUnit.MILLISECONDS) //此配置項，會定時的向服務器發送一個消息來保持長連接; 只有 http2 和 webSocket 中有使用

	.protocols( protocols ) //  Protocol.HTTP_1_1 / ...
	.retryOnConnectionFailure(true)//連接失敗時是否重試
	.followRedirects(true)//重定向
	.connectionPool(new ConnectionPool(maxIdleConnections, keepAliveDuration, TimeUnit.MILLISECONDS))
	//.addNetworkInterceptor(new EncryptInterceptor())
	//.addInterceptor( new MyOkHttpRetryInterceptor(builder) )//本重置攔截器，尚不可靠
	//.addInterceptor(new CommonHeaderInterceptor())
	//.addInterceptor(new CacheInterceptor())
	//.addInterceptor(new HttpLoggerInterceptor())
	.build();

超時參數

connectTimeout

指的是建立連接所用的時間，適用于網絡狀況正常的情況下，兩端連接所用的時間。
通過跟源碼發現這個值用在了 socket.connect(address, connectTimeout);

即：最終設置給了socket (確切的說應該是rawSocket)

readTimeout 最終設置給了rawSocket 以及在socket基礎上創建的BufferedSource

writeTimeout 最終設置給了在socket基礎上創建的BufferedSink

okhttp => http / socket => tcp

okhttp底層基于socket, 故 Timeout 自然也是設置給Socket 的 connect / read / write
而socket是對于傳輸層的抽象。我們這里討論的是http, 所以對socket設置各種timeout 其實也就是對于TCP的timeout進行配置

TCP協議（握手/揮手/發包/丟包重傳/滑動窗口/擁塞控制等細節）以及socket屬于前置知識

源碼探究

okhttp 采用了責任鏈的設計模式

用一條抽象的 Chain 將一堆 Interceptor 串起來

從發出 request 到接收 response 的路徑類似于 node.js 中 koa2 的“洋蔥模型”（圖1），而 okhttp 的 Interceptor 作用就相當于koa2中的 middleware

圖1: koa洋蔥模型

“洋蔥”的每一層都是一個Interceptor，每一層都專注于自己的事情(單一職責)，比如日志、mock api、弱網模擬、統一header、APP層緩存、通訊加密等，功能拆分，互不影響，從框架層面來講也是對AOP思想的具體實踐。（AOP可不僅僅是傳統意義上的字節碼插樁）

圖2: okhttp中的洋蔥模型

okhttp本身已提供了幾個Interceptor的默認實現

CacheInterceptor : 對于 http1.1 緩存機制的具體實現（cache-controll等）

ConnectInterceptor : 專門負責創建/復用TCP連接, 里面的 ConnectionPool 就是對 http1.1 中 keep-alive（TCP連接復用）和 pipline機制（用多條TCP連接實現并發請求）的具體實現，而超時相關的設置也是從這里切入。

okhttp3.internal.connection.Transmitter

`okhttp3.RealCall#newRealCall` + `okhttp3.internal.connection.Transmitter` : 配置 callTimeout

okhttp3.RealCall

package okhttp3;

final class RealCall implements Call {  
  ...

  private RealCall(OkHttpClient client, Request originalRequest, boolean forWebSocket) {
    this.client = client;
    this.originalRequest = originalRequest;
    this.forWebSocket = forWebSocket;
  }

  static RealCall newRealCall(OkHttpClient client, Request originalRequest, boolean forWebSocket) {
    // Safely publish the Call instance to the EventListener.
    RealCall call = new RealCall(client, originalRequest, forWebSocket);
    call.transmitter = new Transmitter(client, call);
    return call;
  }

  ...

}

okhttp3.internal.connection.Transmitter

package okhttp3.internal.connection;

public final class Transmitter {
  private final OkHttpClient client;
  private final RealConnectionPool connectionPool;
  private final Call call;
  private final EventListener eventListener;
  private final AsyncTimeout timeout = new AsyncTimeout() {
    @Override protected void timedOut() {
      cancel();//超時將 cancel 請求
    }
  };

  // ...

  public Transmitter(OkHttpClient client, Call call) {
    this.client = client;
    this.connectionPool = Internal.instance.realConnectionPool(client.connectionPool());
    this.call = call;
    this.eventListener = client.eventListenerFactory().create(call);
    this.timeout.timeout(client.callTimeoutMillis(), MILLISECONDS);//callTimeout
  }

  public void timeoutEnter() {
    timeout.enter();
  }

  private @Nullable IOException timeoutExit(@Nullable IOException cause) {
    if (timeoutEarlyExit) return cause;
    if (!timeout.exit()) return cause;

    InterruptedIOException e = new InterruptedIOException("timeout");//留意此行，InterruptedIOException
    if (cause != null) e.initCause(cause);

    return e;
  }


  public void cancel() {//取消請求 (如：請求超時時)
    Exchange exchangeToCancel;
    RealConnection connectionToCancel;
    synchronized (connectionPool) {
      canceled = true;
      exchangeToCancel = exchange;
      connectionToCancel = exchangeFinder != null && exchangeFinder.connectingConnection() != null
          ? exchangeFinder.connectingConnection()
          : connection;
    }
    if (exchangeToCancel != null) {
      exchangeToCancel.cancel();
    } else if (connectionToCancel != null) {
      connectionToCancel.cancel();
    }
  }

Realcall : 內置 ConnectInterceptor / CallServerInterceptor 等阻攔器

okhttp3.RealCall.AsyncCall#execute

okhttp3.RealCall : 每次調用

okhttp3.RealCall.AsyncCall#execute

    @Override protected void execute() {
      boolean signalledCallback = false;
      transmitter.timeoutEnter();
      try {
        Response response = getResponseWithInterceptorChain();//關鍵行 : 通過攔截器鏈式調用 的方式 獲取 response
        signalledCallback = true;
        responseCallback.onResponse(RealCall.this, response);
      } catch (IOException e) {
        if (signalledCallback) {
          // Do not signal the callback twice!
          Platform.get().log(INFO, "Callback failure for " + toLoggableString(), e);
        } else {
          responseCallback.onFailure(RealCall.this, e);
        }
      } catch (Throwable t) {
        cancel();
        if (!signalledCallback) {
          IOException canceledException = new IOException("canceled due to " + t);
          canceledException.addSuppressed(t);
          responseCallback.onFailure(RealCall.this, canceledException);
        }
        throw t;
      } finally {
        client.dispatcher().finished(this);
      }
    }

okhttp3.RealCall#getResponseWithInterceptorChain

  Response getResponseWithInterceptorChain() throws IOException {
    // Build a full stack of interceptors.
    List<Interceptor> interceptors = new ArrayList<>();
    interceptors.addAll(client.interceptors());
    interceptors.add(new RetryAndFollowUpInterceptor(client));
    interceptors.add(new BridgeInterceptor(client.cookieJar()));
    interceptors.add(new CacheInterceptor(client.internalCache()));
    interceptors.add(new ConnectInterceptor(client));//內置了對 ConnectInterceptor 的引用
    if (!forWebSocket) {
      interceptors.addAll(client.networkInterceptors());
    }
    interceptors.add(new CallServerInterceptor(forWebSocket));

    Interceptor.Chain chain = new RealInterceptorChain(interceptors, transmitter, null, 0,
        originalRequest, this, client.connectTimeoutMillis(),
        client.readTimeoutMillis(), client.writeTimeoutMillis());

    boolean calledNoMoreExchanges = false;
    try {
      Response response = chain.proceed(originalRequest);
      if (transmitter.isCanceled()) {
        closeQuietly(response);
        throw new IOException("Canceled");
      }
      return response;
    } catch (IOException e) {
      calledNoMoreExchanges = true;
      throw transmitter.noMoreExchanges(e);
    } finally {
      if (!calledNoMoreExchanges) {
        transmitter.noMoreExchanges(null);
      }
    }
  }

ConnectInterceptor

okhttp3.internal.connection.ConnectInterceptor

/** Opens a connection to the target server and proceeds to the next interceptor. */
public final class ConnectInterceptor implements Interceptor {
  public final OkHttpClient client;

  public ConnectInterceptor(OkHttpClient client) {
    this.client = client;
  }

  @Override public Response intercept(Chain chain) throws IOException {
    RealInterceptorChain realChain = (RealInterceptorChain) chain;
    Request request = realChain.request();
    StreamAllocation streamAllocation = realChain.streamAllocation();

    // We need the network to satisfy this request. Possibly for validating a conditional GET.
    boolean doExtensiveHealthChecks = !request.method().equals("GET");
    // 入口在 newStream 方法
    HttpCodec httpCodec = streamAllocation.newStream(client, chain, doExtensiveHealthChecks);

    RealConnection connection = streamAllocation.connection();
    return realChain.proceed(request, streamAllocation, httpCodec, connection);
  }
}

上面的 StreamAllocation#newStream 方法就做了2件事

public HttpCodec newStream(OkHttpClient client, Interceptor.Chain chain, boolean doExtensiveHealthChecks) {
    // 這里的chain就是RealInterceptorChain，它里面的各種timeout值都是通過我們創建HttpClient時原封不動賦給它的，下面只是它的一些get方法；
    int connectTimeout = chain.connectTimeoutMillis();
    int readTimeout = chain.readTimeoutMillis();
    int writeTimeout = chain.writeTimeoutMillis();
    int pingIntervalMillis = client.pingIntervalMillis();
    boolean connectionRetryEnabled = client.retryOnConnectionFailure();
    //簡化后的代碼
    ...
      // 3.1  findHealthyConnection 會調用 findConnection
      RealConnection resultConnection = findHealthyConnection(connectTimeout, readTimeout,
          writeTimeout, pingIntervalMillis, connectionRetryEnabled, doExtensiveHealthChecks);
      // 3.2
      HttpCodec resultCodec = resultConnection.newCodec(client, chain, this);
      return resultCodec;
  }

okio.AsyncTimeout

package okio;

public class AsyncTimeout extends Timeout {
    ...
}

callTimeout,readTimeout,writeTimeout和okio的AsyncTimeout有著密不可分的關系,其內部維護了一個靜態內部類Watchdog: 單獨開一個線程死循環判斷是否超時

okio.AsyncTimeout.Watchdog

  private static final class Watchdog extends Thread {
    Watchdog() {
      super("Okio Watchdog");
      setDaemon(true);
    }

    public void run() {
      while (true) {
        try {
          AsyncTimeout timedOut;
          synchronized (AsyncTimeout.class) {
            timedOut = awaitTimeout();

            // Didn't find a node to interrupt. Try again.
            if (timedOut == null) continue;

            // The queue is completely empty. Let this thread exit and let another watchdog thread
            // get created on the next call to scheduleTimeout().
            if (timedOut == head) {
              head = null;
              return;
            }
          }

          // Close the timed out node.
          timedOut.timedOut();
        } catch (InterruptedException ignored) {
        }
      }
    }
  }

參考文獻

okhttp Timeout 超時設置與用法解釋 - jianshu
圖文詳解OkHttp的超時時間 - CSDN 【推薦】

Y 推薦資源

X 參考文獻

OkHttp3基礎使用 - CSDN
面試官：簡單說下 okHttp原理分析~ - Zhihu 【推薦】

posted @ 2025-03-03 21:45 千千寰宇閱讀(213) 評論(0) 收藏舉報

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千千寰宇

大數據與Java軟件開發從業者，數智化轉型實踐者。

[計算機網絡/HTTP/網絡請求] Okhttp: 網絡請求框架

序

概述：Okhttp

安裝指南

Maven依賴

使用指南

get請求

同步請求

異步請求

取消請求

結果處理

post請求

同步POST

異步POST

post請求提交多種 MediaType 格式

text/x-markdown : String、文件

application/json : json

application/x-www-form-urlencoded : 提交表單

multipart/* : 提交復雜請求體

更多 MedisType

請求配置項

最佳實踐: MyOkHttpClientConfig

攔截器的使用

Cookie的使用

連接池 : OkHttp ConnectionPool

基礎概念

優勢

參數項

應用場景

常用方法

借助連接池可解決的常見問題

Q: 連接池中的連接超時 / 配置連接池

Q: 連接池的默認配置

Q: 過期連接的處理策略？

Q: 連接池中的連接數過多

Q: 連接池中的連接無法釋放

參考文獻

綜合應用

案例1：封裝OkHttp單例模式 : OkHttpUtils(自定義)

案例2：配置https的自簽證書和信任所有證書

HTTPS / SSL 證書

使用自簽證書

信任所有證書

原理與架構

okhttp 請求過程

FAQ for okhttp

Q: OkHttp3 超時設置(callTimeout/connectTimeout/readTimeout)?

場景導入: Socket closed , SocketTimeoutException

OkHttpClient 配置解釋

源碼探究

okhttp3.internal.connection.Transmitter

okhttp3.RealCall#newRealCall + okhttp3.internal.connection.Transmitter : 配置 callTimeout

Realcall : 內置 ConnectInterceptor / CallServerInterceptor 等阻攔器

okhttp3.RealCall.AsyncCall#execute

okhttp3.RealCall#getResponseWithInterceptorChain

ConnectInterceptor

okio.AsyncTimeout

參考文獻

Y 推薦資源

X 參考文獻

公告

`text/x-markdown` : String、文件

`application/json` : json

`application/x-www-form-urlencoded` : 提交表單

`multipart/*` : 提交復雜請求體

`okhttp3.RealCall#newRealCall` + `okhttp3.internal.connection.Transmitter` : 配置 callTimeout