一篇博客上手request和response

概念

request：獲取請(qǐng)求數(shù)據(jù)
response：設(shè)置響應(yīng)數(shù)據(jù)

Request

request繼承體系

ServletRequest——Java提供的請(qǐng)求對(duì)象根接口
HttpServletRequest——Java提供的對(duì)http協(xié)議封裝的請(qǐng)求對(duì)象接口
RequestFacade——tomcat實(shí)現(xiàn)定義類

request獲取數(shù)據(jù)

package com.itheijma.web;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedReader;
import java.io.IOException;

@WebServlet("/req1")
public class RequestDemo1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //String method() 獲取請(qǐng)求方式
        String method = req.getMethod();
        System.out.println(method);
        //String getContextPath() 獲取虛擬目錄（項(xiàng)目訪問(wèn)路徑）
        String contextPath = req.getContextPath();
        System.out.println(contextPath);
        //StringBuffer getRequestURL() 獲取URL（統(tǒng)一資源定位符）
        StringBuffer url = req.getRequestURL();
        System.out.println(url.toString());
        //String getRequestURI() 獲取URI（統(tǒng)一資源標(biāo)識(shí)符）
        String uri = req.getRequestURI();
        System.out.println(uri);
        //String getQueryString() 獲取請(qǐng)求參數(shù)（get方式）
        String queryString = req.getQueryString();
        System.out.println(queryString);

        //------------
        //獲取請(qǐng)求頭
        String agent = req.getHeader("user-agent");
        System.out.println(agent);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //獲取post請(qǐng)求體：請(qǐng)求參數(shù)

        // 1. 獲取字符輸入流
        BufferedReader br = req.getReader();
        // 2. 讀取數(shù)據(jù)
        String line = br.readLine();
        System.out.println(line);

    }
}

request通用的方式獲取數(shù)據(jù)

package com.itheijma.web;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Map;

@WebServlet("/req2")
public class RequestDemo2 extends HttpServlet{
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //get請(qǐng)求邏輯
//        System.out.println("get...");

        // 1.獲取所有參數(shù)的map集合
        Map<String, String[]> map = req.getParameterMap();
        for (String key : map.keySet()) {
            //username:zhangsan
            System.out.print(key+":");

            //獲取值
            String[] values = map.get(key);
            for (String value : values) {
                System.out.print(value + " ");
            }

            System.out.println();
        }

        System.out.println("----------");

        // 2.根據(jù)key獲取參數(shù)值，數(shù)組
        String[] hobbies = req.getParameterValues("hobby");
        for (String hobby : hobbies) {

            System.out.println(hobby);
        }

        // 3. 根據(jù)key獲取單個(gè)參數(shù)值
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        System.out.println(username);
        System.out.println(password);


    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //post請(qǐng)求邏輯
        this.doGet(req,resp);


//        System.out.println("post...");
//        // 1.獲取所有參數(shù)的map集合
//        Map<String, String[]> map = req.getParameterMap();
//        for (String key : map.keySet()) {
//            //username:zhangsan
//            System.out.print(key+":");
//
//            //獲取值
//            String[] values = map.get(key);
//            for (String value : values) {
//                System.out.print(value + " ");
//            }
//
//            System.out.println();
//        }
//
//        System.out.println("----------");
//
//        // 2.根據(jù)key獲取參數(shù)值，數(shù)組
//        String[] hobbies = req.getParameterValues("hobby");
//        for (String hobby : hobbies) {
//
//            System.out.println(hobby);
//        }
//
//        // 3. 根據(jù)key獲取單個(gè)參數(shù)值
//        String username = req.getParameter("username");
//        String password = req.getParameter("password");
//        System.out.println(username);
//        System.out.println(password);


    }
}

request請(qǐng)求參數(shù)中文亂碼解決方法

package com.itheijma.web;



import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.nio.charset.StandardCharsets;


/**
 * 中文亂碼問(wèn)題解決方案
 */
@WebServlet("/req3")
public class RequestDemo3 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 1. 解決亂碼 POST 獲取參數(shù)方式:getReader()讀取數(shù)據(jù)流
        request.setCharacterEncoding("utf-8"); //設(shè)置字符輸入流的編碼


        // 2. 獲取username
        String username = request.getParameter("username");
        System.out.println("解決亂碼前："+username);


        // 3. 解決亂碼 GET 獲取參數(shù)方式:getQueryString
        // 亂碼原因：tomcat進(jìn)行url解碼，默認(rèn)的字符集ISO-8859-1
//        // 3.1 先對(duì)亂碼數(shù)據(jù)進(jìn)行編碼：轉(zhuǎn)為字節(jié)數(shù)組
//        byte[] bytes = username.getBytes(StandardCharsets.ISO_8859_1);
//        // 3.2 字節(jié)數(shù)組解碼
//        username = new String(bytes, StandardCharsets.UTF_8);

        username = new String(username.getBytes(StandardCharsets.ISO_8859_1),StandardCharsets.UTF_8);

        System.out.println("解決亂碼后"+username);


    }
}

request請(qǐng)求轉(zhuǎn)發(fā)

請(qǐng)求轉(zhuǎn)發(fā)（forward）：一種在服務(wù)器內(nèi)部的資源跳轉(zhuǎn)方式。
請(qǐng)求轉(zhuǎn)發(fā)特點(diǎn)：

瀏覽器地址欄路徑不發(fā)生變化
只能轉(zhuǎn)發(fā)到當(dāng)前服務(wù)器的內(nèi)部資源
一次請(qǐng)求，可以在轉(zhuǎn)發(fā)的資源間使用request共享數(shù)據(jù)
req4

package com.itheijma.web;



import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.nio.charset.StandardCharsets;


/**
 * 請(qǐng)求轉(zhuǎn)發(fā)
 */
@WebServlet("/req4")
public class RequestDemo4 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("demo4");

        //存儲(chǔ)數(shù)據(jù)
        request.setAttribute("msg","hello");

        //請(qǐng)求轉(zhuǎn)發(fā)
        request.getRequestDispatcher("/req5").forward(request,response);
    }
}

req5

package com.itheijma.web;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/req5")
public class RequestDemo5 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("demo5");

        //獲取數(shù)據(jù)
        Object msg = request.getAttribute("msg");
        System.out.println(msg);
    }
}

response

Response完成重定向

重定向：一種資源跳轉(zhuǎn)的方式
resp1

package com.itheima.web.response;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/resp1")
public class ResponseDemo1 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("resp1...");

//        // 重定向
//        // 1. 設(shè)置狀態(tài)碼 302
//        response.setStatus(302);
//        // 2. 設(shè)置響應(yīng)頭 Location
//        response.setHeader("Location","/tomcat-demo2/resp2");

        // 簡(jiǎn)化方式完成重定向
        response.sendRedirect("/tomcat-demo2/resp2");

    }
}

resp2

package com.itheima.web.response;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/resp2")
public class ResponseDemo2 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("resp2...");
    }
}

重定向特點(diǎn)：

瀏覽器地址欄路徑發(fā)生變化
可以重定向到任意位置的資源（服務(wù)器內(nèi)、外部均可）
兩次請(qǐng)求，不能在多個(gè)資源使用request共享數(shù)據(jù)

資源路徑問(wèn)題（什么時(shí)候加虛擬目錄）
瀏覽器使用：需要加虛擬目錄
服務(wù)端使用：不需要加虛擬目錄

動(dòng)態(tài)獲取虛擬目錄

        //動(dòng)態(tài)獲取虛擬目錄
        String contextPath = request.getContextPath();
        response.sendRedirect(contextPath + "/resp2");

Response響應(yīng)字符數(shù)據(jù)

package com.itheima.web.response;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;


/**
 * 響應(yīng)字符數(shù)據(jù)：設(shè)置字符數(shù)據(jù)的響應(yīng)體
 */
@WebServlet("/resp3")
public class ResponseDemo3 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=utf-8");
        //獲取字符輸出流
        PrintWriter writer = response.getWriter();
        //content-type
        //response.setHeader("content-type","text/html");
        writer.write("你好");
        writer.write("<h1>aaa</h1>");

        //細(xì)節(jié)：流不需要關(guān)閉
    }
}

Response響應(yīng)字節(jié)數(shù)據(jù)

package com.itheima.web.response;

import org.apache.commons.io.IOUtils;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.PrintWriter;


/**
 * 響應(yīng)字節(jié)數(shù)據(jù)：設(shè)置字節(jié)數(shù)據(jù)的響應(yīng)體
 */
@WebServlet("/resp4")
public class ResponseDemo4 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // 1. 讀取文件
        FileInputStream fis = new FileInputStream("e://a.jpg");

        // 2. 獲取response字節(jié)輸出流
        ServletOutputStream os = response.getOutputStream();

        // 3. 完成流的copy

//        byte[] buff = new byte[1024];
//        int len = 0;
//        while ((len = fis.read(buff)) != -1){
//            os.write(buff,0,len);
//        }
        IOUtils.copy(fis,os);//使用工具類

        fis.close();
    }
}

pom文件導(dǎo)入工具類

<dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.6</version>
        </dependency>

posted @ 2023-04-19 15:48 鶴城閱讀(311) 評(píng)論(0) 收藏舉報(bào)

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