SpringBoot動態更新yml文件
前言
在系統運行過程中，可能由于一些配置項的簡單變動需要重新打包啟停項目，這對于在運行中的項目會造成數據丟失，客戶操作無響應等情況發生，針對這類情況對開發框架進行升級提供yml文件實時修改更新功能
項目依賴
項目基于的是2.0.0.RELEASE版本，所以snakeyaml需要單獨引入，高版本已包含在內
<dependency>
<groupId>org.yaml</groupId>
<artifactId>snakeyaml</artifactId>
<version>1.23</version>
</dependency>
網上大多數方法是引入spring-cloud-context配置組件調用ContextRefresher的refresh方法達到同樣的效果，考慮以下兩點未使用
- 開發框架使用了logback日志，引入spring-cloud-context會造成日志配置讀取錯誤
- 引入spring-cloud-context會同時引入spring-boot-starter-actuator組件，會開放一些健康檢查路由及端口，需要對框架安全方面進行額外控制
YML文件內容獲取
讀取resource文件下的文件需要使用ClassPathResource獲取InputStream
public String getTotalYamlFileContent() throws Exception {
String fileName = "application.yml";
return getYamlFileContent(fileName);
}
public String getYamlFileContent(String fileName) throws Exception {
ClassPathResource classPathResource = new ClassPathResource(fileName);
return onvertStreamToString(classPathResource.getInputStream());
}
public static String convertStreamToString(InputStream inputStream) throws Exception{
return IOUtils.toString(inputStream, "utf-8");
}
YML文件內容更新
我們獲取到yml文件內容后可視化顯示到前臺進行展示修改，將修改后的內容通過yaml.load方法轉換成Map結構，再使用yaml.dumpAsMap轉換為流寫入到文件
public void updateTotalYamlFileContent(String content) throws Exception {
String fileName = "application.yml";
updateYamlFileContent(fileName, content);
}
public void updateYamlFileContent(String fileName, String content) throws Exception {
Yaml template = new Yaml();
Map<String, Object> yamlMap = template.load(content);
ClassPathResource classPathResource = new ClassPathResource(fileName);
Yaml yaml = new Yaml();
//字符輸出
FileWriter fileWriter = new FileWriter(classPathResource.getFile());
//用yaml方法把map結構格式化為yaml文件結構
fileWriter.write(yaml.dumpAsMap(yamlMap));
//刷新
fileWriter.flush();
//關閉流
fileWriter.close();
}
YML屬性刷新
yml屬性在程序中讀取使用一般有三種
- 使用Value注解
@Value("${system.systemName}")
private String systemName;
- 通過enviroment注入讀取
@Autowired
private Environment environment;
environment.getProperty("system.systemName")
- 使用ConfigurationProperties注解讀取
@Component
@ConfigurationProperties(prefix = "system")
public class SystemConfig {
private String systemName;
}
Property刷新
我們通過environment.getProperty方法讀取的配置集合實際是存儲在PropertySources中的，我們只需要把鍵值對全部取出存儲在propertyMap中，將更新后的yml文件內容轉換成相同格式的ymlMap，兩個Map進行合并，調用PropertySources的replace方法進行整體替換即可
但是yaml.load后的ymlMap和PropertySources取出的propertyMap兩者數據解構是不同的，需要進行手動轉換
propertyMap集合就是單純的key，value鍵值對，key是properties形式的名稱，例如system.systemName=>xxxxx集團管理系統
ymlMap集合是key，LinkedHashMap的嵌套層次結構，例如system=>(systemName=>xxxxx集團管理系統)
- 轉換方法如下
public HashMap<String, Object> convertYmlMapToPropertyMap(Map<String, Object> yamlMap) {
HashMap<String, Object> propertyMap = new HashMap<String, Object>();
for (String key : yamlMap.keySet()) {
String keyName = key;
Object value = yamlMap.get(key);
if (value != null && value.getClass() == LinkedHashMap.class) {
convertYmlMapToPropertyMapSub(keyName, ((LinkedHashMap<String, Object>) value), propertyMap);
} else {
propertyMap.put(keyName, value);
}
}
return propertyMap;
}
private void convertYmlMapToPropertyMapSub(String keyName, LinkedHashMap<String, Object> submMap, Map<String, Object> propertyMap) {
for (String key : submMap.keySet()) {
String newKey = keyName + "." + key;
Object value = submMap.get(key);
if (value != null && value.getClass() == LinkedHashMap.class) {
convertYmlMapToPropertyMapSub(newKey, ((LinkedHashMap<String, Object>) value), propertyMap);
} else {
propertyMap.put(newKey, value);
}
}
}
- 刷新方法如下
String name = "applicationConfig: [classpath:/" + fileName + "]";
MapPropertySource propertySource = (MapPropertySource) environment.getPropertySources().get(name);
Map<String, Object> source = propertySource.getSource();
Map<String, Object> map = new HashMap<>(source.size());
map.putAll(source);
Map<String, Object> propertyMap = convertYmlMapToPropertyMap(yamlMap);
for (String key : propertyMap.keySet()) {
Object value = propertyMap.get(key);
map.put(key, value);
}
environment.getPropertySources().replace(name, new MapPropertySource(name, map));
注解刷新
不論是Value注解還是ConfigurationProperties注解，實際都是通過注入Bean對象的屬性方法使用的，我們先自定注解RefreshValue來修飾屬性所在Bean的class
通過實現InstantiationAwareBeanPostProcessorAdapter接口在系統啟動時過濾篩選對應的Bean存儲下來，在更新yml文件時通過spring的event通知更新對應
bean的屬性即可
- 注冊事件使用EventListener注解
@EventListener
public void updateConfig(ConfigUpdateEvent configUpdateEvent) {
if(mapper.containsKey(configUpdateEvent.key)){
List<FieldPair> fieldPairList = mapper.get(configUpdateEvent.key);
if(fieldPairList.size()>0){
for (FieldPair fieldPair:fieldPairList) {
fieldPair.updateValue(environment);
}
}
}
}
- 通知觸發事件使用ApplicationContext的publishEvent方法
@Autowired
private ApplicationContext applicationContext;
for (String key : propertyMap.keySet()) {
applicationContext.publishEvent(new YamlConfigRefreshPostProcessor.ConfigUpdateEvent(this, key));
}
YamlConfigRefreshPostProcessor的完整代碼如下
@Component
public class YamlConfigRefreshPostProcessor extends InstantiationAwareBeanPostProcessorAdapter implements EnvironmentAware {
private Map<String, List<FieldPair>> mapper = new HashMap<>();
private Environment environment;
@Override
public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
processMetaValue(bean);
return super.postProcessAfterInstantiation(bean, beanName);
}
@Override
public void setEnvironment(Environment environment) {
this.environment = environment;
}
private void processMetaValue(Object bean) {
Class clz = bean.getClass();
if (!clz.isAnnotationPresent(RefreshValue.class)) {
return;
}
if (clz.isAnnotationPresent(ConfigurationProperties.class)) {
//@ConfigurationProperties注解
ConfigurationProperties config = (ConfigurationProperties) clz.getAnnotation(ConfigurationProperties.class);
for (Field field : clz.getDeclaredFields()) {
String key = config.prefix() + "." + field.getName();
if(mapper.containsKey(key)){
mapper.get(key).add(new FieldPair(bean, field, key));
}else{
List<FieldPair> fieldPairList = new ArrayList<>();
fieldPairList.add(new FieldPair(bean, field, key));
mapper.put(key, fieldPairList);
}
}
} else {
//@Valuez注解
try {
for (Field field : clz.getDeclaredFields()) {
if (field.isAnnotationPresent(Value.class)) {
Value val = field.getAnnotation(Value.class);
String key = val.value().replace("${", "").replace("}", "");
if(mapper.containsKey(key)){
mapper.get(key).add(new FieldPair(bean, field, key));
}else{
List<FieldPair> fieldPairList = new ArrayList<>();
fieldPairList.add(new FieldPair(bean, field, key));
mapper.put(key, fieldPairList);
}
}
}
} catch (Exception e) {
e.printStackTrace();
System.exit(-1);
}
}
}
public static class FieldPair {
private static PropertyPlaceholderHelper propertyPlaceholderHelper = new PropertyPlaceholderHelper("${", "}",
":", true);
private Object bean;
private Field field;
private String value;
public FieldPair(Object bean, Field field, String value) {
this.bean = bean;
this.field = field;
this.value = value;
}
public void updateValue(Environment environment) {
boolean access = field.isAccessible();
if (!access) {
field.setAccessible(true);
}
try {
if (field.getType() == String.class) {
String updateVal = environment.getProperty(value);
field.set(bean, updateVal);
}
else if (field.getType() == Integer.class) {
Integer updateVal = environment.getProperty(value,Integer.class);
field.set(bean, updateVal);
}
else if (field.getType() == int.class) {
int updateVal = environment.getProperty(value,int.class);
field.set(bean, updateVal);
}
else if (field.getType() == Boolean.class) {
Boolean updateVal = environment.getProperty(value,Boolean.class);
field.set(bean, updateVal);
}
else if (field.getType() == boolean.class) {
boolean updateVal = environment.getProperty(value,boolean.class);
field.set(bean, updateVal);
}
else {
String updateVal = environment.getProperty(value);
field.set(bean, JSONObject.parseObject(updateVal, field.getType()));
}
} catch (IllegalAccessException e) {
e.printStackTrace();
}
field.setAccessible(access);
}
public Object getBean() {
return bean;
}
public void setBean(Object bean) {
this.bean = bean;
}
public Field getField() {
return field;
}
public void setField(Field field) {
this.field = field;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
}
public static class ConfigUpdateEvent extends ApplicationEvent {
String key;
public ConfigUpdateEvent(Object source, String key) {
super(source);
this.key = key;
}
}
@EventListener
public void updateConfig(ConfigUpdateEvent configUpdateEvent) {
if(mapper.containsKey(configUpdateEvent.key)){
List<FieldPair> fieldPairList = mapper.get(configUpdateEvent.key);
if(fieldPairList.size()>0){
for (FieldPair fieldPair:fieldPairList) {
fieldPair.updateValue(environment);
}
}
}
}
}
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