Spring refresh()源碼解析
正文
public void refresh() throws BeansException, IllegalStateException { synchronized(this.startupShutdownMonitor) { // 1. 初始化前的預處理 this.prepareRefresh(); // 2. 刷新Bean工廠 ConfigurableListableBeanFactory beanFactory = this.obtainFreshBeanFactory(); // 3. BeanFactory的預處理配置 this.prepareBeanFactory(beanFactory); try { // 4. BeanFactory的後置處理 this.postProcessBeanFactory(beanFactory); // 5. 執行BeanFactory後置處理器 this.invokeBeanFactoryPostProcessors(beanFactory); // 6. 註冊Bean的後置處理器 this.registerBeanPostProcessors(beanFactory); // 7. 初始化MessageSource this.initMessageSource(); // 8. 初始化事件派發器 this.initApplicationEventMulticaster(); // 9. 子類的多態onRefresh this.onRefresh(); // 10. 註冊監聽器 this.registerListeners(); // 11. 初始化所有剩下的單例Bean this.finishBeanFactoryInitialization(beanFactory); // 12. 完成容器的創建工作 this.finishRefresh(); } catch (BeansException var9) { if (this.logger.isWarnEnabled()) { this.logger.warn("Exception encountered during context initialization - cancelling refresh attempt: " + var9); } this.destroyBeans(); this.cancelRefresh(var9); throw var9; } finally { // 13. 清除緩存 this.resetCommonCaches(); } } }
一、prepareRefresh:初始化前的預處理
protected void prepareRefresh() { //設置容器啟動時間 this.startupDate = System.currentTimeMillis(); //設置容器關閉狀態為false this.closed.set(false); //設置容器激活狀態為true this.active.set(true); if (this.logger.isDebugEnabled()) { if (this.logger.isTraceEnabled()) { this.logger.trace("Refreshing " + this); } else { this.logger.debug("Refreshing " + this.getDisplayName()); } } //1.1初始化屬性資源 this.initPropertySources(); //1.2校驗 this.getEnvironment().validateRequiredProperties(); this.earlyApplicationEvents = new LinkedHashSet(); }
1.1初始化屬性值
初始化方法是個模壓方法,由子類重寫
protected void initPropertySources() { }
Web容器GenericWebApplicationContext重寫瞭此方法
protected void initPropertySources() { //獲取環境信息 ConfigurableEnvironment env = getEnvironment(); //判斷是否是web配置環境 if (env instanceof ConfigurableWebEnvironment) { ((ConfigurableWebEnvironment) env).initPropertySources(this.servletContext, null); } }
最終由StandardServletEnvironment進行初始化
public void initPropertySources(@Nullable ServletContext servletContext, @Nullable ServletConfig servletConfig) { //使用web容器工具初始化 WebApplicationContextUtils.initServletPropertySources(getPropertySources(), servletContext, servletConfig); }
把 Servlet 的一些初始化參數放入IOC容器中
public static void initServletPropertySources(MutablePropertySources sources, @Nullable ServletContext servletContext, @Nullable ServletConfig servletConfig) { Assert.notNull(sources, "'propertySources' must not be null"); String name = "servletContextInitParams"; if (servletContext != null && sources.contains(name) && sources.get(name) instanceof StubPropertySource) { sources.replace(name, new ServletContextPropertySource(name, servletContext)); } name = "servletConfigInitParams"; if (servletConfig != null && sources.contains(name) && sources.get(name) instanceof StubPropertySource) { sources.replace(name, new ServletConfigPropertySource(name, servletConfig)); } }
1.2屬性校驗
通過占位符解析器校驗資源集合
public void validateRequiredProperties() throws MissingRequiredPropertiesException { this.propertyResolver.validateRequiredProperties(); }
這裡的解析器作為常量在環境被實例化時就被創建出來的,PropertySourcesPropertyResolver是占位符解析器,將數據源中占位符替換成目標值
校驗是否有需要被占位符修飾的屬性,如果有但是資源中找不到對應屬性的key就會拋出異常
public void validateRequiredProperties() { MissingRequiredPropertiesException ex = new MissingRequiredPropertiesException(); for (String key : this.requiredProperties) { if (this.getProperty(key) == null) { ex.addMissingRequiredProperty(key); } } if (!ex.getMissingRequiredProperties().isEmpty()) { throw ex; } }
案例: 資源文件
name=zhansan age=${name},10 encoding=utf-8 name2=${name}
測試代碼
@Test public void test1() throws Exception { //省略propertySources PropertyResolver propertyResolver = new PropertySourcesPropertyResolver(getPropertySources()); System.out.println(propertyResolver.getProperty("age")); System.out.println(propertyResolver.getProperty("encoding")); System.out.println(propertyResolver.resolvePlaceholders("must be encoding ${encoding}")); //輸出must be encoding gbk }
輸出結果
10,zhansan
utf-8
must be encoding utf-8
二、obtainFreshBeanFactory:刷新Bean工廠
protected ConfigurableListableBeanFactory obtainFreshBeanFactory() { //2.1刷新Bean工廠 refreshBeanFactory(); return getBeanFactory(); }
將容器刷新標識改為true,並且設置瞭工廠序列化id
protected final void refreshBeanFactory() throws IllegalStateException { if (!this.refreshed.compareAndSet(false, true)) { throw new IllegalStateException( "GenericApplicationContext does not support multiple refresh attempts: just call 'refresh' once"); } this.beanFactory.setSerializationId(getId()); }
三、prepareBeanFactory:Bean工廠預處理
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) { // 設置BeanFactory的類加載器、表達式解析器等 beanFactory.setBeanClassLoader(getClassLoader()); beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader())); beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment())); // 3.1 添加Aware執行器 beanFactory.addBeanPostProcessor(new ApplicationContextDProcessor(this)); beanFactory.ignoreDependencyInterface(EnvironmentAware.class); beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class); beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class); beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class); beanFactory.ignoreDependencyInterface(MessageSourceAware.class); beanFactory.ignoreDependencyInterface(ApplicationContextAware.class); // 3.2 自動註入的支持 beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory); beanFactory.registerResolvableDependency(ResourceLoader.class, this); beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this); beanFactory.registerResolvableDependency(ApplicationContext.class, this); // 3.3 添加監聽器執行器 beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this)); // Detect a LoadTimeWeaver and prepare for weaving, if found. if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) { beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory)); // Set a temporary ClassLoader for type matching. beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader())); } // Register default environment beans. if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) { beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment()); } if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) { beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties()); } if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) { beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment()); } }
3.1 ApplicationContextDProcessor:Aware執行器
ApplicationContextDProcessor實現瞭BeanPostProcessor的postProcessBeforeInitialization接口,在所有Bean初始化前會執行當前方法
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { //判斷Bean是Aware的子類 if (!(bean instanceof EnvironmentAware || bean instanceof EmbeddedValueResolverAware || bean instanceof ResourceLoaderAware || bean instanceof ApplicationEventPublisherAware || bean instanceof MessageSourceAware || bean instanceof ApplicationContextAware)){ return bean; } AccessControlContext acc = null; if (System.getSecurityManager() != null) { acc = this.applicationContext.getBeanFactory().getAccessControlContext(); } if (acc != null) { AccessController.doPrivileged((PrivilegedAction<Object>) () -> { invokeAwareInterfaces(bean); return null; }, acc); } else { //回調執行Aware接口 invokeAwareInterfaces(bean); } return bean; }
如果當前Bean是Aware的子類,那麼將Bean強轉成Aware類型,通過回調將信息設置到Bean中
private void invokeAwareInterfaces(Object bean) { if (bean instanceof EnvironmentAware) { ((EnvironmentAware) bean).setEnvironment(this.applicationContext.getEnvironment()); } if (bean instanceof EmbeddedValueResolverAware) { ((EmbeddedValueResolverAware) bean).setEmbeddedValueResolver(this.embeddedValueResolver); } if (bean instanceof ResourceLoaderAware) { ((ResourceLoaderAware) bean).setResourceLoader(this.applicationContext); } if (bean instanceof ApplicationEventPublisherAware) { ((ApplicationEventPublisherAware) bean).setApplicationEventPublisher(this.applicationContext); } if (bean instanceof MessageSourceAware) { ((MessageSourceAware) bean).setMessageSource(this.applicationContext); } if (bean instanceof ApplicationContextAware) { ((ApplicationContextAware) bean).setApplicationContext(this.applicationContext); } }
3.2 registerResolvableDependency:自動註入的支持
如果過容器中有多個相同接口的實現類,那麼在自動註入的時候會註入註冊的實現類
beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory); beanFactory.registerResolvableDependency(ResourceLoader.class, this); beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this); beanFactory.registerResolvableDependency(ApplicationContext.class, this);
3.3 添加監聽器執行器
ApplicationListenerDetector主要作用是添加和銷毀監聽器,實現瞭BeanPostProcessor的postProcessAfterInitialization(Bean實例化之後)方法和DestructionAwareBeanPostProcessor的postProcessBeforeDestruction(Bean銷毀之前)方法
詳情:https://www.jb51.net/article/277948.htm
四、BeanFactory的後置處理
這是個模壓方法,由子類AnnotationConfigServletWebServerApplicationContext實現
protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) { }
AnnotationConfigServletWebServerApplicationContext首先調瞭父類 ServletWebServerApplicationContext 的 postProcessBeanFactory 方法
protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) { //4.1後置處理Bean工廠 super.postProcessBeanFactory(beanFactory); if (this.basePackages != null && this.basePackages.length > 0) { //basePackages為空不會執行 this.scanner.scan(this.basePackages); } if (!this.annotatedClasses.isEmpty()) { this.reader.register(ClassUtils.toClassArray(this.annotatedClasses)); } }
4.1 後置處理bean工廠
父類ServletWebServerApplicationContext首先向Bean工廠中註入瞭一個執行器
protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) { //4.1.1註入執行器 beanFactory.addBeanPostProcessor(new WebApplicationContextServletContextAwareProcessor(this)); beanFactory.ignoreDependencyInterface(ServletContextAware.class); //4.1.2註冊作用域 registerWebApplicationScopes(); }
4.1.1 WebApplicationContextServletContextAwareProcessor
WebApplicationContextServletContextAwareProcessor繼承瞭ServletContextAwareProcessor
ServletContextAwareProcessor繼承瞭BeanPostProcessor實現瞭postProcessBeforeInitialization(Bean初始化前執行)
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { //註入ServletContext if (getServletContext() != null && bean instanceof ServletContextAware) { ((ServletContextAware) bean).setServletContext(getServletContext()); } //註入ServletConfig if (getServletConfig() != null && bean instanceof ServletConfigAware) { ((ServletConfigAware) bean).setServletConfig(getServletConfig()); } return bean; }
4.1.2 registerWebApplicationScopes 註冊web的應用域
// 所在類及方法:ServletWebServerApplicationContext#registerWebApplicationScopes private void registerWebApplicationScopes() { ExistingWebApplicationScopes existingScopes = new ExistingWebApplicationScopes(getBeanFactory()); WebApplicationContextUtils.registerWebApplicationScopes(getBeanFactory()); existingScopes.restore(); }
ExistingWebApplicationScopes是ServletWebServerApplicationContext類中的一個靜態類
源碼如下:
public static class ExistingWebApplicationScopes { static { Set<String> scopes = new LinkedHashSet<>(); scopes.add(WebApplicationContext.SCOPE_REQUEST); scopes.add(WebApplicationContext.SCOPE_SESSION); SCOPES = Collections.unmodifiableSet(scopes); } // 這是構造方法,大概就是根據SCOPES獲取beanFactory中已經註冊的scope,然後放入scopes // 需要註意的是,在上面的方法中,第二行才在向beanFactory中註冊,也就是這時的beanFactory裡面沒有request和session這兩個scop // 所以這裡就完成瞭beanFactory的賦值。建議打斷點進去看看 public ExistingWebApplicationScopes(ConfigurableListableBeanFactory beanFactory) { this.beanFactory = beanFactory; for (String scopeName : SCOPES) { Scope scope = beanFactory.getRegisteredScope(scopeName); if (scope != null) { this.scopes.put(scopeName, scope); } } } // 由於上面的方法並沒有值存入scopes,所以這裡也就沒執行裡面的內容 public void restore() { this.scopes.forEach((key, value) -> { if (logger.isInfoEnabled()) { logger.info("Restoring user defined scope " + key); } this.beanFactory.registerScope(key, value); }); } }
WebApplicationContextUtils.registerWebApplicationScopes(),這個方法就是向beanFactory註冊web的scope瞭,源碼如下
public static void registerWebApplicationScopes(ConfigurableListableBeanFactory beanFactory) { registerWebApplicationScopes(beanFactory, null); } public static void registerWebApplicationScopes(ConfigurableListableBeanFactory beanFactory, @Nullable ServletContext sc) { // 註冊作用域 beanFactory.registerScope(WebApplicationContext.SCOPE_REQUEST, new RequestScope());// 註冊request SCOP beanFactory.registerScope(WebApplicationContext.SCOPE_SESSION, new SessionScope());// 註冊session SCOP if (sc != null) { ServletContextScope appScope = new ServletContextScope(sc); beanFactory.registerScope(WebApplicationContext.SCOPE_APPLICATION, appScope); // 註冊application SCOP // Register as ServletContext attribute, for ContextCleanupListener to detect it. sc.setAttribute(ServletContextScope.class.getName(), appScope); } // 添加依賴項 beanFactory.registerResolvableDependency(ServletRequest.class, new RequestObjectFactory()); beanFactory.registerResolvableDependency(ServletResponse.class, new ResponseObjectFactory()); beanFactory.registerResolvableDependency(HttpSession.class, new SessionObjectFactory()); beanFactory.registerResolvableDependency(WebRequest.class, new WebRequestObjectFactory()); if (jsfPresent) { FacesDependencyRegistrar.registerFacesDependencies(beanFactory); } }
以上就是Spring refresh()源碼解析的詳細內容,更多關於Spring refresh()的資料請關註WalkonNet其它相關文章!
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