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public void refresh() throws BeansException, IllegalStateException { synchronized(this.startupShutdownMonitor) { // 1. 初始化前的预处理 this.prepareRefresh(); // 2. 刷新Bean工厂 ConfigurableListableBeanFactory beanFactory = this.obtainFreshBeanFactory(); // 3. BeanFactory的预处理配置 this.prepareBeanFactory(beanFactory); try { // 4. BeanFactory的后置处理 this.postProcessBeanFactory(beanFactory); // 5. 执行BeanFactory后置处理器 this.invokeBeanFactoryPostProcessors(beanFactory); // 6. 注册Bean的后置处理器 this.registerBeanPostProcessors(beanFactory); // 7. 初始化MessageSource this.initMessageSource(); // 8. 初始化事件派发器 this.initApplicationEventMulticaster(); // 9. 子类的多态onRefresh this.onRefresh(); // 10. 注册监听器 this.registerListeners(); // 11. 初始化所有剩下的单例Bean this.finishBeanFactoryInitialization(beanFactory); // 12. 完成容器的创建工作 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. 清除缓存 this.resetCommonCaches(); } }} |
一、prepareRefresh：初始化前的预处理
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protected void prepareRefresh() { //设置容器启动时间 this.startupDate = System.currentTimeMillis(); //设置容器关闭状态为false this.closed.set(false); //设置容器激活状态为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初始化属性资源 this.initPropertySources(); //1.2校验 this.getEnvironment().validateRequiredProperties(); this.earlyApplicationEvents = new LinkedHashSet();} |
1.1初始化属性值
初始化方法是个模压方法，由子类重写
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protected void initPropertySources() {} |
Web容器GenericWebApplicationContext重写了此方法
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protected void initPropertySources() { //获取环境信息 ConfigurableEnvironment env = getEnvironment(); //判断是否是web配置环境 if (env instanceof ConfigurableWebEnvironment) { ((ConfigurableWebEnvironment) env).initPropertySources(this.servletContext, null); }} |
最终由StandardServletEnvironment进行初始化
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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 的一些初始化参数放入IOC容器中
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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属性校验
通过占位符解析器校验资源集合
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public void validateRequiredProperties() throws MissingRequiredPropertiesException { this.propertyResolver.validateRequiredProperties();} |
这里的解析器作为常量在环境被实例化时就被创建出来的，PropertySourcesPropertyResolver是占位符解析器，将数据源中占位符替换成目标值
校验是否有需要被占位符修饰的属性，如果有但是资源中找不到对应属性的key就会抛出异常
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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： 资源文件
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name=zhansanage=${name},10encoding=utf-8name2=${name} |
测试代码
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@Testpublic 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}")); //输出must be encoding gbk} |
输出结果
10,zhansan
utf-8
must be encoding utf-8
二、obtainFreshBeanFactory：刷新Bean工厂
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protected ConfigurableListableBeanFactory obtainFreshBeanFactory() { //2.1刷新Bean工厂 refreshBeanFactory(); return getBeanFactory();} |
将容器刷新标识改为true，并且设置了工厂序列化id
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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工厂预处理
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protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) { // 设置BeanFactory的类加载器、表达式解析器等 beanFactory.setBeanClassLoader(getClassLoader()); beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader())); beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment())); // 3.1 添加Aware执行器 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 自动注入的支持 beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory); beanFactory.registerResolvableDependency(ResourceLoader.class, this); beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this); beanFactory.registerResolvableDependency(ApplicationContext.class, this); // 3.3 添加监听器执行器 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执行器
ApplicationContextDProcessor实现了BeanPostProcessor的postProcessBeforeInitialization接口，在所有Bean初始化前会执行当前方法
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public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { //判断Bean是Aware的子类 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 { //回调执行Aware接口 invokeAwareInterfaces(bean); } return bean;} |
如果当前Bean是Aware的子类，那么将Bean强转成Aware类型，通过回调将信息设置到Bean中
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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：自动注入的支持
如果过容器中有多个相同接口的实现类，那么在自动注入的时候会注入注册的实现类
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beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);beanFactory.registerResolvableDependency(ResourceLoader.class, this);beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);beanFactory.registerResolvableDependency(ApplicationContext.class, this); |
3.3 添加监听器执行器
ApplicationListenerDetector主要作用是添加和销毁监听器,实现了BeanPostProcessor的postProcessAfterInitialization（Bean实例化之后）方法和DestructionAwareBeanPostProcessor的postProcessBeforeDestruction（Bean销毁之前）方法
详情：http://www.tuohang.net/article/265608.html
四、BeanFactory的后置处理
这是个模压方法,由子类AnnotationConfigServletWebServerApplicationContext实现
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protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {} |
AnnotationConfigServletWebServerApplicationContext首先调了父类 ServletWebServerApplicationContext 的 postProcessBeanFactory 方法
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protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) { //4.1后置处理Bean工厂 super.postProcessBeanFactory(beanFactory); if (this.basePackages != null && this.basePackages.length > 0) { //basePackages为空不会执行 this.scanner.scan(this.basePackages); } if (!this.annotatedClasses.isEmpty()) { this.reader.register(ClassUtils.toClassArray(this.annotatedClasses)); }} |
4.1 后置处理bean工厂
父类ServletWebServerApplicationContext首先向Bean工厂中注入了一个执行器
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protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) { //4.1.1注入执行器 beanFactory.addBeanPostProcessor(new WebApplicationContextServletContextAwareProcessor(this)); beanFactory.ignoreDependencyInterface(ServletContextAware.class); //4.1.2注册作用域 registerWebApplicationScopes();} |
4.1.1 WebApplicationContextServletContextAwareProcessor
WebApplicationContextServletContextAwareProcessor继承了ServletContextAwareProcessor
ServletContextAwareProcessor继承了BeanPostProcessor实现了postProcessBeforeInitialization（Bean初始化前执行）
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public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { //注入ServletContext if (getServletContext() != null && bean instanceof ServletContextAware) { ((ServletContextAware) bean).setServletContext(getServletContext()); } //注入ServletConfig if (getServletConfig() != null && bean instanceof ServletConfigAware) { ((ServletConfigAware) bean).setServletConfig(getServletConfig()); } return bean;} |
4.1.2 registerWebApplicationScopes 注册web的应用域
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// 所在类及方法：ServletWebServerApplicationContext#registerWebApplicationScopes private void registerWebApplicationScopes() { ExistingWebApplicationScopes existingScopes = new ExistingWebApplicationScopes(getBeanFactory()); WebApplicationContextUtils.registerWebApplicationScopes(getBeanFactory()); existingScopes.restore(); } |
ExistingWebApplicationScopes是ServletWebServerApplicationContext类中的一个静态类
源码如下：
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public static class ExistingWebApplicationScopes { static { Set<String> scopes = new LinkedHashSet<>(); scopes.add(WebApplicationContext.SCOPE_REQUEST); scopes.add(WebApplicationContext.SCOPE_SESSION); SCOPES = Collections.unmodifiableSet(scopes); } // 这是构造方法，大概就是根据SCOPES获取beanFactory中已经注册的scope，然后放入scopes // 需要注意的是，在上面的方法中，第二行才在向beanFactory中注册，也就是这时的beanFactory里面没有request和session这两个scop // 所以这里就完成了beanFactory的赋值。建议打断点进去看看 public ExistingWebApplicationScopes(ConfigurableListableBeanFactory beanFactory) { this.beanFactory = beanFactory; for (String scopeName : SCOPES) { Scope scope = beanFactory.getRegisteredScope(scopeName); if (scope != null) { this.scopes.put(scopeName, scope); } } } // 由于上面的方法并没有值存入scopes，所以这里也就没执行里面的内容 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()，这个方法就是向beanFactory注册web的scope了，源码如下
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public static void registerWebApplicationScopes(ConfigurableListableBeanFactory beanFactory) { registerWebApplicationScopes(beanFactory, null);} public static void registerWebApplicationScopes(ConfigurableListableBeanFactory beanFactory, @Nullable ServletContext sc) { // 注册作用域 beanFactory.registerScope(WebApplicationContext.SCOPE_REQUEST, new RequestScope());// 注册request SCOP beanFactory.registerScope(WebApplicationContext.SCOPE_SESSION, new SessionScope());// 注册session SCOP if (sc != null) { ServletContextScope appScope = new ServletContextScope(sc); beanFactory.registerScope(WebApplicationContext.SCOPE_APPLICATION, appScope); // 注册application SCOP // Register as ServletContext attribute, for ContextCleanupListener to detect it. sc.setAttribute(ServletContextScope.class.getName(), appScope); } // 添加依赖项 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()源码解析的详细内容，更多关于Spring refresh()的资料请关注服务器之家其它相关文章！
原文链接：https://juejin.cn/post/7202531472720789559
