Spring refresh()源码解析
作者:无名之辈J 发布时间:2022-09-04 18:45:52
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 *
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
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
protected void initPropertySources() {
}
Web容器GenericWebApplicationContext重写了此方法
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
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
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
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
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
name=zhansan
age=${name},10
encoding=utf-8
name2=${name}
测试代码
@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}")); //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
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
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
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 * 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
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
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
beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
beanFactory.registerResolvableDependency(ResourceLoader.class, this);
beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
beanFactory.registerResolvableDependency(ApplicationContext.class, this);
3.3 添加 * 执行器
ApplicationListenerDetector主要作用是添加和销毁 * ,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:https://www.jb51.net/article/277948.htm
四、BeanFactory的后置处理
这是个模压方法,由子类AnnotationConfigServletWebServerApplicationContext实现
protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
}
AnnotationConfigServletWebServerApplicationContext首先调了父类 ServletWebServerApplicationContext 的 postProcessBeanFactory 方法
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
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)
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
// 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:
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
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);
}
}
来源:https://juejin.cn/post/7202531472720789559
猜你喜欢
- 这篇文章主要介绍了java加载property文件配置过程解析,文中通过示例代码介绍的非常详细,对大家的学习或者工作具有一定的参考学习价值,
- 以下是介绍利用List的subList方法实现对List分页,废话不多说了,直接看代码把/** *//** * List分页 &
- 关于Plupload的介绍,相信它的官网http://www.plupload.com/已经给得很详细了。Plupload的上传原理简单点说
- 1.1 概述分布式系统:分布式系统指由很多台计算机组成的一个整体!这个整体一致对外,并且处理同一请求!系统对内透明,对外不透明!内部的每台计
- 本文实例为大家分享了C#实现截图工具小项目的具体代码,供大家参考,具体内容如下1.起因一直用的截图是qq的截图,所以想要实现一个简单点的截图
- springboot 针对jackson是自动化配置的,如果需要修改,有两种方式:方式一:通过application.yml配置属性说明:#
- 前言windows自带的游戏《扫雷》是陪伴了无数人的经典游戏,本程序参考《扫雷》的规则进行了简化,用java语言实现,采用了swing技术进
- 图片的复制无非有两种方法,一种是图片直接上传到服务器,另外一种转换成二进制流的base64码目前限chrome浏览器使用首先以um-edit
- 在使用Java web开发的后端工程师们大多会使用Maven作为项目构建以及编译的工具,微服务和大中台当道的今天,更加关注maven的细节是
- 题目要求思路一:DFS+序列化设计一种规则将所有子树序列化,保证不同子树的序列化字符串不同,相同子树的序列化串相同。用哈希表存所有的字符串,
- 一般而言,Spring的依赖注入有三种:构造器注入、setter注入以及接口注入。本文主要讲构造器注入与setter注入。1、构造器注入为了
- 为了实现不同环境构建的不同需求,这里使用到了 profile。因为 profile 能够在构建时修改 pom 的一个子集,或者添加额外的配置
- 1. dip: device independent pixels(设备独立像素). 不同设备有不同的显示效果,这个和设备硬件有关,一般我们
- 一、首先在Spring Boot项目中,手动添加异常方法进行测试@Transactional(rollbackFor=Exception.c
- 这篇文章主要介绍了Java实现TCP/IP协议的收发数据(服务端)代码实例,文中通过示例代码介绍的非常详细,对大家的学习或者工作具有一定的参
- 前言借用《Effactive Java》这本书中的话,float和double类型的主要设计目标是为了科学计算和工程计算。他们执行二进制浮点
- 本文实例讲述了Java擦除和转换。分享给大家供大家参考,具体如下:一 点睛在严格的泛型代码里,带泛型声明的类总应该带着类型参数。
- 实践过程效果代码public partial class Form1 : Form {
- 冒泡排序算法演示图:public static void bubbleSort(int[] array) { &
- 演示代码如下:package swt_jface.demo11; import org.eclipse.swt.SWT; import or