Spring中常用重要的介面

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Spring (ApplicationContext 初始化Bean的方法 refresh())

public void refresh() throws BeansException, IllegalStateException {synchronized (this.startupShutdownMonitor) {// Prepare this context for refreshing.prepareRefresh();// Tell the subclass to refresh the internal bean factory.ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();// Prepare the bean factory for use in this context.prepareBeanFactory(beanFactory);try {// Allows post-processing of the bean factory in context subclasses.postProcessBeanFactory(beanFactory);// Invoke factory processors registered as beans in the context.invokeBeanFactoryPostProcessors(beanFactory);// Register bean processors that intercept bean creation.//建立Bean並post等方法registerBeanPostProcessors(beanFactory);// Initialize message source for this context.initMessageSource();// Initialize event multicaster for this context.initApplicationEventMulticaster();// Initialize other special beans in specific context subclasses.onRefresh();// Check for listener beans and register them.registerListeners();// Instantiate all remaining (non-lazy-init) singletons.finishBeanFactoryInitialization(beanFactory);// Last step: publish corresponding event.finishRefresh();}catch (BeansException ex) {// Destroy already created singletons to avoid dangling resources.destroyBeans();// Reset ‘active‘ flag.cancelRefresh(ex);// Propagate exception to caller.throw ex;}}}

　　

 

Spring 架構中想自己在bean的初始化階段自訂一些邏輯，或者想擷取一些資源，非常有用的介面有

BeanPostProcessor,// properties 設定完成，InitializingBean的 afterPropertiesSet()， init-method完成後對bean進行一些邏輯處理

InitializingBean,// 提供afterPropertiesSet()，位於init-method之前調用（這兩方法都可用於實現bean init方法）；

DestructionAwareBeanPostProcessor,//postProcessBeforeDestruction(Object bean, String beanName) 方法於 destory方法之前調用；

BeanFactoryAware // setBeanFactory(BeanFactory beanFactory) 介面使Bean初始化完成後擷取BeanFactory資源，以便操作。類似的還有ApplicationContextAware....

public interface BeanPostProcessor {    /**property values已經設定完成，     * Apply this BeanPostProcessor to the given new bean instance <i>before</i> any bean     * initialization callbacks (like InitializingBean‘s <code>afterPropertiesSet</code>     * or a custom init-method). The bean will already be populated with property values.     * The returned bean instance may be a wrapper around the original.     * @param bean the new bean instance     * @param beanName the name of the bean     * @return the bean instance to use, either the original or a wrapped one; if     * <code>null</code>, no subsequent BeanPostProcessors will be invoked     * @throws org.springframework.beans.BeansException in case of errors     * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet     */    Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException;    /**     * Apply this BeanPostProcessor to the given new bean instance <i>after</i> any bean     * initialization callbacks (like InitializingBean‘s <code>afterPropertiesSet</code>     * or a custom init-method). The bean will already be populated with property values.     * The returned bean instance may be a wrapper around the original.     * <p>In case of a FactoryBean, this callback will be invoked for both the FactoryBean     * instance and the objects created by the FactoryBean (as of Spring 2.0). The     * post-processor can decide whether to apply to either the FactoryBean or created     * objects or both through corresponding <code>bean instanceof FactoryBean</code> checks.     * <p>This callback will also be invoked after a short-circuiting triggered by a     * {@link InstantiationAwareBeanPostProcessor#postProcessBeforeInstantiation} method,     * in contrast to all other BeanPostProcessor callbacks.     * @param bean the new bean instance     * @param beanName the name of the bean     * @return the bean instance to use, either the original or a wrapped one; if     * <code>null</code>, no subsequent BeanPostProcessors will be invoked     * @throws org.springframework.beans.BeansException in case of errors     * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet     * @see org.springframework.beans.factory.FactoryBean     */    Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException;}

/**已經完成了property 填充（完成InitializingBean 介面的afterPropertiesSet（）調用，如果指定init-method 方法，也已經完成的調用（after..()之後））
　　　
     * Initialize the given bean instance, applying factory callbacks     * as well as init methods and bean post processors.     * <p>Called from {@link #createBean} for traditionally defined beans,     * and from {@link #initializeBean} for existing bean instances.     * @param beanName the bean name in the factory (for debugging purposes)     * @param bean the new bean instance we may need to initialize     * @param mbd the bean definition that the bean was created with     * (can also be <code>null</code>, if given an existing bean instance)     * @return the initialized bean instance (potentially wrapped)     * @see BeanNameAware     * @see BeanClassLoaderAware     * @see BeanFactoryAware     * @see #applyBeanPostProcessorsBeforeInitialization     * @see #invokeInitMethods     * @see #applyBeanPostProcessorsAfterInitialization     */    protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {        if (System.getSecurityManager() != null) {            AccessController.doPrivileged(new PrivilegedAction<Object>() {                public Object run() {                    invokeAwareMethods(beanName, bean);                    return null;                }            }, getAccessControlContext());        }        else {            invokeAwareMethods(beanName, bean);        }                Object wrappedBean = bean;        if (mbd == null || !mbd.isSynthetic()) {            wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);//調用BeanPostProcessor的before方法        }        try {            invokeInitMethods(beanName, wrappedBean, mbd);        }        catch (Throwable ex) {            throw new BeanCreationException(                    (mbd != null ? mbd.getResourceDescription() : null),                    beanName, "Invocation of init method failed", ex);        }        if (mbd == null || !mbd.isSynthetic()) {            wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);//調用

BeanPostProcessor的after方法

} return wrappedBean; }

BeanFactory bf =   new XmlBeanFactory(new ClassPathResource("spring.xml"));

bf 只是儲存一些BeanDeinationMap， 並不會馬上執行個體化，需要後續調用getBean才初始化：

ApplicationContext ac2 = new ClassPathXmlApplicationContext("spring.xml");

ac2 會馬上將spring.xml中定義的bean執行個體化加到factory的緩衝中。

例子用ApplicationContext ：

spring.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"     xmlns:context="http://www.springframework.org/schema/context"    xmlns:aop="http://www.springframework.org/schema/aop"    xmlns:tx="http://www.springframework.org/schema/tx"    xmlns:mvc="http://www.springframework.org/schema/mvc"        xsi:schemaLocation="http://www.springframework.org/schema/beans      http://www.springframework.org/schema/beans/spring-beans-3.2.xsd      http://www.springframework.org/schema/context      http://www.springframework.org/schema/context/spring-context-3.2.xsd      http://www.springframework.org/schema/aop      http://www.springframework.org/schema/aop/spring-aop-3.2.xsd      http://www.springframework.org/schema/tx      http://www.springframework.org/schema/tx/spring-tx-3.2.xsd      http://www.springframework.org/schema/mvc      http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd      ">      <alias name="user" alias="testxx"/>      <bean id="father" abstract="true">      <property name="local" value="Us"/>      </bean>      <bean id="user" class="com.donghua.bean.User" parent="father">      <property name="name" value="Allen"/>      <property name="age" value="6"/>      </bean>       <bean id="user3" class="com.donghua.bean.User3" init-method="myInit" destroy-method="destroy">      <property name="name" value="Allen3"/>      <property name="age" value="61"/>      </bean>      <bean id="factory" class="com.donghua.bean.MyBeanFactory"/></beans>

　User3:

package com.donghua.bean;import org.springframework.beans.BeansException;import org.springframework.beans.factory.BeanFactory;import org.springframework.beans.factory.BeanFactoryAware;import org.springframework.beans.factory.InitializingBean;import org.springframework.beans.factory.config.BeanPostProcessor;import org.springframework.beans.factory.config.DestructionAwareBeanPostProcessor;public class User3 implements BeanPostProcessor, InitializingBean, DestructionAwareBeanPostProcessor,BeanFactoryAware{BeanFactory beanFactory;private String name;private int age;public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public void myInit(){System.out.println("this is my init....."+this.getAge());}@Overridepublic String toString() {return "User [name=" + name + ", age=" + age + "]";}@Overridepublic Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {// TODO Auto-generated method stubSystem.out.println("This is the post before..............");return bean;}@Overridepublic Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {// TODO Auto-generated method stubSystem.out.println("This is the post after..............");return bean;}@Overridepublic void afterPropertiesSet() throws Exception {// TODO Auto-generated method stubSystem.out.println("this is InitializingBean method..."+ "(called by before init method, after set property values)."+this.getAge());}@Overridepublic void postProcessBeforeDestruction(Object bean, String beanName) throws BeansException {// TODO Auto-generated method stubSystem.out.println("this is DestructionAwareBeanPostProcessor, called when destroy bean...");}public void destroy(){System.out.println("this is destroy method....");}@Overridepublic void setBeanFactory(BeanFactory beanFactory) throws BeansException {// TODO Auto-generated method stubthis.beanFactory = beanFactory;}public void getUser2(){User u =(User) beanFactory.getBean("user");System.out.println(u.toString()+" this is user2...");}}

　

package com.donghua.test;import org.springframework.beans.factory.BeanFactory;import org.springframework.beans.factory.xml.XmlBeanFactory;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import org.springframework.core.io.ClassPathResource;import com.donghua.anotation.User2;import com.donghua.bean.MyBeanFactory;import com.donghua.bean.User;import com.donghua.bean.User3;public class Test {public static void main(String[] args) {ApplicationContext ac2 = new ClassPathXmlApplicationContext("spring.xml");User3 u3 = (User3) ac2.getBean("user3");System.out.println(u3);u3.getUser2();((ClassPathXmlApplicationContext) ac2).close();  }}

　輸出順序：

this is InitializingBean method...(called by before init method, after set property values).61      //InitializingBean
this is my init.....61　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　//init-method　　　
This is the post before..............　　　　　　　　　　　　　　　　　　　　　　　　　　　　//BeanPostProcesser
This is the post after..............
This is the post before..............
This is the post after..............
User [name=Allen3, age=61]
User [name=Allen, age=6] this is user2...                                                                                  
this is DestructionAwareBeanPostProcessor, called when destroy bean...                                   // DestructionAwareBeanPostProcessor                
this is DestructionAwareBeanPostProcessor, called when destroy bean...
this is destroy method....　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　//destory method　　　　　　　　　　　

 

　

 

Spring中常用重要的介面