Web+spring容器的生命周期与 各种 Listener

Web+spring容器的生命周期与 各种 Listener

web容器中的 Listener 配置

Listener 种类与配置

监听器Listener就是在application,session,request三个对象创建、销毁或者往其中添加修改删除属性时自动执行代码的功能组件。

Listener是Servlet的监听器，可以监听客户端的请求，服务端的操作等。

ServletContextListener

主要是基于对 ServletContext  初始化与销毁的监听

配置

在 web.xml 中

    <listener>
        <listener-class>com.java.listener.web.AppServletContextListenerlistener-class>
    listener>

AppServletContextListener 类

package com.java.listener.web;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
public class AppServletContextListener implements ServletContextListener {

    @Override
    public void contextDestroyed(ServletContextEvent event) {
        // TODO serletContext销毁     
    }

    @Override
    public void contextInitialized(ServletContextEvent event) {
        // TODO serletContext创建     
  }
}

ServletRequestListener

主要是基于对 ServletRequest  初始化与销毁的监听 即 一个request 生命周期 当你访问服务器时生成一个request 访问成功后 request即被销毁

配置

在 web.xml 中

     <listener>
        <listener-class>com.java.listener.web.AppServletRequestListenerlistener-class>
    listener>

AppServletRequestListener 类

package com.java.listener.web;

import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;

public class AppServletRequestListener implements ServletRequestListener {

    @Override
    public void requestDestroyed(ServletRequestEvent request) {
        // TODO request销毁事件
 }
    @Override
    public void requestInitialized(ServletRequestEvent request) {
        // TODO request初始化事件
  }
}

HttpSessionListener

主要是基于对 HttpSession  初始化与销毁的监听 即 一个 HttpSession 生命周期

配置

在 web.xml 中

    <listener>
        <listener-class>com.java.listener.web.AppHttpSessionListenerlistener-class>
    listener>

AppHttpSessionListener 类

package com.java.listener.web;

import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

public class AppHttpSessionListener implements HttpSessionListener {

    @Override
    public void sessionCreated(HttpSessionEvent session) {
        // TODO session创建   
    }
    @Override
    public void sessionDestroyed(HttpSessionEvent session) {
        // TODO session销毁   
    }
}

spring 容器的生命周期

web 容器与 spring 容器类似，都是存放java 对象实例的容器 都是有一个 上下文 管理各种对象实例（bean）

监听容器以及容器中的 bean 的一系列操作 的接口有

ApplicationContextAware

BeanFactoryAware

BeanNameAware

InitializingBean

DiposableBean

BeanFactoryPostProcessor

BeanPostProcessor

InstantiationAwareBeanPostProcessorAdapter

当我们创建类并实现这些接口，就会调用这些接口的方法，经过测试这些接口bean的调用顺序并没有绝对关系（有部分有关系），谁配在前面谁先加载并执行实现方法

ApplicationContextAware 类

public class SpringApplicationContextAware implements ApplicationContextAware {

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        // TODO ApplicationContextAware接口方法执行   setApplicationContext
        //通常这个方法用来获取    applicationContext 类以便后续能通过 applicationContext 获取bean对象 等操作 
    }

}

BeanFactoryAware 类

public class AppBeanFactoryAware implements BeanFactoryAware {

    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        // TODO Auto-generated method stub
        //可以获取  beanFactory 对象 进行操作     
    }

}

BeanNameAware 类

public class AppBeanNameAware implements BeanNameAware{

    @Override
    public void setBeanName(String name) {
        // TODO Auto-generated method stub
    }
}

InitializingBean 类

public class AppInitializingBean implements InitializingBean {

    @Override
    public void afterPropertiesSet() throws Exception {
        // TODO Auto-generated method stub
    }

}

DiposableBean 类

public class AppDiposableBean implements DisposableBean {

    @Override
    public void destroy() throws Exception {
        // TODO Auto-generated method stub
    }

}

BeanFactoryPostProcessor 类

public class AppBeanFactoryPostProcessor implements BeanFactoryPostProcessor {

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        // TODO Auto-generated method stub
        //同样可以获取beanFactory

    }

}

BeanPostProcessor 类

public class AppBeanPostProcessor implements BeanPostProcessor {

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        // TODO 用于bean被初始化前 
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        // TODO 用于bean被初始化后     
        return bean;
    }

}

InstantiationAwareBeanPostProcessorAdapter 类

public class AppInstantiationAwareBeanPostProcessorAdapter extends InstantiationAwareBeanPostProcessorAdapter {

    @Override
    public Class predictBeanType(Class beanClass, String beanName) {
        // TODO Auto-generated method stub
        return super.predictBeanType(beanClass, beanName);
    }

    @Override
    public Constructor[] determineCandidateConstructors(Class beanClass, String beanName) throws BeansException {
        // TODO Auto-generated method stub
        return super.determineCandidateConstructors(beanClass, beanName);
    }

    @Override
    public Object getEarlyBeanReference(Object bean, String beanName) throws BeansException {
        // TODO Auto-generated method stub
        return super.getEarlyBeanReference(bean, beanName);
    }

    @Override
    public Object postProcessBeforeInstantiation(Class beanClass, String beanName) throws BeansException {
        // TODO bean对象实例化前调用        

        return super.postProcessBeforeInstantiation(beanClass, beanName);
    }

    @Override
    public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
        // TODO bean对象实例化后调用

        return super.postProcessAfterInstantiation(bean, beanName);
    }

    @Override
    public PropertyValues postProcessPropertyValues(PropertyValues pvs, PropertyDescriptor[] pds, Object bean,
            String beanName) throws BeansException {
        // TODO 设置bean的属性时调用        
        return super.postProcessPropertyValues(pvs, pds, bean, beanName);
    }

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        // TODO bean对象初始化时调用        
        return super.postProcessBeforeInitialization(bean, beanName);
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        // TODO bean对象初始化后调用

        return super.postProcessAfterInitialization(bean, beanName);
    }

}

由于都是对于 bean 的操作 ,BeanPostProcessor 类 与 InstantiationAwareBeanPostProcessorAdapter 的调用上有交集;

调用流程：

AppInstantiationAwareBeanPostProcessorAdapter 的 postProcessBeforeInstantiation

AppInstantiationAwareBeanPostProcessorAdapter 的 postProcessAfterInstantiation 方法

AppInstantiationAwareBeanPostProcessorAdapter 的 postProcessPropertyValues 方法

AppInstantiationAwareBeanPostProcessorAdapter 的 postProcessBeforeInitialization 方法

AppBeanPostProcessor 的 postProcessBeforeInitialization 方法

AppInstantiationAwareBeanPostProcessorAdapter 的 postProcessAfterInitialization 方法

AppBeanPostProcessor 的 postProcessAfterInitialization 方法

spring 的 ContextLoaderListener 类

用于对 ServletContext 对象的监听 ，ServletContext对象 对于web容器是单例的，所有用户对应同一个，通过 getServletContext().setAttribute 方法可以设置全局应用的属性

public class AppContextLoaderListener extends ContextLoaderListener {

    @Override
    public void closeWebApplicationContext(ServletContext servletContext) {
        // TODO Auto-generated method stub
        super.closeWebApplicationContext(servletContext);
    }



    @Override
    public WebApplicationContext initWebApplicationContext(ServletContext servletContext) {
        // TODO 初始化 ServletContext 上下文 这个方法在contextInitialized 方法之前调用       
        return super.initWebApplicationContext(servletContext);
    }



    @Override
    public void contextInitialized(ServletContextEvent event) {
        // TODO 上下文初始化成功        
        super.contextInitialized(event);        
    }





    @Override
    public void contextDestroyed(ServletContextEvent event) {
        // TODO Auto-generated method stub
        super.contextDestroyed(event);
    }



}

以上就是spring + web 容器的各种监听类的配置，可以用于应用初始化时，全局变量与配置，以及应用启动时需要做的一下逻辑处理 等

最后附上配置文件总代码

web.xml

<web-app>
  <display-name>Archetype Created Web Applicationdisplay-name>



    <listener>
        <listener-class>com.java.listener.web.AppServletContextListenerlistener-class>
    listener>
    <listener>
        <listener-class>com.java.listener.web.AppServletRequestListenerlistener-class>
    listener>
    <listener>
        <listener-class>com.java.listener.web.AppHttpSessionListenerlistener-class>
    listener>

    <listener>
    <listener-class>com.java.listener.spring.AppContextLoaderListenerlistener-class>
    listener>



      <servlet>
        <servlet-name>springMVCservlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>
        <init-param>
            <param-name>contextConfigLocationparam-name>
            <param-value>/WEB-INF/applicationContext.xmlparam-value>
        init-param>
        <load-on-startup>1load-on-startup>
    servlet>
    <servlet-mapping>
        <servlet-name>springMVCservlet-name>
        <url-pattern>/url-pattern>
    servlet-mapping>

    <servlet>
        <servlet-name>InitServletservlet-name>
        <display-name>InitServletdisplay-name>
        <description>description>
        <servlet-class>com.java.servlet.InitServletservlet-class>
        <load-on-startup>1load-on-startup>
    servlet>


web-app>

spring bean配置

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">

 <bean id="springApplicationContextAware" class="com.java.listener.spring.SpringApplicationContextAware">bean>

 <bean id="appBeanFactoryAware" class="com.java.listener.spring.AppBeanFactoryAware">bean>
 <bean id="appBeanNameAware" class="com.java.listener.spring.AppBeanNameAware">bean>
 <bean id="appInitializingBean" class="com.java.listener.spring.AppInitializingBean">bean>
 <bean id="appDiposableBean" class="com.java.listener.spring.AppDiposableBean">bean>
 <bean id="appBeanFactoryPostProcessor" class="com.java.listener.spring.AppBeanFactoryPostProcessor">bean>
 <bean id="appInstantiationAwareBeanPostProcessorAdapter" class="com.java.listener.spring.AppInstantiationAwareBeanPostProcessorAdapter">bean>
 <bean id="appBeanPostProcessor" class="com.java.listener.spring.AppBeanPostProcessor">bean>

beans>