Listener、Filter、Servlet 初始化顺序

Listener、Filter、Servlet都有一个初始化的过程，对应的方法分别为：

contextInitialized(ServletContextEvent arg0)

init(FilterConfig filterConfig)

init(ServletConfig config)

那么它们的初始化顺序是什么呢？

Listener > Filter > Servlet

TestServlet.java

    Java代码         
 package com.cos;     
 import java.io.IOException;     
 import javax.servlet.GenericServlet;     
 import javax.servlet.ServletConfig;     
 import javax.servlet.ServletException;     
 import javax.servlet.ServletRequest;     
 import javax.servlet.ServletResponse;     
      
 public class TestServlet extends GenericServlet {     
     @Override     
     public void init(ServletConfig config){     
         System.out.println("Servlet 初始化 。。。");     
     }     
     @Override     
     public void service(ServletRequest arg0, ServletResponse arg1) throws ServletException, IOException {     
         System.out.println("Servlet service 。。。");     
     }     
 }    

TestFilter.java

    Java代码         
 package com.cos;     
 import java.io.IOException;     
 import javax.servlet.Filter;     
 import javax.servlet.FilterChain;     
 import javax.servlet.FilterConfig;     
 import javax.servlet.ServletException;     
 import javax.servlet.ServletRequest;     
 import javax.servlet.ServletResponse;     
      
 public class TestFilter implements Filter{     
     public void init(FilterConfig filterConfig) throws ServletException {     
         System.out.println("Filter 初始化。。。");     
     }     
     public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {     
         System.out.println("doFilter 。。。");     
         chain.doFilter(request, response);     
     }     
     public void destroy() {     
         System.out.println("Filter 销毁。。。");     
     }     
 }    

TestListener.java

    Java代码         
 package com.cos;     
 import javax.servlet.ServletContextEvent;     
 import javax.servlet.ServletContextListener;     
      
 public class TestListener implements ServletContextListener{     
     public void contextInitialized(ServletContextEvent arg0) {     
         System.out.println("Listener 初始化。。。");     
     }     
     public void contextDestroyed(ServletContextEvent arg0) {     
         System.out.println("Listener 销毁。。。");     
     }     
 }    

web.xml

    Xml代码         
 <?xml version="1.0" encoding="UTF-8"?>     
 <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">     
     <servlet>     
         <servlet-name>s</servlet-name>     
         <servlet-class>com.cos.TestServlet</servlet-class>     
     </servlet>     
     <servlet-mapping>     
         <servlet-name>s</servlet-name>     
         <url-pattern>/login</url-pattern>     
     </servlet-mapping>     
     <filter>     
         <filter-name>f</filter-name>     
         <filter-class>com.cos.TestFilter</filter-class>     
     </filter>     
     <filter-mapping>     
         <filter-name>f</filter-name>     
         <url-pattern>/*</url-pattern>     
     </filter-mapping>     
     <listener>     
         <listener-class>com.cos.TestListener</listener-class>     
     </listener>     
 </web-app>    