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Servlet 2.5 配置 web.xml 添加 Servlet

• 创建 Servlet
  /demo/src/main/java/com/jerry/demo/servlet/MyServlet.java

public class MyServlet extends HttpServlet {
   	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   		response.setCharacterEncoding("utf-8");		response.getWriter().append("Servlet 2.5 通过配置 web.xml 注册 Servlet ");	}}

• 配置 web.xml
  /demo/src/main/webapp/WEB-INF/web.xml

       
    
     myServlet
        
    
     com.jerry.demo.servlet.MyServlet
      
     
       
    
     myServlet
        
    
     /test
      
   

Servlet 3.0 添加注解 @WebServlet 添加 Servlet

Servlet 3.0 新增了注解 用来注册Servlet

@WebServlet("/test")public class MyServlet extends HttpServlet {
   	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   		response.setCharacterEncoding("utf-8");		response.getWriter().append("Servlet 3.0 使用注解 @WebServlet 注册 Servlet ");	}}

Servlet 3.1 编程式 添加 Servlet

• Servlet 3.1 支持 编程式添加和配置Servlet。web.xml不再是必须的了。

SpringBoot 零配置的源头就在于此，SpringBoot中SpringMVC的dispatcherServlet就是从这里注册的 。

• 创建 Servlet
  /demo/src/main/java/com/jerry/demo/MyServlet.java

public class MyServlet extends HttpServlet {
   	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   		response.setCharacterEncoding("utf-8");		response.getWriter().append("Servlet 3.1 编程式添加  servlet 成功!");	}}

添加个启动监听器，用来添加 servlet(这里使用监听器只是图方便，扩展知识请看 )

package com.jerry.demo.listener;@WebListenerpublic class AppContextListener implements ServletContextListener {
   	/**	 * context 初始化	 */    @Override    public void contextInitialized(ServletContextEvent event) {
           ServletContext servletContext = event.getServletContext();        /* 	        这句等同于			
   			    
    
     myServlet
    			    
    
     com.jerry.demo.servlet.MyServlet
    			
   		*/        ServletRegistration.Dynamic registration = servletContext.addServlet("myServlet", MyServlet.class );         /* 	        这句等同于			
   				
    
     myServlet
    				
    
     /test
    			
   		*/        registration.addMapping("/test");    }    	/**	 * context 销毁	 */    @Override    public void contextDestroyed(ServletContextEvent sce) {
       	System.out.println("AppContext 死翘了~~~!");    }}

URL- Patterns

     
    
     watermelon
      
    
     /fruit/summer/*
    
    
     
    
     garden
      
    
     /seeds/*
    
    
     
    
     list
      
    
     /seedlist
    
    
     
    
     kiwi
      
    
     *.abc
    
   

参考资料

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