Servlet----------通过 HttpServlet 开发Servlet

通过继承HttpServlet抽象类，功能更强大。

通过HttpServlet方法开发Servlet需要重写doGet和doPost方法。这是目前用的最多的一种方法。

如： class MyHttpServlet extends HttpServlet

 1 package cn.servlet;
 2 
 3 import java.io.IOException;
 4 import java.io.PrintWriter;
 5 
 6 import javax.servlet.ServletException;
 7 import javax.servlet.http.HttpServlet;
 8 import javax.servlet.http.HttpServletRequest;
 9 import javax.servlet.http.HttpServletResponse;
10 
11 public class MyHttpServlet extends HttpServlet {
12     //在HttpServlet中，设计者对post提交和get提交分别处理  
13     //<form action="提交给？" method="post|get">，默认是get提交  
14     //其实，doGet和doPost最终也去调用了Servlet接口中的service()方法
15     public void doGet(HttpServletRequest request, HttpServletResponse response)
16             throws ServletException, IOException {
17 
18         PrintWriter out = response.getWriter();
19         out.print("<h1>I am doGet()..................</h1>");
20     }
21 
22 
23     public void doPost(HttpServletRequest request, HttpServletResponse response)
24             throws ServletException, IOException {
25         PrintWriter out = response.getWriter();
26         out.print("<h1>I am doPost().................</h1>");
27     }
28 }

部署：

  <serlvet>
  　　<servlet-name>MyHttpServlet</servlet-name>
   　 <servlet-class>cn.servlet.MyHttpServlet</servlet-class>
  </servlet>
  <servlet-mapping>
      <servlet-name>MyHttpServlet</servlet-name>
      <url-pattern>/servlet/MyHttpServlet</url-pattern>
  </servlet-mapping>

由结果可知，默认调用的是doGet方法,,,,而Get方法在表单时会在地址栏中显示用户名和密码，而Post方法不会。