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

 package cn.servlet;

 import java.io.IOException;
 import java.io.PrintWriter;

 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 public class MyHttpServlet extends HttpServlet {
     //在HttpServlet中，设计者对post提交和get提交分别处理
     //<form action="提交给？" method="post|get">，默认是get提交
     //其实，doGet和doPost最终也去调用了Servlet接口中的service()方法
     public void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {

         PrintWriter out = response.getWriter();
         out.print("<h1>I am doGet()..................</h1>");
     }

     public void doPost(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         PrintWriter out = response.getWriter();
         out.print("<h1>I am doPost().................</h1>");
     }
 }

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。