jsp第二章

一，什么是servlet

servlet是一个java程序，是在服务器上运行已处理客户端请求并做出响应的程序

二，servlet生命周期

实例化——servlet容器创建servlet的实例
初始化——该容器调用init()方法
服务——如果请求servlet则该容器调用service()方法
销毁——销毁实例之前调用destroy()方法
代码如下：
package org.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**

• Servlet implementation class Second
  */
  //注解
  @WebServlet("/second")
  public class Second extends HttpServlet {
  private static final long serialVersionUID = 1L;

  /**

  • @see HttpServlet#HttpServlet()
    */
    public Second() {
    super();
    // TODO Auto-generated constructor stub
    }

  /**

  • @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
    */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    response.getWriter().append("Served at: ").append(request.getContextPath());
    System.out.println(“get请求方式”);
    }

  /**

  • @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
    */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    doGet(request, response);

  }
  @Override
  public void destroy() {
  // TODO Auto-generated method stub
  super.destroy();
  System.out.println(“销毁”);
  }
  @Override
  public void init() throws ServletException {
  // TODO Auto-generated method stub
  super.init();
  System.out.println(“初始化”);
  }
  }

三， Javax.servlet Javax.servlet .http