一个简单的jsp和servlet应用（入门之选）

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1.jsp页面代码

<%@page import="java.util.Date"%><%@ page language="java" contentType="text/html; charset=utf-8"    pageEncoding="utf-8"%><jsp:useBean id="user" scope="request" class="jsp.demo.entity.User"></jsp:useBean><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>hello</title></head><body>  <%    if(user.getName() !=null){    if(user.getName()==""){    out.println("用户名不能为空！");    }else{  %>  你好：<%=user.getName() %>   <% }} %>  <form action="/testweb/Userlogin" method="post">    <input type="text" name="name" value="">    <input type="submit" name="submit" value="提交" >  </form></body></html>

2.User类

package jsp.demo.entity;/** * User Bean为了封装jsp表单中的数据 * @author Administrator * */public class User {private String name;//用户名public String getName() {return name;}public void setName(String name) {this.name = name;}}

3.servlet代码

package jsp.servlet.demo;import java.io.IOException;import javax.servlet.RequestDispatcher;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import jsp.demo.entity.User;/** * Servlet implementation class Userlogin */public class Userlogin extends HttpServlet {private static final long serialVersionUID = 1L;           /**     * @see HttpServlet#HttpServlet()     */    public Userlogin() {        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}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// 获取输入信息String name = request.getParameter("name");User user = new User();user.setName(name);    //将user添加到response对象中request.setAttribute("user", user);//将请求转向指定的页面RequestDispatcher rdt = request.getRequestDispatcher("/jsp/login.jsp");rdt.forward(request, response);}}

4.web.xml配置文件

   <servlet>    <description></description>    <display-name>Userlogin</display-name>    <servlet-name>Userlogin</servlet-name>    <servlet-class>jsp.servlet.demo.Userlogin</servlet-class>  </servlet>    <servlet-mapping>    <servlet-name>Userlogin</servlet-name>    <url-pattern>/Userlogin</url-pattern>  </servlet-mapping>

ps：1.注意页面action请求路径和web中的<url-pattern>/Userlogin</url-pattern>关系

2.请求的method和servlet中的处理方法对应（当然可以用service(HttpServletRequest arg0, HttpServletResponse arg1)方式，可以避免不对应情况）