登陆示例（利用jsp,servlet）不连接数据库

来源：互联网发布：同福3队吊打棒子知乎编辑：程序博客网时间：2024/05/21 22:46

首先是项目的目录结构

先对web.xml文件做处理

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0">  <display-name>servlet_study</display-name>  <servlet>    <servlet-name>LoginServlet</servlet-name>    <servlet-class>com.scup.servlet.LoginServlet</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>LoginServlet</servlet-name>    <url-pattern>/LoginServlet</url-pattern>  </servlet-mapping>  <welcome-file-list>    <welcome-file>index.html</welcome-file>  </welcome-file-list></web-app>

Login.jsp（登录页）

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!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>登录页面</title></head><body>

//getContextPath()是对提交至处理文件的路径处理，提交方式为post<form action="<%=request.getContextPath() %>/LoginServlet" method="post">   username:<input  type="text" name="username" /><br />   password:<input type="password" name="password" /><br />   <input type="submit" value="登录" />   <input type="reset" value="重置" /></form></body></html>

success.jsp（登录成功)

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!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>成功登录</title></head><body><h1>登录成功</h1>username：<%=request.getParameter("username") %><br />password:<%=request.getParameter("password") %><br /><a href="Login.jsp">返回登录页面</a></body></html>

error.jsp(登录失败)

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!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>登陆失败</title>
</head>
<body>
<h1>登录失败</h1>
username：<%=request.getParameter("username") %><br />
password:<%=request.getParameter("password") %><br />
<a href="Login.jsp">返回登录页面</a>
</body>
</html>

LoginServlet（请求响应处理）

继承HttpServlet父类

package com.scup.servlet;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 com.sun.xml.internal.ws.client.RequestContext;public class LoginServlet extends HttpServlet {/** *  */private static final long serialVersionUID = -4875351145322914247L;@Overrideprotected void service(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {// TODO Auto-generated method stubString username=req.getParameter("username");String password=req.getParameter("password");System.out.println("用户名："+username);System.out.println("密码："+password);super.service(req, resp);}

}
使用doGet或doPOST方法实现信息的提交获取

package com.scup.servlet;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 com.sun.xml.internal.ws.client.RequestContext;public class LoginServlet extends HttpServlet {/** *  */private static final long serialVersionUID = -4875351145322914247L;@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {// TODO Auto-generated method stubSystem.out.print("进入doget方法");System.out.print("(调用dopost方法)");//调用dopost方法doPost(req, resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {// TODO Auto-generated method stubSystem.out.println("进入dopost方法");String username=req.getParameter("username");String password=req.getParameter("password");System.out.println("用户名："+username);System.out.println("密码："+password);String forward=null;if (username.equals("scup")&&password.equals("1122")) {//请求转发//由于sendRedirect方法不能将提交信息保存，所以使用forward标记（原方法见图2）forward="http://www.baidu.com";//RequestDispatcher(请求调度器，转发给forward地址)//RequestDispatcher rd=req.getRequestDispatcher(forward);//rd.forward(req, resp);  //由于forWord的内容（百度首页）不在同一应用目录，所以req.getContextPath()+"/01/success.jsp"这种方法会报404错误

                         //请求重定向resp.sendRedirect(forward);}else{forward="/01/error.jsp";RequestDispatcher rd=req.getRequestDispatcher(forward);rd.forward(req, resp);

                        //请求重定向//resp.sendRedirect(req.getContextPath()+"/01/error.jsp");}}}

图2

各位需要对http 的post，get方法熟悉，了解post与get提交的区别，重定向方法无法获得表单提交的数据。

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