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java jsp+servlet实现登录网页设计

2012-02-17 09:06 573 查看
java jsp+servlet实现登录网页设计

[align=center][/align]

这次涉及到四个文件:

登录页面:login.jsp
登录成功欢迎页面:success.jsp

登录失败页面:fail.jsp

Servlet处理文件:LoginServlet.java
其实还涉及到一个文件:web.xml,这个后面再说:
下面分别介绍这几个文件:

//--------------------------------------------------------------------------------------------------------------------

LoginServlet.java 内容：
package org.cai.servlet ;
import java.sql.* ;

import java.io.* ;

import javax.servlet.http.* ;

import javax.servlet.* ;
public class LoginServlet extends HttpServlet implements Servlet{

public LoginServlet(){

}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{

}

// protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{

// System.out.println("-------------------------") ;

// doPost(request, response) ;

// }

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{

response.setContentType("text/html;charset=gb2312") ;

request.setCharacterEncoding("gb2312") ;

String result = "" ;

//获取用户名

String username = request.getParameter("username") ;

String psw = request.getParameter("password") ;

if ((username == "") || (username==null) || (username.length() > 20 )){

try{

result = "请输入用户名(不能超过20个字符)!" ;

request.setAttribute("message" ,result) ;

response.sendRedirect("login.jsp") ;

}catch(Exception e){

e.printStackTrace() ;

}

}
if ((psw == "") || (psw==null) || (psw.length() > 20 )){

try{

result = "请输入密码(不能超过20个字符)!" ;

request.setAttribute("message" ,result) ;

response.sendRedirect("login.jsp") ;

}catch(Exception e){

e.printStackTrace() ;

}

}

//登记JDBC驱动程序

try{

Class.forName("org.gjt.mm.mysql.Driver") ;

}catch(ClassNotFoundException e){

e.printStackTrace() ;

System.out.println("Class Not Found Exception . ") ;

}

//连接URL

String url ="jdbc:mysql://localhost:3306/learnJSP" ;

Connection conn = null ;

Statement stmt = null ;

ResultSet rs = null ;

try{

conn = DriverManager.getConnection(url, "root", "root") ;

stmt = conn.createStatement() ;

//SQL语句

String sql ="select * from userInfo where username='"+username+"' and userpsw= '"+psw+"'" ;

rs = stmt.executeQuery(sql) ;//返回查询结果

}catch(SQLException e){

e.printStackTrace() ;

}

HttpSession session = request.getSession() ;

session.setAttribute("username", username) ;

//System.out.println("+++++++++++++++++++++++"+ username) ;

try{

if (rs.next()){ //如果记录集非空，表明有匹配的用户名和密码，登陆成功

// 登录成功后将username设置为session变量的username

// 这样在后面就可以通过 session.getAttribute("username") 来获取用户名，

// 同时这样还可以作为用户登录与否的判断依据

session.setAttribute("age",rs.getString("age")) ;

session.setAttribute("sex",rs.getString("sex")) ;

session.setAttribute("weight",rs.getString("weight")) ;

response.sendRedirect("success.jsp") ;

}else{

session.setAttribute("message", "用户名或密码不匹配。");

response.sendRedirect("fail.jsp") ;

}

}catch(SQLException e){

e.printStackTrace() ;

}

}

private static final long serialVersionUID = 1L;
}
//--------------------------------------------------------------------------------------------------------------------

login.jsp内容：

<%@ page language="java" contentType="text/html;charset=gb2312"%>
<html>

<head>

<title>登陆</title>

</head>

<body>

<form method="POST" name="frmLogin" action="LoginServlet">

<h1 align="center">用户登录</h1><br />

<center>

<table border=1>

<tr>

<td>用户名：</td>

<td>

<input type="text" name="username" value="Your name" size="20" maxlength="20" onfocus="if (this.value=='Your name') this.value='';" />

</td>

</tr>

<tr>

<td>密  码：</td>

<td>

<input type="password" name="password" value="Your password" size="20" maxlength="20" onfocus="if (this.value=='Your password') this.value='';" />

</td>

</tr>

<tr>

<td>

<input type="submit" name="Submit" value="提交" onClick="return validateLogin()" />

</td>

<td>

<input type="reset" name="Reset" value="重置" />

</td>

</tr>

</table>

</center>

</form>

<script language="javascript">

function validateLogin(){

var sUserName = document.frmLogin.username.value ;

var sPassword = document.frmLogin.password.value ;

if ((sUserName =="") || (sUserName=="Your name")){

alert("请输入用户名!");

return false ;

}

if ((sPassword =="") || (sPassword=="Your password")){

alert("请输入密码!");

return false ;

}

}

</script>

</body>

</html>

//--------------------------------------------------------------------------------------------------------------------

success.jsp 内容；

<%@ page language="java" contentType="text/html;charset=gb2312" pageEncoding ="gb2312"%>

<html>

<head>

<title>欢迎</title>

</head>

<body>

<%

String userName = (String)session.getAttribute("username") ;

String age = (String)session.getAttribute("age") ;

String weight = (String)session.getAttribute("weight") ;

String sex = (String)session.getAttribute("sex") ;
System.out.println("性别：A" + sex +"A") ;

if (sex.trim().equals("M")) {

sex ="男" ;

}else{

sex = "女" ;

}

%>

<div align="center">

<%=userName %>

欢迎您，登陆成功！<br />

<font color="blue">登陆用户信息：</font>

<table border =1 >

<tr>

<td> 姓名： </td>

<td>  <%=userName %>  </td>

</tr>

<tr>

<td> 年龄： </td>

<td>  <%=age %>  </td>

</tr>

<tr>

<td> 体重： </td>

<td>  <%=weight %> kg </>

</tr>

<tr>

<td> 性别： </td>

<td>  <%=sex %>  </>

</tr>

</table>

<a href="login.jsp">返回</a>

</div>

</body>

</html>

//--------------------------------------------------------------------------------------------------------------------

fail.jsp 内容：
<%@ page language="java" contentType="text/html;charset=gb2312" pageEncoding ="gb2312"%>

<html>

<head>

<title>登陆失败</title>

</head>

<body>

<%

String userName = (String)session.getAttribute("username") ;

String msg = (String)session.getAttribute("message") ;

%>

<div align="center">

<%=userName %>

对不起，登陆失败！<br />

<font color="red">原因： </font>

<%=msg %>

<br/>

<br/>

5秒后将返回登陆界面。

</div>

<%

response.setHeader("Refresh","5;URL=/learnJSP/login.jsp");

%>

</body>

</html>

//--------------------------------------------------------------------------------------------------------------------

mysql数据库中需要创建数据库learnJSP，其中创建表userInfo 创建表语句为：

create database learnJSP ;

use learnJSP

create table userInfo(id int not null primary key,username char(20) not null,userpsw char(20) ,age int ,weight int ,sex enum('M','F')) ;

需要把连接mysql的jar包放到项目的lib目录中
//--------------------------------------------------------------------------------------------------------------------
web.xml 内容：
<?xml version="1.0" encoding="ISO-8859-1"?>

<!DOCTYPE web-app

PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"

"http://java.sun.com/dtd/web-app_2_3.dtd">

<web-app>

<welcome-file-list>

<welcome-file>index.jsp</welcome-file>

</welcome-file-list>

<servlet>

<servlet-name>

LoginServlet

</servlet-name>

<servlet-class>

org.cai.servlet.LoginServlet

</servlet-class>

</servlet>
<servlet-mapping>

<servlet-name>LoginServlet</servlet-name>

<url-pattern>/LoginServlet</url-pattern>

</servlet-mapping>

</web-app>

//--------------------------------------------------------------------------------------------------------------------

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