本文实例讲述了JSP+Servlet+JavaBean实现登录网页的方法。分享给大家供大家参考。具体如下：
这里涉及到四个文件:
1. 登录页面:login.html
2. 登录成功欢迎页面:login_success.jsp
3. 登录失败页面:login_failure.jsp
4. 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:
1. 登录页面:login.html
<!-- 该Login页面是一个简单的登录界面 -->
<!--
该JSP程序是用来测试与MySQL数据库的连接，
需要一个数据库：LearnJSP，和其中一个表：userinfo
表中有两个字段分别为：UserName varchar (20) not null,UserPwd varchar (20) not null
-->
<html>
<head>
<title>登录</title>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<meta http-equiv="Content-Language" content="ch-cn">
</head>
<body>
<!-- Form 用来提取用户填入并提交的信息-->
<form method="post" name="frmLogin" action="LoginServlet">
<h1 align="center">用户登录</h1><br>
<div align="center">用户名：
<input type="text" name="txtUserName" value="Your name"
size="20" maxlength="20"
onfocus="if(this.value=='Your name')this.value='';"><br>密码：
<input type="password" name="txtPassword" value="Your password"
size="20" maxlength="20"
onfocus="if(this.value=='Your password')this.value='';"><br>
<input type="submit" name="Submit" value="提交" onClick="validateLogin();" >
<input type="reset" name="Reset" value="重置"><br>
</div>
</form>
<!-- javaScript 函数 validateLogin(),用来验证用户名和密码是否为空 -->
<script language="javaScript">
function validateLogin()
{
var sUserName = document.frmLogin.txtUserName.value;
var sPassword = document.frmLogin.txtPassword.value;
if( sUserName=="" )
{
alert("请输入用户名！");
return false;
}
if( sPassword=="" )
{
alert("请输入密码！");
return false;
}
}
</script>
</body>
</html>
2. 登录成功欢迎页面:login_success.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP 'login_failure.jsp' starting page</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css"> --> </head> <body> <% String userName = (String)session.getAttribute ( "UserName" ); %> <div align=center> <%=userName%> 欢迎您，登录成功！ </div> </body> </html>
3. 登录失败页面:login_failure.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP 'login_failure.jsp' starting page</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css"> --> </head> <body> <% String userName = (String)session.getAttribute ( "UserName" ); %> <div align=center> <%=userName%> 对不起，登录失败！ </div> </body> </html>
4. Servlet处理文件:LoginServlet.java
/**
* 该JSP程序是用来测试与MySQL数据库的连接，
* 需要一个数据库：LearnJSP，和其中一个表：userinfo
* 表中有两个字段分别为：UserName varchar (20) not null,UserPwd varchar (20) not null
*/
package zieckey.login.servlet;
import java.sql.Statement;
import java.io.IOException;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginServlet extends HttpServlet implements Servlet
{
public LoginServlet ()
{
// TODO Auto-generated constructor stub
}
/*
* (non-Javadoc)
*
* @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest,
* javax.servlet.http.HttpServletResponse)
*/
@Override
protected void doGet ( HttpServletRequest arg0, HttpServletResponse arg1 )
throws ServletException, IOException
{
}
/*
* (non-Javadoc)
*
* @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest,
* javax.servlet.http.HttpServletResponse)
*/
@Override
protected void doPost ( HttpServletRequest request, HttpServletResponse response )
throws ServletException, IOException
{
response.setContentType ( "text/html" );
String result = "";
// 获取用户名
String sUserName = request.getParameter ( "txtUserName" );
if ( sUserName == "" || sUserName == null || sUserName.length ( ) > 20 )
{
try
{
result = "请输入用户名（不超过20字符）！";
request.setAttribute ( "ErrorUserName", result );
response.sendRedirect ( "login.html" );
} catch ( Exception e )
{
}
}
// 获取密码
String sPasswd = request.getParameter ( "txtPassword" );
if ( sPasswd == "" || sPasswd == null || sPasswd.length ( ) > 20 )
{
try
{
result = "请输入密码（不超过20字符）！";
request.setAttribute ( "ErrorPassword", result );
response.sendRedirect ( "login.html" );
} catch ( Exception e )
{
}
}
// 登记JDBC驱动程序
try
{
Class.forName ( "org.gjt.mm.mysql.Driver" ).newInstance ( );
} catch ( InstantiationException e )
{
// TODO Auto-generated catch block
e.printStackTrace ( );
System.out.println ("InstantiationException");
} catch ( IllegalAccessException e )
{
// TODO Auto-generated catch block
e.printStackTrace ( );
System.out.println ("IllegalAccessException");
} catch ( ClassNotFoundException e )
{
// TODO Auto-generated catch block
e.printStackTrace ( );
System.out.println ("ClassNotFoundException");
}
// 连接参数与Access不同
String url = "jdbc:mysql://localhost/LearnJSP";
// 建立连接
java.sql.Connection connection = null;
Statement stmt = null;
ResultSet rs = null;
try
{
connection = DriverManager.getConnection ( url, "root", "011124" );
stmt = connection.createStatement ( );
// SQL语句
String sql = "select * from userinfo where username='" + sUserName
+ "' and userpwd = '" + sPasswd + "'";
rs = stmt.executeQuery ( sql );// 返回查询结果
} catch ( SQLException e )
{
// TODO Auto-generated catch block
e.printStackTrace ( );
}
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sUserName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
request.getSession ( ).setAttribute ( "UserName", sUserName );
response.sendRedirect ( "login_success.jsp" );
} else
{
// 否则登录失败
//response.sendRedirect ( "MyJsp.jsp" );
response.sendRedirect ( "login_failure.jsp" );
}
} catch ( SQLException e )
{
// TODO Auto-generated catch block
e.printStackTrace ( );
}
try
{
if ( null!=rs )
{
rs.close ( );
}
if ( null!=stmt )
{
stmt.close ( );
}
if ( null!=connection )
{
connection.close ( );
}
} catch ( SQLException e )
{
// TODO Auto-generated catch block
e.printStackTrace ( );
}
}
/**
*
*/
private static final long serialVersionUID = 1L;
}
为了让这个网站正常运行还要到web.xml中注册一下,
现该文件内容修改如下:
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.4" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <servlet> <display-name>LoginServlet</display-name> <servlet-name>LoginServlet</servlet-name> <servlet-class>zieckey.login.servlet.LoginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/LoginServlet</url-pattern> </servlet-mapping> </web-app>
好了,这几个文件就可以构成我们的这个登录界面了.
注意事项:
1. 文件目录形式
login.html,login_success.html,login_failure.html这三个文件放在同一目录,
LoginServlet.java该文件的字节码文件LoginServlet.class放在WEB-INF/classes目录下(注意jar包顺序)
现在整个工程的目录形式是:
M:/Tomcat5.5/webapps/JSP_Servlet_JavaBean_Login 的目录
007-01-18 15:16 <DIR> META-INF
007-01-18 15:16 <DIR> WEB-INF
007-01-18 16:17 1,801 login.html
007-01-18 15:48 858 login_failure.jsp
007-01-18 15:40 234 login_success.html
007-01-18 15:46 781 MyJsp.jsp
007-01-18 16:12 859 login_success.jsp
M:/Tomcat5.5/webapps/JSP_Servlet_JavaBean_Login/WEB-INF 的目录
007-01-18 15:16 <DIR> classes
007-01-18 15:16 <DIR> lib
007-01-18 16:21 606 web.xml
M:/Tomcat5.5/webapps/JSP_Servlet_JavaBean_Login/WEB-INF/classes/zieckey/login/servlet 的目录
2007-01-18 16:18 3,900 LoginServlet.class
2. 其他注意事项
数据库MySQL服务器程序要先启动起来.
希望本文所述对大家的JSP程序设计有所帮助。
