本文實例講述了JSP+Servlet+JavaBean實現登錄網頁的方法。分享給大家供大家參考。具體如下：
這裡涉及到四個文件:
1. 登錄頁面:login.html
2. 登錄成功歡迎頁面:login_success.jsp
3. 登錄失敗頁面:login_failure.jsp
4. Servlet處理文件:LoginServlet.java
其實還涉及到一個文件:web.xml,這個後面再說:
下面分別介紹這幾個文件:
1. 登錄頁面:login.html
<!-- 該Login頁面是一個簡單的登錄界面 -->
<!--
該JSP程序是用來測試與MySQL數據庫的連接，
需要一個數據庫：LearnJSP，和其中一個表：userinfo
表中有兩個字段分別為：UserName varchar (20) not null,UserPwd varchar (20) not null
-->
<html>
<head>
<title>登錄</title>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<meta http-equiv="Content-Language" content="ch-cn">
</head>
<body>
<!-- Form 用來提取用戶填入並提交的信息-->
<form method="post" name="frmLogin" action="LoginServlet">
<h1 align="center">用戶登錄</h1><br>
<div align="center">用戶名：
<input type="text" name="txtUserName" value="Your name"
size="20" maxlength="20"
onfocus="if(this.value=='Your name')this.value='';"><br>密碼：
<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 函數 validateLogin(),用來驗證用戶名和密碼是否為空 -->
<script language="javaScript">
function validateLogin()
{
var sUserName = document.frmLogin.txtUserName.value;
var sPassword = document.frmLogin.txtPassword.value;
if( sUserName=="" )
{
alert("請輸入用戶名！");
return false;
}
if( sPassword=="" )
{
alert("請輸入密碼！");
return false;
}
}
</script>
</body>
</html>
2. 登錄成功歡迎頁面: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%> 歡迎您，登錄成功！ </div> </body> </html>
3. 登錄失敗頁面: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%> 對不起，登錄失敗！ </div> </body> </html>
4. Servlet處理文件:LoginServlet.java
/**
* 該JSP程序是用來測試與MySQL數據庫的連接，
* 需要一個數據庫：LearnJSP，和其中一個表：userinfo
* 表中有兩個字段分別為：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 = "";
// 獲取用戶名
String sUserName = request.getParameter ( "txtUserName" );
if ( sUserName == "" || sUserName == null || sUserName.length ( ) > 20 )
{
try
{
result = "請輸入用戶名（不超過20字符）！";
request.setAttribute ( "ErrorUserName", result );
response.sendRedirect ( "login.html" );
} catch ( Exception e )
{
}
}
// 獲取密碼
String sPasswd = request.getParameter ( "txtPassword" );
if ( sPasswd == "" || sPasswd == null || sPasswd.length ( ) > 20 )
{
try
{
result = "請輸入密碼（不超過20字符）！";
request.setAttribute ( "ErrorPassword", result );
response.sendRedirect ( "login.html" );
} catch ( Exception e )
{
}
}
// 登記JDBC驅動程序
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");
}
// 連接參數與Access不同
String url = "jdbc:mysql://localhost/LearnJSP";
// 建立連接
java.sql.Connection connection = null;
Statement stmt = null;
ResultSet rs = null;
try
{
connection = DriverManager.getConnection ( url, "root", "011124" );
stmt = connection.createStatement ( );
// SQL語句
String sql = "select * from userinfo where username='" + sUserName
+ "' and userpwd = '" + sPasswd + "'";
rs = stmt.executeQuery ( sql );// 返回查詢結果
} catch ( SQLException e )
{
// TODO Auto-generated catch block
e.printStackTrace ( );
}
try
{
if ( rs.next ( ) )// 如果記錄集非空，表明有匹配的用戶名和密碼，登陸成功
{
// 登錄成功後將sUserName設置為session變量的UserName
// 這樣在後面就可以通過 session.getAttribute("UserName") 來獲取用戶名，
// 同時這樣還可以作為用戶登錄與否的判斷依據
request.getSession ( ).setAttribute ( "UserName", sUserName );
response.sendRedirect ( "login_success.jsp" );
} else
{
// 否則登錄失敗
//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;
}
為了讓這個網站正常運行還要到web.xml中注冊一下,
現該文件內容修改如下:
<?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,這幾個文件就可以構成我們的這個登錄界面了.
注意事項:
1. 文件目錄形式
login.html,login_success.html,login_failure.html這三個文件放在同一目錄,
LoginServlet.java該文件的字節碼文件LoginServlet.class放在WEB-INF/classes目錄下(注意jar包順序)
現在整個工程的目錄形式是:
M:/Tomcat5.5/webapps/JSP_Servlet_JavaBean_Login 的目錄
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 的目錄
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 的目錄
2007-01-18 16:18 3,900 LoginServlet.class
2. 其他注意事項
數據庫MySQL服務器程序要先啟動起來.
希望本文所述對大家的JSP程序設計有所幫助。
