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。
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