请教大家一个数据库挂接问题

menglianjing · 发表于 2004-6-8 22:18:15

1 login.jsp
[php]
<%@ page contentType="text/html;charset=gb2312" language="java"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB2312">
<title>jsp连接数据库测试</title>
<script language="javascript">
function login(frm)
{
if(frm.userName.value == "")
{
alert("用户名不能为空");
frm.userName.focus();
return false;
}
else if(frm.userPassword.value == "")
{
alert("密码不能为空");
frm.userPassword.focus();
return false;
}
else
{
return true;
}
}
</script>
</head>
<body>
<center>
<form name="frm" method="post" action="login_confirm.jsp" onSubmit="return login(this)">
<table>
<tr>
<td>用户名：</td>
<td><input type="text" name="userName"></td>
</tr>
<tr>
<td>密码：</td>
<td><input type="password" name="userPassword"></td>
</tr>
<tr>
<td><input type="submit" name="submit" value="提交"></td>
</tr>
</table>
</form>
现在是北京时间：
<%= new java.util.Date().toLocaleString()%>
</center>
</body>
</html>
[/php]

2 login_confirm.jsp
[php]
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%@ page contentType="text/html;charset=gb2312" language="java" import="java.sql.*"%>
<jsp:useBean id="query" class="testBean.QueryBean" scope="page"/>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB2312">
<title>连接数据库</title>
</head>
<body>
<%
String userName = request.getParameter("userName");
String userPassword = request.getParameter("userPassword");
out.println(userName);
out.println(userPassword);
int flag = query.demand(userName,userPassword);
out.println(flag);
/*switch(flag)
{
case 1:
response.sendRedirect("succeed.html");
break;
case 0:
response.sendRedirect("fail.html");
break;
}*/
%>
</body>
</html>
[/php]

3 testBean
[php]
package testBean;
import java.sql.*;
import javax.sql.*;
import java.io.*;

public class QueryBean
{
private PreparedStatement pstmt = null;
private Connection con = null;
private ResultSet rs = null;

public int demand(String userName,String userPassword)
{
System.out.println(userName);
System.out.println(userPassword);
int flag = 0;
try
{

Class.forName("org.gjt.mm.mysql.Driver").newInstance();
con = DriverManager.getConnection("jdbc:mysql://127.0.0.1/jxd","root","");
pstmt = con.prepareStatement("SELECT username,userpassword FROM user_test WHERE username=? AND userpassword=?");
pstmt.setString(1,userName);
pstmt.setString(2,userPassword);
rs = pstmt.executeQuery();
if(rs.next())
{
flag = 1;
}
rs.close();
con.close();

}
catch(Exception e)
{
e.printStackTrace();
}
return flag;
}
}
[/php]

问题是无论输入的数据正确与否，都只输出0！！为什么？
jdk:1.5.0
tomcat:5.0.25
数据库:jxd
表:user_test

谢谢大家!

waveDuke · 发表于 2004-6-9 00:34:30

在if(rs.next())前加入:rs.beforeFirst()看看行不行

PS:jdk1.5出来了?什么时候出的?
孤陋寡闻了...

NIGI · 发表于 2004-6-9 08:41:40

to AirFish:
The jdk 1.5 beta 2 has already available

click here: to down:
http://java.sun.com/j2se/1.5.0/download.jsp

NIGI · 发表于 2004-6-9 08:47:28

to menglianjing:

  I met this question before.Maybe you havn't connected the mysql.

If you will ,please change the JDBC Driver to try again, use

  Class.forName("com.mysql.jdbc.Driver").

menglianjing · 发表于 2004-6-9 08:47:33

你的意思是把游标先移到最前面吗？

menglianjing · 发表于 2004-6-9 08:49:32

如果没有连接数据库应该报错才对，不过我也回去试试，谢谢你

waveDuke · 发表于 2004-6-9 09:18:18

没连接上数据库应该在：
pstmt = con.prepareStatement("SELECT username,userpassword FROM user_test WHERE username=? AND userpassword=?");
这句或之前就报错了(如果你抛了错)

PS：thanks supcc

menglianjing · 发表于 2004-6-9 09:27:44

是的，我是抛了异常，源程序是这样的，发到论坛上为了省事就合成Exception了。但是我执行的时候并没有抛异常

waveDuke · 发表于 2004-6-9 09:34:36

应该连上了吧。。。
控制台会输出连接信息的，可以查看一下

NIGI · 发表于 2004-6-9 10:16:11

I met the question is this:
While compile the source in Eclipse i can connected and no exception to throw, but can't connected to mysql when i deploy under tomcat.So I changed jdbc driver.
Successful.

Maybe useful for you.

Please copy the exception ,tomcat's console, let us see more.

		自动登录	找回密码
密码			注册