您所在位置：主题：JavaBean封装数据库，Jsp连接总出错
handware
[专家分：0] 发布于 2006-04-11 12:13:00
请高手指点，谢谢！
我用JavaBean封装对Access数据库的连接与查询，但在Jsp中用JavaBean的时候总出错，请大家帮我看看，是哪儿出错了，谢谢！
[color=800000][size=4]下面是数据库JavaBean[/size][/color]
package test;
import java.sql.*;
import java.io.*;
public class exercise1
{
Connection con=null;
Statement strt=null;
ResultSet rs=null;
public exercise1()
{
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
}catch(ClassNotFoundException e)
{}
}
public ResultSet chaxun(String sql)
{
try{
con=DriverManager.getConnection("jdbc:odbc:sun:","","");
strt=con.createStatement();
rs=strt.executeQuery(sql);
}catch(SQLException e)
{
}
return rs;
}
}
[color=000080][size=5]下面是Jsp文件[/size][/color]
<%@ page import="java.sql.*,java.io.*,test.*" %>
<html>
<head>
<title>
</title>
</head>
<body>
<jsp:useBean id="girl" scope="page" class="test.exercise1"/>
<%
String sql="select * from user";
boolean f=true;
ResultSet rs;
rs=girl.chaxun(sql);
if(rs.next())
{
out.println("hello");
}else
{
out.println("ni hao");
}
%>
</body>
[color=FF00FF][size=4]出现的错误如下：[/size][/color]message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:372)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
root cause
java.lang.NullPointerException
org.apache.jsp.ceshi_jsp._jspService(ceshi_jsp.java:67)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
note The full stack trace of the root cause is available in the Apache Tomcat/5.0.28 logs.
我用JavaBean封装对Access数据库的连接与查询，但在Jsp中用JavaBean的时候总出错，请大家帮我看看，是哪儿出错了，谢谢！
[color=800000][size=4]下面是数据库JavaBean[/size][/color]
package test;
import java.sql.*;
import java.io.*;
public class exercise1
{
Connection con=null;
Statement strt=null;
ResultSet rs=null;
public exercise1()
{
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
}catch(ClassNotFoundException e)
{}
}
public ResultSet chaxun(String sql)
{
try{
con=DriverManager.getConnection("jdbc:odbc:sun:","","");
strt=con.createStatement();
rs=strt.executeQuery(sql);
}catch(SQLException e)
{
}
return rs;
}
}
[color=000080][size=5]下面是Jsp文件[/size][/color]
<%@ page import="java.sql.*,java.io.*,test.*" %>
<html>
<head>
<title>
</title>
</head>
<body>
<jsp:useBean id="girl" scope="page" class="test.exercise1"/>
<%
String sql="select * from user";
boolean f=true;
ResultSet rs;
rs=girl.chaxun(sql);
if(rs.next())
{
out.println("hello");
}else
{
out.println("ni hao");
}
%>
</body>
[color=FF00FF][size=4]出现的错误如下：[/size][/color]message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:372)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
root cause
java.lang.NullPointerException
org.apache.jsp.ceshi_jsp._jspService(ceshi_jsp.java:67)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
note The full stack trace of the root cause is available in the Apache Tomcat/5.0.28 logs.
