您所在位置：主题：[讨论].JSP通过数据源访问数据库时出错!!!!
lightmath
[专家分：0] 发布于 2007-09-14 09:49:00
我用的是Tomcat5.5，MySQL数据库。并且server.xml和web.xml文件也都从新设置了。
然后我把DbJsp.jsp放在webapps\bookstore\目录下。数据库也已经建好了,JDBC驱动程序也拷贝到了common\lib目录下。当我访问DbJsp.jsp时，弹出下面的提示：
Cannot create JDBC driver of class '' for connect URL 'null'
请大家帮我看看是怎么一回事？
DbJsp.jsp代码如下：
<!--首先导入一些必要的packages-->
<%@ page import="java.io.*"%>
<%@ page import="java.util.*"%>
<%@ page import="java.sql.*"%>
<%@ page import="javax.sql.*"%>
<%@ page import="javax.naming.*"%>
<%@ page import="com.mysql.jdbc.Connection"%>
<!--设置中文输出-->
<%@ page contentType="text/html; charset=GB2312" %>
<html>
<head>
<title>DbJsp1.jsp</title>
</head>
<body>
<%
//以try开始
try
{
java.sql.Connection con;
Statement stmt;
ResultSet rs;
//建立数据库连接
Context ctx = new InitialContext();
DataSource ds =(DataSource)ctx.lookup("java:comp/env/jdbc/BookDB");
con = ds.getConnection();
//创建一个JDBC声明
stmt = con.createStatement();
//增加新记录
stmt.executeUpdate("INSERT INTO books (id,name,title,price) VALUES ('999','Tom','Tomcat Bible',44.5)");
//查询记录
rs = stmt.executeQuery("SELECT id,name,title,price from books");
//输出查询结果
out.println("<table border=1 width=400>");
while (rs.next())
{
String col1 = rs.getString(1);
String col2 = rs.getString(2);
String col3 = rs.getString(3);
float col4 = rs.getFloat(4);
//convert character encoding
col1=new String(col1.getBytes("ISO-8859-1"),"GB2312");
col2=new String(col2.getBytes("ISO-8859-1"),"GB2312");
col3=new String(col3.getBytes("ISO-8859-1"),"GB2312");
//打印所显示的数据
out.println("<tr><td>"+col1+"</td><td>"+col2+"</td><td>"+col3+"</td><td>"+col4+"</td></tr>");
}
out.println("</table>");
//删除新增加的记录
stmt.executeUpdate("DELETE FROM books WHERE id='999'");
//关闭数据库连结
rs.close();
stmt.close();
con.close();
}
//捕获错误信息
catch (Exception e) {out.println(e.getMessage());}
%>
</body>
</html>[color=FF0000]Cannot create JDBC driver of class '' for connect URL 'null'[/color][color=000000][/color]
然后我把DbJsp.jsp放在webapps\bookstore\目录下。数据库也已经建好了,JDBC驱动程序也拷贝到了common\lib目录下。当我访问DbJsp.jsp时，弹出下面的提示：
Cannot create JDBC driver of class '' for connect URL 'null'
请大家帮我看看是怎么一回事？
DbJsp.jsp代码如下：
<!--首先导入一些必要的packages-->
<%@ page import="java.io.*"%>
<%@ page import="java.util.*"%>
<%@ page import="java.sql.*"%>
<%@ page import="javax.sql.*"%>
<%@ page import="javax.naming.*"%>
<%@ page import="com.mysql.jdbc.Connection"%>
<!--设置中文输出-->
<%@ page contentType="text/html; charset=GB2312" %>
<html>
<head>
<title>DbJsp1.jsp</title>
</head>
<body>
<%
//以try开始
try
{
java.sql.Connection con;
Statement stmt;
ResultSet rs;
//建立数据库连接
Context ctx = new InitialContext();
DataSource ds =(DataSource)ctx.lookup("java:comp/env/jdbc/BookDB");
con = ds.getConnection();
//创建一个JDBC声明
stmt = con.createStatement();
//增加新记录
stmt.executeUpdate("INSERT INTO books (id,name,title,price) VALUES ('999','Tom','Tomcat Bible',44.5)");
//查询记录
rs = stmt.executeQuery("SELECT id,name,title,price from books");
//输出查询结果
out.println("<table border=1 width=400>");
while (rs.next())
{
String col1 = rs.getString(1);
String col2 = rs.getString(2);
String col3 = rs.getString(3);
float col4 = rs.getFloat(4);
//convert character encoding
col1=new String(col1.getBytes("ISO-8859-1"),"GB2312");
col2=new String(col2.getBytes("ISO-8859-1"),"GB2312");
col3=new String(col3.getBytes("ISO-8859-1"),"GB2312");
//打印所显示的数据
out.println("<tr><td>"+col1+"</td><td>"+col2+"</td><td>"+col3+"</td><td>"+col4+"</td></tr>");
}
out.println("</table>");
//删除新增加的记录
stmt.executeUpdate("DELETE FROM books WHERE id='999'");
//关闭数据库连结
rs.close();
stmt.close();
con.close();
}
//捕获错误信息
catch (Exception e) {out.println(e.getMessage());}
%>
</body>
</html>[color=FF0000]Cannot create JDBC driver of class '' for connect URL 'null'[/color][color=000000][/color]
