用java连接mysql问题

[sinopatic]

代码如下：
package ch13;

import java.sql.*;
public class UseDriverManager {
public static void main(String args[]){
String url="jdbc:mysql://localhost/sql_test";
String userName="root";
String password="sinopatic";
Connection conn=null;

try{
System.out.println("Before the first time connect to Database");
conn=DriverManager.getConnection(url,userName,password);
System.out.println("After the first time connect to Database");
}
catch(SQLException e){
System.out.println("There are some problems occur when first connect to database");
}
if(conn==null)
System.out.println("First connection fail...");
else
System.out.println("First connection successful!");

try{
System.out.println("\n Before mount the driver");
Class.forName("com.mysql.jdbc.Driver");
System.out.println("After mount the driver");
}
catch(ClassNotFoundException e){
System.out.println("There are some problems occur when mount the driver...");
}

try{
conn = null;
System.out.println("\n Before the sencond time connecting the the Database");
conn=DriverManager.getConnection(url,userName,password);
System.out.println("After the second time connect to the Database");
}
catch(SQLException e){
System.out.println("There are some problems occur when first connect to database");

}
if(conn==null)
System.out.println("Sencond connection fail...");
else
System.out.println("Second connection successful!");

try{
conn.close();
}
catch(SQLException e){
System.out.println("There are some problems occur when close the connection to the Database");
}




}
}

－－－－－－－－－－－－－－－－－－－－－－－－
启动mysql，在eclipse中运行，连接不上：
ClassNotFoundException
Insert SQLException
Exception in thread "main" java.lang.NullPointerException
at ch13.UseDriver.main(UseDriver.java:33)

[KOfeng]

必须先加载驱动Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");,从而才能交由驱动管理器控制.

[believefym]

Class.forName("com.mysql.jdbc.Driver");
－－－－
放前面去
try catch太多了，直接在main上throw掉，然后去掉try catch便于测试

[gyang]

太乱了，写的啥奥。

[blueswind8306]

1.mysql的默认连接端口是3306,而你的连接字符串没有加上端口号.
将String url="jdbc:mysql://localhost/sql_test";
改为String url="jdbc:mysql://localhost:3306/sql_test";
试试
2.看看你有没有引mysql的jar包!

[meadking]

1这是jdbc的驱动！下载mysql-connector-java-3.1.10-bin.jar
2设置jdbc的classpath
SET CLASSPATH=.;%JAVA_HOME%\mysql-connector-java-3.1.10-bin.jar
3程序中加载驱动Class.forName
4个人建议：先测试加载的驱动是否成功！然后再接着下一步！呵呵一步一步来了！呵呵！
http://my.6cncn.cn
6cncn.cn
[e-mail]

[sinopatic]

我试试看....

[sinopatic]

还要设置环境变量的啊..

[believefym]

用了eclipse就别设什么环境变量了，eclipse自己有个包管理的，把包添加到user library，然后在工程里导入就可以了

[sinopatic]

搞定了～谢谢大家了啊