第一次用java连接mysql 失败，郁闷了很长时间了

os是fc6，mysql-server-5.0.27-1, mysql-connector-java-5.0.4 jdk 5.0. 下面是一个很简单的连接代码：
import java.sql.*;public class mySqlTest
{
  public static void main(String[] args)
  {
    try
    {
      Connection conn;   
      Class.forName("com.mysql.jdbc.Driver");
      conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/firstSql?useUnicode=true&characterEncoding=utf8","dba","sql");
    }catch (Exception ex)
    {
      System.out.println("Error : " + ex.toString());
    }
  }
}编译没有出错，运行时出错：
Error : com.mysql.jdbc.CommunicationsException: Communications link failure due to underlying exception: ** BEGIN NESTED EXCEPTION ** com.mysql.jdbc.CommunicationsException
MESSAGE: Communications link failure due to underlying exception: ** BEGIN NESTED EXCEPTION ** java.io.EOFExceptionSTACKTRACE:java.io.EOFException
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1913)
at com.mysql.jdbc.MysqlIO.readPacket(MysqlIO.java:539)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:971)
at com.mysql.jdbc.Connection.createNewIO(Connection.java:2670)
at com.mysql.jdbc.Connection.<init>(Connection.java:1531)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:266)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
at mySqlTest.main(mySqlTest.java:11)
** END NESTED EXCEPTION **Last packet sent to the server was 6 ms ago.STACKTRACE:com.mysql.jdbc.CommunicationsException: Communications link failure due to underlying exception: ** BEGIN NESTED EXCEPTION ** java.io.EOFExceptionSTACKTRACE:java.io.EOFException
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1913)
at com.mysql.jdbc.MysqlIO.readPacket(MysqlIO.java:539)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:971)
at com.mysql.jdbc.Connection.createNewIO(Connection.java:2670)
at com.mysql.jdbc.Connection.<init>(Connection.java:1531)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:266)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
at mySqlTest.main(mySqlTest.java:11)
** END NESTED EXCEPTION **Last packet sent to the server was 6 ms ago.
at com.mysql.jdbc.MysqlIO.readPacket(MysqlIO.java:569)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:971)
at com.mysql.jdbc.Connection.createNewIO(Connection.java:2670)
at com.mysql.jdbc.Connection.<init>(Connection.java:1531)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:266)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
at mySqlTest.main(mySqlTest.java:11)
** END NESTED EXCEPTION **Last packet sent to the server was 1 ms ago.问题就是出在 getConnection(); 
使用mysql前端连接却很正常 参照这个帖依然不行
http://community.csdn.net/Expert/TopicView3.asp?id=5079853