求助：jsp连接Mysql数据库出现问题，，，，，，
jsp连接Mysql数据库出现问题。

我的测试程序是：

import   java.io.*;
import   java.sql.*;

public   class   DbUtil   {
static   String   driverName= "com.mysql.jdbc.Driver ";
static   String   dbUrl= "jdbc:mysql:// ";
static   String   user   = "root ";
static   String   password   = "12345678 ";

        public   DbUtil()   {   }

      public   static   java.sql.Connection   connectToDb(String   hostName,   String     databaseName)throws   Exception
{
                Connection   connection=null;
                String   connName   =   dbUrl   +   hostName+ ":3306 "+ "/ "+databaseName;
                Class.forName(driverName).newInstance();
                connection   =   DriverManager.getConnection(connName,user,password);
                System.out.print( "Connect   to   DB   OK... ");
                return   connection;
               
}

public   static   java.sql.Connection   connectToDb(String   databaseName)throws   Exception{
return(connectToDb( "localhost ",   databaseName));
}

public   static   java.sql.Connection   connectToDb()throws   Exception{
return(connectToDb( "localhost ",   "addressbook "));
}

public   static   void   main(String[]   args)throws   Exception{
try{
DbUtil   db   =   new   DbUtil();
db.connectToDb();
}catch(Exception   e){
e.printStackTrace();
}
}

}

运行时出现如下错误：

java.sql.SQLException:   Communication   link   failure:   java.io.IOException,   underlying   cause:   Unexpected   end   of   input   stream

**   BEGIN   NESTED   EXCEPTION   **  

java.io.IOException
MESSAGE:   Unexpected   end   of   input   stream

STACKTRACE:

java.io.IOException:   Unexpected   end   of   input   stream
at   com.mysql.jdbc.MysqlIO.readPacket(MysqlIO.java:1096)
at   com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:626)
at   com.mysql.jdbc.Connection.createNewIO(Connection.java:1562)
at   com.mysql.jdbc.Connection. <init> (Connection.java:491)
at   com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:346)
at   java.sql.DriverManager.getConnection(Unknown   Source)
at   java.sql.DriverManager.getConnection(Unknown   Source)
at   addressbook.model.DbUtil.connectToDb(DbUtil.java:25)
at   addressbook.model.DbUtil.connectToDb(DbUtil.java:36)
at   addressbook.model.DbUtil.main(DbUtil.java:42)