jdbc连mysql。急急急！

今天帮同学用jsp连数据库出现如下错误：
同样内容的程序（密码什么的都有改）在我的机子上运行完全没问题。
莫非是因为他是vista？？
请问到底什么问题呢？急！！谢谢！
——————————————JSP内容————————————————
<%@ page contentType="text/html; charset=gb2312" %>
<%@ page language="java" %>
<%@ page import="com.mysql.jdbc.Driver" %>
<%@ page import="java.sql.*" %>
<%
String driverName="com.mysql.jdbc.Driver";
String userName="root";
String userPasswd="315041653";
String dbName="mysql";
String tableName="db";
String url="jdbc:mysql://localhost/"+"?user="+userName+"&password="+userPasswd;
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection connection=DriverManager.getConnection(url);
connection.close(); 
%>
——————————————报错内容——————————————————
HTTP Status 500 -type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException: Communications link failureLast packet sent to the server was 0 ms ago.
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:498)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:308)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:259)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
root cause
javax.servlet.ServletException: Communications link failureLast packet sent to the server was 0 ms ago.
org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:841)
org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:774)
org.apache.jsp.WebRoot.a_jsp._jspService(a_jsp.java:64)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:308)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:259)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
root cause
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failureLast packet sent to the server was 0 ms ago.
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
java.lang.reflect.Constructor.newInstance(Unknown Source)
com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2120)
com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:723)
com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
java.lang.reflect.Constructor.newInstance(Unknown Source)
com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)
com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:282)
java.sql.DriverManager.getConnection(Unknown Source)
java.sql.DriverManager.getConnection(Unknown Source)
org.apache.jsp.WebRoot.a_jsp._jspService(a_jsp.java:56)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:308)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:259)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
root cause
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failureLast packet sent to the server was 0 ms ago.
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
java.lang.reflect.Constructor.newInstance(Unknown Source)
com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:335)
com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2043)
com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:723)
com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
java.lang.reflect.Constructor.newInstance(Unknown Source)
com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)
com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:282)
java.sql.DriverManager.getConnection(Unknown Source)
java.sql.DriverManager.getConnection(Unknown Source)
org.apache.jsp.WebRoot.a_jsp._jspService(a_jsp.java:56)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:308)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:259)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
root cause
java.net.ConnectException: Connection refused: connect
java.net.PlainSocketImpl.socketConnect(Native Method)
java.net.PlainSocketImpl.doConnect(Unknown Source)
java.net.PlainSocketImpl.connectToAddress(Unknown Source)
java.net.PlainSocketImpl.connect(Unknown Source)
java.net.SocksSocketImpl.connect(Unknown Source)
java.net.Socket.connect(Unknown Source)
java.net.Socket.connect(Unknown Source)
java.net.Socket.<init>(Unknown Source)
java.net.Socket.<init>(Unknown Source)
com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:253)
com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:284)
com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2043)
com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:723)
com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
java.lang.reflect.Constructor.newInstance(Unknown Source)
com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)
com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:282)
java.sql.DriverManager.getConnection(Unknown Source)
java.sql.DriverManager.getConnection(Unknown Source)
org.apache.jsp.WebRoot.a_jsp._jspService(a_jsp.java:56)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:308)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:259)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.33 logs.Apache Tomcat/5.5.33

解决方案 »

  1.   

    你的url有问题，没写端口
    String url="jdbc:mysql://localhost:3306/"+"?user="+userName+"&password="+userPasswd;
      

  2.   

    String url="jdbc:mysql://localhost/"+"?user="+userName+"&password="+userPasswd;
    Class.forName("com.mysql.jdbc.Driver").newInstance();
    Connection connection=DriverManager.getConnection(url);
    connection.close();后面忘记了跟端口了！
      

  3.   

    String url="jdbc:mysql://localhost/"+"?user="+userName+"&password="+userPasswd;
      没写数据库名 "localhost/" + dbname + "?user"
      

  4.   

    参考下贴中的检查方法并贴出你的检查结果(#43楼)http://topic.csdn.net/u/20090920/22/14d4f597-b7d4-4c24-b0db-abb2956e66c3.html
    [收集]mysql   无法联接故障现象及原因
      

  5.   

    3楼正解  如果3楼不好使的话  是不是你把tomcat的默认8080端口号改了？
    如果改了，那么写法是localhost：xxxx   xxxx为你改的那个端口号   如果这样还不好使的话 把localhost改写成1xx.xxx.xxx.xxx这种ip形式  我忘了是多少了  很少用到 。
    下面是一个jsp连数据库的例子，你看看 现在mysql里自己创建一个数据库 输入点儿例子<%@page contentType="text/html;charset=gb2312" %>
    <%@page language="java" import="java.sql.*" %>
    <%
    Connection conn = null;
    Statement stmt = null;
    ResultSet rs = null;
    try
    {
        //载入MySQL的JDBC驱动类
        Class.forName("com.mysql.jdbc.Driver");
        //获得数据库连接
        String sConn = "jdbc:mysql://localhost/dbname?user=root&password=****";
        conn = DriverManager.getConnection( sConn );  
        //创建Statement对象
        stmt = conn.createStatement();
        //执行SQL语句
        String query = "select * from user_info";
        rs = stmt.executeQuery( query );
    %>
    <html>
    <head>
      <title>JSP使用JDBC连接MySQL</title>
    </head>
    <body>
      <table border=1 cellspacing=0 cellpadding=0>
        <tr bgcolor=gray>
          <td>FirstName</td>
          <td>LastName</td>
          <td>NickName</td>
        </tr>
    <%
        //循环操作返回的数据集
        while( !rs.isLast() )
        {
           rs.next();
    %>
        <tr>
          <td><%=rs.getString("first_name")%></td>
          <td><%=rs.getString("last_name")%></td>
          <td><%=rs.getString("nick_name")%></td>
        </tr>
    <%
        }
    }
    catch(Exception e)
    {
        System.out.println("error occured!!");
    }
    finally
    {
        //释放数据库连接
        rs.close();
        stmt.close();
        conn.close();
    }
    %>
      </table>
    </body>
    </html>