使用JDBC连接到MySQL

Question

我一直试图在eclipse中使用JDBC连接到我的外部MySQL服务器位置http://mysql10.000webhost.com，但我一直收到错误。这里是我的代码：

import java.sql.Connection; 
    import java.sql.DriverManager; 
    import java.sql.ResultSet; 
    import java.sql.SQLException; 
    import java.sql.Statement; 

    import com.mysql.jdbc.PreparedStatement; 

    //import com.mysql.jdbc.Driver; 

    public class Main { 
     public static void main(String[] args) throws SQLException { 
      try{ 
      Class.forName("com.mysql.jdbc.Driver").newInstance(); 
    Connection conn=DriverManager.getConnection("jdbc:mysql://mysql10.000webhost.com/database","username","password"); 
    java.sql.PreparedStatement statement = conn.prepareStatement("SELECT * FROM promoid"); 
    ResultSet result=statement.executeQuery(); 
    while(result.next()) 
    { 
     System.out.println(result.getString(1)); 
    } 
     } 

     catch (Exception e) 
     { 
      e.printStackTrace(); 
     } 
    } 
    } 

这里是我得到的错误：

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure 

    The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. 
     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) 
     at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) 
     at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) 
     at java.lang.reflect.Constructor.newInstance(Unknown Source) 
     at com.mysql.jdbc.Util.handleNewInstance(Util.java:411) 
     at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1121) 
     at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:355) 
     at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2479) 
     at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2516) 
     at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2301) 
     at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:834) 
     at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47) 
     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) 
     at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) 
     at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) 
     at java.lang.reflect.Constructor.newInstance(Unknown Source) 
     at com.mysql.jdbc.Util.handleNewInstance(Util.java:411) 
     at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:416) 
     at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:317) 
     at java.sql.DriverManager.getConnection(Unknown Source) 
     at java.sql.DriverManager.getConnection(Unknown Source) 
     at Main.main(Main.java:15) 
    Caused by: java.net.ConnectException: Connection timed out: connect 
     at java.net.PlainSocketImpl.socketConnect(Native Method) 
     at java.net.PlainSocketImpl.doConnect(Unknown Source) 
     at java.net.PlainSocketImpl.connectToAddress(Unknown Source) 
     at java.net.PlainSocketImpl.connect(Unknown Source) 
     at java.net.SocksSocketImpl.connect(Unknown Source) 
     at java.net.Socket.connect(Unknown Source) 
     at java.net.Socket.connect(Unknown Source) 
     at java.net.Socket.<init>(Unknown Source) 
     at java.net.Socket.<init>(Unknown Source) 
     at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:259) 
     at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:305) 
     ... 15 more 

能JDBC无法连接到数据库本地主机之外？

Answer 1

Caused by: java.net.ConnectException: Connection timed out: connect. 

你有主机mysql10.000webhost.com试图通过Telnet登录port 3306（MySQL的默认）？

我敢打赌，他们阻止你的防火墙。