java - 为什么我的 MYSQL 不能用 java 运行？

Question

这是我必须测试我的数据库的代码:

package mysql;
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.SQLException;

public class JDBCExample {

  public static void main(String[] argv) {

    System.out.println("-------- MySQL JDBC Connection Testing ------------");

    try {
        Class.forName("com.mysql.jdbc.Driver");
    } catch (ClassNotFoundException e) {
        System.out.println("Where is your MySQL JDBC Driver?");
        e.printStackTrace();
        return;
    }

    System.out.println("MySQL JDBC Driver Registered!");
    Connection connection = null;

    try {
        connection = DriverManager
        .getConnection("jdbc:mysql://192.99.148.171:3306/aldorps_aldorpva_donation","aldorps_donation", "stan1234");

    } catch (SQLException e) {
        System.out.println("Connection Failed! Check output console");
        e.printStackTrace();
        return;
    }

    if (connection != null) {
        System.out.println("You made it, take control your database now!");
    } else {
        System.out.println("Failed to make connection!");
    }
  }
}

我收到的错误是:

-------- MySQL JDBC Connection Testing ------------
MySQL JDBC Driver Registered!
Connection Failed! Check output console
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet successfully received from the server was 1.445.894.001.265 milliseconds ago.  The last packet sent successfully to the server was 0 milliseconds ago.
    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:406)
    at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2214)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:773)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
    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:406)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:352)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:282)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at mysql.JDBCExample.main(JDBCExample.java:25)
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet successfully received from the server was 1.445.894.001.261 milliseconds ago.  The last packet sent successfully to the server was 0 milliseconds ago.
    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:406)
    at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:341)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2137)
    ... 12 more
Caused by: java.net.ConnectException: Connection timed out: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connect(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:253)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:290)
    ... 13 more

现在我想这可能是因为端口 3306 在我的电脑上没有打开，但这没有多大意义，因为这不是本地主机，对吗？

你们知道该怎么做吗？

Answer 1

java.net.ConnectException: Connection timed out: connect

与Java无关。这可能意味着有防火墙阻碍。查看是否可以从客户端 Telnet 到该主机的端口 3306。