JDBC + MYSQL通信链接失败

Question

我肯定做错了什么，或者我错过了某些事情，但无法弄清楚那是什么。 我安装了XAMPP Apache / MYSQL。 我在本地连接，一切正常。 我尝试更进一步，以远程访问数据库。

问题

1. 当我在浏览器中键入myip / xampp时，我只看到“ 连接已重置 ”，但对于其他所有人来说还可以吗？ （Xampp欢迎页面）

2. 无法通过JDBC error com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure连接error com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure之前error com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure正常工作，并且仅更改主机名。

这是代码。

public DBConnect(String whichDataBase){
    try {
        Class.forName("com.mysql.jdbc.Driver");
        con = DriverManager.getConnection("jdbc:mysql://localhost:3306/"+whichDataBase+"?characterEncoding=UTF-8","monty","some_pass");
        st = con.createStatement();
    } catch (Exception e) {
        System.out.println("error "+e);}
}

在数据库状态选项卡上，它看起来像是“连接”？ （请参阅主机，但命令= sleep并如上所述出现Java错误）。 但是，当我使用VPN时，其连接正常吗？ O_O

我做的事

• 路由器上的端口转发80和3306（在http://www.yougetsignal.com/tools/open-ports/上测试）

• 在my.ini更改了socket = "TCP/IP"

• 注释掉#enable-named-pipe和#skip-networking

• bind-address="0.0.0.0" （也请检查127.0.0.1 ）

• 数据库用户在localhost和%上获得了ALL PRIVILEGES和GRANT

我是初学者，感谢您的帮助！

编辑：

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:377)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1036)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:338)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2232)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2265)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2064)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:790)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44)
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:377)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:395)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:325)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at DBConnect.<init>(DBConnect.java:17)
at Poro.actionPerformed(Poro.java:297)
at javax.swing.JComboBox.fireActionEvent(Unknown Source)
at javax.swing.JComboBox.contentsChanged(Unknown Source)
at javax.swing.AbstractListModel.fireContentsChanged(Unknown Source)
at javax.swing.DefaultComboBoxModel.setSelectedItem(Unknown Source)
at javax.swing.DefaultComboBoxModel.addElement(Unknown Source)
at javax.swing.JComboBox.addItem(Unknown Source)
at Poro.<init>(Poro.java:231)
at Poro.main(Poro.java:287)
Caused by: java.net.ConnectException: Connection refused: 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 com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:213)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:297)
... 24 more

Answer 1

尝试以这种方式做到这一点：

public class MysqlConnect {

    static String template = "jdbc:mysql://localhost/%s?useEncoding=true&characterEncoding=UTF-8&user=%s&password=%s";

    public void connect(String database, String user, String password) {

        Connection conn = null;

        try {
            Class.forName("com.mysql.jdbc.Driver").newInstance();
            conn = DriverManager.getConnection(String.format(template, database, user, password));
            //...
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
}

因此，调用Class.forName("com.mysql.jdbc.Driver").newInstance()并将username和password添加到您的连接字符串中。

还要检查以下内容： 使用JDBC连接到MySQL

Answer 2

我有同样的错误。 我已经尝试过这种方式（修改dit的答案代码），它对我有用 ：

public class SqlConnection {
    static String template = "jdbc:mysql://localhost/%s?useEncoding=true&characterEncoding=UTF-8&user=%s&password=%s";

    public static Connection dbConnector() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection connection = DriverManager.getConnection(String.format(template, <database-name>, <username>, "password"));
            System.out.println("Connected succesfully");
            return connection;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
}

注意 ：您必须在DriverManager.getConnection方法中修改数据库名称 ， 用户名和密码 。 最后，您可以致电：

SqlConnection.dbConnector();

现在，我可以看到“连接成功”。