连接 MySQL 的 JAVA Bukkit 插件

Question

我正在尝试将我的 MineCraft 插件连接到 SQL 数据库。但我好像做不到... 我是java编程新手，所以就到这里吧。 我真的不知道错误是从哪里来的。 我的主 Java 文件..

    package com.TristanCode.MyWebVote;

import java.sql.SQLException;
import org.bukkit.event.Listener;
import org.bukkit.plugin.PluginManager;
import org.bukkit.plugin.java.JavaPlugin;
import java.sql.Connection;
import code.husky.mysql.MySQL;

public class MyWebVote extends JavaPlugin implements Listener { 

    MySQL sql;
    Connection c = null;

  //On Server Start/Stop.   
    public void onEnable() {
        System.out.println("[MyWebVote] by TristanCode has been enabled!");
        PluginManager pm = getServer().getPluginManager();
        pm.registerEvents(new Main(this), this);

        //Get configuration file
        getConfig().options().copyDefaults(true);
        saveConfig();

        //Activate SQL
        connect();
    }
    public void onDisable() {
        System.out.println("[CashCraft] by TristanCode has been disabled!");
    }

   private synchronized void connect() {
        System.out.println("Starting connection...");
        sql = new MySQL(this, getConfig().getString("database.host"), getConfig().getString("database.port"), getConfig().getString("database.dbname"), getConfig().getString("database.user"), getConfig().getString("database.pass"));

                try {
                    c = sql.openConnection();
                    c.prepareStatement("CREATE DATABASE IF NOT EXISTS Tokens").execute();
                    c.prepareStatement("CREATE TABLE IF NOT EXISTS Tokens (id INTEGER not null,uuid VARCHAR(70) not null,tokens FLOAT(30),PRIMARY KEY (id))").executeUpdate();
                    System.out.println("Connection has been established successfully! It took ms to connect.");
                } catch (ClassNotFoundException e) {
                    e.printStackTrace();
                } catch (SQLException e) {
                    e.printStackTrace();
                }

        }
}

这是主要的错误日志。

[14:38:48 WARN]: 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.
[14:38:48 WARN]:    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
[14:38:48 WARN]:    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
[14:38:48 WARN]:    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
[14:38:48 WARN]:    at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
[14:38:48 WARN]:    at com.mysql.jdbc.Util.handleNewInstance(Util.java:407)
[14:38:48 WARN]:    at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116)
[14:38:48 WARN]:    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:343)
[14:38:48 WARN]:    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2334)
[14:38:48 WARN]:    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2371)
[14:38:48 WARN]:    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2163)
[14:38:48 WARN]:    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:794)
[14:38:48 WARN]:    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
[14:38:48 WARN]:    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
[14:38:48 WARN]:    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
[14:38:48 WARN]:    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
[14:38:48 WARN]:    at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
[14:38:48 WARN]:    at com.mysql.jdbc.Util.handleNewInstance(Util.java:407)
[14:38:48 WARN]:    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:378)
[14:38:48 WARN]:    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
[14:38:48 WARN]:    at java.sql.DriverManager.getConnection(DriverManager.java:571)
[14:38:48 WARN]:    at java.sql.DriverManager.getConnection(DriverManager.java:215)
[14:38:48 WARN]:    at code.husky.mysql.MySQL.openConnection(MySQL.java:58)
[14:38:48 WARN]:    at com.TristanCode.MyWebVote.MyWebVote.connect(MyWebVote.java:37)
[14:38:48 WARN]:    at com.TristanCode.MyWebVote.MyWebVote.onEnable(MyWebVote.java:26)
[14:38:48 WARN]:    at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:321)
[14:38:48 WARN]:    at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:332)
[14:38:48 WARN]:    at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:404)
[14:38:48 WARN]:    at org.bukkit.craftbukkit.v1_8_R3.CraftServer.loadPlugin(CraftServer.java:341)
[14:38:48 WARN]:    at org.bukkit.craftbukkit.v1_8_R3.CraftServer.enablePlugins(CraftServer.java:313)
[14:38:48 WARN]:    at org.bukkit.craftbukkit.v1_8_R3.CraftServer.reload(CraftServer.java:721)
[14:38:48 WARN]:    at org.bukkit.Bukkit.reload(Bukkit.java:543)
[14:38:48 WARN]:    at org.bukkit.command.defaults.ReloadCommand.execute(ReloadCommand.java:25)
[14:38:48 WARN]:    at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:140)
[14:38:48 WARN]:    at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchCommand(CraftServer.java:621)
[14:38:48 WARN]:    at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchServerCommand(CraftServer.java:607)
[14:38:48 WARN]:    at net.minecraft.server.v1_8_R3.DedicatedServer.aO(DedicatedServer.java:371)
[14:38:48 WARN]:    at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:336)
[14:38:48 WARN]:    at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:632)
[14:38:48 WARN]:    at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:540)
[14:38:48 WARN]:    at java.lang.Thread.run(Thread.java:745)
[14:38:48 WARN]: Caused by: java.net.ConnectException: Connection refused
[14:38:48 WARN]:    at java.net.PlainSocketImpl.socketConnect(Native Method)
[14:38:48 WARN]:    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
[14:38:48 WARN]:    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
[14:38:48 WARN]:    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
[14:38:48 WARN]:    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
[14:38:48 WARN]:    at java.net.Socket.connect(Socket.java:579)
[14:38:48 WARN]:    at java.net.Socket.connect(Socket.java:528)
[14:38:48 WARN]:    at java.net.Socket.<init>(Socket.java:425)
[14:38:48 WARN]:    at java.net.Socket.<init>(Socket.java:241)
[14:38:48 WARN]:    at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:254)
[14:38:48 WARN]:    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:292)

Answer 1

我从未使用过这种方式连接到 SQL Server，假设您的代码是正确的，请检查您的主机以确保数据库端口已转发，并确保您的 IP 允许远程 SQL。如果一切都已完成并且效果良好，请尝试使用它进行连接。

Connection connection = DriverManager.getConnection("jdbc:mysql://"+getConfig().getString("database.host")+"/"+getConfig().getString("database.port")+"/"+getConfig().getString("database.dbname"), getConfig().getString("database.user"), getConfig().getString("database.pass"));