我正在尝试使用MySQL支持制作Bukkit插件。我正在制作的插件是一个eco插件，因此我必须将所有播放器的名称放在MySQL表中。如果尚未注册，我正在使用PlayerJoinEvent在数据库中注册该播放器。当我启用我的插件时，它没有给出任何错误，但是当玩家加入时（即当PlayerJoinEvent被触发时）会出现错误。
在onEnable（）
中调用connect（）方法我得到的错误
[19:07:54 INFO]: UUID of player behhhans is da772a82-cdc9-3b79-962b-4cdc7623dd7a
[19:07:54 ERROR]: Could not pass event PlayerLoginEvent to Tokeconomy v1.0
org.bukkit.event.EventException
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:294) ~[spigot.jar:git-Spigot-1523]
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.jav
a:62) ~[spigot.jar:git-Spigot-1523]
at org.bukkit.plugin.TimedRegisteredListener.callEvent(TimedRegisteredLi
stener.java:30) ~[spigot.jar:git-Spigot-1523]
at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.j
ava:502) [spigot.jar:git-Spigot-1523]
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.j
ava:487) [spigot.jar:git-Spigot-1523]
at net.minecraft.server.v1_7_R3.PlayerList.attemptLogin(PlayerList.java:
400) [spigot.jar:git-Spigot-1523]
at net.minecraft.server.v1_7_R3.LoginListener.c(LoginListener.java:97) [
spigot.jar:git-Spigot-1523]
at net.minecraft.server.v1_7_R3.LoginListener.a(LoginListener.java:43) [
spigot.jar:git-Spigot-1523]
at net.minecraft.server.v1_7_R3.NetworkManager.a(NetworkManager.java:187
) [spigot.jar:git-Spigot-1523]
at net.minecraft.server.v1_7_R3.ServerConnection.c(ServerConnection.java
:81) [spigot.jar:git-Spigot-1523]
at net.minecraft.server.v1_7_R3.MinecraftServer.v(MinecraftServer.java:7
20) [spigot.jar:git-Spigot-1523]
at net.minecraft.server.v1_7_R3.DedicatedServer.v(DedicatedServer.java:2
83) [spigot.jar:git-Spigot-1523]
at net.minecraft.server.v1_7_R3.MinecraftServer.u(MinecraftServer.java:5
83) [spigot.jar:git-Spigot-1523]
at net.minecraft.server.v1_7_R3.MinecraftServer.run(MinecraftServer.java
:489) [spigot.jar:git-Spigot-1523]
at net.minecraft.server.v1_7_R3.ThreadServerApplication.run(SourceFile:6
28) [spigot.jar:git-Spigot-1523]
Caused by: java.lang.NullPointerException
at me.bramhaag.Tokeconomy.MySQLHandler.createAccount(MySQLHandler.java:1
02) ~[?:?]
at me.bramhaag.Tokeconomy.EventListener.onLogin(EventListener.java:27) ~
[?:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.7.0
_65]
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.7.0
_65]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1
.7.0_65]
at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.7.0_65]
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:292) ~[spigot.jar:git-Spigot-1523]
... 14 more
[19:07:54 INFO]: behhhans[/127.0.0.1:57702] logged in with entity id 6067 at ([w
orld] 710.6999999880791, 41.0, 309.4669731960532)
MySQLHandler类：
package me.bramhaag.Tokeconomy;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class MySQLHandler {
private Main plugin;
public MySQLHandler (Main plugin)
{
this.plugin = plugin;
}
Connection conn = null;
private String host, port, user, password, database;
public MySQLHandler(String host, String port, String database, String user, String password) {
this.host = host; this.port = port; this.user = user; this.password = password; this.database = database;
}
public void connect() {
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://" + host + ":" + port + "/" + database + "?user=" + user + "&password=" + password);
conn.createStatement().execute("CREATE TABLE IF NOT EXISTS `tokens` (`Name` varchar(32), `amount` int)");
} catch (ClassNotFoundException e) { e.printStackTrace();
} catch (SQLException e) { e.printStackTrace(); }
}
public void createAccount(String player) throws SQLException {
try (PreparedStatement pstat = conn.prepareStatement("SELECT 1 FROM tokens WHERE name=? LIMIT 1"))// Error line (Line 102)!
{
pstat.setString(1, player);
try (ResultSet rs = pstat.executeQuery())
{
if (!rs.next())
{
pstat.executeUpdate("UPDATE `tokens` (`Name`,`amount`) VALUE ('" + player + "', '" + 0 + "')");
}
}
}
}
public void updateLast(String player) {
try {
conn.createStatement().execute("UPDATE `bsp` SET `lastlogin` = '"+ String.valueOf(System.currentTimeMillis()) +"'");
} catch (SQLException e) { e.printStackTrace(); }
}
public int getTokens(String pname) throws SQLException {
ResultSet rs = conn.createStatement().executeQuery("SELECT * FROM `tokens` WHERE `Name`='"+ pname + "';");
if(!rs.next()) {
return 0;
}
return rs.getInt("amount");
}
public void updatePlayerAdd(String pname, double amount) throws SQLException {
int tokens = this.getTokens(pname);
if(tokens!=0) {
conn.createStatement().executeUpdate("UPDATE `tokens` SET `amount`='"+ (tokens + amount)+"' WHERE `Name`='"+ pname + "';");
} else {
conn.createStatement().executeUpdate("INSERT INTO `tokens` (`Name`, `amount`) VALUES('" + pname +",'1');");
}
}
public void updatePlayerReject(String pname, double amount) throws SQLException {
int tokens = this.getTokens(pname);
if(tokens!=0) {
conn.createStatement().executeUpdate("UPDATE `tokens` SET `amount`='"+ (tokens - amount)+"' WHERE `Name`='"+ pname + "';");
} else {
conn.createStatement().executeUpdate("INSRT INTO `tokens` (`Name`, `amount`) VALUES('" + pname +",'1');");
}
}
public void updatePlayerSet(String pname, double amount) throws SQLException {
int tokens = this.getTokens(pname);
if(tokens!=0) {
conn.createStatement().executeUpdate("UPDATE `tokens` SET `amount`='"+ (amount)+"' WHERE `Name`='"+ pname + "';");
} else {
conn.createStatement().executeUpdate("INSRT INTO `tokens` (`Name`, `amount`) VALUES('" + pname +",'1');");
}
}
}
EventHandler类：
package me.bramhaag.Tokeconomy;
import java.sql.SQLException;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerJoinEvent;
public class EventListener implements Listener {
private Main plugin;
public EventListener (Main plugin)
{
this.plugin = plugin;
}
MySQLHandler mysql = new MySQLHandler(plugin);
@EventHandler
public void onJoin(PlayerJoinEvent e) throws SQLException {
Player p = e.getPlayer();
String name = p.getName();
mysql.createAccount(name);
}
}
有人可能会查看我的代码并找到错误吗？
由于
答案 0 :(得分：1)
我必须要使用它：
DriverManager.getConnection("jdbc:mysql://" + this.hostname + ":" + this.port + "/" + this.database, this.user, this.password);