Java - NotSerializedException(保存对象)

Question

所以今天我正在为 Minecraft 服务器开发一个插件。为此，我创建了一个代表赛道的“Track”类。为了存储所有现有轨道及其数据，我想保存整个轨道对象，这使一切对我来说更容易。总之，我在 Track 类中实现了 Serialized，以便稍后使用 ObjectOutputStream。当我开始保存轨道时，Java 创建了一个对象文件，但它也给了我一个警告/错误:

14:19:00] [Server thread/WARN]: java.io.NotSerializableException: org.bukkit.craftbukkit.v1_8_R2.CraftWorld [14:19:00] [Server thread/WARN]: at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1184) [14:19:00] [Server thread/WARN]: at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548) [14:19:00] [Server thread/WARN]: at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509) [14:19:00] [Server thread/WARN]: at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432) [14:19:00] [Server thread/WARN]: at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) [14:19:00] [Server thread/WARN]: at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348) [14:19:00] [Server thread/WARN]: at de.avarion.speedrunners.Main.saveTracks(Main.java:206) [14:19:00] [Server thread/WARN]: at de.avarion.speedrunners.Main.onDisable(Main.java:48) [14:19:00] [Server thread/WARN]: at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:323) [14:19:00] [Server thread/WARN]: at org.bukkit.plugin.java.JavaPluginLoader.disablePlugin(JavaPluginLoader.java:359) [14:19:00] [Server thread/WARN]: at org.bukkit.plugin.SimplePluginManager.disablePlugin(SimplePluginManager.java:424) [14:19:00] [Server thread/WARN]: at org.bukkit.plugin.SimplePluginManager.disablePlugins(SimplePluginManager.java:417) [14:19:00] [Server thread/WARN]: at org.bukkit.craftbukkit.v1_8_R2.CraftServer.disablePlugins(CraftServer.java:335) [14:19:00] [Server thread/WARN]: at net.minecraft.server.v1_8_R2.MinecraftServer.stop(MinecraftServer.java:458) [14:19:00] [Server thread/WARN]: at net.minecraft.server.v1_8_R2.MinecraftServer.run(MinecraftServer.java:590) [14:19:00] [Server thread/WARN]: at java.lang.Thread.run(Thread.java:745)

这是我的 Track 类(class)的一部分。我注意到 eclipse 警告我轨道类没有声明最终的静态serialVersionUID字段。我尝试实现默认并生成的serialVersionUID，但我没有帮助:

import java.io.Serializable;
import java.util.ArrayList;

import org.bukkit.GameMode;
import org.bukkit.Location;
import org.bukkit.Material;
import org.bukkit.World;
import org.bukkit.block.Sign;
import org.bukkit.entity.Player;

public class Track implements Serializable {

private int playerSize;

private String name;
private World world;
private ArrayList<Player> players;
private Location spawn;

private Sign sign;
private Material finishBlocks;
private Material speedBlocks;

public Track(World world, String name, int playerSize) {
    this.world = world;
    this.name = name; 
    this.playerSize = playerSize;
    this.players = new ArrayList<Player>();
}
//and so on.....

现在，这是我保存跟踪对象的代码片段:

private void saveTracks() {
    FileOutputStream outputStream = null;
    ObjectOutputStream objectOutput = null;
    try {
        File directory = new File("tracks");
        if(!directory.exists()) directory.mkdir();
        for(Track track : tracks) {
            outputStream = new FileOutputStream("tracks/" + track.getName() + ".ser");
            objectOutput = new ObjectOutputStream(outputStream);
            objectOutput.writeObject(track);
        }
    }
    catch (IOException e) {
          e.printStackTrace();
    }
    finally {
          if (objectOutput != null) try { objectOutput.close(); } catch (IOException e) {}
          if (outputStream != null) try { outputStream.close(); } catch (IOException e) {}
    }
}

就像我说的那样，Java 创建了对象，所以它可以工作。但我不知道如何摆脱警告。

感谢您的帮助

Answer 1

由于某些实例字段未序列化而引发此异常。所以请检查所有实例变量。如果某些实例变量不需要序列化，请向该变量添加transient。

根据 java 文档:

当实例需要具有可序列化接口(interface)时抛出。序列化运行时或实例的类可以抛出此异常。参数应该是类的名称。