# Minecraft Fabric Modding - Command

~~指令的創建共分為三個部分：`Mixin + DataSaver`、`Command`、`Events`~~

## Mixin + Data Saver

在 `mixin` 資料夾中加入 `ModEntityDataSaver.java`：

@Mixin(Entity.class)
public abstract class ModEntityDataSaver implements IEntityDataSaver {
    private NbtCompound persistentData;

    @Override
    public NbtCompound getPersistentData() {
        if(this.persistentData == null) {
            this.persistentData = new NbtCompound();
        }
        return persistentData;
    }

    @Inject(method = "writeNbt", at = @At("HEAD"))
    protected void injectWriteMethod(NbtCompound nbt, CallbackInfoReturnable info) {
        if(persistentData != null) {
            nbt.put("<ModId>.player_data", persistentData);
        }
    }

    @Inject(method = "readNbt", at = @At("HEAD"))
    protected void injectReadMethod(NbtCompound nbt, CallbackInfo info) {
        if (nbt.contains("<ModId>.player_data", 10)) {
            persistentData = nbt.getCompound("<ModId>.player_data");
        }
    }
}

在 `util` 資料夾中以介面(interface)形式加入 `IEntityDataSaver.java`：

public interface IEntityDataSaver {
    NbtCompound getPersistentData();
}

## Command

以下以 SetHome、ReturnHome 為例。

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###### tags: `Minecraft Fabric Modding`