Plugin Mixins

Warnung

These docs were written for SpongeAPI 7 and are likely out of date. If you feel like you can help update them, please submit a PR!

Mixins can be used to modify classes at runtime before they are loaded. You can use them in plugins if you want to optimize a part of the game specifically for your server - without having to fork Sponge. The modifications will be bundled directly with your plugin and are only active as long as the plugin is loaded.

Siehe auch

Mixin documentation: Mixin documentation including an introduction to Mixins.
Example plugin: Example plugin which uses Plugin Mixins to print a message when the server is starting.

Setup

Add the Mixin library as dependency to your plugin:

dependencies {
    compile 'org.spongepowered:mixin:0.7.11-SNAPSHOT'
}

Add a new Mixin configuration for your plugin, e.g. mixins.myplugin.json inside your resource folder:

{
    "required": true,
    "minVersion": "0.7.10",
    "package": "com.example.myplugin.mixin",
    "refmap": "mixins.myplugin.refmap.json",
    "target": "@env(DEFAULT)",
    "compatibilityLevel": "JAVA_8",
    "mixins": [
        "MixinMinecraftServer"
    ]
}

Add a Mixin class to the specified package:

package com.example.myplugin.mixin;

import net.minecraft.server.MinecraftServer;
import org.spongepowered.asm.mixin.Mixin;

@Mixin(MinecraftServer.class)
public abstract class MixinMinecraftServer {

}

Debuggen

Normally, the Mixin configuration is registered inside JAR manifest of the plugin. Since the plugin is not packaged in a JAR while debugging inside the IDE you need specify the Mixins to apply as command line options:

Add a --mixin <mixin config file name> option for each Mixin configuration file to the program arguments of your run configuration:
--mixin mixins.myplugin.json

Production

If your Mixin is working in your development environment you still need to make some changes to make it work in production:

Apply the MixinGradle plugin to your build script:

buildscript {
    repositories {
        maven {
            name = 'sponge'
            url = 'https://repo.spongepowered.org/repository/maven-public/'
        }
    }
    dependencies {
        classpath 'org.spongepowered:mixingradle:0.6-SNAPSHOT'
    }
}

apply plugin: 'org.spongepowered.mixin'

Set the refmap from your Mixin configuration:

sourceSets {
    main {
        ext.refMap = "mixins.myplugin.refmap.json"
    }
}

Add your Mixin configuration to the JAR manifest. The FMLCorePluginContainsFMLMod manifest entry is necessary if you want to load your Mixin on SpongeForge:

jar {
    manifest.attributes(
        'TweakClass': 'org.spongepowered.asm.launch.MixinTweaker',
        'MixinConfigs': 'mixins.myplugin.json',
        'FMLCorePluginContainsFMLMod': 'true',
    )
}

Make sure to re-build the plugin using Gradle. The Mixin should then get applied by SpongeVanilla and SpongeForge.
gradle clean build