Java tutorial
/* * This file is part of Sponge, licensed under the MIT License (MIT). * * Copyright (c) SpongePowered.org <http://www.spongepowered.org> * Copyright (c) contributors * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ package org.spongepowered.mod.asm.transformers; import static org.objectweb.asm.ClassWriter.COMPUTE_FRAMES; import static org.objectweb.asm.ClassWriter.COMPUTE_MAXS; import net.minecraft.launchwrapper.IClassTransformer; import net.minecraftforge.fml.common.event.FMLEvent; import net.minecraftforge.fml.common.eventhandler.Cancelable; import net.minecraftforge.fml.common.eventhandler.Event; import org.apache.logging.log4j.Logger; import org.objectweb.asm.ClassReader; import org.objectweb.asm.ClassWriter; import org.objectweb.asm.Opcodes; import org.objectweb.asm.Type; import org.objectweb.asm.tree.AnnotationNode; import org.objectweb.asm.tree.ClassNode; import org.objectweb.asm.tree.FieldInsnNode; import org.objectweb.asm.tree.InsnNode; import org.objectweb.asm.tree.MethodInsnNode; import org.objectweb.asm.tree.MethodNode; import org.objectweb.asm.tree.VarInsnNode; import org.spongepowered.api.event.state.InitializationEvent; import org.spongepowered.api.event.state.PreInitializationEvent; import org.spongepowered.api.event.state.ServerStartingEvent; import org.spongepowered.asm.util.ASMHelper; import java.io.File; import java.util.ArrayList; import java.util.HashMap; import java.util.Map; @Cancelable public class EventTransformer implements IClassTransformer { private static final Map<String, Class<?>> events = new HashMap<String, Class<?>>(); static { events.put("net.minecraftforge.fml.common.event.FMLPreInitializationEvent", PreInitializationEvent.class); events.put("net.minecraftforge.fml.common.event.FMLInitializationEvent", InitializationEvent.class); events.put("net.minecraftforge.fml.common.event.FMLServerStartingEvent", ServerStartingEvent.class); } protected static MethodNode createGetGameMethod() { MethodNode methodNode = new MethodNode(Opcodes.ASM4, Opcodes.ACC_PUBLIC, "getGame", "()Lorg/spongepowered/api/Game;", null, null); methodNode.instructions.add(new FieldInsnNode(Opcodes.GETSTATIC, "org/spongepowered/mod/SpongeMod", "instance", "Lorg/spongepowered/mod/SpongeMod;")); methodNode.instructions.add(new MethodInsnNode(Opcodes.INVOKEVIRTUAL, "org/spongepowered/mod/SpongeMod", "getGame", "()Lorg/spongepowered/mod/SpongeGame;", false)); methodNode.instructions.add(new InsnNode(Opcodes.ARETURN)); methodNode.maxLocals = 1; methodNode.maxStack = 1; return methodNode; } protected static MethodNode createGetSimpleNameMethod() { MethodNode methodNode = new MethodNode(Opcodes.ASM4, Opcodes.ACC_PUBLIC, "getSimpleName", "()Ljava/lang/String;", null, null); methodNode.instructions.add(new VarInsnNode(Opcodes.ALOAD, 0)); methodNode.instructions.add(new MethodInsnNode(Opcodes.INVOKESPECIAL, "java/lang/Object", "getClass", "()Ljava/lang/Class;", false)); methodNode.instructions.add(new MethodInsnNode(Opcodes.INVOKEVIRTUAL, "java/lang/Class", "getSimpleName", "()Ljava/lang/String;", false)); methodNode.instructions.add(new InsnNode(Opcodes.ARETURN)); methodNode.maxLocals = 1; methodNode.maxStack = 1; return methodNode; } protected static MethodNode createIsCancellableMethod() { MethodNode methodNode = new MethodNode(Opcodes.ASM4, Opcodes.ACC_PUBLIC, "isCancellable", "()Z", null, null); methodNode.instructions.add(new VarInsnNode(Opcodes.ALOAD, 0)); methodNode.instructions.add(new MethodInsnNode(Opcodes.INVOKESPECIAL, "net/minecraftforge/fml/common/eventhandler/Event", "isCancelable", "()Z", false)); methodNode.instructions.add(new InsnNode(Opcodes.IRETURN)); methodNode.maxLocals = 1; methodNode.maxStack = 1; return methodNode; } protected static MethodNode createIsCancelledMethod() { MethodNode methodNode = new MethodNode(Opcodes.ASM4, Opcodes.ACC_PUBLIC, "isCancelled", "()Z", null, null); methodNode.instructions.add(new VarInsnNode(Opcodes.ALOAD, 0)); methodNode.instructions.add(new MethodInsnNode(Opcodes.INVOKESPECIAL, "net/minecraftforge/fml/common/eventhandler/Event", "isCanceled", "()Z", false)); methodNode.instructions.add(new InsnNode(Opcodes.IRETURN)); methodNode.maxLocals = 1; methodNode.maxStack = 1; return methodNode; } protected static MethodNode createSetCancelledMethod() { MethodNode methodNode = new MethodNode(Opcodes.ASM4, Opcodes.ACC_PUBLIC, "setCancelled", "(Z)V", null, null); methodNode.instructions.add(new VarInsnNode(Opcodes.ALOAD, 0)); methodNode.instructions.add(new VarInsnNode(Opcodes.ILOAD, 1)); methodNode.instructions.add(new MethodInsnNode(Opcodes.INVOKESPECIAL, "net/minecraftforge/fml/common/eventhandler/Event", "setCanceled", "(Z)V", false)); methodNode.instructions.add(new InsnNode(Opcodes.RETURN)); methodNode.maxLocals = 1; methodNode.maxStack = 1; return methodNode; } @Override public byte[] transform(String name, String transformedName, byte[] bytes) { if (bytes == null || transformedName.startsWith("net.minecraft.") || transformedName.equals("net.minecraftforge.fml.common.event.FMLEvent") || transformedName.equals("net.minecraftforge.fml.common.eventhandler.Event") || transformedName.indexOf('.') == -1) { return bytes; } try { ClassReader cr = new ClassReader(bytes); ClassNode classNode = new ClassNode(); cr.accept(classNode, 0); String parentName = classNode.superName.replace('/', '.'); Class<?> parent = this.getClass().getClassLoader().loadClass(parentName); // Only process FMLEvents and Forge Events sub-classes if ((!Event.class.isAssignableFrom(parent)) && (!FMLEvent.class.isAssignableFrom(parent))) { return bytes; } Class<?> interf = events.get(transformedName); if (interf != null && interf.isInterface()) { String interfaceName = Type.getInternalName(interf); classNode.interfaces.add(interfaceName); } // Method forwarding for all events classNode.methods.add(createGetGameMethod()); classNode.methods.add(createGetSimpleNameMethod()); if (Event.class.isAssignableFrom(parent)) { // Forge Event method forwarding if (classNode.interfaces.contains("org/spongepowered/api/event/Cancellable")) { if (classNode.visibleAnnotations == null) { classNode.visibleAnnotations = new ArrayList<AnnotationNode>(); } classNode.visibleAnnotations .add(new AnnotationNode("Lnet/minecraftforge/fml/common/eventhandler/Cancelable;")); classNode.methods.add(createIsCancelledMethod()); classNode.methods.add(createSetCancelledMethod()); } classNode.methods.add(createIsCancellableMethod()); } // TODO: This is a temporary thing to make PreInit work. The different things needed to make different events work should be abstracted. if (interf != null && PreInitializationEvent.class.isAssignableFrom(interf)) { ASMHelper.generateSelfForwardingMethod(classNode, "getConfigurationDirectory", "getModConfigurationDirectory", Type.getType(File.class)); ASMHelper.generateSelfForwardingMethod(classNode, "getPluginLog", "getModLog", Type.getType(Logger.class)); } ClassWriter cw = new ClassWriter(cr, COMPUTE_MAXS | COMPUTE_FRAMES); classNode.accept(cw); return cw.toByteArray(); } catch (Throwable t) { t.printStackTrace(); return bytes; } } }