org.fabric3.implementation.bytecode.reflection.BytecodeHelper Maven / Gradle / Ivy
/*
* Fabric3
* Copyright (c) 2009-2015 Metaform Systems
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* Portions originally based on Apache Tuscany 2007
* licensed under the Apache 2.0 license.
*/
package org.fabric3.implementation.bytecode.reflection;
import org.fabric3.implementation.pojo.spi.reflection.ServiceInvoker;
import org.fabric3.spi.classloader.BytecodeClassLoader;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
import static org.objectweb.asm.Opcodes.ACC_PUBLIC;
/**
*
*/
public class BytecodeHelper {
/**
* Creates a no-args constructor.
*
* @param cw the class writer
*/
public static void writeConstructor(ClassWriter cw, Class superType) {
String descriptor = Type.getDescriptor(ServiceInvoker.class);
MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, "", "()V", null, null);
mv.visitCode();
Label label = new Label();
mv.visitLabel(label);
mv.visitLineNumber(6, label);
mv.visitVarInsn(Opcodes.ALOAD, 0);
mv.visitMethodInsn(Opcodes.INVOKESPECIAL, Type.getInternalName(superType), "", "()V");
mv.visitInsn(Opcodes.RETURN);
Label l1 = new Label();
mv.visitLabel(l1);
mv.visitLocalVariable("this", descriptor, null, label, l1, 0);
mv.visitMaxs(1, 1);
mv.visitEnd();
}
/**
* Instantiates an instance of the class.
*
* @param type the expected type
* @param className the class name
* @param classLoader the classloader defining the class
* @param cw the class writer
* @return the instance
*/
public static T instantiate(Class type, String className, BytecodeClassLoader classLoader, ClassWriter cw) {
byte[] data = cw.toByteArray();
Class invokerClass = classLoader.defineClass(className, data);
try {
return type.cast(invokerClass.newInstance());
} catch (InstantiationException | IllegalAccessException e) {
throw new AssertionError(e);
}
}
}