/** Generate class bytes for java.lang.Runnable implementation and return the same. */ public byte[] generate(Method method, String className) { int modifiers = method.getModifiers(); // make sure that the method is public static // and accepts no arguments if (!Modifier.isStatic(modifiers) || !Modifier.isPublic(modifiers) || method.getParameterTypes().length != 0) { throw new IllegalArgumentException(); } Class clazz = method.getDeclaringClass(); modifiers = clazz.getModifiers(); // make sure that the class is public as well if (!Modifier.isPublic(modifiers)) { throw new IllegalArgumentException(); } ClassWriter cw = InstrumentUtils.newClassWriter(); cw.visit( V1_1, ACC_PUBLIC, className, null, "java/lang/Object", new String[] {"java/lang/Runnable"}); // creates a MethodWriter for the (implicit) constructor MethodVisitor mw = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null); // pushes the 'this' variable mw.visitVarInsn(ALOAD, 0); // invokes the super class constructor mw.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V"); mw.visitInsn(RETURN); mw.visitMaxs(1, 1); mw.visitEnd(); // creates a MethodWriter for the 'main' method mw = cw.visitMethod(ACC_PUBLIC, "run", "()V", null, null); // invokes the given method mw.visitMethodInsn( INVOKESTATIC, Type.getInternalName(method.getDeclaringClass()), method.getName(), Type.getMethodDescriptor(method)); mw.visitInsn(RETURN); mw.visitMaxs(1, 1); mw.visitEnd(); return cw.toByteArray(); }
public static void main(final String[] args) throws Exception { if (args.length != 1) { System.err.println("Usage: java com.sun.btrace.runtime.ErrorReturnInstrumentor <class>"); System.exit(1); } args[0] = args[0].replace('.', '/'); FileInputStream fis = new FileInputStream(args[0] + ".class"); ClassReader reader = new ClassReader(new BufferedInputStream(fis)); FileOutputStream fos = new FileOutputStream(args[0] + ".class"); ClassWriter writer = InstrumentUtils.newClassWriter(); InstrumentUtils.accept( reader, new ClassVisitor(Opcodes.ASM4, writer) { public MethodVisitor visitMethod( int access, String name, String desc, String signature, String[] exceptions) { MethodVisitor mv = super.visitMethod(access, name, desc, signature, exceptions); return new ErrorReturnInstrumentor(mv, null, args[0], args[0], access, name, desc); } }); fos.write(writer.toByteArray()); }