Java ClassVisitor类代码示例

import org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
private void writeConstructor(ClassVisitor visitor, Type generatedType, Type superclassType, StructSchema<?> delegateSchema, Type backingStateType) {
    String constructorDescriptor;
    Type delegateType;
    if (delegateSchema == null) {
        delegateType = null;
        constructorDescriptor = Type.getMethodDescriptor(Type.VOID_TYPE, backingStateType, TYPE_CONVERTER_TYPE);
    } else {
        delegateType = Type.getType(delegateSchema.getType().getConcreteClass());
        constructorDescriptor = Type.getMethodDescriptor(Type.VOID_TYPE, backingStateType, TYPE_CONVERTER_TYPE, delegateType);
    }
    MethodVisitor constructorVisitor = declareMethod(visitor, CONSTRUCTOR_NAME, constructorDescriptor, CONCRETE_SIGNATURE);

    invokeSuperConstructor(constructorVisitor, superclassType);
    assignStateField(constructorVisitor, generatedType);
    assignTypeConverterField(constructorVisitor, generatedType);
    if (delegateType != null) {
        assignDelegateField(constructorVisitor, generatedType, delegateType);
    }
    setCanCallSettersField(constructorVisitor, generatedType, true);
    finishVisitingMethod(constructorVisitor);
}
 

import org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
/**
 * See {@link org.objectweb.asm.util.CheckClassAdapter#CheckClassAdapter(ClassVisitor, boolean)}.
 * @param api the api version
 */
protected DrillCheckClassAdapter(final int api, final ClassVisitor cv,
    final boolean checkDataFlow) {
  super(api);

  /*
   * We set up a chain of class visitors:
   * this -> InnerAccessStripper -> CheckClassAdapter -> AccessRestorer -> cv
   * Note the AccessRestorer references accessStripper to get the original
   * access bits; the inner class could not be constructed before the call to
   * super(), hence the need to set the delegate after that.
   */
  accessStripper = new InnerClassAccessStripper(api, new CheckClassAdapter(
      new AccessRestorer(api, cv), checkDataFlow));
  setDelegate(accessStripper);
}
 

import org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
private void writeViewPropertyDslMethods(ClassVisitor visitor, Type generatedType, Collection<ModelProperty<?>> viewProperties, Class<?> viewClass) {
    boolean writable = Iterables.any(viewProperties, new Predicate<ModelProperty<?>>() {
        @Override
        public boolean apply(ModelProperty<?> viewProperty) {
            return viewProperty.isWritable();
        }
    });
    // TODO:LPTR Instead of the first view property, we should figure out these parameters from the actual property
    ModelProperty<?> firstProperty = viewProperties.iterator().next();

    writeConfigureMethod(visitor, generatedType, firstProperty, writable);
    writeSetMethod(visitor, generatedType, firstProperty);
    writeTypeConvertingSetter(visitor, generatedType, viewClass, firstProperty);

    // TODO - this should be applied to all methods, including delegating methods
    writeReadOnlySetter(visitor, viewClass, writable, firstProperty);
}
 

import org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
@Override
public void begin(final String name, final Attributes attrs) {
    String desc = attrs.getValue("desc");
    boolean visible = Boolean.valueOf(attrs.getValue("visible"))
            .booleanValue();
    int typeRef = Integer.parseInt(attrs.getValue("typeRef"));
    TypePath typePath = TypePath.fromString(attrs.getValue("typePath"));

    Object v = peek();
    if (v instanceof ClassVisitor) {
        push(((ClassVisitor) v).visitTypeAnnotation(typeRef, typePath,
                desc, visible));
    } else if (v instanceof FieldVisitor) {
        push(((FieldVisitor) v).visitTypeAnnotation(typeRef, typePath,
                desc, visible));
    } else if (v instanceof MethodVisitor) {
        push(((MethodVisitor) v).visitTypeAnnotation(typeRef, typePath,
                desc, visible));
    }
}
 

import org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
private void writeSetter(ClassVisitor visitor, Type generatedType, String propertyName, Class<?> propertyClass, WeaklyTypeReferencingMethod<?, ?> weakSetter) {
    Type propertyType = Type.getType(propertyClass);
    Label calledOutsideOfConstructor = new Label();

    Method setter = weakSetter.getMethod();

    // the regular typed setter
    String methodDescriptor = Type.getMethodDescriptor(Type.VOID_TYPE, propertyType);
    MethodVisitor methodVisitor = declareMethod(visitor, setter.getName(), methodDescriptor, AsmClassGeneratorUtils.signature(setter));

    putCanCallSettersFieldValueOnStack(methodVisitor, generatedType);
    jumpToLabelIfStackEvaluatesToTrue(methodVisitor, calledOutsideOfConstructor);
    throwExceptionBecauseCalledOnItself(methodVisitor);

    methodVisitor.visitLabel(calledOutsideOfConstructor);
    putStateFieldValueOnStack(methodVisitor, generatedType);
    putConstantOnStack(methodVisitor, propertyName);
    putFirstMethodArgumentOnStack(methodVisitor, propertyType);
    if (propertyClass.isPrimitive()) {
        boxType(methodVisitor, propertyClass);
    }
    invokeStateSetMethod(methodVisitor);

    finishVisitingMethod(methodVisitor);
}
 

import org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
private void generateTests() throws IOException {
  ClassReader cr = new ClassReader(new FileInputStream(classNamePath.toFile()));
  ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);
  cr.accept(
      new ClassVisitor(Opcodes.ASM5, cw) {
        @Override
        public void visitEnd() {
          generateMethodTest1(cw);
          generateMethodTest2(cw);
          generateMethodTest3(cw);
          generateMethodTest4(cw);
          generateMethodTest5(cw);
          generateMethodTest6(cw);
          generateMethodTest7(cw);
          generateMethodTest8(cw);
          generateMethodTest9(cw);
          generateMethodTest10(cw);
          generateMethodTest11(cw);
          generateMethodTest12(cw);
          generateMethodTest13(cw);
          generateMethodMain(cw);
          super.visitEnd();
        }
      }, 0);
  new FileOutputStream(classNamePath.toFile()).write(cw.toByteArray());
}
 

import org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
/**
 *  Generate test with an invokedynamic, a static bootstrap method without extra args and
 *  args to the target method.
 */
private void generateMethodTest2(ClassVisitor cv) {
  MethodVisitor mv = cv.visitMethod(Opcodes.ACC_PUBLIC + Opcodes.ACC_STATIC, "test2", "()V",
      null, null);
  MethodType mt = MethodType.methodType(
          CallSite.class, MethodHandles.Lookup.class, String.class, MethodType.class);
  Handle bootstrap = new Handle( Opcodes.H_INVOKESTATIC, Type.getInternalName(InvokeCustom.class),
      "bsmLookupStatic", mt.toMethodDescriptorString(), false);
  mv.visitLdcInsn(new Boolean(true));
  mv.visitLdcInsn(new Byte((byte) 127));
  mv.visitLdcInsn(new Character('c'));
  mv.visitLdcInsn(new Short((short) 1024));
  mv.visitLdcInsn(new Integer(123456));
  mv.visitLdcInsn(new Float(1.2f));
  mv.visitLdcInsn(new Long(123456789));
  mv.visitLdcInsn(new Double(3.5123456789));
  mv.visitLdcInsn("String");
  mv.visitInvokeDynamicInsn("targetMethodTest2", "(ZBCSIFJDLjava/lang/String;)V", bootstrap);
  mv.visitInsn(Opcodes.RETURN);
  mv.visitMaxs(-1, -1);
}
 

import org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
/**
 *  Generate test with an invokedynamic, a static bootstrap method with an extra arg that is a
 *  MethodHandle of kind invokespecial.
 */
private void generateMethodTest4(ClassVisitor cv) {
  MethodVisitor mv = cv.visitMethod(Opcodes.ACC_PUBLIC + Opcodes.ACC_STATIC, "test4", "()V",
      null, null);
  MethodType mt = MethodType.methodType(CallSite.class, MethodHandles.Lookup.class, String.class,
      MethodType.class, MethodHandle.class);
  Handle bootstrap = new Handle( Opcodes.H_INVOKESTATIC, Type.getInternalName(InvokeCustom.class),
      "bsmCreateCallSite", mt.toMethodDescriptorString(), false);
  mv.visitTypeInsn(Opcodes.NEW, Type.getInternalName(InvokeCustom.class));
  mv.visitInsn(Opcodes.DUP);
  mv.visitMethodInsn(
      Opcodes.INVOKESPECIAL, Type.getInternalName(InvokeCustom.class), "<init>", "()V", false);
  mv.visitInvokeDynamicInsn("targetMethodTest5", "(Linvokecustom/InvokeCustom;)V", bootstrap,
      new Handle( Opcodes.H_INVOKESPECIAL, Type.getInternalName(Super.class),
          "targetMethodTest5", "()V", false));
  mv.visitInsn(Opcodes.RETURN);
  mv.visitMaxs(-1, -1);
}
 

import org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
/**
 *  Generate test with an invokedynamic, a static bootstrap method with an extra arg that is a
 *  MethodHandle of kind invoke interface. The target method is a default method into an interface
 *  that is at the end of a chain of interfaces.
 */
private void generateMethodTest6(ClassVisitor cv) {
  MethodVisitor mv = cv.visitMethod(Opcodes.ACC_PUBLIC + Opcodes.ACC_STATIC, "test6", "()V",
      null, null);
  MethodType mt = MethodType.methodType(CallSite.class, MethodHandles.Lookup.class, String.class,
      MethodType.class, MethodHandle.class);
  Handle bootstrap = new Handle(Opcodes.H_INVOKESTATIC, Type.getInternalName(InvokeCustom.class),
      "bsmCreateCallCallingtargetMethodTest7", mt.toMethodDescriptorString(), false);
  mv.visitTypeInsn(Opcodes.NEW, Type.getInternalName(InvokeCustom.class));
  mv.visitInsn(Opcodes.DUP);
  mv.visitMethodInsn(
      Opcodes.INVOKESPECIAL, Type.getInternalName(InvokeCustom.class), "<init>", "()V", false);
  mv.visitInvokeDynamicInsn("targetMethodTest7", "(Linvokecustom/J;)V", bootstrap,
      new Handle(Opcodes.H_INVOKEINTERFACE, Type.getInternalName(J.class),
          "targetMethodTest7", "()V", true));
  mv.visitInsn(Opcodes.RETURN);
  mv.visitMaxs(-1, -1);
}
 

import org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
/**
 *  Generate test with an invokedynamic, a static bootstrap method with an extra arg that is a
 *  MethodHandle of kind invoke interface. The target method is a method into an interface
 *  that is shadowed by another definition into a sub interfaces.
 */
private void generateMethodTest7(ClassVisitor cv) {
  MethodVisitor mv = cv.visitMethod(Opcodes.ACC_PUBLIC + Opcodes.ACC_STATIC, "test7", "()V",
      null, null);
  MethodType mt = MethodType.methodType(CallSite.class, MethodHandles.Lookup.class, String.class,
      MethodType.class, MethodHandle.class);
  Handle bootstrap = new Handle(Opcodes.H_INVOKESTATIC, Type.getInternalName(InvokeCustom.class),
      "bsmCreateCallCallingtargetMethodTest8", mt.toMethodDescriptorString(), false);
  mv.visitTypeInsn(Opcodes.NEW, Type.getInternalName(InvokeCustom.class));
  mv.visitInsn(Opcodes.DUP);
  mv.visitMethodInsn(
      Opcodes.INVOKESPECIAL, Type.getInternalName(InvokeCustom.class), "<init>", "()V", false);
  mv.visitInvokeDynamicInsn("targetMethodTest8", "(Linvokecustom/J;)V", bootstrap,
      new Handle(Opcodes.H_INVOKEINTERFACE, Type.getInternalName(J.class),
          "targetMethodTest8", "()V", true));
  mv.visitInsn(Opcodes.RETURN);
  mv.visitMaxs(-1, -1);
}
 

import org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
/**
 *  Generate test with an invokedynamic, a static bootstrap method with an extra arg that is a
 *  MethodHandle of kind invoke virtual. The target method is a method into a class implementing
 *  an abstract method and that shadows a default method from an interface.
 */
private void generateMethodTest9(ClassVisitor cv) {
  MethodVisitor mv = cv.visitMethod(Opcodes.ACC_PUBLIC + Opcodes.ACC_STATIC, "test9", "()V",
      null, null);
  MethodType mt = MethodType.methodType(CallSite.class, MethodHandles.Lookup.class, String.class,
      MethodType.class, MethodHandle.class);
  Handle bootstrap = new Handle(Opcodes.H_INVOKESTATIC, Type.getInternalName(InvokeCustom.class),
      "bsmCreateCallCallingtargetMethodTest10", mt.toMethodDescriptorString(), false);
  mv.visitTypeInsn(Opcodes.NEW, Type.getInternalName(InvokeCustom.class));
  mv.visitInsn(Opcodes.DUP);
  mv.visitMethodInsn(
      Opcodes.INVOKESPECIAL, Type.getInternalName(InvokeCustom.class), "<init>", "()V", false);
  mv.visitInvokeDynamicInsn("targetMethodTest10", "(Linvokecustom/InvokeCustom;)V", bootstrap,
      new Handle(Opcodes.H_INVOKEVIRTUAL, Type.getInternalName(InvokeCustom.class),
          "targetMethodTest10", "()V", false));
  mv.visitInsn(Opcodes.RETURN);
  mv.visitMaxs(-1, -1);
}
 

import org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
/**
 *  Generate test with an invokedynamic, a static bootstrap method with an extra arg that is a
 *  MethodHandle of kind get static. The method handle read a static field from a class.
 */
private void generateMethodTest10(ClassVisitor cv) {
  MethodVisitor mv = cv.visitMethod(Opcodes.ACC_PUBLIC + Opcodes.ACC_STATIC, "test10", "()V",
      null, null);
  MethodType mt = MethodType.methodType(CallSite.class, MethodHandles.Lookup.class, String.class,
      MethodType.class, MethodHandle.class);
  Handle bootstrap = new Handle(Opcodes.H_INVOKESTATIC, Type.getInternalName(InvokeCustom.class),
      "bsmCreateCallCallingtargetMethod", mt.toMethodDescriptorString(), false);
  mv.visitFieldInsn(Opcodes.GETSTATIC,
      "java/lang/System",
      "out",
      "Ljava/io/PrintStream;");
  mv.visitInvokeDynamicInsn("staticField1", "()Ljava/lang/String;", bootstrap,
      new Handle(Opcodes.H_GETSTATIC, Type.getInternalName(InvokeCustom.class),
          "staticField1", "Ljava/lang/String;", false));
  mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL,
      "java/io/PrintStream",
      "println",
      "(Ljava/lang/String;)V", false);
  mv.visitInsn(Opcodes.RETURN);
  mv.visitMaxs(-1, -1);
}
 

import org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
/**
 *  Generate test with an invokedynamic, a static bootstrap method with an extra arg that is a
 *  MethodHandle of kind get instance. The method handle read an instance field from a class.
 */
private void generateMethodTest12(ClassVisitor cv) {
  MethodVisitor mv = cv.visitMethod(Opcodes.ACC_PUBLIC + Opcodes.ACC_STATIC, "test12", "()V",
      null, null);
  MethodType mt = MethodType.methodType(CallSite.class, MethodHandles.Lookup.class, String.class,
      MethodType.class, MethodHandle.class);
  Handle bootstrap = new Handle(Opcodes.H_INVOKESTATIC, Type.getInternalName(InvokeCustom.class),
      "bsmCreateCallCallingtargetMethod", mt.toMethodDescriptorString(), false);
  mv.visitFieldInsn(Opcodes.GETSTATIC,
      "java/lang/System",
      "out",
      "Ljava/io/PrintStream;");
  mv.visitTypeInsn(Opcodes.NEW, Type.getInternalName(InvokeCustom.class));
  mv.visitInsn(Opcodes.DUP);
  mv.visitMethodInsn(
      Opcodes.INVOKESPECIAL, Type.getInternalName(InvokeCustom.class), "<init>", "()V", false);
  mv.visitInvokeDynamicInsn("instanceField1", "(Linvokecustom/InvokeCustom;)Ljava/lang/String;",
      bootstrap, new Handle(Opcodes.H_GETFIELD, Type.getInternalName(InvokeCustom.class),
          "instanceField1", "Ljava/lang/String;", false));
  mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL,
      "java/io/PrintStream",
      "println",
      "(Ljava/lang/String;)V", false);
  mv.visitInsn(Opcodes.RETURN);
  mv.visitMaxs(-1, -1);
}
 

import org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
@Override
    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {

        if(className.startsWith(TransformConfig.getInstance().getPackageScan())) {
            logger.log(Level.INFO, "-------------------CLASS---------------------");
            logger.log(Level.INFO, "className: " + className);
            ClassReader cr = new ClassReader(classfileBuffer);
            ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS);

            ClassVisitor classVisitor = new HookClassAdapter(Opcodes.ASM5, cw);
            cr.accept(classVisitor, ClassReader.SKIP_FRAMES);
//            try {
//                FileOutputStream fos = new FileOutputStream(new File("classMod.class"));
//                fos.write(cw.toByteArray());
//                fos.close();
//            } catch (IOException e) {
//                e.printStackTrace();
//            }

            return cw.toByteArray();
        }
        return null;

    }
 

import org.objectweb.asm.ClassVisitor; //导入依赖的package包/类
/**
 * Generate simple <pre>super()</pre> calling constructor
 *
 * @param classVisitor ClassVisitor instance
 * @param superClass Super class name (use {@link Object} for non-extending classes
 *                   (or explictly extending Object, which is redundant anyway)
 */
public static void generateSimpleSuperConstructor(@NotNull ClassVisitor classVisitor, @NotNull String superClass) {
    MethodVisitor mv = Ensure.notNull(classVisitor, "ClassWriter shouldn't be null!")
            .visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
    mv.visitCode();
    mv.visitVarInsn(ALOAD, 0);
    mv.visitMethodInsn(INVOKESPECIAL, unqualifyName(superClass), "<init>", "()V", false);
    mv.visitInsn(RETURN);
    mv.visitMaxs(1, 0);
    mv.visitEnd();
}