org.springframework.cglib.beans.ImmutableBean Maven / Gradle / Ivy

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/*
 * Copyright 2003,2004 The Apache Software Foundation
 *
 *  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
 *
 *      https://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.
 */
package org.springframework.cglib.beans;

import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;
import java.security.ProtectionDomain;

import org.springframework.asm.ClassVisitor;
import org.springframework.asm.Type;
import org.springframework.cglib.core.AbstractClassGenerator;
import org.springframework.cglib.core.ClassEmitter;
import org.springframework.cglib.core.CodeEmitter;
import org.springframework.cglib.core.Constants;
import org.springframework.cglib.core.EmitUtils;
import org.springframework.cglib.core.MethodInfo;
import org.springframework.cglib.core.ReflectUtils;
import org.springframework.cglib.core.Signature;
import org.springframework.cglib.core.TypeUtils;
/**
 * @author Chris Nokleberg
 */
@SuppressWarnings({"rawtypes", "unchecked"})
public class ImmutableBean
{
	private static final Type ILLEGAL_STATE_EXCEPTION =
	  TypeUtils.parseType("IllegalStateException");
	private static final Signature CSTRUCT_OBJECT =
	  TypeUtils.parseConstructor("Object");
	private static final Class[] OBJECT_CLASSES = { Object.class };
	private static final String FIELD_NAME = "CGLIB$RWBean";

	private ImmutableBean() {
	}

	public static Object create(Object bean) {
		Generator gen = new Generator();
		gen.setBean(bean);
		return gen.create();
	}

	public static class Generator extends AbstractClassGenerator {
		private static final Source SOURCE = new Source(ImmutableBean.class.getName());
		private Object bean;
		private Class target;

		public Generator() {
			super(SOURCE);
		}

		public void setBean(Object bean) {
			this.bean = bean;
			target = bean.getClass();
			// SPRING PATCH BEGIN
			setContextClass(target);
			// SPRING PATCH END
		}

		@Override
		protected ClassLoader getDefaultClassLoader() {
			return target.getClassLoader();
		}

		@Override
		protected ProtectionDomain getProtectionDomain() {
			return ReflectUtils.getProtectionDomain(target);
		}

		public Object create() {
			String name = target.getName();
			setNamePrefix(name);
			return super.create(name);
		}

		@Override
		public void generateClass(ClassVisitor v) {
			Type targetType = Type.getType(target);
			ClassEmitter ce = new ClassEmitter(v);
			ce.begin_class(Constants.V1_8,
						   Constants.ACC_PUBLIC,
						   getClassName(),
						   targetType,
						   null,
						   Constants.SOURCE_FILE);

			ce.declare_field(Constants.ACC_FINAL | Constants.ACC_PRIVATE, FIELD_NAME, targetType, null);

			CodeEmitter e = ce.begin_method(Constants.ACC_PUBLIC, CSTRUCT_OBJECT, null);
			e.load_this();
			e.super_invoke_constructor();
			e.load_this();
			e.load_arg(0);
			e.checkcast(targetType);
			e.putfield(FIELD_NAME);
			e.return_value();
			e.end_method();

			PropertyDescriptor[] descriptors = ReflectUtils.getBeanProperties(target);
			Method[] getters = ReflectUtils.getPropertyMethods(descriptors, true, false);
			Method[] setters = ReflectUtils.getPropertyMethods(descriptors, false, true);

			for (Method getter2 : getters) {
				MethodInfo getter = ReflectUtils.getMethodInfo(getter2);
				e = EmitUtils.begin_method(ce, getter, Constants.ACC_PUBLIC);
				e.load_this();
				e.getfield(FIELD_NAME);
				e.invoke(getter);
				e.return_value();
				e.end_method();
			}

			for (Method setter2 : setters) {
				MethodInfo setter = ReflectUtils.getMethodInfo(setter2);
				e = EmitUtils.begin_method(ce, setter, Constants.ACC_PUBLIC);
				e.throw_exception(ILLEGAL_STATE_EXCEPTION, "Bean is immutable");
				e.end_method();
			}

			ce.end_class();
		}

		@Override
		protected Object firstInstance(Class type) {
			return ReflectUtils.newInstance(type, OBJECT_CLASSES, new Object[]{ bean });
		}

		// TODO: optimize
		@Override
		protected Object nextInstance(Object instance) {
			return firstInstance(instance.getClass());
		}
	}
}