spring笔记-AopProxy(AOP)

1.Spring对动态代理的支持

下图可以看到AopProxy接口实现了JDK和Cglib方式的动态代理支持,AopProxyFactory则负责创建AopProxy

2.JdkDynamicAopProxy的使用

我们先从JdkDynamicAopProxy的实际使用开始着手

代码示例1-JdkDynamicAopProxy的使用

    @Test
    public void testProxyIsJustInterface() throws Throwable {
        TestBean raw = new TestBean();
        raw.setAge(32);
        AdvisedSupport pc = new AdvisedSupport(ITestBean.class);
        pc.setTarget(raw);
        JdkDynamicAopProxy aop = new JdkDynamicAopProxy(pc);

        ITestBean proxy = (ITestBean) aop.getProxy();
        proxy.setName("test");
        assertTrue(proxy instanceof ITestBean);
        assertFalse(proxy instanceof TestBean);
    }

JdkDynamicAopProxy构造函数需要传入一个AdvisedSupport

3.AdvisedSupport

3.1 Advised

Advised接口提供了管理Advice接口以及Advisor接口的功能,Advice接口即增强类,会在方法执行前后执行,Advisor看3.3介绍

3.2 关于Advice的介绍

代码示例2-使用AdvisedSupport添加Advice

    @Test
    public void testProxy2() throws Throwable {
        TestBean raw = new TestBean();
        raw.setAge(32);
        AdvisedSupport pc = new AdvisedSupport(ITestBean.class);
        pc.setTarget(raw);

        {
            MethodBeforeAdvice mi = new MethodBeforeAdvice()
            {
                @Override
                public void before(Method method, Object[] args, Object target) throws Throwable {
                    System.out.println("before");
                }
            };
            pc.addAdvice(mi);
        }

        {
            AfterReturningAdvice mi = new AfterReturningAdvice()
            {
                @Override
                public void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable {
                    System.out.println("after");
                }
            };
            pc.addAdvice(mi);
        }

        JdkDynamicAopProxy aop = new JdkDynamicAopProxy(pc);

        ITestBean proxy = (ITestBean) aop.getProxy();
        proxy.setName("test");
        assertTrue(proxy instanceof ITestBean);
        assertFalse(proxy instanceof TestBean);
    }

输出结果:

before
setName
after

3.3 Advisor

Advisor是Pointcut和Advice的组合,比如上面的例子, ITestBean每次调用方法都会执行Advice相关代码,Pointcut相当于添加执行的条件,比如只在调用setName方法的时候执行

代码示例3-使用AdvisedSupport添加Advisor

    class TestBeanAdvisor extends StaticMethodMatcherPointcutAdvisor {

        public int count;

        public TestBeanAdvisor() {
            setAdvice(new MethodBeforeAdvice() {
                @Override
                public void before(Method method, Object[] args, @Nullable Object target) throws Throwable {
                    System.out.println("before");
                }
            });
        }

        @Override
        public boolean matches(Method method, @Nullable Class targetClass) {
            return method.getName().equals("setName");

        }
    }

    @Test
    public void testProxy3() throws Throwable {
        TestBean raw = new TestBean();
        raw.setAge(32);
        AdvisedSupport pc = new AdvisedSupport(ITestBean.class);
        pc.setTarget(raw);
        pc.addAdvisor(new TestBeanAdvisor());
        JdkDynamicAopProxy aop = new JdkDynamicAopProxy(pc);
        ITestBean proxy = (ITestBean) aop.getProxy();
        proxy.setName("test");
        proxy.setAge(2);
        assertTrue(proxy instanceof ITestBean);
        assertFalse(proxy instanceof TestBean);
    }

4.DefaultAopProxyFactory

可以用DefaultAopProxyFactory来根据ProxyConfig参数(AdvisedSupport)来动态创建AopProxy,比如设置optimize为true，则为cglib动态代理对象

使用DefaultAopProxyFactory创建AopProxy

    @Test
    public void testProxy4() throws Throwable {
        TestBean raw = new TestBean();
        raw.setAge(32);
        AdvisedSupport pc = new AdvisedSupport(ITestBean.class);
        pc.setTarget(raw);
        pc.addAdvisor(new TestBeanAdvisor());

        pc.setOptimize(true);

        AopProxyFactory aopProxyFactory=new DefaultAopProxyFactory();
        AopProxy aop = aopProxyFactory.createAopProxy(pc);
        ITestBean proxy = (ITestBean) aop.getProxy();
        proxy.setName("test");
        proxy.setAge(2);
    }

参考:
http://book.51cto.com/art/200908/147288.htm
https://www.jianshu.com/p/1dd6a26c881b