aop技术

粗粒度，细粒度

使用代理

客户端------>代理对象----->目标对象

代理放行了，就调用目标对象的方法

静态代理（很少用），动态代理

为目标对象创建动态代理对象，Proxy类，jdk提供

InvocationHandler其实是回调

public class JDKProxyFactory implements InvocationHandler {
    private Object targetObject;
    public Object createProxyInstance(Object targetObject){
        this.targetObject=targetObject;
        //生成的动态代理实例要实现目标代理的所有接口
        return Proxy.newProxyInstance(
                this.targetObject.getClass().getClassLoader(),
                this.targetObject.getClass().getInterfaces(),this);
        
    }
    @Override
    public Object invoke(Object proxy, Method method, Object[] args)
            throws Throwable {
        // TODO Auto-generated method stub
        System.out.println("begin invoking....");
        PersonServiceBean personService=(PersonServiceBean)this.targetObject;
        Object result=null;
        if(personService.getUser()!=null){
            result=method.invoke(targetObject, args);
        }else{
            System.out.println("你没有权限");
        }
        System.out.println("end invoking....");
        
        return result;
    }
}

测试代码

@Test
    public void proxyTest(){
        JDKProxyFactory factory=new JDKProxyFactory();
        PersonService service=(PersonService) factory.createProxyInstance(new PersonServiceBean("aaa"));
        service.save("bbb");
    }

输出：

begin invoking....
save
end invoking....

如果目标对象没有实现任何接口

使用cglib-nodep-2.1_3.jar

public class CGlibProxyFactory implements MethodInterceptor{
    private Object targetObject;
    public Object createProxyInstance(Object targetObject){
        this.targetObject=targetObject;
        Enhancer enhancer=new Enhancer();
        enhancer.setSuperclass(this.targetObject.getClass());
        enhancer.setCallback(this);
        return enhancer.create();
    }
    @Override
    public Object intercept(Object proxy, Method method, Object[] args,
            MethodProxy methodProxy) throws Throwable {
        // TODO Auto-generated method stub
        PersonServiceBean bean=(PersonServiceBean) this.targetObject;
        Object result=null;
        if(bean.getUser()!=null){
            result=methodProxy.invoke(this.targetObject, args);
        }
        return null;
    }
}