Spring的动态代理

AOP是Spring的重要组成部分，而AOP正是通过代理实现的。如果代理对象实现了接口，则默认使用jdk动态代理，也可强制使用cglib代理，如果未实现接口则只能使用cglib代理。

       JDK动态代理： https://chenjumin.iteye.com/blog/2437314， https://chenjumin.iteye.com/blog/339554

       CGLIB动态代理： https://chenjumin.iteye.com/blog/2437315

 

Spring提供三个代理处理类：ProxyFactory、ProxyFactoryBean、AspectJProxyFactory

 

先定义公共类：

public interface CountryMapper {
	void show();
}

public class CountryMapperImpl implements CountryMapper {
	@Override
	public void show(){
		System.out.println("invoke show...");
	}
}

public class CustomMethodInterceptor implements MethodInterceptor{
	@Override
	public Object invoke(MethodInvocation invocation) throws Throwable {
		System.out.println("before...");
        Object object = invocation.proceed();
        System.out.println("after...");
        return object;
	}
}

@Component("customMethodInterceptor2")
public class CustomMethodInterceptor2 implements MethodInterceptor{
	@Override
	public Object invoke(MethodInvocation invocation) throws Throwable {
		System.out.println("2 before...");
        Object object = invocation.proceed();
        System.out.println("2 after...");
        return object;
	}
}

 

ProxyFactory的使用范例：

@Test
public void test1()throws Exception{
	//代理对象未指定接口，使用CGLIB生成代理类
	ProxyFactory factory1 = new ProxyFactory();
	//factory1.setExposeProxy(true); //对外发布代理对象，在目标对象方法中可以通过AopContext.currentProxy()访问当前代理对象
	factory1.setTarget(new CountryMapperImpl());
	factory1.addAdvice(new CustomMethodInterceptor());
	CountryMapperImpl countryMapperImpl = (CountryMapperImpl) factory1.getProxy();
	countryMapperImpl.show();
}

@Test
public void test2()throws Exception{
	//代理对象指定接口，使用JDK Proxy生成代理类
	ProxyFactory factory2 = new ProxyFactory();
	//factory2.setExposeProxy(true);
	factory2.setInterfaces(new Class[] {CountryMapper.class});
	factory2.setTarget(new CountryMapperImpl());
	factory2.addAdvice(new CustomMethodInterceptor());
	CountryMapper countryMapper = (CountryMapper) factory2.getProxy();
	countryMapper.show();
}

 

ProxyFactoryBean的使用范例：

@Test
public void test3()throws Exception{
	//ProxyFactoryBean
	//AnnotationConfigApplicationContext 基于注解类的配置
	AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext("com.seasy");
	
	ProxyFactoryBean proxyFactoryBean = new ProxyFactoryBean();
	proxyFactoryBean.setBeanFactory(applicationContext.getBeanFactory());
	proxyFactoryBean.setInterfaces(CountryMapper.class);
	proxyFactoryBean.setInterceptorNames("customMethodInterceptor2");
	proxyFactoryBean.setTarget(applicationContext.getBean(CountryMapper.class));
	
	applicationContext.getBeanFactory().registerSingleton("proxyFactoryBean", proxyFactoryBean);
	CountryMapper countryMapper2 = (CountryMapper)applicationContext.getBean("proxyFactoryBean");
	countryMapper2.show();
}

 

AspectJProxyFactory的使用范例：

@Test
public void test4()throws Exception{
	//AspectJProxyFactory
	CountryMapper countryMapper3 = new CountryMapperImpl();
	AspectJProxyFactory proxyFactory = new AspectJProxyFactory();
	proxyFactory.setTarget(countryMapper3);
	proxyFactory.addAspect(MyAspect.class);
	proxyFactory.setProxyTargetClass(true);
	CountryMapper proxy = proxyFactory.getProxy();
	proxy.show();
}

@Aspect
public class MyAspect {
	@Pointcut("execution(* com.seasy..*(..))")
    private void beforeAdd() {}

    @Before("beforeAdd()")
    public void before1() {
        System.out.println("-----------before-----------");
    }
}