SpringFramework之ProxyFactory
Spring版本是5.0.4.release.
ProxyFactory在Springaop中占有举足轻重的地位，用来间接创建代理，如下List-1所示，我们给ServiceImpl创建代理。
List-1
public interface IService {
String hello();
}
public class ServiceImpl implements IService {
@Override
public String hello() {
System.out.println("service的hello方法");
return "Hello";
}
}
import org.springframework.aop.MethodBeforeAdvice;
import java.lang.reflect.Method;
public class BeforeAdvice implements MethodBeforeAdvice {
@Override
public void before(Method method, Object[] args, Object target) throws Throwable {
System.out.println("beforeAdvice的before方法");
}
}
import org.springframework.aop.AfterReturningAdvice;
import java.lang.reflect.Method;
public class AfterAdvice implements AfterReturningAdvice {
@Override
public void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable {
System.out.println("AfterAdvice的afterReturning方法");
}
}
import org.junit.Test;
import org.springframework.aop.framework.ProxyFactory;
public class AopTest {
@Test
public void test(){
ProxyFactory proxyFactory = new ProxyFactory();
proxyFactory.setInterfaces(IService.class);
proxyFactory.setTarget(new ServiceImpl());
proxyFactory.addAdvice(new BeforeAdvice());
proxyFactory.addAdvice(new AfterAdvice());
IService proxy = (IService) proxyFactory.getProxy();
String result = proxy.hello();
System.out.println(result);
}
}运行结果如下List-2
List-2
beforeAdvice的before方法
service的hello方法
AfterAdvice的afterReturning方法
HelloproxyFactory.addAdvice(new BeforeAdvice())时，会将Advice转换为Advisor，最后再调用addAdvisor方法。
当我们调用ProxyFactory的getProxy时，会先调用createAopProxy()->getAopProxyFactory().createAopProxy(this)，AopProxyFactory是DefaultAopProxyFactory——在另一篇里面讲到。createAopProxy方法里面把this传入，ProxyFactory实现了AdvisedSupport，所以在createAopProxy时将ProxyFactory中设置的targetSource、advice等传递到了DefaultAopProxyFactory，之后传递到JdkDynamicAopProxy中。
最后getProxy调用的是JdkDynamicAopProxy的getProxy方法，如下List-3所示，Proxy.newProxyInstance的方法中，最后的InvocationHandler是this——JdkDynamicAopProxy实现了InvocationHandler，所以当我们调用目标类的方法时，会调用JdkDynamicAopProxy的invoke方法。
List-3
public Object getProxy(@Nullable ClassLoader classLoader) {
if (logger.isDebugEnabled()) {
logger.debug("Creating JDK dynamic proxy: target source is " + this.advised.getTargetSource());
}
Class<?>[] proxiedInterfaces = AopProxyUtils.completeProxiedInterfaces(this.advised, true);
findDefinedEqualsAndHashCodeMethods(proxiedInterfaces);
return Proxy.newProxyInstance(classLoader, proxiedInterfaces, this);
}这里就引出了一个问题，在JdkDynamicAopProxy的invoke方法中，拦截器链是怎么构造出来了。
Reference
(adsbygoogle = window.adsbygoogle || []).push({});腾讯云开发者
