19-Spring AOP源码分析-代理对象调用目标方法

1. 1-Spring架构源码分析-Spring源码搭建
2. 2-Spring架构源码分析-SSM框架说明
3. 3-Spring架构源码分析-spring体系
4. 4-Spring架构源码分析-Spring IOC机制设计思想和源码解读
5. 5-Spring架构源码分析-Spring IOC之 Spring 统一资源加载策略
6. 6-Spring架构源码分析-IoC 之加载 BeanDefinition
7. 7-Spring架构源码分析-IoC 之注册 BeanDefinitions
8. 8-Spring架构源码分析-IoC 之解析Bean：解析 import 标签
9. 9-Spring架构源码分析-IoC 之解析 bean 标签：开启解析进程
10. 10-Spring架构源码分析-IoC 之解析 bean标签：BeanDefinition
11. 11-Spring架构源码分析-IoC 之注册解析的 BeanDefinitions
12. 12-Spring架构源码分析-IoC 之装载 BeanDefinitions 总结
13. 13-Spring架构源码分析-IoC 之开启 Bean 的加载
14. 14-Spring架构源码分析-IoC 之加载 Bean：总结
15. 15-Spring架构源码分析-Spring代理与AOP
16. 16-Spring AOP源码分析-@EnableAspectJAutoProxy和AspectJAutoProxyRegistrar
17. 17-Spring AOP源码分析-AnnotationAwareAspectJAutoProxyCreator
18. 18-Spring AOP源码分析-AOP与BeanPostProcessor处理器
19. 19-Spring AOP源码分析-代理对象调用目标方法
20. 20-spring mvc设计思想和源码解读-spring mvc 功能特性
21. 21-mvc 体系结构源码详解
22. 22-Spring MVC源码跟踪
23. 23-Spring事务源码分析

代理对象调用目标方法

背景知识:

@EnableAspectJAutoProxy(exposeProxy = true) 这个东东是用来干什么的？

没有配置exposeProxy 暴露代理对象的时候我们方法调用

我们在Mod方法中 通过this来调用本类的方法add()方法的时候，发现add()的方法不会被拦截

而我们配置了后exposeProxy的属性，我们发现可以通过

**int retVal = ((Calculate) AopContext.currentProxy()).add(numA,numB);

**

调用的时候，发现了add()方法可以被拦截

原理:把这个exposeProxy设置为true，会把代理对象存放在线程变量中,

AopContext.currentProxy())是从线程变量中获取代理对象（源码中分析）

应用场景(事物方法调用事物方法需要二个都起作用需要配置这个东东)

public interface Calculate {      /**      * 加法      * @param numA      * @param numB      * @return      */      int add(int numA,int numB);      /**      * 减法      * @param numA      * @param numB      * @return      */      int reduce(int numA,int numB);      /**      * 除法      * @param numA      * @param numB      * @return      */      int div(int numA,int numB);      /**      * 乘法      * @param numA      * @param numB      * @return      */      int multi(int numA,int numB);       int mod(int numA,int numB); }  public class TulingCalculate implements Calculate {      public int add(int numA, int numB) {          return numA+numB;     }      public int reduce(int numA, int numB) {         return numA-numB;     }      public int div(int numA, int numB) {         return numA/numB;     }      public int multi(int numA, int numB) {         return numA*numB;     }      public int mod(int numA,int numB){         int retVal = ((Calculate) AopContext.currentProxy()).add(numA,numB);          //int retVal = this.add(numA,numB);         return retVal%numA;     } } 

*代理对象调用源代码:*

	public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { 		MethodInvocation invocation; 		Object oldProxy = null; 		boolean setProxyContext = false;  		TargetSource targetSource = this.advised.targetSource; 		Class<?> targetClass = null; 		Object target = null;  		try { 		   			Object retVal;                          //是否暴露代理对象 			if (this.advised.exposeProxy) { 				//把代理对象添加到TheadLocal中 				oldProxy = AopContext.setCurrentProxy(proxy); 				setProxyContext = true; 			}              //获取被代理对象 			target = targetSource.getTarget(); 			if (target != null) { 			    //设置被代理对象的class 				targetClass = target.getClass(); 			}  			//把增强器转为方法拦截器链 			List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);  		    //若方法拦截器链为空 			if (chain.isEmpty()) {                 //通过反射直接调用目标方法 				Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args); 				retVal = AopUtils.invokeJoinpointUsingReflection(target, method, argsToUse); 			} 			else { 				//创建方法拦截器调用链条 				invocation = new ReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain); 				//执行拦截器链 				retVal = invocation.proceed(); 			}  			//获取方法的返回值类型 			Class<?> returnType = method.getReturnType(); 			if (retVal != null && retVal == target && 					returnType != Object.class && returnType.isInstance(proxy) && 					!RawTargetAccess.class.isAssignableFrom(method.getDeclaringClass())) { 				//如果方法返回值为 this，即 return this; 则将代理对象 proxy 赋值给 retVal  				retVal = proxy; 			} 			//如果返回值类型为基础类型，比如 int，long 等，当返回值为 null，抛出异常 			else if (retVal == null && returnType != Void.TYPE && returnType.isPrimitive()) { 				throw new AopInvocationException( 						"Null return value from advice does not match primitive return type for: " + method); 			} 			return retVal; 		} 		finally { 			if (target != null && !targetSource.isStatic()) { 				// Must have come from TargetSource. 				targetSource.releaseTarget(target); 			} 			if (setProxyContext) { 				// Restore old proxy. 				AopContext.setCurrentProxy(oldProxy); 			} 		} 	}  =====================org.springframework.aop.framework.AdvisedSupport#getInterceptorsAndDynamicInterceptionAdvice=========== 把增强器中转为方法拦截器链 	public List<Object> getInterceptorsAndDynamicInterceptionAdvice(Method method, Class<?> targetClass) { 		//从缓存中获取缓存key 第一次肯定获取不到 		MethodCacheKey cacheKey = new MethodCacheKey(method); 		//通过cacheKey获取缓存值 		List<Object> cached = this.methodCache.get(cacheKey); 		 		//从缓存中没有获取到 		if (cached == null) { 		    //获取所有的拦截器 			cached = this.advisorChainFactory.getInterceptorsAndDynamicInterceptionAdvice( 					this, method, targetClass); 		    //放入缓存..... 			this.methodCache.put(cacheKey, cached); 		} 		return cached; 	}  =====================org.springframework.aop.framework.AdvisorChainFactory#getInterceptorsAndDynamicInterceptionAdvice==== 	public List<Object> getInterceptorsAndDynamicInterceptionAdvice( 			Advised config, Method method, Class<?> targetClass) {  	    //创建拦截器集合长度是增强器的长度 		List<Object> interceptorList = new ArrayList<Object>(config.getAdvisors().length); 		 		Class<?> actualClass = (targetClass != null ? targetClass : method.getDeclaringClass()); 		boolean hasIntroductions = hasMatchingIntroductions(config, actualClass); 		AdvisorAdapterRegistry registry = GlobalAdvisorAdapterRegistry.getInstance();                  //遍历所有的增强器集合 		for (Advisor advisor : config.getAdvisors()) { 			//判断增强器是不是PointcutAdvisor 			if (advisor instanceof PointcutAdvisor) { 				//把增强器转为PointcutAdvisor 				PointcutAdvisor pointcutAdvisor = (PointcutAdvisor) advisor; 				//通过方法匹配器对增强器进行匹配 				if (config.isPreFiltered() || pointcutAdvisor.getPointcut().getClassFilter().matches(actualClass)) { 					MethodMatcher mm = pointcutAdvisor.getPointcut().getMethodMatcher(); 					//能够匹配 					if (MethodMatchers.matches(mm, method, actualClass, hasIntroductions)) { 						//把增强器转为拦截器 						MethodInterceptor[] interceptors = registry.getInterceptors(advisor); 						if (mm.isRuntime()) { 							// Creating a new object instance in the getInterceptors() method 							// isn't a problem as we normally cache created chains. 							for (MethodInterceptor interceptor : interceptors) { 								interceptorList.add(new InterceptorAndDynamicMethodMatcher(interceptor, mm)); 							} 						} 						else { 							interceptorList.addAll(Arrays.asList(interceptors)); 						} 					} 				} 			} 			else if (advisor instanceof IntroductionAdvisor) { 				IntroductionAdvisor ia = (IntroductionAdvisor) advisor; 				if (config.isPreFiltered() || ia.getClassFilter().matches(actualClass)) { 					Interceptor[] interceptors = registry.getInterceptors(advisor); 					interceptorList.addAll(Arrays.asList(interceptors)); 				} 			} 			else { 				Interceptor[] interceptors = registry.getInterceptors(advisor); 				interceptorList.addAll(Arrays.asList(interceptors)); 			} 		}  		return interceptorList; 	} 

------------------------------------------------------------ 完 --------------------------------------------------------------------

背景知识:

@EnableAspectJAutoProxy(exposeProxy = true) 这个东东是用来干什么的？

没有配置exposeProxy 暴露代理对象的时候我们方法调用

我们在Mod方法中 通过this来调用本类的方法add()方法的时候，发现add()的方法不会被拦截

而我们配置了后exposeProxy的属性，我们发现可以通过

**int retVal = ((Calculate) AopContext.currentProxy()).add(numA,numB);

**

调用的时候，发现了add()方法可以被拦截

原理:把这个exposeProxy设置为true，会把代理对象存放在线程变量中,

AopContext.currentProxy())是从线程变量中获取代理对象（源码中分析）

应用场景(事物方法调用事物方法需要二个都起作用需要配置这个东东)