Spring AOP 链式调用过程源码解析

蔚落 2022-11-12 12:53 197阅读 0赞

# 引言 #

**概述：** AOP系列文章：  
[【1】Spring Aop初始化源码分析][1_Spring Aop]  
[【2】Spring AOP创建代理对象源码解析][2_Spring AOP]  
[【3】Spring AOP 链式调用过程源码解析][3_Spring AOP]  
[【4】Spring 事务执行过程源码解析][4_Spring]

# 1 工程概述 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70]

## 1.1 pom ##

<properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            <maven.compiler.source>1.8</maven.compiler.source>
            <maven.compiler.target>1.8</maven.compiler.target>
            <spring.version>5.2.8.RELEASE</spring.version>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.13</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-context</artifactId>
                <version>${ spring.version}</version>
            </dependency>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>1.16.20</version>
            </dependency>
            
            <dependency>
                <groupId>org.slf4j</groupId>
                <artifactId>slf4j-api</artifactId>
                <version>1.7.10</version>
            </dependency>
            <dependency>
                <groupId>ch.qos.logback</groupId>
                <artifactId>logback-classic</artifactId>
                <version>1.1.2</version>
            </dependency>
            <dependency>
                <groupId>ch.qos.logback</groupId>
                <artifactId>logback-core</artifactId>
                <version>1.1.2</version>
            </dependency>
    
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-aspects</artifactId>
                <version>${ spring.version}</version>
            </dependency>
        </dependencies>

## 1.2 配置文件 ##

@Configuration
    @EnableAspectJAutoProxy
    @Import(ServiceAopConfig.class)
    public class AopConfig { 
    
    
    }
    
    @Configuration
    @Aspect
    public class ServiceAopConfig { 
    
        /** * 声明切点 */
        @Pointcut("execution(* com.rosh.service.*.*(..))")
        public void pointCut() { 
    
        }
    
        @Around("pointCut()")
        public Object around(ProceedingJoinPoint proceedingJoinPoint) throws Throwable { 
            System.out.println("ServiceAopConfig invoke around start");
            Object proceed = proceedingJoinPoint.proceed();
            System.out.println("ServiceAopConfig invoke around end");
            return proceed;
        }
    
        @Before("pointCut()")
        public void before(){ 
            System.out.println("ServiceAopConfig invoke before");
        }
    
        @After("pointCut()")
        public void after() { 
            System.out.println("ServiceAopConfig invoke after");
        }
    }

## 1.3 Service ##

public interface StudentService { 
    
         void addStudent();
    
    }
    
    
    @Service
    public class StudentServiceImpl implements StudentService { 
    
        @Override
        public void addStudent() { 
            System.out.println("StudentServiceImpl invoke addStudent()");
        }
    }

## 1.4 RoshTest ##

public class RoshTest { 
    
        @Test
        public void mainTest(){ 
    
            AnnotationConfigApplicationContext applicationContext=new AnnotationConfigApplicationContext("com.rosh");
            StudentService studentService = (StudentService) applicationContext.getBean("studentServiceImpl");
            studentService.addStudent();
    
    
        }
    
    }

## 1. 5 结果 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 1]

# 2 前置步骤概述 #

(1) BeanFactoryAspectJAdvisorsBuilder会收集项目中所有advisor(pointCut+advice)。
    (2) AbstractAutoProxyCreator在进行后置增强时，会获取当前bean的有效advisor列表。
    (3) 如果advisor列表不为空那么创建代理对象,首先创建ProxyFactory工厂配置增强类型(默认使用JDK，如果当前增强bean不是接口实现类，那么使用cglib)，一个代理对象对应一个代理工厂，并把有效的advisor存入工厂中，并且把工厂信息存入代理对象，最后返回代理对象。

protected Object createProxy(Class<?> beanClass, @Nullable String beanName,
    			@Nullable Object[] specificInterceptors, TargetSource targetSource) { 
    
    		if (this.beanFactory instanceof ConfigurableListableBeanFactory) { 
    			AutoProxyUtils.exposeTargetClass((ConfigurableListableBeanFactory) this.beanFactory, beanName, beanClass);
    		}
    
    		/** * 【1】创建代理工厂，赋值。 */
    		ProxyFactory proxyFactory = new ProxyFactory();
    		proxyFactory.copyFrom(this);
    
    		/** * 【2】 proxyTargetClass为true时代表使用cglib，为false使用jdk，默认值是false。 * 判断当前被代理对象是使用jdk增强还是使用cglib增强 * */
    		if (!proxyFactory.isProxyTargetClass()) { 
    			//根据最开始@EnableAspectJAutoProxy注解中的proxyTargetClass参数判断是否应该使用cglib代理
    			if (shouldProxyTargetClass(beanClass, beanName)) { 
    				proxyFactory.setProxyTargetClass(true);
    			}
    			else { 
    				//如果是接口增强那么使用jdk，否则使用cglib
    				evaluateProxyInterfaces(beanClass, proxyFactory);
    			}
    		}
    		//构建advisor
    		Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
    		//把advisor加入到代理工厂中
    		proxyFactory.addAdvisors(advisors);
    		//把targetSource对象加入代理工厂(实际对象、被代理对象)
    		proxyFactory.setTargetSource(targetSource);
    		customizeProxyFactory(proxyFactory);
    
    		proxyFactory.setFrozen(this.freezeProxy);
    		if (advisorsPreFiltered()) { 
    			proxyFactory.setPreFiltered(true);
    		}
    
    		/** * 【3】 获取代理对象 */
    		return proxyFactory.getProxy(getProxyClassLoader());
    	}

# 3 调取源码解析 #

**描述：** JdkDynamicAopProxy invoke方法详解：

@Override
    	@Nullable
    	public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { 
    		Object oldProxy = null;
    		boolean setProxyContext = false;
    
    		/** * 【1】获取代理工厂 */
    		TargetSource targetSource = this.advised.targetSource;
    		Object target = null;
    
    		try { 
    			if (!this.equalsDefined && AopUtils.isEqualsMethod(method)) { 
    				// The target does not implement the equals(Object) method itself.
    				return equals(args[0]);
    			}
    			else if (!this.hashCodeDefined && AopUtils.isHashCodeMethod(method)) { 
    				// The target does not implement the hashCode() method itself.
    				return hashCode();
    			}
    			else if (method.getDeclaringClass() == DecoratingProxy.class) { 
    				// There is only getDecoratedClass() declared -> dispatch to proxy config.
    				return AopProxyUtils.ultimateTargetClass(this.advised);
    			}
    			else if (!this.advised.opaque && method.getDeclaringClass().isInterface() &&
    					method.getDeclaringClass().isAssignableFrom(Advised.class)) { 
    				// Service invocations on ProxyConfig with the proxy config...
    				return AopUtils.invokeJoinpointUsingReflection(this.advised, method, args);
    			}
    
    			Object retVal;
    
    			if (this.advised.exposeProxy) { 
    				// Make invocation available if necessary.
    				oldProxy = AopContext.setCurrentProxy(proxy);
    				setProxyContext = true;
    			}
    
    			// Get as late as possible to minimize the time we "own" the target,
    			// in case it comes from a pool.
    			/** * 【2】 获取真实对象 */
    			target = targetSource.getTarget();
    			Class<?> targetClass = (target != null ? target.getClass() : null);
    
    			// Get the interception chain for this method.
    			/** * 【3】 获取方法链 * * (1) 根据代理工厂获取有效的advisors * (2) 遍历advisors，匹配类、匹配方法为true的advisor,获取advice，封装成MethodInterceptor对象。 * (3) 将构建出来的MethodInterceptor对象,添加到拦截链中。 * */
    			List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);
    
    			// Check whether we have any advice. If we don't, we can fallback on direct
    			// reflective invocation of the target, and avoid creating a MethodInvocation.
    
    			/** * 【4】 如果没有调用链，直接反射调用方法 */
    			if (chain.isEmpty()) { 
    				// We can skip creating a MethodInvocation: just invoke the target directly
    				// Note that the final invoker must be an InvokerInterceptor so we know it does
    				// nothing but a reflective operation on the target, and no hot swapping or fancy proxying.
    				Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
    				retVal = AopUtils.invokeJoinpointUsingReflection(target, method, argsToUse);
    			}
    			else { 
    				// We need to create a method invocation...
    				MethodInvocation invocation =
    						new ReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain);
    				// Proceed to the joinpoint through the interceptor chain.
    
    				/** * 【5】 链式调取 */
    				retVal = invocation.proceed();
    			}
    
    			// Massage return value if necessary.
    			Class<?> returnType = method.getReturnType();
    			if (retVal != null && retVal == target &&
    					returnType != Object.class && returnType.isInstance(proxy) &&
    					!RawTargetAccess.class.isAssignableFrom(method.getDeclaringClass())) { 
    				// Special case: it returned "this" and the return type of the method
    				// is type-compatible. Note that we can't help if the target sets
    				// a reference to itself in another returned object.
    				retVal = proxy;
    			}
    			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);
    			}
    		}
    	}

# 4 获取调用链源码解析 #

public List<Object> getInterceptorsAndDynamicInterceptionAdvice(Method method, @Nullable Class<?> targetClass) { 
    		MethodCacheKey cacheKey = new MethodCacheKey(method);
    		List<Object> cached = this.methodCache.get(cacheKey);
    		if (cached == null) { 
    
    			/** * 获取调用链 */
    			cached = this.advisorChainFactory.getInterceptorsAndDynamicInterceptionAdvice(
    					this, method, targetClass);
    			this.methodCache.put(cacheKey, cached);
    		}
    		return cached;
    	}

@Override
    	public List<Object> getInterceptorsAndDynamicInterceptionAdvice(
    			Advised config, Method method, @Nullable Class<?> targetClass) { 
    
    		// This is somewhat tricky... We have to process introductions first,
    		// but we need to preserve order in the ultimate list.
    		AdvisorAdapterRegistry registry = GlobalAdvisorAdapterRegistry.getInstance();
    
    		/** * 【1】 从代理工厂中获取真实对象（被代理对象）的advisor */
    		Advisor[] advisors = config.getAdvisors();
    		List<Object> interceptorList = new ArrayList<>(advisors.length);
    		Class<?> actualClass = (targetClass != null ? targetClass : method.getDeclaringClass());
    		Boolean hasIntroductions = null;
    
    		for (Advisor advisor : advisors) { 
    			if (advisor instanceof PointcutAdvisor) { 
    				// Add it conditionally.
    				PointcutAdvisor pointcutAdvisor = (PointcutAdvisor) advisor;
    
    				/** * 【2】 判断advisor是否匹配类和方法 */
    				if (config.isPreFiltered() || pointcutAdvisor.getPointcut().getClassFilter().matches(actualClass)) { 
    					MethodMatcher mm = pointcutAdvisor.getPointcut().getMethodMatcher();
    					boolean match;
    					if (mm instanceof IntroductionAwareMethodMatcher) { 
    						if (hasIntroductions == null) { 
    							hasIntroductions = hasMatchingIntroductions(advisors, actualClass);
    						}
    						match = ((IntroductionAwareMethodMatcher) mm).matches(method, actualClass, hasIntroductions);
    					}
    					else { 
    						match = mm.matches(method, actualClass);
    					}
    
    					/** * 【3】 如果pointcut 匹配类 并且匹配方法 */
    					if (match) { 
    						//获取advisor中的advice，并且包装成MethodInterceptor类型的对象
    						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;
    	}

# 5 debug #

## 5.1 获取调用链 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 2]  
**描述：** 从代理工厂中获取当前类有效的advisor，遍历advisor。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 3]

**描述：** 如果pointCut 匹配类，匹配方法那么把advice封装成MethodInterceptor对象并且存入返回链中。

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 4]

**描述：** 获取调用链  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 5]

## 5.2 调取分析 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 6]

**描述：** 终止条件，索引等于最后一个advice。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 7]  
**描述：** 链式调用  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 8]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 9]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 10]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 11]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 12]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 13]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 14]

[1_Spring Aop]: https://blog.csdn.net/qq_34125999/article/details/115057552
[2_Spring AOP]: https://blog.csdn.net/qq_34125999/article/details/115107521
[3_Spring AOP]: https://blog.csdn.net/qq_34125999/article/details/115155125
[4_Spring]: https://blog.csdn.net/qq_34125999/article/details/115220975
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