Spring Aop源码分析

最近看了SpringAop的源码实现  大概记录一下aop的源码流程

创建一个最简单的一个测试类

package com.zcg.learn.Test;

import org.aopalliance.aop.Advice;
import org.junit.Test;
import org.springframework.aop.aspectj.AspectJExpressionPointcutAdvisor;
import org.springframework.aop.aspectj.annotation.AspectJProxyFactory;
import org.springframework.aop.framework.Advised;
import org.springframework.aop.framework.ProxyFactory;
import org.springframework.tests.aop.advice.CountingAfterReturningAdvice;
import org.springframework.tests.aop.advice.CountingBeforeAdvice;

import com.zcg.learn.UserService;
import com.zcg.learn.UserServiceImpl;

/**
* SpringAop源码分析测试类
* @author zcg
* 2018/3/1
*
*/
public class SpringAopTest {

/**
* 创建代理
*/
@Test
public void createProxyTest() {
Object target = new UserServiceImpl();
ProxyFactory pf = new ProxyFactory(target);
//CountingBeforeAdvice 前置通知计数器
CountingBeforeAdvice countingBeforeAdvice = new CountingBeforeAdvice();
pf.addAdvice(countingBeforeAdvice);
UserService service = (UserService) pf.getProxy();
service.addUser();
}

/**
* 动态添加 移除通知
*/
@Test
public void createProxyTest2() {
Object target = new UserServiceImpl();
ProxyFactory pf = new ProxyFactory(target);
UserService service = (UserService) pf.getProxy();
Advised advised = (Advised) service;
CountingBeforeAdvice countingBeforeAdvice = new CountingBeforeAdvice();
CountingAfterReturningAdvice countingAfterReturningAdvice = new CountingAfterReturningAdvice();
advised.addAdvice(countingAfterReturningAdvice);
advised.addAdvice(countingBeforeAdvice);
service.addUser();
advised.removeAdvice(countingAfterReturningAdvice);
service.addUser();
}

@Test
public void createProxyAspectJByTest() {
Object target = new UserServiceImpl();
AspectJProxyFactory pf = new AspectJProxyFactory(target);
AspectJExpressionPointcutAdvisor advisor = new AspectJExpressionPointcutAdvisor();
advisor.setExpression("execution(* *.addUser(..))");
CountingBeforeAdvice counting = new CountingBeforeAdvice();
advisor.setAdvice(counting);
pf.addAdvisor(advisor);
UserService userService = pf.getProxy();
userService.addUser();
/**
* advice 通知拦截器
* advisor 通知加切入点适配器
*/

}

}

其中测试方式

@Test
public void createProxyTest() {
Object target = new UserServiceImpl();

ProxyFactory pf = new ProxyFactory(target);
//CountingBeforeAdvice 前置通知计数器
CountingBeforeAdvice countingBeforeAdvice = new CountingBeforeAdvice();
pf.addAdvice(countingBeforeAdvice);
UserService service = (UserService) pf.getProxy();
service.addUser();
}

1.target 以构造参数的形式放入在ProxyFactory中，实际上将该tartget放入在AdvisedSupport类中

2.countingBeforeAdvice 为Spring Aop自带的前置通知计数

3.1 UserService service = (UserService) pf.getProxy();从中获取代理类

ProxyFactory类中 extends ProxyCreatorSupport

/*

* 代理生成工厂
*/
@SuppressWarnings("serial")
public class ProxyFactory extends ProxyCreatorSupport {

/**
* Create a new proxy according to the settings in this factory.
* <p>Can be called repeatedly. Effect will vary if we've added
* or removed interfaces. Can add and remove interceptors.
* <p>Uses a default class loader: Usually, the thread context class loader
* (if necessary for proxy creation).
* @return the proxy object
*/
public Object getProxy() {
return createAopProxy().getProxy();
}

}

3.2 createAopProxy()方法是父类ProxyCreatorSupport里面的方法

protected final synchronized AopProxy createAopProxy() {
if (!this.active) {
activate();
}

//得到Aop代理工厂和在当前代理工厂创建该代理类
return getAopProxyFactory().createAopProxy(this);
}

其中getAopProxyFactory().createAopProxy(this)在DefaultAopProxyFa1ctory类中执行 具体代码如下

@SuppressWarnings("serial")
public class DefaultAopProxyFactory implements AopProxyFactory, Serializable {

@Override
public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException {
if (config.isOptimize() || config.isProxyTargetClass() || hasNoUserSuppliedProxyInterfaces(config)) {
Class<?> targetClass = config.getTargetClass();
if (targetClass == null) {
throw new AopConfigException("TargetSource cannot determine target class: " +
"Either an interface or a target is required for proxy creation.");
}

//r如果目标类有接口或者是代理类，则走jdk的动态代理 否则走cglib的动态代理
if (targetClass.isInterface() || Proxy.isProxyClass(targetClass)) {
return new JdkDynamicAopProxy(config);
}
return new ObjenesisCglibAopProxy(config);
}
else {
return new JdkDynamicAopProxy(config);
}
}

/**
* Determine whether the supplied {@link AdvisedSupport} has only the
* {@link org.springframework.aop.SpringProxy} interface specified
* (or no proxy interfaces specified at all).
*/
private boolean hasNoUserSuppliedProxyInterfaces(AdvisedSupport config) {
Class<?>[] ifcs = config.getProxiedInterfaces();
return (ifcs.length == 0 || (ifcs.length == 1 && SpringProxy.class.isAssignableFrom(ifcs[0])));
}

}

3.3 JdkDynamicAopProxy类实现了InvocationHandler 对invoke进行的重写 核心代码如下

final class JdkDynamicAopProxy implements AopProxy, InvocationHandler, Serializable {

@Override
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 {
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;
}

// May be null. Get as late as possible to minimize the time we "own" the target,
// in case it comes from a pool.
target = targetSource.getTarget();
if (target != null) {
targetClass = target.getClass();
}

// Get the interception chain for this method. 生成通知链条 当前对象和方式是否在拦截范围内
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.
//如果没有调用掉直接执行方式
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...

//初始化MethodInvocation类
invocation = new ReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain);
// Proceed to the joinpoint through the interceptor chain.

执行调用链的所有方法和本身方法
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);
}
}
}

}

其中的 AdvisedSupport类的this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass)方法主要得到代理的所有拦截器方法

核心代码如下

public List<Object> getInterceptorsAndDynamicInterceptionAdvice(Method method, Class<?> targetClass) {
MethodCacheKey cacheKey = new MethodCacheKey(method);
List<Object> cached = this.methodCache.get(cacheKey);
if (cached == null) {
cached = this.advisorChainFactory.getInterceptorsAndDynamicInterceptionAdvice(
this, method, targetClass);
this.methodCache.put(cacheKey, cached);
}
return cached;
}

getInterceptorsAndDynamicInterceptionAdvice方法核心代码如下：

public class DefaultAdvisorChainFactory implements AdvisorChainFactory, Serializable {

@Override
public List<Object> getInterceptorsAndDynamicInterceptionAdvice(
Advised config, Method method, Class<?> targetClass) {

// This is somewhat tricky... We have to process introductions first,
// but we need to preserve order in the ultimate list.
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();

for (Advisor advisor : config.getAdvisors()) {
if (advisor instanceof PointcutAdvisor) {
// Add it conditionally.
PointcutAdvisor pointcutAdvisor = (PointcutAdvisor) advisor;
if (config.isPreFiltered() || pointcutAdvisor.getPointcut().getClassFilter().matches(actualClass)) {
MethodInterceptor[] interceptors = registry.getInterceptors(advisor);
MethodMatcher mm = pointcutAdvisor.getPointcut().getMethodMatcher();
if (MethodMatchers.matches(mm, method, actualClass, hasIntroductions)) {
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;
}

}

3.4 invocation.proceed()核心代码如下

public class ReflectiveMethodInvocation implements ProxyMethodInvocation, Cloneable{

@Override
public Object proceed() throws Throwable {
// We start with an index of -1 and increment early.
if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) {
return invokeJoinpoint();
}

Object interceptorOrInterceptionAdvice =
this.interceptorsAndDynamicMethodMatchers.get(++this.currentInterceptorIndex);
if (interceptorOrInterceptionAdvice instanceof InterceptorAndDynamicMethodMatcher) {
// Evaluate dynamic method matcher here: static part will already have
// been evaluated and found to match.

//执行所有调用链的所有方法
InterceptorAndDynamicMethodMatcher dm =
(InterceptorAndDynamicMethodMatcher) interceptorOrInterceptionAdvice;
if (dm.methodMatcher.matches(this.method, this.targetClass, this.arguments)) {
return dm.interceptor.invoke(this);
}
else {
// Dynamic matching failed.
// Skip this interceptor and invoke the next in the chain.
return proceed();
}
}
else {
// It's an interceptor, so we just invoke it: The pointcut will have
// been evaluated statically before this object was constructed.
return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this);
}
}

}

其中前置拦截器方法如下

@SuppressWarnings("serial")
public class MethodBeforeAdviceInterceptor implements MethodInterceptor, Serializable {

private MethodBeforeAdvice advice;

/**
* Create a new MethodBeforeAdviceInterceptor for the given advice.
* @param advice the MethodBeforeAdvice to wrap
*/
public MethodBeforeAdviceInterceptor(MethodBeforeAdvice advice) {
Assert.notNull(advice, "Advice must not be null");
this.advice = advice;
}

//重写invoke方法

@Override
public Object invoke(MethodInvocation mi) throws Throwable {
this.advice.before(mi.getMethod(), mi.getArguments(), mi.getThis() );
return mi.proceed();
}

}

后置通知拦截器方法

@SuppressWarnings("serial")
public class AfterReturningAdviceInterceptor implements MethodInterceptor, AfterAdvice, Serializable {

private final AfterReturningAdvice advice;

/**
* Create a new AfterReturningAdviceInterceptor for the given advice.
* @param advice the AfterReturningAdvice to wrap
*/
public AfterReturningAdviceInterceptor(AfterReturningAdvice advice) {
Assert.notNull(advice, "Advice must not be null");
this.advice = advice;
}

@Override
public Object invoke(MethodInvocation mi) throws Throwable {
Object retVal = mi.proceed();
this.advice.afterReturning(retVal, mi.getMethod(), mi.getArguments(), mi.getThis());
return retVal;
}

}

流程大概如此  可能有点模糊，如果想继续学习加我QQ:1051980588 一起探讨和看其他相关的源码解析视频