springAop源码分析（三）
一、接上篇博客，所有的切面方法都找到后，并缓存起来了，接下来应该如何，请看下图
二、源码分析
了解过getBean源码的对这里应该不陌生，本章将从这里开始：applyBeanPostProcessorsAfterInitialization
protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {
if (System.getSecurityManager() != null) {
AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
invokeAwareMethods(beanName, bean);
return null;
}
}, getAccessControlContext());
}
else {
invokeAwareMethods(beanName, bean);
}
Object wrappedBean = bean;
if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
}
try {
invokeInitMethods(beanName, wrappedBean, mbd);
}
catch (Throwable ex) {
throw new BeanCreationException(
(mbd != null ? mbd.getResourceDescription() : null),
beanName, "Invocation of init method failed", ex);
}
if (mbd == null || !mbd.isSynthetic()) {
//本章分析从这里开始
wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
}
return wrappedBean;
}
至于为什么会执行此方法，因为AbstractAutoProxyCreator–》实现SmartInstantiationAwareBeanPostProcessor–》继承InstantiationAwareBeanPostProcessor–》继承BeanPostProcessor
protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
if (beanName != null && this.targetSourcedBeans.contains(beanName)) {
return bean;
}
if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) {
return bean;
}
if (isInfrastructureClass(bean.getClass()) || shouldSkip(bean.getClass(), beanName)) {
this.advisedBeans.put(cacheKey, Boolean.FALSE);
return bean;
}
// Create proxy if we have advice.
//核心方法，寻找增强器
Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
if (specificInterceptors != DO_NOT_PROXY) {
this.advisedBeans.put(cacheKey, Boolean.TRUE);
Object proxy = createProxy(
bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));
this.proxyTypes.put(cacheKey, proxy.getClass());
return proxy;
}
this.advisedBeans.put(cacheKey, Boolean.FALSE);
return bean;
}
protected Object[] getAdvicesAndAdvisorsForBean(Class<?> beanClass, String beanName, TargetSource targetSource) {
List<Advisor> advisors = findEligibleAdvisors(beanClass, beanName);
if (advisors.isEmpty()) {
return DO_NOT_PROXY;
}
return advisors.toArray();
}
下面这几段方法匹配的代码大致说明一下：循环增强器，获取PointcutAdvisor中的pointCut，获取pointCut中的方法选择器，匹配类中的方法，并不是每个方法都匹配，这一块主要是判断这个要代理的类是否含有该增强器（是对增强器的筛选），但是这个过程中筛选过的方法将存入AspectJExpressionPointcut类中的shadowMatchCache（说明：key是方法，value是ShadowMatch对象包含对方法的处理结果）缓存中。
@Override
public boolean matches(Method method, Class<?> targetClass, boolean beanHasIntroductions) {
checkReadyToMatch();
Method targetMethod = AopUtils.getMostSpecificMethod(method, targetClass);
ShadowMatch shadowMatch = getShadowMatch(targetMethod, method);
// Special handling for this, target, @this, @target, @annotation
// in Spring - we can optimize since we know we have exactly this class,
// and there will never be matching subclass at runtime.
if (shadowMatch.alwaysMatches()) {
return true;
}
else if (shadowMatch.neverMatches()) {
return false;
}
else {
// the maybe case
if (beanHasIntroductions) {
return true;
}
// A match test returned maybe - if there are any subtype sensitive variables
// involved in the test (this, target, at_this, at_target, at_annotation) then
// we say this is not a match as in Spring there will never be a different
// runtime subtype.
RuntimeTestWalker walker = getRuntimeTestWalker(shadowMatch);
return (!walker.testsSubtypeSensitiveVars() || walker.testTargetInstanceOfResidue(targetClass));
}
}
private ShadowMatch getShadowMatch(Method targetMethod, Method originalMethod) {
// Avoid lock contention for known Methods through concurrent access...
ShadowMatch shadowMatch = this.shadowMatchCache.get(targetMethod);
if (shadowMatch == null) {
synchronized (this.shadowMatchCache) {
// Not found - now check again with full lock...
PointcutExpression fallbackExpression = null;
Method methodToMatch = targetMethod;
shadowMatch = this.shadowMatchCache.get(targetMethod);
if (shadowMatch == null) {
try {
try {
shadowMatch = this.pointcutExpression.matchesMethodExecution(methodToMatch);
}
catch (ReflectionWorldException ex) {
// Failed to introspect target method, probably because it has been loaded
// in a special ClassLoader. Let's try the declaring ClassLoader instead...
try {
fallbackExpression = getFallbackPointcutExpression(methodToMatch.getDeclaringClass());
if (fallbackExpression != null) {
shadowMatch = fallbackExpression.matchesMethodExecution(methodToMatch);
}
}
catch (ReflectionWorldException ex2) {
fallbackExpression = null;
}
}
if (shadowMatch == null && targetMethod != originalMethod) {
methodToMatch = originalMethod;
try {
shadowMatch = this.pointcutExpression.matchesMethodExecution(methodToMatch);
}
catch (ReflectionWorldException ex3) {
// Could neither introspect the target class nor the proxy class ->
// let's try the original method's declaring class before we give up...
try {
fallbackExpression = getFallbackPointcutExpression(methodToMatch.getDeclaringClass());
if (fallbackExpression != null) {
shadowMatch = fallbackExpression.matchesMethodExecution(methodToMatch);
}
}
catch (ReflectionWorldException ex4) {
fallbackExpression = null;
}
}
}
}
catch (Throwable ex) {
// Possibly AspectJ 1.8.10 encountering an invalid signature
logger.debug("PointcutExpression matching rejected target method", ex);
fallbackExpression = null;
}
if (shadowMatch == null) {
shadowMatch = new ShadowMatchImpl(org.aspectj.util.FuzzyBoolean.NO, null, null, null);
}
else if (shadowMatch.maybeMatches() && fallbackExpression != null) {
shadowMatch = new DefensiveShadowMatch(shadowMatch,
fallbackExpression.matchesMethodExecution(methodToMatch));
}
//将这个方法匹配的结果放入map中缓存
this.shadowMatchCache.put(targetMethod, shadowMatch);
}
}
}
return shadowMatch;
}
当前拦截器满足，直接加入到集合中
创建ProxyFactory并初始化，通过proxyFactory.getProxy(getProxyClassLoader());获取代理
==proxyFactory.getProxy(getProxyClassLoader())==以jdk代理为例
@Override
public Object getProxy(ClassLoader classLoader) {
if (logger.isDebugEnabled()) {
logger.debug("Creating JDK dynamic proxy: target source is " + this.advised.getTargetSource());
}
//为给定的AOP配置确定代理的完整接口集。
Class<?>[] proxiedInterfaces = AopProxyUtils.completeProxiedInterfaces(this.advised, true);
//接口是否定义了 equals和hashcode方法 正常是没有的
findDefinedEqualsAndHashCodeMethods(proxiedInterfaces);
//创建代理对象 this是JdkDynamicAopProxy
//JdkDynamicAopProxy 同时实现了InvocationHandler 接口
return Proxy.newProxyInstance(classLoader, proxiedInterfaces, this);
}
public static Object newProxyInstance(ClassLoader loader,
Class<?>[] interfaces,
InvocationHandler h)
throws IllegalArgumentException
{
Objects.requireNonNull(h);
final Class<?>[] intfs = interfaces.clone();
final SecurityManager sm = System.getSecurityManager();
if (sm != null) {
checkProxyAccess(Reflection.getCallerClass(), loader, intfs);
}
/*
* Look up or generate the designated proxy class.
*/
// 装载真实对象的类加载器与接口，获得 $Proxy0 类
Class<?> cl = getProxyClass0(loader, intfs);
/*
* Invoke its constructor with the designated invocation handler.
*/
try {
if (sm != null) {
checkNewProxyPermission(Reflection.getCallerClass(), cl);
}
// 使用反射获得构造器
final Constructor<?> cons = cl.getConstructor(constructorParams);
final InvocationHandler ih = h;
// 检查真实角色的类是否是public可获取的
if (!Modifier.isPublic(cl.getModifiers())) {
AccessController.doPrivileged(new PrivilegedAction<Void>() {
public Void run() {
// 不是就强行破解权限，设置为可获取
cons.setAccessible(true);
return null;
}
});
}
// 装载 实现了invoke()方法的InvocationHandler接口，与下面$Proxy0的构造方法一致
return cons.newInstance(new Object[]{
h});
} catch (IllegalAccessException|InstantiationException e) {
throw new InternalError(e.toString(), e);
} catch (InvocationTargetException e) {
Throwable t = e.getCause();
if (t instanceof RuntimeException) {
throw (RuntimeException) t;
} else {
throw new InternalError(t.toString(), t);
}
} catch (NoSuchMethodException e) {
throw new InternalError(e.toString(), e);
}
}
举例说明
public final class $Proxy0
extends Proxy
implements Providable
{
private static Method m1;
private static Method m2;
private static Method m0;
public $Proxy0(InvocationHandler paramInvocationHandler)
{
super(paramInvocationHandler);
}
public final boolean equals(Object paramObject)
{
try
{
return ((Boolean)this.h.invoke(this, m1, new Object[] {
paramObject })).booleanValue();
}
catch (Error|RuntimeException localError)
{
throw localError;
}
catch (Throwable localThrowable)
{
throw new UndeclaredThrowableException(localThrowable);
}
}
public final String toString()
{
try
{
return (String)this.h.invoke(this, m2, null);
}
catch (Error|RuntimeException localError)
{
throw localError;
}
catch (Throwable localThrowable)
{
throw new UndeclaredThrowableException(localThrowable);
}
}
public final int hashCode()
{
try
{
return ((Integer)this.h.invoke(this, m0, null)).intValue();
}
catch (Error|RuntimeException localError)
{
throw localError;
}
catch (Throwable localThrowable)
{
throw new UndeclaredThrowableException(localThrowable);
}
}
static
{
try
{
m1 = Class.forName("java.lang.Object").getMethod("equals", new Class[] {
Class.forName("java.lang.Object") });
m2 = Class.forName("java.lang.Object").getMethod("toString", new Class[0]);
m0 = Class.forName("java.lang.Object").getMethod("hashCode", new Class[0]);
return;
}
catch (NoSuchMethodException localNoSuchMethodException)
{
throw new NoSuchMethodError(localNoSuchMethodException.getMessage());
}
catch (ClassNotFoundException localClassNotFoundException)
{
throw new NoClassDefFoundError(localClassNotFoundException.getMessage());
}
}
}
三总结，本章就到这里，具体的动态代理增强器如何调用，将再下一篇博客说明。