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Spring中AOP创建代理的方法
这篇文章主要讲解了“Spring中AOP创建代理的方法”，文中的讲解内容简单清晰，易于学习与理解，下面请大家跟着小编的思路慢慢深入，一起来研究和学习“Spring中AOP创建代理的方法”吧！
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1、准备创建代理
protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
//1.寻找增强器
Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
if (specificInterceptors != DO_NOT_PROXY) {
//2.创建代理
Object proxy = createProxy(bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));
return proxy;
}
}protected Object[] getAdvicesAndAdvisorsForBean(Class beanClass, String beanName, TargetSource targetSource) {
//第六篇AOP寻找增强器已经分析了该步骤
List advisors = findEligibleAdvisors(beanClass, beanName);
if (advisors.isEmpty()) {
return DO_NOT_PROXY;
}
return advisors.toArray();
}protected Object createProxy(Class beanClass, String beanName, Object[] specificInterceptors,
TargetSource targetSource) {
//对于代理类的创建及处理,交给了ProxyFactory去处理,此函数中只是做一些准备工作
ProxyFactory proxyFactory = new ProxyFactory();
//获取当前类中相关属性
proxyFactory.copyFrom(this);
if (!shouldProxyTargetClass(beanClass, beanName)) {
//形如interface com.lwh.spring.JdkProxy.PersonService
Class[] targetInterfaces = ClassUtils.getAllInterfacesForClass(beanClass, this.proxyClassLoader);
for (Class targetInterface : targetInterfaces) {
//添加代理接口
proxyFactory.addInterface(targetInterface);
}
}
//将拦截器封装为增强器,此处的拦截器类型就是增强器
Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
for (Advisor advisor : advisors) {
//并添加到ProxyFactory中
proxyFactory.addAdvisor(advisor);
}
//SingletonTargetSource for target object [com.lwh.spring.JdkProxy.PersonServiceImpl@1130520d]
proxyFactory.setTargetSource(targetSource);
//定制代理,空实现,由子类实现
customizeProxyFactory(proxyFactory);
proxyFactory.setFrozen(this.freezeProxy);
if (advisorsPreFiltered()) {
proxyFactory.setPreFiltered(true);
}
//创建代理
return proxyFactory.getProxy(this.proxyClassLoader);
}protected Advisor[] buildAdvisors(String beanName, Object[] specificInterceptors) {
Advisor[] commonInterceptors = resolveInterceptorNames();
Listpublic Advisor wrap(Object adviceObject) throws UnknownAdviceTypeException {
if (adviceObject instanceof Advisor) {
return (Advisor) adviceObject;
}
if (!(adviceObject instanceof Advice)) {
throw new UnknownAdviceTypeException(adviceObject);
}
Advice advice = (Advice) adviceObject;
if (advice instanceof MethodInterceptor) {
return new DefaultPointcutAdvisor(advice);
}
for (AdvisorAdapter adapter : this.adapters) {
if (adapter.supportsAdvice(advice)) {
return new DefaultPointcutAdvisor(advice);
}
}
throw new UnknownAdviceTypeException(advice);
}2、创建代理
return proxyFactory.getProxy(this.proxyClassLoader);
public Object getProxy(ClassLoader classLoader) {
return createAopProxy().getProxy(classLoader);
}
protected final synchronized AopProxy createAopProxy() {
if (!this.active) {
activate();
}
return getAopProxyFactory().createAopProxy(this);
}//此函数真正完成了代理的创建
public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException {
//三个条件影响Spring的判断
//1.optimize属性,不推荐用户使用这个设置
//2.proxytargetclass属性,之前分析过
//3.是否存在代理接口
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.");
}
if (targetClass.isInterface()) {
//使用JDK动态代理
return new JdkDynamicAopProxy(config);
}
return CglibProxyFactory.createCglibProxy(config);
}
else {
//目标对象实现了接口,默认使用JDK动态代理
return new JdkDynamicAopProxy(config);
}
}3、获取代理
public Object getProxy(ClassLoader classLoader) {
//先是创建代理,再是获取代理
return createAopProxy().getProxy(classLoader);
}
public Object getProxy(ClassLoader classLoader) {
//获取代理接口,此处其实就是JDK的动态代理实现了,建议复习下JDK的动态代理
Class[] proxiedInterfaces = AopProxyUtils.completeProxiedInterfaces(this.advised);
findDefinedEqualsAndHashCodeMethods(proxiedInterfaces);
//返回代理对象
return Proxy.newProxyInstance(classLoader, proxiedInterfaces, this);
}JDK动态代理的关键就是实现InvocationHandler方法并实现其invoke方法,而此处的JdkDynamicAopProxy 实现了InvocationHandler接口,所以其中一定有invoke方法. 看笔记得知,获取到的是代理对象 PersonService personService = ctx.getBean("personService", PersonService.class); 此处实际调用的是生成的代理类中的sayHello方法,看下图,因为是之前做的笔记,所以包名不一致,但意思很明显,在代理类中sayHello方法 又会调用InvocationHandler中的invoke方法,此h对象,即InvocationHandler是在Proxy.newProxyInstance时设置进去的,所以下面调用 sayHello方法时先会进入JdkDynamicAopProxy的invoke方法personService.sayHello();
4、分析方法调用
//获取代理对象
PersonService personService = ctx.getBean("personService", PersonService.class);
//方法调用
personService.sayHello();
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
MethodInvocation invocation;
Object oldProxy = null;
boolean setProxyContext = false;
//SingletonTargetSource for target object [com.lwh.spring.JdkProxy.PersonServiceImpl@6986852]
TargetSource targetSource = this.advised.targetSource;
Class targetClass = null;
Object target = null;
try {
//删去了部分代码
Object retVal;
//SingletonTargetSource for target object [com.lwh.spring.JdkProxy.PersonServiceImpl@6986852]
target = targetSource.getTarget();
if (target != null) {
//class com.lwh.spring.JdkProxy.PersonServiceImpl
targetClass = target.getClass();
}
//获取当前方法的拦截器链
List
public Object proceed() throws Throwable {
// We start with an index of -1 and increment early.
//执行完所有增强方法后执行切点方法,维护了一个currentInterceptorIndex计数器,递增
if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) {
return invokeJoinpoint();
}
//List interceptorsAndDynamicMethodMatchers,记录了要执行的增强方法,通过下标获取要执行的增强方法
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.
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);
}
}感谢各位的阅读，以上就是“Spring中AOP创建代理的方法”的内容了，经过本文的学习后，相信大家对Spring中AOP创建代理的方法这一问题有了更深刻的体会，具体使用情况还需要大家实践验证。这里是创新互联，小编将为大家推送更多相关知识点的文章，欢迎关注！
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