一、前言
web.xml里面配置
1<listener> 2 <listener-class>org.springframework.web.context.request.RequestContextListener</listener-class> 3</listener>
component-bean.xml里面配置
1 <bean id="lavaPvgInfo" class="com.alibaba.lava.privilege.PrivilegeInfo" 2 scope="request"> 3 <property name="aesKey" value="666" /> 4 <aop:scoped-proxy /> 5 </bean>
测试Rpc
1@WebResource("/testService")public class TestRpc { @Autowired 2 private PrivilegeInfo pvgInfo; @ResourceMapping("test") public ActionResult test(ErrorContext context) { 3 ActionResult result = new ActionResult(); 4 5 String aseKey = pvgInfo.getAesKey(); 6 pvgInfo.setAesKey("888"); 7 System.out.println("aseKey---" + aseKey); return result; 8 } 9}
二、源码分析
2.1 使用装饰模式对Bean定义进行修改
先上时序图：
可知上面时序图完成了对RequestScope对象定义的修改创建了代理bean，具体修改内容是修改了beanClass为ScopedProxyFactoryBean，并且保存了原来的bean定义originatingBeanDefinition。
下面看下主要代码ScopedProxyUtils中的createScopedProxy
1public static BeanDefinitionHolder createScopedProxy(BeanDefinitionHolder definition, 2 BeanDefinitionRegistry registry, boolean proxyTargetClass) { 3 4 String originalBeanName = definition.getBeanName(); 5 BeanDefinition targetDefinition = definition.getBeanDefinition(); // 保持原来的beanName不变，但是基于原来的bean定义创建代理bean定义, 6 // 保存原来的bean定义到代理bean里面为后面创建代理类做准备. 7 RootBeanDefinition proxyDefinition = new RootBeanDefinition(ScopedProxyFactoryBean.class); 8 proxyDefinition.setOriginatingBeanDefinition(definition.getBeanDefinition()); 9 proxyDefinition.setSource(definition.getSource()); 10 proxyDefinition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE); 11 12 String targetBeanName = getTargetBeanName(originalBeanName); 13 proxyDefinition.getPropertyValues().add("targetBeanName", targetBeanName); if (proxyTargetClass) { 14 targetDefinition.setAttribute(AutoProxyUtils.PRESERVE_TARGET_CLASS_ATTRIBUTE, Boolean.TRUE); // ScopedFactoryBean's "proxyTargetClass" default is TRUE, so we don't need to set it explicitly here. 15 } else { 16 proxyDefinition.getPropertyValues().add("proxyTargetClass", Boolean.FALSE); 17 } // Copy autowire settings from original bean definition. 18 proxyDefinition.setAutowireCandidate(targetDefinition.isAutowireCandidate()); 19 proxyDefinition.setPrimary(targetDefinition.isPrimary()); if (targetDefinition instanceof AbstractBeanDefinition) { 20 proxyDefinition.copyQualifiersFrom((AbstractBeanDefinition) targetDefinition); 21 } // The target bean should be ignored in favor of the scoped proxy. 22 targetDefinition.setAutowireCandidate(false); 23 targetDefinition.setPrimary(false); // 注册代理前的bean到容器，在创建代理bean时候使用.targetBeanName=scopedTarget.lavaPvgInfo 24 registry.registerBeanDefinition(targetBeanName, targetDefinition); // 返回代理bean定义作为原来的bean定义 25 return new BeanDefinitionHolder(proxyDefinition, originalBeanName, definition.getAliases()); 26 }
2.2 创建代理Bean
先上时序图
主要代码如下：
1 public void setBeanFactory(BeanFactory beanFactory) { 2 ... 3 ConfigurableBeanFactory cbf = (ConfigurableBeanFactory) beanFactory; this.scopedTargetSource.setBeanFactory(beanFactory); //创建代理工厂 4 ProxyFactory pf = new ProxyFactory(); 5 pf.copyFrom(this); 6 pf.setTargetSource(this.scopedTargetSource); 7 8 ... // Add an introduction that implements only the methods on ScopedObject. 9 ScopedObject scopedObject = new DefaultScopedObject(cbf, this.scopedTargetSource.getTargetBeanName()); 10 pf.addAdvice(new DelegatingIntroductionInterceptor(scopedObject)); // Add the AopInfrastructureBean marker to indicate that the scoped proxy 11 // itself is not subject to auto-proxying! Only its target bean is. 12 pf.addInterface(AopInfrastructureBean.class); this.proxy = pf.getProxy(cbf.getBeanClassLoader()); 13 } 14 15public Object getProxy(ClassLoader classLoader) { 16 .... try {//获取目标类，也就是被代理的 17 Class rootClass = this.advised.getTargetClass(); 18 Assert.state(rootClass != null, "Target class must be available for creating a CGLIB proxy"); 19 20 Class proxySuperClass = rootClass; if (ClassUtils.isCglibProxyClass(rootClass)) { 21 proxySuperClass = rootClass.getSuperclass(); 22 Class[] additionalInterfaces = rootClass.getInterfaces(); for (Class additionalInterface : additionalInterfaces) { this.advised.addInterface(additionalInterface); 23 } 24 } // Validate the class, writing log messages as necessary. 25 validateClassIfNecessary(proxySuperClass); // Configure CGLIB Enhancer... 26 Enhancer enhancer = createEnhancer(); if (classLoader != null) { 27 enhancer.setClassLoader(classLoader); if (classLoader instanceof SmartClassLoader && 28 ((SmartClassLoader) classLoader).isClassReloadable(proxySuperClass)) { 29 enhancer.setUseCache(false); 30 } 31 } //设置被代理类为超类，这样解释了为啥代理后的类能够赋值给被代理类不会发生错误 32 enhancer.setSuperclass(proxySuperClass); 33 enhancer.setStrategy(new UndeclaredThrowableStrategy(UndeclaredThrowableException.class)); 34 enhancer.setInterfaces(AopProxyUtils.completeProxiedInterfaces(this.advised)); 35 enhancer.setInterceptDuringConstruction(false); //获取拦截器，其中就有DynamicAdvisedInterceptor 36 Callback[] callbacks = getCallbacks(rootClass); 37 enhancer.setCallbacks(callbacks); 38 enhancer.setCallbackFilter(new ProxyCallbackFilter( this.advised.getConfigurationOnlyCopy(), this.fixedInterceptorMap, this.fixedInterceptorOffset)); 39 40 Class[] types = new Class[callbacks.length]; for (int x = 0; x < types.length; x++) { 41 types[x] = callbacks[x].getClass(); 42 } 43 enhancer.setCallbackTypes(types); // Generate the proxy class and create a proxy instance. 44 Object proxy; if (this.constructorArgs != null) { 45 proxy = enhancer.create(this.constructorArgTypes, this.constructorArgs); 46 } else { 47 proxy = enhancer.create(); 48 } return proxy; 49 }
2.3 调用时序图
代码：
1private static class DynamicAdvisedInterceptor implements MethodInterceptor, Serializable { 2 3 ... public Object intercept(Object proxy, Method method, Object[] args, MethodProxy methodProxy) throws Throwable { 4 Object oldProxy = null; boolean setProxyContext = false; 5 Class targetClass = null; 6 Object target = null; try { if (this.advised.exposeProxy) { // Make invocation available if necessary. 7 oldProxy = AopContext.setCurrentProxy(proxy); 8 setProxyContext = true; 9 } // 获取被代理类 10 target = getTarget(); if (target != null) { 11 targetClass = target.getClass(); 12 } 13 List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass); 14 Object retVal; // Check whether we only have one InvokerInterceptor: that is, 15 // no real advice, but just reflective invocation of the target. 16 if (chain.isEmpty() && Modifier.isPublic(method.getModifiers())) { 17 18 retVal = methodProxy.invoke(target, args); 19 } else { // We need to create a method invocation... 20 retVal = new CglibMethodInvocation(proxy, target, method, args, targetClass, chain, methodProxy).proceed(); 21 } 22 retVal = massageReturnTypeIfNecessary(proxy, target, method, retVal); return retVal; 23 } finally { if (target != null) { 24 releaseTarget(target); 25 } if (setProxyContext) { // Restore old proxy. 26 AopContext.setCurrentProxy(oldProxy); 27 } 28 } 29 } 30}
getTarget是关键方法，看下：
1 protected Object getTarget() throws Exception { return this.advised.getTargetSource().getTarget(); 2 } public Object getTarget() throws Exception { return getBeanFactory().getBean(getTargetBeanName()); 3 }
所以最后是从IOC获取目标类bean.下面看下getBean代码：
1//获取RequestScope对象String scopeName = mbd.getScope();final Scope scope = this.scopes.get(scopeName);if (scope == null) { throw new IllegalStateException("No Scope registered for scope '" + scopeName + "'"); 2}try { //调用RequestScope对象对象的get方法 3 Object scopedInstance = scope.get(beanName, new ObjectFactory<Object>() { public Object getObject() throws BeansException { 4 beforePrototypeCreation(beanName); try { return createBean(beanName, mbd, args); 5 } finally { 6 afterPrototypeCreation(beanName); 7 } 8 } 9 }); 10 bean = getObjectForBeanInstance(scopedInstance, name, beanName, mbd); 11}catch (IllegalStateException ex) { throw new BeanCreationException(beanName, "Scope '" + scopeName + "' is not active for the current thread; " + "consider defining a scoped proxy for this bean if you intend to refer to it from a singleton", 12 ex); 13}
requestscope的get方法：
1 public Object get(String name, ObjectFactory objectFactory) { //获取当前线程属性集合 2 RequestAttributes attributes = RequestContextHolder.currentRequestAttributes(); 3 Object scopedObject = attributes.getAttribute(name, getScope()); if (scopedObject == null) {//不在属性集则调用createBean创建，然后放入集合 4 scopedObject = objectFactory.getObject(); 5 attributes.setAttribute(name, scopedObject, getScope()); 6 } return scopedObject; 7 }
可知requestAttributesHolder属性是threadlocal
1public abstract class RequestContextHolder { private static final boolean jsfPresent = 2 ClassUtils.isPresent("javax.faces.context.FacesContext", RequestContextHolder.class.getClassLoader()); private static final ThreadLocal<RequestAttributes> requestAttributesHolder = new NamedThreadLocal<RequestAttributes>("Request attributes"); private static final ThreadLocal<RequestAttributes> inheritableRequestAttributesHolder = new NamedInheritableThreadLocal<RequestAttributes>("Request context"); 3}
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