spring学习----AOP

AOP概念

advice（通知）做什么事（before、after、afterReturing、afterThrowing等等）
pointcut（切点）：什么地方
advisor（通知器）：使用那个通知(advice)，在那个切点使用(pointcut)

spring AOP继承关系

• ProxyConfig 数据基类
• AdvisedSupport 封装通知、通知器操作
• ProxyCreatorSupport 子类创建代理对象的辅助类
• ProxyFactoryBean springAOP应用 代理对象生成的具体类 （可以使用声明式配置）
• ProxyFactory springAOP应用 代理对象生成的具体类 （编程式使用springAOP功能）
• AspectJProxyFactory 代理对象生成 继承spring和AspectJ

以ProxyFactoryBean 为例说明

public class ProxyFactoryBean extends ProxyCreatorSupport implements FactoryBean<Object>, BeanClassLoaderAware, BeanFactoryAware

• 实现 FactoryBean通过getObject方法获取代理对象
• 实现 BeanClassLoaderAware 获取当前容器的classLoader JDKDynamicProxy必要参数
• 实现 BeanFactoryAware 获取beanFactory

源码分析

AbstractBeanFactory类

protected <T> T doGetBean(            final String name, final Class<T> requiredType, final Object[] args, boolean typeCheckOnly)            throws BeansException {        final String beanName = transformedBeanName(name);        Object bean;        // Eagerly check singleton cache for manually registered singletons.        // 从缓存中获取已实例化的bean        Object sharedInstance = getSingleton(beanName);        if (sharedInstance != null && args == null) {            if (logger.isDebugEnabled()) {                if (isSingletonCurrentlyInCreation(beanName)) {                    logger.debug("Returning eagerly cached instance of singleton bean '" + beanName +                            "' that is not fully initialized yet - a consequence of a circular reference");                }                else {                    logger.debug("Returning cached instance of singleton bean '" + beanName + "'");                }            }            // 对获取的实例处理   如果没有继承FactoryBean直接返回实例              // 否则调用getObject  aop的代理对象的生成入口就在此处            bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);        }protected Object getObjectForBeanInstance(            Object beanInstance, String name, String beanName, RootBeanDefinition mbd) {        // Don't let calling code try to dereference the factory if the bean isn't a factory.        if (BeanFactoryUtils.isFactoryDereference(name) && !(beanInstance instanceof FactoryBean)) {            throw new BeanIsNotAFactoryException(transformedBeanName(name), beanInstance.getClass());        }        // Now we have the bean instance, which may be a normal bean or a FactoryBean.        // If it's a FactoryBean, we use it to create a bean instance, unless the        // caller actually wants a reference to the factory.        if (!(beanInstance instanceof FactoryBean) || BeanFactoryUtils.isFactoryDereference(name)) {            return beanInstance;        }        Object object = null;        if (mbd == null) {            object = getCachedObjectForFactoryBean(beanName);        }        if (object == null) {            // Return bean instance from factory.            FactoryBean<?> factory = (FactoryBean<?>) beanInstance;            // Caches object obtained from FactoryBean if it is a singleton.            if (mbd == null && containsBeanDefinition(beanName)) {                mbd = getMergedLocalBeanDefinition(beanName);            }            boolean synthetic = (mbd != null && mbd.isSynthetic());            object = getObjectFromFactoryBean(factory, beanName, !synthetic);        }        return object;    }

FactoryBeanRegistrySupport

private Object doGetObjectFromFactoryBean(final FactoryBean<?> factory, final String beanName)            throws BeanCreationException {        Object object;        try {            if (System.getSecurityManager() != null) {                AccessControlContext acc = getAccessControlContext();                try {                    object = AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {                        @Override                        public Object run() throws Exception {                                return factory.getObject();                            }                        }, acc);                }                catch (PrivilegedActionException pae) {                    throw pae.getException();                }            }            else {                // AOP代理对象生成                object = factory.getObject();            }        }        catch (FactoryBeanNotInitializedException ex) {            throw new BeanCurrentlyInCreationException(beanName, ex.toString());        }        catch (Throwable ex) {            throw new BeanCreationException(beanName, "FactoryBean threw exception on object creation", ex);        }        // Do not accept a null value for a FactoryBean that's not fully        // initialized yet: Many FactoryBeans just return null then.        if (object == null && isSingletonCurrentlyInCreation(beanName)) {            throw new BeanCurrentlyInCreationException(                    beanName, "FactoryBean which is currently in creation returned null from getObject");        }        return object;    }

ProxyFactoryBean

 public Object getObject() throws BeansException {        //初始化通知器        this.initializeAdvisorChain();        if(this.isSingleton()) {            return this.getSingletonInstance();        } else {            if(this.targetName == null) {                this.logger.warn("Using non-singleton proxies with singleton targets is often undesirable. Enable prototype proxies by setting the \'targetName\' property.");            }            return this.newPrototypeInstance();        }    }

ProxyCreatorSupport

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

DefaultAopProxyFactory

 public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException {        if(!config.isOptimize() && !config.isProxyTargetClass() && !this.hasNoUserSuppliedProxyInterfaces(config)) {            return new JdkDynamicAopProxy(config);        } else {            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.");            } else {            // 使用何种方式生成代理对象            // 继承接口的方式使用jdk动态代理            // 否则使用cglib                return (AopProxy)(!targetClass.isInterface() && !Proxy.isProxyClass(targetClass)?new ObjenesisCglibAopProxy(config):new JdkDynamicAopProxy(config));            }        }    }

AOP ProxyFactoryBean示例

bean xml配置

<!-- ======================spring AOP配置=========================================-->    <bean id="myBeforeAdvice" class="com.chenfei.advice.MyBeforeAdvice"></bean>    <bean id="bussinessService" class="com.chenfei.service.impl.BussinessServiceImpl"></bean>    <bean id="myProxy" class="org.springframework.aop.framework.ProxyFactoryBean">        <property name="proxyInterfaces">            <value>com.chenfei.service.IBussinessService</value>        </property>        <property name="target">            <ref bean="bussinessService"/>        </property>        <property name="interceptorNames">            <list>                <value>myBeforeAdvice</value>            </list>        </property>    </bean>

advice

public class MyBeforeAdvice implements MethodBeforeAdvice{    @Override    public void before(Method method, Object[] objects, Object o) throws Throwable {        System.out.println("=========我是前置通知方法=============");    }}

需要生成代理类的接口

public interface IBussinessService {    void bussiness();    void sayHello();}

需要生成代理类的目标对象

public class BussinessServiceImpl implements IBussinessService{    @Override    public void bussiness() {        System.out.println("=========我是业务方法==========");    }    @Override    public void sayHello() {        System.out.println("=========我是say Hello==========");    }}

测试方法

public class TestSpringAOP {    @Test    public void test(){        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("classpath:beans.xml");        IBussinessService bussinessServiceImpl =  applicationContext.getBean("myProxy",IBussinessService.class);        bussinessServiceImpl.bussiness();        bussinessServiceImpl.sayHello();    }}