关于spring aop 的介绍
一、基础接口和类
1、Person接口的源码
Java代码
public interface Person {
public void info();
public void show(String message);
}
public interface Person {
public void info();
public void show(String message);
}
2、PersonImpl类的源码
Java代码
public class PersonImpl implements Person {
private String name;
private int age;
public void setName(String name) {
this.name = name;
}
public void setAge(int age) {
this.age = age;
}
public void info() {
System.out.println("\t我叫" + name + ",今年" + age + "岁。");
}
public void show(String message) {
System.out.println(message);
}
}
public class PersonImpl implements Person {
private String name;
private int age;
public void setName(String name) {
this.name = name;
}
public void setAge(int age) {
this.age = age;
}
public void info() {
System.out.println("\t我叫" + name + ",今年" + age + "岁。");
}
public void show(String message) {
System.out.println(message);
}
}
3、bean的配置
Xml代码
<!-- 目标对象 -->
<bean id="personTarget" value="xxx"/>
<property name="age" value="xx"/>
</bean>
<!-- 目标对象 -->
<bean id="personTarget" value="xxx"/>
<property name="age" value="xx"/>
</bean>
二、Spring AOP支持的通知类型
一）环绕通知（Around advice）
实现环绕通知需要实现org.aopalliance.intercept.MethodInterceptor接口。
1、PersonAroundAdvice类的源码
Java代码
public class PersonAroundAdvice implements MethodInterceptor {
public Object invoke(MethodInvocation invocation) throws Throwable {
System.out.println("AroundAdvice：方法调用前");
//不要忘记调用invocation的proceed方法哦
Object result = invocation.proceed();
System.out.println("AroundAdvice：方法调用后");
return result;
}
}
public class PersonAroundAdvice implements MethodInterceptor {
public Object invoke(MethodInvocation invocation) throws Throwable {
System.out.println("AroundAdvice：方法调用前");
//不要忘记调用invocation的proceed方法哦
Object result = invocation.proceed();
System.out.println("AroundAdvice：方法调用后");
return result;
}
}
2、bean配置
Xml代码
<bean id="personAroundAdvice" value="com.cjm.aop.Person"/>
<property name="target" ref="personTarget"/>
<property name="interceptorNames">
<list>
<value>personAroundAdvice</value>
</list>
</property>
</bean>
<bean id="personAroundAdvice" value="com.cjm.aop.Person"/>
<property name="target" ref="personTarget"/>
<property name="interceptorNames">
<list>
<value>personAroundAdvice</value>
</list>
</property>
</bean>
3、测试代码
Java代码
ApplicationContext context = new FileSystemXmlApplicationContext("classpath:com/cjm/aop/beans.xml");
Person p = (Person)context.getBean("person"); //注意这里是代理工厂Bean的ID
p.info();
ApplicationContext context = new FileSystemXmlApplicationContext("classpath:com/cjm/aop/beans.xml");
Person p = (Person)context.getBean("person"); //注意这里是代理工厂Bean的ID
p.info();
二）前置通知（Before advice）
实现前置通知需要实现org.springframework.aop.MethodBeforeAdvice接口。
1、PersonBeforeAdvice类的源码
Java代码
public class PersonBeforeAdvice implements MethodBeforeAdvice {
public void before(Method method, Object[] args, Object target) throws Throwable {
System.out.println("BeforeAdvice：方法调用前");
}
}
public class PersonBeforeAdvice implements MethodBeforeAdvice {
public void before(Method method, Object[] args, Object target) throws Throwable {
System.out.println("BeforeAdvice：方法调用前");
}
}
2、bean配置
Xml代码
<bean id="personBeforeAdvice" value="com.cjm.aop.Person"/>
<property name="target" ref="personTarget"/>
<property name="interceptorNames">
<list>
<value>personBeforeAdvice</value>
</list>
</property>
</bean>
<bean id="personBeforeAdvice" value="com.cjm.aop.Person"/>
<property name="target" ref="personTarget"/>
<property name="interceptorNames">
<list>
<value>personBeforeAdvice</value>
</list>
</property>
</bean>
三）返回后通知（After Returning advice）
实现返回后通知需要实现org.springframework.aop.AfterReturningAdvice接口。
1、PersonAfterReturningAdvice类的源码
Java代码
public class PersonAfterReturningAdvice implements AfterReturningAdvice {
public void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable {
System.out.println("AfterReturningAdvice：方法调用后");
}
}
public class PersonAfterReturningAdvice implements AfterReturningAdvice {
public void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable {
System.out.println("AfterReturningAdvice：方法调用后");
}
}
2、bean配置
Xml代码
<bean id="personAfterReturningAdvice" value="com.cjm.aop.Person"/>
<property name="target" ref="personTarget"/>
<property name="interceptorNames">
<list>
<value>personAfterReturningAdvice</value>
</list>
</property>
</bean>
<bean id="personAfterReturningAdvice" value="com.cjm.aop.Person"/>
<property name="target" ref="personTarget"/>
<property name="interceptorNames">
<list>
<value>personAfterReturningAdvice</value>
</list>
</property>
</bean>
3、以上的配置中，通知对目标对象的所有方法都会起作用。如果需要过滤掉一部分方法，可以用正则表达式切入点配置器或者方法名匹配切入点配置器实现。
Xml代码
<!-- 通知与正则表达式切入点一起配置 -->
<!-- Advisor等于切入点加通知 -->
<!-- 方法名匹配切入点配置器：org.springframework.aop.support.NameMatchMethodPointcutAdvisor -->
<bean id="personPointcutAdvisor" ref="personAfterReturningAdvice"/>
<property name="patterns">
<list>
<value>.*info.*</value>
</list>
</property>
</bean>
<bean id="person" value="com.cjm.aop.Person"/>
<property name="target" ref="personTarget"/>
<property name="interceptorNames">
<list>
<value>personPointcutAdvisor</value>
</list>
</property>
</bean>
<!-- 通知与正则表达式切入点一起配置 -->
<!-- Advisor等于切入点加通知 -->
<!-- 方法名匹配切入点配置器：org.springframework.aop.support.NameMatchMethodPointcutAdvisor -->
<bean id="personPointcutAdvisor" ref="personAfterReturningAdvice"/>
<property name="patterns">
<list>
<value>.*info.*</value>
</list>
</property>
</bean>
<bean id="person" value="com.cjm.aop.Person"/>
<property name="target" ref="personTarget"/>
<property name="interceptorNames">
<list>
<value>personPointcutAdvisor</value>
</list>
</property>
</bean>
四）异常通知（Throws advice）
当连接点抛出异常时，异常通知被调用。实现异常通知需要实现org.springframework.aop.ThrowsAdvice接口，该接口不包含任何方法，但在实现该接口时必须实现如下形式的方法：
afterThrowing([Method], [args], [target], Throwable subclass)
可以实现一个或多个这样的方法。在这些方法中，只有第四个参数是必需的，前三个参数可选。
1、PersonThrowsAdvice类的源码
Java代码
public class PersonThrowsAdvice implements ThrowsAdvice {
public void afterThrowing(FileNotFoundException ex){
System.out.println("ThrowsAdvice >> FileNotFoundException：" + ex.toString());
}
public void afterThrowing(Object[] args, Exception ex){
System.out.println("ThrowsAdvice >> Exception：" + ex.getMessage());
}
public void afterThrowing(Method method, Object[] args, Object target, Throwable ex){
System.out.println("ThrowsAdvice >> Throwable：" + ex.getMessage());
}
}
public class PersonThrowsAdvice implements ThrowsAdvice {
public void afterThrowing(FileNotFoundException ex){
System.out.println("ThrowsAdvice >> FileNotFoundException：" + ex.toString());
}
public void afterThrowing(Object[] args, Exception ex){
System.out.println("ThrowsAdvice >> Exception：" + ex.getMessage());
}
public void afterThrowing(Method method, Object[] args, Object target, Throwable ex){
System.out.println("ThrowsAdvice >> Throwable：" + ex.getMessage());
}
}
2、bean配置
Xml代码
<bean id="personThrowsAdvice" value="com.cjm.aop.Person"/>
<property name="target" ref="personTarget"/>
<property name="interceptorNames">
<list>
<value>personThrowsAdvice</value>
</list>
</property>
</bean>
<bean id="personThrowsAdvice" value="com.cjm.aop.Person"/>
<property name="target" ref="personTarget"/>
<property name="interceptorNames">
<list>
<value>personThrowsAdvice</value>
</list>
</property>
</bean>
五）引入通知（Introduction advice）
引入通知是一种特殊的通知，它能将新的成员变量、成员方法引入到目标类中。它不能作用于任何切入点，因为它只作用于类层次，而不是方法层次。实现引入通知需要实现IntroductionAdvisor和IntroductionInterceptor接口。
引入通知不能调用proceed方法。Advisor必须针对每个实例，并且是有状态的。
引入通知的效果类似于设计模式中的访问者模式（Visitor Pattern）。
1、Lockable接口的源码
Java代码
public interface Lockable {
void lock();
void unlock();
boolean locked();
}
public interface Lockable {
void lock();
void unlock();
boolean locked();
}
2、LockableImpl类的源码
Java代码
public class LockableImpl extends DelegatingIntroductionInterceptor implements Lockable {
private boolean locked;
public void lock() {
this.locked = true;
}
public void unlock() {
this.locked = false;
}
public boolean locked() {
return this.locked;
}
@Override
public Object invoke(MethodInvocation invocation) throws Throwable {
if(this.locked){
throw new RuntimeException("加锁，无法执行");
}
//这里不能调用invocation的proceed方法
//通常不需要改写invoke方法，直接调用父类的该方法即可
return super.invoke(invocation);
}
}
public class LockableImpl extends DelegatingIntroductionInterceptor implements Lockable {
private boolean locked;
public void lock() {
this.locked = true;
}
public void unlock() {
this.locked = false;
}
public boolean locked() {
return this.locked;
}
@Override
public Object invoke(MethodInvocation invocation) throws Throwable {
if(this.locked){
throw new RuntimeException("加锁，无法执行");
}
//这里不能调用invocation的proceed方法
//通常不需要改写invoke方法，直接调用父类的该方法即可
return super.invoke(invocation);
}
}
3、PersonIntroductionAdvice类的源码
Java代码
public class PersonIntroductionAdvice extends DefaultIntroductionAdvisor {
public PersonIntroductionAdvice(){
super(new LockableImpl(), Lockable.class);
}
}
public class PersonIntroductionAdvice extends DefaultIntroductionAdvisor {
public PersonIntroductionAdvice(){
super(new LockableImpl(), Lockable.class);
}
}
4、bean配置
Xml代码
<!-- Advice必须针对每个实例，所以scope要设为prototype -->
<bean id="personIntroductionAdvice" scope="prototype"/>
<bean id="person" value="com.cjm.aop.Person"/>
<property name="target" ref="personTarget"/>
<property name="interceptorNames">
<list>
<value>personIntroductionAdvice</value>
</list>
</property>
</bean>
<!-- Advice必须针对每个实例，所以scope要设为prototype -->
<bean id="personIntroductionAdvice" scope="prototype"/>
<bean id="person" value="com.cjm.aop.Person"/>
<property name="target" ref="personTarget"/>
<property name="interceptorNames">
<list>
<value>personIntroductionAdvice</value>
</list>
</property>
</bean>
5、测试代码
Java代码
ApplicationContext context = new FileSystemXmlApplicationContext("classpath:com/cjm/aop/beans.xml");
//获得目标bean的代理bean
Person p = (Person)context.getBean("person");
//执行代理bean的方法，此时并未调用lock方法，可以执行
p.info();
Lockable lockable = (Lockable)p;
lockable.lock();
//目标bean已被锁定，此处将抛出异常
p.info();
转自http://chenjumin.iteye.com/blog/364948