AOP简单实例

原理图:

1. 功能需求: 在调用service1之前完成写日志功能[前置通知]

2. 工程结构:

TestServiceInter .java

package com.itcast.aop.service;

// 接口1
public interface TestServiceInter {
// 目标方法
public void sayHello();
}

Test1Service.java

package com.itcast.aop.service;

// 要被写日志的service
public class Test1Service implements TestServiceInter {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
// 目标方法实现
@Override
public void sayHello() {
System.out.println("Hello, " + this.name);
}
}

MyMethodBeforeAdvice.java

package com.itcast.aop.service;

import java.lang.reflect.Method;

import org.springframework.aop.MethodBeforeAdvice;

// 前置通知[在目标方法之前执行]
public class MyMethodBeforeAdvice implements MethodBeforeAdvice {
/**
* method: 目标方法[即sayHello()]
* args: 目标方法的参数[即sayHello(参数1, 参数2, 参数3, ...)]
* target: 被代理的对象[接口实现类, 即Test1Service类]
*/
@Override
public void before(Method method, Object[] args, Object target)
throws Throwable {
for (Object arg: args) {
System.out.println(arg);
}
System.out.println("在这里写日志..." + method + " | " + args + " | " + target.getClass().getName());
}
}

beans.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">


<bean id="test1Service" class="com.itcast.aop.service.Test1Service">
<property name="name" value="张三" />
</bean>


<bean id="myMethodBeforeAdvice" class="com.itcast.aop.service.MyMethodBeforeAdvice" />


<bean id="proxyFactoryBean" class="org.springframework.aop.framework.ProxyFactoryBean">

<property name="proxyInterfaces">
<list>
<value>com.itcast.aop.service.TestServiceInter</value>

</list>
</property>

<property name="target" ref="test1Service" />

<property name="interceptorNames">
<value>myMethodBeforeAdvice</value>
</property>
</bean>
</beans>

ApplicationContextInit.java

package com.itcast.aop.util;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

// ApplicationContext是一个重量级的类, 很耗内存, 所以要设计成单例
public class ApplicationContextInit {
private static ApplicationContext ac = null;
private ApplicationContextInit() {

}
public static ApplicationContext getApplicationContext() {
if (ac == null) {
ac = new ClassPathXmlApplicationContext("beans.xml");
}
return ac;
}
}

AOPTest.java

package com.itcast.aop.test;

import org.springframework.context.ApplicationContext;

import com.itcast.aop.service.TestServiceInter;
import com.itcast.aop.util.ApplicationContextInit;

// 测试类
public class AOPTest {
public static void main(String[] args) {
ApplicationContext ac = ApplicationContextInit.getApplicationContext();
TestServiceInter ti = (TestServiceInter) ac.getBean("proxyFactoryBean");　　// 面向接口编程
ti.sayHello();
}
}

运行结果:

---------------------------------------------------------------------------------------

功能需求: 在调用sayHelo()方法之后关闭资源[后置通知]

MyAfterReturningAdvice.java

package com.itcast.aop.service;

import java.lang.reflect.Method;

import org.springframework.aop.AfterReturningAdvice;

// 后置通知
public class MyAfterReturningAdvice implements AfterReturningAdvice {
/**
* returnValue: 目标方法的返回值
* method: 目标方法
* args: 目标方法的参数
* target: 被代理的对象
*/
@Override
public void afterReturning(Object returnValue, Method method, Object[] args,
Object target) throws Throwable {
System.out.println("后置通知: 关闭资源...");
}
}

beans.xml

测试:

---------------------------------------------------------------------------------------

[环绕通知]: 可以选择在目标方法执行前/后执行

MyMethodInterceptor.java

package com.itcast.aop.service;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;

// 环绕通知
public class MyMethodInterceptor implements MethodInterceptor {
/**
* method: 目标方法
*/
@Override
public Object invoke(MethodInvocation method) throws Throwable {
System.out.println("环绕通知: 目标方法前调用...");
Object object = method.proceed();
System.out.println("环绕通知: 目标方法后调用...");
return object;
}
}

beans.xml

测试

[异常通知]: 目标方法发生异常时执行

Test1Service.java

MyThrowsAdvice.java

package com.itcast.aop.service;

import java.lang.reflect.Method;
import org.springframework.aop.ThrowsAdvice;

// 异常通知: 在目标方法执行过程中出异常时调用
// ThrowsAdvice: 此接口是标识性接口, 没有任何方法
public class MyThrowsAdvice implements ThrowsAdvice {
/**
* @param method: 目标方法
* @param objects: 目标方法的参数
* @param target: 被代理的对象, 即: Test1Service对象
* @param exception: 捕获到的异常
*/
public void afterThrowing(Method method, Object[] objects, Object target, Exception exception) {
　　System.out.println("异常通知: 出异常了---->" + exception.getMessage());
}
}