Java基础-SSM之Spring的AOP编程

　　　　　　　　　　　　Java基础-SSM之Spring的AOP编程

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　作者：尹正杰

版权声明：原创作品，谢绝转载！否则将追究法律责任。

 　　  Spring的本质说白了就是动态代理，接下来我们会体验AOP的用法。它是对OOP的增强，适用于系统级功能。

 一.MethodBeforeAdvice接口的应用

1>.引入新的依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>cn.org.yinzhengjie</groupId>
    <artifactId>MySpring</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>4.3.5.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>aopalliance</groupId>
            <artifactId>aopalliance</artifactId>
            <version>1.0</version>
        </dependency>
    </dependencies>
    
</project>

2>.定义通知类

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:y1053419035@qq.com
*/
package cn.org.yinzhengjie.spring.aop.advice;

import org.springframework.aop.MethodBeforeAdvice;

import java.lang.reflect.Method;

/**
 * 前置通知
 */
public class MyMethodBeforeAdvice implements MethodBeforeAdvice {
    public void before(Method method, Object[] args, Object target) throws Throwable {
        String mname = method.getName() ;
        System.out.printf("当前处理的对象 : %s
调用对象的方法 : %s
调用参数 : %s
" , target.toString(),mname.toString(),args.toString());
        System.out.println("============= MyMethodBeforeAdvice代码执行完毕 =============");
    }
}

3>.编写实现WelcomeService和WelcomeService2两个接口的类

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:y1053419035@qq.com
*/
package cn.org.yinzhengjie.spring.aop.advice;

public interface WelcomeService {
    public abstract void sayHello();
}

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:y1053419035@qq.com
*/
package cn.org.yinzhengjie.spring.aop.advice;

public interface WelcomeService2 {
    public abstract void sayHello2();
}

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:y1053419035@qq.com
*/
package cn.org.yinzhengjie.spring.aop.advice;


public class WelcomeServiceImpl implements WelcomeService,WelcomeService2{
    private String name ;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void sayHello() {
        System.out.println(name);
    }

    public void sayHello2() {
        System.out.println("Hello Wold");
    }
}

4>.编写Spring的配置文件

<?xml version="1.0"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
                                http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
                                http://www.springframework.org/schema/aop
                                http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
                                http://www.springframework.org/schema/context
                                http://www.springframework.org/schema/context/spring-context-4.3.xsd
                                http://www.springframework.org/schema/tx
                                http://www.springframework.org/schema/tx/spring-tx-4.3.xsd">
    <!-- 前置通知 -->
    <bean id="beforeAdvice" class="cn.org.yinzhengjie.spring.aop.advice.MyMethodBeforeAdvice" />

    <!-- 目标对象 -->
    <bean id="wsTarget" class="cn.org.yinzhengjie.spring.aop.advice.WelcomeServiceImpl">
        <property name="name" value="I'm yinzhengjie !!!" />
    </bean>

    <!-- 代理对象 -->
    <bean id="wsProxy" class="org.springframework.aop.framework.ProxyFactoryBean">
        <!-- 代理接口集 -->
        <property name="proxyInterfaces">
            <list>
                <value>cn.org.yinzhengjie.spring.aop.advice.WelcomeService</value>
                <value>cn.org.yinzhengjie.spring.aop.advice.WelcomeService2</value>
            </list>
        </property>
        <!-- 拦截器名集合 -->
        <property name="interceptorNames">
            <list>
                <value>beforeAdvice</value>
            </list>
        </property>

        <!-- 注意，目标类的名字为"target"关键字，而ref是真正需要被代理的对象连接。一个代理对象一次性只能代理一个类，如果想要代理多个类，需要重新单独定义bean标签哟！ -->
        <property name="target" ref="wsTarget" />

    </bean>
</beans>

5>.编写单元测试类代码

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:y1053419035@qq.com
*/
package cn.org.yinzhengjie.spring.aop.advice;

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

public class TestAop {
    @Test
    public void testAOP1(){
        ApplicationContext ac = new ClassPathXmlApplicationContext("aop.xml") ;
        WelcomeService ws = (WelcomeService) ac.getBean("wsProxy");
        ws.sayHello();

        WelcomeService2 ws2 = (WelcomeService2)ws;
        ws2.sayHello2();

    }
}

　　以上代码测试结果如下：

二.AOP的四个通知编程案例

　　上面我们已经介绍了Spring的AOP编程中的一个前置通知，其实除了前置通知还有后置通知，循环通知以及异常通知。其实配置文件的方法和上面类似，只不过他们有各自的优点，下面我简单的做个介绍：

　　　　前置通知：主要负责处理调用目标对象之前执行的代码；

　　　　后置通知：主要负责处理调用目标对象之后的执行代码；

　　　　环绕通知：它执行的优先级是在后置通知之前，在前置通知之后的执行的代码，它可以把方法包起来处理，比如在调用方法之前执行一段代码，在调用方法之后，还可以执行一段代码，另外，相比前置通知和通知通知，它还新增了一个返回值的功能；

　　　　异常通知：它执行的优先级暂时没法确定，而且不一定执行，顾名思义，它是在有异常的时候才会触发的代码！因此即使你写了这样的通知，有可能你看不到它的执行结果，除非你故意写一段可能出现异常的代码；

1>.编写测试代码

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:y1053419035@qq.com
*/
package cn.org.yinzhengjie.spring.aop.advice;

public interface WelcomeService {
    public abstract void sayHello();
}

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:y1053419035@qq.com
*/
package cn.org.yinzhengjie.spring.aop.advice;

public interface WelcomeService2 {
    public abstract void sayHello2();
}

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:y1053419035@qq.com
*/
package cn.org.yinzhengjie.spring.aop.advice;


public class WelcomeServiceImpl implements WelcomeService,WelcomeService2{
    private String name ;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void sayHello() {
        System.out.println(name);
    }

    public void sayHello2() {
        System.out.println("Hello Wold");
    }
}

2>.编写通知类

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:y1053419035@qq.com
*/
package cn.org.yinzhengjie.spring.aop.advice;

import org.springframework.aop.MethodBeforeAdvice;

import java.lang.reflect.Method;

/**
 * 前置通知
 */
public class MyMethodBeforeAdvice implements MethodBeforeAdvice {
    public void before(Method method, Object[] args, Object target) throws Throwable {
        String mname = method.getName() ;
        System.out.printf("当前处理的对象 : %s
调用对象的方法 : %s
调用参数 : %s
" , target.toString(),mname.toString(),args.toString());
        System.out.println("============= MyMethodBeforeAdvice代码执行完毕 =============");
    }
}

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:y1053419035@qq.com
*/
package cn.org.yinzhengjie.spring.aop.advice;

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

/**
 * 环绕通知,可以篡改行为
 */
public class MyMethodInterceptor  implements MethodInterceptor {

    public Object invoke(MethodInvocation invocation) throws Throwable {
        System.out.println("begin");
        //调用目标对象方法的返回值
        Object tis = invocation.getThis();
        System.out.println(tis);
        Object ret = invocation.proceed() ;
        System.out.println("end");
        return ret;
    }
}

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:y1053419035@qq.com
*/
package cn.org.yinzhengjie.spring.aop.advice;

import org.springframework.aop.AfterReturningAdvice;

import java.lang.reflect.Method;

public class MyAfterReturningAdvice  implements AfterReturningAdvice {
    public void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable {
        System.out.println("over");
    }
}

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:y1053419035@qq.com
*/
package cn.org.yinzhengjie.spring.aop.advice;

import org.springframework.aop.ThrowsAdvice;

import java.lang.reflect.Method;

/**
 * 异常通知
 */
public class MyThrowableAdvice implements ThrowsAdvice {
    public void afterThrowing(Method method, Object[] args, Object target, Exception ex){
        System.out.println("出事了！！" + ex.toString());
    }
}

3>.编写Spring的配置文件

<?xml version="1.0"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
                        http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
                        http://www.springframework.org/schema/aop
                        http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
                        http://www.springframework.org/schema/context
                        http://www.springframework.org/schema/context/spring-context-4.3.xsd
                        http://www.springframework.org/schema/tx
                        http://www.springframework.org/schema/tx/spring-tx-4.3.xsd">
    <!-- 通知 -->
    <bean id="beforeAdvice" class="cn.org.yinzhengjie.spring.aop.advice.MyMethodBeforeAdvice" />
    <bean id="afterAdvice" class="cn.org.yinzhengjie.spring.aop.advice.MyAfterReturningAdvice" />
    <bean id="aroundAdvice" class="cn.org.yinzhengjie.spring.aop.advice.MyMethodInterceptor" />
    <bean id="throwableAdvice" class="cn.org.yinzhengjie.spring.aop.advice.MyThrowableAdvice" />


    <!-- 目标对象 -->
    <bean id="wsTarget" class="cn.org.yinzhengjie.spring.aop.advice.WelcomeServiceImpl">
        <property name="name" value="tom" />
    </bean>

    <!-- 代理对象 -->
    <bean id="wsProxy" class="org.springframework.aop.framework.ProxyFactoryBean">
        <!-- 代理接口集 -->
        <property name="proxyInterfaces">
            <list>
                <value>cn.org.yinzhengjie.spring.aop.advice.WelcomeService</value>
                <value>cn.org.yinzhengjie.spring.aop.advice.WelcomeService2</value>
            </list>
        </property>
        <!-- 拦截器名集合 -->
        <property name="interceptorNames">
            <list>
                <value>beforeAdvice</value>
                <value>afterAdvice</value>
                <value>aroundAdvice</value>
                <value>throwableAdvice</value>
            </list>
        </property>
        <property name="target" ref="wsTarget" />
    </bean>
</beans>

4>.编写测试代码

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:y1053419035@qq.com
*/
package cn.org.yinzhengjie.spring.aop.advice;

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

public class TestAop {
    @Test
    public void testAOP1(){
        ApplicationContext ac = new ClassPathXmlApplicationContext("aop.xml") ;
        WelcomeService ws = (WelcomeService) ac.getBean("wsProxy");
        ws.sayHello();

        WelcomeService2 ws2 = (WelcomeService2)ws;
        ws2.sayHello2();

    }
}

5>.运行以上代码执行结果如下：