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Java基础-SSM之Spring的AOP编程
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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\n调用对象的方法 : %s\n调用参数 : %s\n" , 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();
}
WelcomeService.java 文件内容
/*
@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();
}
WelcomeService2.java 文件内容
/*
@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();
}
WelcomeService.java 文件内容
/*
@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();
}
WelcomeService2.java 文件内容
/*
@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");
}
}
WelcomeServiceImpl.java 文件内容
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\n调用对象的方法 : %s\n调用参数 : %s\n" , target.toString(),mname.toString(),args.toString());
System.out.println("============= MyMethodBeforeAdvice代码执行完毕 =============");
}
}
MyMethodBeforeAdvice.java 文件内容
/*
@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;
}
}
MyMethodInterceptor.java 文件内容
/*
@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");
}
}
MyAfterReturningAdvice.java 文件内容
/*
@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());
}
}
MyThrowableAdvice.java 文件内容
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：
