Spring面向切面

1.AspectJ - AOP

面向切面编程是面向对象的一个补充

在保存用户前添加一个日志，再加上时刻的记录。 总之，就是方法前后加一点业务逻辑

新建资源库：
Preference>Java>BuildPath>UserLibraries，AddLibrary>UserLibrary

/Spring_AOP/src/yuki/spring/aop/imitate/UserService.java

package yuki.spring.aop.imitate;

public interface UserService {

    void save();
}

/Spring_AOP/src/yuki/spring/aop/imitate/UserServiceImpl.java

package yuki.spring.aop.imitate;

public class UserServiceImpl implements UserService{

    public void save(){
        System.out.println("user saved...");
    }
}

/Spring_AOP/src/yuki/spring/aop/imitate/Intercepter.java

package yuki.spring.aop.imitate;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;

public abstract class Intercepter implements InvocationHandler {

  private Object target;
  public void setTarget(Object target) {
    this.target = target;
  }
  
  protected abstract void beforeMethod();
  protected abstract void afterMethod();
  
  @Override
  public Object invoke(Object proxy, Method m, Object[] args)
      throws Throwable {
    beforeMethod();
    m.invoke(target, args);
    afterMethod();
    return null;
  }

}

/Spring_AOP/src/yuki/spring/aop/imitate/LogIntercepter.java

package yuki.spring.aop.imitate;

public class LogIntercepter extends Intercepter {

  @Override
  public void beforeMethod() {
    System.out.println("log start...");
  }

  @Override
  protected void afterMethod() {
    System.out.println("log end...");
  }

}

/Spring_AOP/src/yuki/spring/aop/imitate/TimeIntercepter.java

package yuki.spring.aop.imitate;

public class TimeIntercepter extends Intercepter {

  @Override
  protected void beforeMethod() {
    System.out.println("start:" + System.currentTimeMillis());
  }

  @Override
  protected void afterMethod() {
    System.out.println("end:" + System.currentTimeMillis());
  }

}

/Spring_AOP/src/yuki/spring/aop/imitate/ProxyTest.java

package yuki.spring.aop.imitate;

import java.lang.reflect.Proxy;

public class ProxyTest {

  public static void main(String[] args) {
    UserService service = new UserServiceImpl();
    
    Intercepter[] intercepters = {new LogIntercepter(), new TimeIntercepter()};
    for(Intercepter intercepter : intercepters){
      intercepter.setTarget(service);
      service = (UserService) Proxy.newProxyInstance(
          service.getClass().getClassLoader(), 
          service.getClass().getInterfaces(), intercepter);
    }
    
    service.save();
    
  }

}

上面的程序中，两个类继承了实现InvocationHandler接口的抽象类，

也可以说是间接地实现了InvocationHandler接口；

声明为UserService接口类型的service，

在循环中每一次接收Proxy.newProxyInstance方法的计算结果后就会改变它指向的对象。

运行结果如下：

start:1409496143248
log start...
user saved...
log end...
end:1409496143250

<aop:aspectj-autoproxy></aop:aspectj-autoproxy>

注解的方式实现AOP使用的是aspectj，

aspectj是专门用来产生动态代理的一个框架

可以使用aspectj注解的方式实现spring的AOP，

把这个逻辑织入到原来的逻辑里面去

引入jar：aspectjrt.jar、aspectj-weaver.jar：http://www./Code/Jar/a/aspectj.htm

在类上添加注解 @Aspect和 @Component，在方法上添加注解 @Before

切入点语法 @Before("execution(public void yuki.spring.aop.annotation"

+ ".UserServiceImpl.save(yuki.spring.aop.annotation.User))")

引入jar：aopalliance-.jar：

http://www./Code/Jar/a/Downloadaopalliancejar.htm

@Component要加在对应的实现类上，因为getBean后要获取这个对象

/Spring_AOP/src/yuki/spring/aop/annotation/User.java

package yuki.spring.aop.annotation;

public class User {

}

/Spring_AOP/src/yuki/spring/aop/annotation/UserService.java

package yuki.spring.aop.annotation;

public interface UserService {

    void save(User user);
}

/Spring_AOP/src/yuki/spring/aop/annotation/UserServiceImpl.java

package yuki.spring.aop.annotation;

import org.springframework.stereotype.Component;

@Component("userService")
public class UserServiceImpl implements UserService{

    public void save(User user){
        System.out.println("user saved...");
    }
}

/Spring_AOP/src/annotation.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:aop="http://www./schema/aop"
    xmlns:context="http://www./schema/context" 
    xmlns="http://www./schema/beans"
    xmlns:xsi="http://www./2001/XMLSchema-instance"
    xsi:schemaLocation="http://www./schema/beans 
      http://www./schema/beans/spring-beans-4.0.xsd 
      http://www./schema/aop 
      http://www./schema/aop/spring-aop-4.0.xsd 
      http://www./schema/context 
      http://www./schema/context/spring-context-4.0.xsd ">
    
    <context:annotation-config></context:annotation-config>
    <context:component-scan base-package="yuki.spring.aop.annotation"></context:component-scan>
    
    <aop:aspectj-autoproxy></aop:aspectj-autoproxy>
    
</beans>

/Spring_AOP/src/yuki/spring/aop/annotation/LogIntercepter.java

package yuki.spring.aop.annotation;

import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.stereotype.Component;

@Aspect
@Component
public class LogIntercepter {

    @Before("execution(public void yuki.spring.aop.annotation"
            + ".UserServiceImpl.save(yuki.spring.aop.annotation.User))")
    public void beforeMethod() {
        System.out.println("method start...");
    }

}

/Spring_AOP/src/yuki/spring/aop/annotation/TimeIntercepter.java

package yuki.spring.aop.annotation;

import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.stereotype.Component;

@Aspect
@Component
public class TimeIntercepter {

  @Before("execution("
      + "public * yuki.spring.aop.annotation..*.*(..)"
      + ")")
  public void beforeMethod() {
    System.out.println("before:" + System.currentTimeMillis());
  }

  @AfterReturning("execution( public * yuki.spring.aop.annotation..*.*(..) )")
  public void afterReturningMethod() {
    System.out.println("afterReturning:" + System.currentTimeMillis());
  }
}

/Spring_AOP/src/yuki/spring/aop/annotation/PointcutIntercepter.java

package yuki.spring.aop.annotation;

import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.stereotype.Component;

@Aspect
@Component
public class PointcutIntercepter {

  @Pointcut("execution( public * yuki.spring.aop.annotation..*.*(..) )")
  public void myMethod() {}
  
  @Before("myMethod()")
  public void beforeMethod() {
    System.out.println("PointcutIntercepter::before");
  }

  @AfterReturning("myMethod()")
  public void afterReturningMethod() {
    System.out.println("PointcutIntercepter::afterReturning");
  }
}

/Spring_AOP/src/yuki/spring/aop/annotation/UserServiceTest.java

package yuki.spring.aop.annotation;

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

public class UserServiceTest {

  @Test
  public void testSave() {
    
    @SuppressWarnings("resource")
    ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("annotation.xml");
    UserService service = (UserService) context.getBean("userService");
    service.save(new User());
    context.destroy();
  }

}

运行结果如下：

八月 31, 2014 10:59:10 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 22:59:10 CST 2014]; root of context hierarchy
八月 31, 2014 10:59:10 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [annotation.xml]
method start...
PointcutIntercepter::before
before:1409497152268
user saved...
afterReturning:1409497152268
PointcutIntercepter::afterReturning
八月 31, 2014 10:59:12 下午 org.springframework.context.support.ClassPathXmlApplicationContext doClose
信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 22:59:10 CST 2014]; root of context hierarchy

术语解释：

JoinPoint：连接点、切入点，在哪里把逻辑加进区

PointCut:JoinPoint的集合，可以一次性定义好多切入点

Aspect：切面，切面类加进去的逻辑可以认为是一个切面

Advice：在这个点上建议怎么办，比如 @Before

Target：被织入逻辑的被代理对象

Weave：织入

2.切面和通知

切入点：

// the execution of any public method:

execution(public * *(..))

// the execution of any method with a name beginning with "set":

execution(* set*(..))

// the execution of any method defined by the AccountService interface:

execution(* com.xyz.service.AccountService.*(..))

// the execution of any method defined in the service package:

execution(* com.xyz.service..(..))

// the execution of any method defined in the service package or a sub-package:

execution(* com.xyz.service..*.*(..))

spring也定义了自己的织入点语法，但是我们只要用AspectJ的语法就可以了

通知：

Before、AfterReturn、AfterThrowing、After(意思是finally)

Around：在ProceedingJoinPoint.proceed()前后加逻辑

如果织入点表达式相同，可以定义Pointcut

定义方法名接收织入点表达式的值，使用时 @AfterReturning("pointcut()")

/Spring_AOP/src/yuki/spring/aop/pointcut/User.java

package yuki.spring.aop.pointcut;

public class User {

}

/Spring_AOP/src/yuki/spring/aop/pointcut/UserService.java

package yuki.spring.aop.pointcut;

public interface UserService {

    void save(User user);
}

/Spring_AOP/src/yuki/spring/aop/pointcut/UserServiceImpl.java

package yuki.spring.aop.pointcut;

import org.springframework.stereotype.Component;

@Component("userService")
public class UserServiceImpl implements UserService{

    public void save(User user){
        System.out.println("user saved...");
        //throw new RuntimeException("exception...");
    }
}

/Spring_AOP/src/yuki/spring/aop/pointcut/TransactionAspect.java

package yuki.spring.aop.pointcut;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.stereotype.Component;

@Aspect
@Component
public class TransactionAspect {

  @Pointcut("execution( public * yuki.spring.aop.pointcut..*.*(..) )")
  public void pointcut(){}
  
  @Before("pointcut()")
  public void before(){
    System.out.println("before");
  }
  @AfterReturning("pointcut()")
  public void afterReturning(){
    System.out.println("afterReturning");
  }
  @AfterThrowing("pointcut()")
  public void afterThrowing(){
    System.out.println("afterThrowing");
  }
  
  @Around("pointcut()")
  public void aroundMethod(ProceedingJoinPoint pjp) throws Throwable{
    System.out.println("method around start...");
    pjp.proceed();
    System.out.println("method around end...");
  }
  
}

/Spring_AOP/src/pointcut.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:aop="http://www./schema/aop"
    xmlns:context="http://www./schema/context" 
    xmlns="http://www./schema/beans"
    xmlns:xsi="http://www./2001/XMLSchema-instance"
    xsi:schemaLocation="http://www./schema/beans 
      http://www./schema/beans/spring-beans-4.0.xsd 
      http://www./schema/aop 
      http://www./schema/aop/spring-aop-4.0.xsd 
      http://www./schema/context 
      http://www./schema/context/spring-context-4.0.xsd ">
    
    <context:annotation-config></context:annotation-config>
    <context:component-scan base-package="yuki.spring.aop.pointcut"></context:component-scan>
    
    <aop:aspectj-autoproxy></aop:aspectj-autoproxy>
    
</beans>

/Spring_AOP/src/yuki/spring/aop/pointcut/UserServiceTest.java

package yuki.spring.aop.pointcut;

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

public class UserServiceTest {

  @Test
  public void testSave() {
    
    @SuppressWarnings("resource")
    ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("pointcut.xml");
    UserService service = (UserService) context.getBean("userService");
    service.save(new User());
    context.destroy();
  }

}

运行结果如下：

八月 31, 2014 11:09:22 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 23:09:22 CST 2014]; root of context hierarchy
八月 31, 2014 11:09:22 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [pointcut.xml]
method around start...
before
user saved...
method around end...
afterReturning
八月 31, 2014 11:09:24 下午 org.springframework.context.support.ClassPathXmlApplicationContext doClose
信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 23:09:22 CST 2014]; root of context hierarchy

可以实现声明式的异常管理，

struts2已经实现了声明式的异常管理，

这里略过通知执行的先后顺序

3.cglib

如果被代理的类实现了接口， 

就会使用JDK自带的Proxy和InvocationHandler来实现代理

当被代理的类没有实现接口， 

它会用cglib直接操作二进制码的形式来产生代理的代码

引入jar：cglib-2.2.jar：http://www./Code/Jar/c/Downloadcglib22jar.htm

/Spring_AOP/src/yuki/spring/aop/cglib/UserService.java

package yuki.spring.aop.cglib;

import org.springframework.stereotype.Component;

@Component
public class UserService {

    public void save(){
        System.out.println("user saved...");
    }
}

/Spring_AOP/src/yuki/spring/aop/cglib/CglibAspect.java

package yuki.spring.aop.cglib;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.stereotype.Component;

@Aspect
@Component
public class CglibAspect {

  @Pointcut("execution( public * yuki.spring.aop.cglib..*.*(..) )")
  public void pointcut(){}
  
  @Around("pointcut()")
  public void aroundMethod(ProceedingJoinPoint pjp) throws Throwable{
    System.out.println("method around start...");
    pjp.proceed();
    System.out.println("method around end...");
  }
  
}

/Spring_AOP/src/cglib.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:aop="http://www./schema/aop"
    xmlns:context="http://www./schema/context" 
    xmlns="http://www./schema/beans"
    xmlns:xsi="http://www./2001/XMLSchema-instance"
    xsi:schemaLocation="http://www./schema/beans 
      http://www./schema/beans/spring-beans-4.0.xsd 
      http://www./schema/aop 
      http://www./schema/aop/spring-aop-4.0.xsd 
      http://www./schema/context 
      http://www./schema/context/spring-context-4.0.xsd ">
    
    <context:annotation-config></context:annotation-config>
    <context:component-scan base-package="yuki.spring.aop.cglib"></context:component-scan>
    
    <aop:aspectj-autoproxy></aop:aspectj-autoproxy>
    
</beans>

/Spring_AOP/src/yuki/spring/aop/cglib/UserServiceTest.java

package yuki.spring.aop.cglib;

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

public class UserServiceTest {

  @Test
  public void testSave() {
    
    @SuppressWarnings("resource")
    ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("cglib.xml");
    UserService service = (UserService) context.getBean("userService");
    System.out.println(service.getClass());
    service.save();
    context.destroy();
  }

}

运行结果如下：

八月 31, 2014 11:14:17 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 23:14:17 CST 2014]; root of context hierarchy
八月 31, 2014 11:14:17 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [cglib.xml]
class yuki.spring.aop.cglib.UserService$$EnhancerBySpringCGLIB$$b8ea6837
method around start...
user saved...
method around end...
八月 31, 2014 11:14:19 下午 org.springframework.context.support.ClassPathXmlApplicationContext doClose
信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 23:14:17 CST 2014]; root of context hierarchy

4.xml：AOP

pointcut可以声明在aspect的里面或外面

eclipse：从源码视图切换到设计视图

在执行UserService.save()时，发现符合配置的切入点表达式

对应的是LogAspect.before()，于是先执行before，然后save()

可以直接指定pointcut，也可以在外部指定然后再引用它

如果使用第三方类的切面类逻辑，那么就必须要使用xml配置的方式

/Spring_AOP/src/yuki/spring/aop/xml/UserService.java

package yuki.spring.aop.xml;

import org.springframework.stereotype.Component;

@Component("userService")
public class UserService {

    public void save(){
        System.out.println("user saved...");
    }
}

/Spring_AOP/src/yuki/spring/aop/xml/LogAspect.java

package yuki.spring.aop.xml;

public class LogAspect {

    public void before() {
        System.out.println("method start...");
    }

}

/Spring_AOP/src/xml.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:aop="http://www./schema/aop"
    xmlns:context="http://www./schema/context" 
    xmlns="http://www./schema/beans"
    xmlns:xsi="http://www./2001/XMLSchema-instance"
    xsi:schemaLocation="http://www./schema/beans 
      http://www./schema/beans/spring-beans-4.0.xsd 
      http://www./schema/aop 
      http://www./schema/aop/spring-aop-4.0.xsd 
      http://www./schema/context 
      http://www./schema/context/spring-context-4.0.xsd ">
    
    <context:annotation-config></context:annotation-config>
    <context:component-scan base-package="yuki.spring.aop.xml"></context:component-scan>
    
    <bean id="logAspect" class="yuki.spring.aop.xml.LogAspect"></bean>
    <!-- 
    <aop:config>
        <aop:pointcut id="servicePointcut"
                expression="execution( public * yuki.spring.aop.xml..*.*(..) )" />
        <aop:aspect id="logAspect" ref="logAspect">
            <aop:before method="before" pointcut-ref="servicePointcut"/>
        </aop:aspect>
    </aop:config>
     -->

    <aop:config>
        <aop:aspect id="logAspect" ref="logAspect">
            <aop:before method="before" 
  pointcut="execution( public * yuki.spring.aop.xml..*.*(..) )"/>
        </aop:aspect>
    </aop:config>

</beans>

/Spring_AOP/src/yuki/spring/aop/xml/UserServiceTest.java

package yuki.spring.aop.xml;

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

public class UserServiceTest {

  @Test
  public void testSave() {
    
    @SuppressWarnings("resource")
    ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("xml.xml");
    UserService service = (UserService) context.getBean("userService");
    service.save();
    context.destroy();
  }

}

运行结果如下：

八月 31, 2014 11:19:01 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 23:19:01 CST 2014]; root of context hierarchy
八月 31, 2014 11:19:01 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [xml.xml]
method start...
user saved...
八月 31, 2014 11:19:02 下午 org.springframework.context.support.ClassPathXmlApplicationContext doClose
信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 23:19:01 CST 2014]; root of context hierarchy

5.tomcat debug的热部署

在tomcat的jdk虚拟机参数中添加

-Dcom.sun.management.jmxremote=true

如果修改配置文件，使用了自定义标签的jsp页面，修改了注解，等等情况：还是要重启服务器的

在方法内部修改代码，不用重启服务器，这已经是很大的便捷了，

有兴趣的小伙伴们去研究功能更强大的热部署吧。。。。

目录结构：

本文参考了[尚学堂马士兵_Spring_AOP]的公开课程

更多好文请关注：http://www.cnblogs.com/kodoyang/

>*_*<

kongdongyang

2014/8/31