Sping--AOP--Annotation

最新推荐文章于 2025-08-24 15:22:07 发布

weixin_33670713

最新推荐文章于 2025-08-24 15:22:07 发布

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文章标签： java

原文链接：http://www.cnblogs.com/wujixing/p/5455533.html

本文详细介绍AspectJ的概念及AOP的应用实践，包括切入点、切面逻辑等关键要素的定义，通过具体示例展示了如何使用Spring框架配置AspectJ，实现方法前、后及环绕通知等功能。

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Aspectj 概念:

1. joinpoint:切入点, 比如@Before, @After, @Around

2. Pointcut:切入点集合, 比如 @Pointcut("execution(public * com.bjsxt.service..*.*(..))")

　　public void myMethod(){}; //切入点集合的名字

3. Aspect:切面逻辑, 切面类, 比如LogInterceptor之前加入的@Aspect

4. Advice: 加入点的建议, 类似于Aspect的逻辑, 相当于@Before, 加在切入点的建议.

5. Target: 被代理对象, 逻辑织入哪里...

6. Weave: 织入

AOP的Annotation方式:

1. 加上对应的xsd文件sprin-aop.xsd

2. beans.xml <aop:aspectj-autoproxy/>

3. 此时就可以解析对应的annotation了

4. 建立我们的拦截类

5. 用@Aspect注解这个类

6. 用@Before来注解方法

7. 写明白切入点(execution...)

8. 让spring对我们的拦截器类进行管理 @Component

常见的annotation:

1. @Pointcut

2. @Before

3. @AfterReturning

4. @AfterThrowing

5. @After

6. @Around

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"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-2.5.xsd
           http://www.springframework.org/schema/aop
           http://www.springframework.org/schema/aop/spring-aop-2.5.xsd">
	<context:annotation-config />
	<context:component-scan base-package="com.bjsxt"/>
 	<aop:aspectj-autoproxy />
</beans>

LogInterceptor.java: 注意@Component

package com.bjsxt.aop;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.AfterReturning;
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 LogInterceptor {	
	@Before("execution(public * com.bjsxt.dao..*.*(..)))")
	public void before() {
		System.out.println("method before");
	}
	@AfterReturning("execution(public * com.bjsxt.dao..*.*(..)))")
	public void AfterReturning() {
		System.out.println("method after returning");
	}	
}

简化成下面写法:

package com.bjsxt.aop;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.AfterReturning;
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 LogInterceptor {
	@Pointcut("execution(public * com.bjsxt.dao..*.*(..))")
	public void myMethod(){};
	
	@Before("myMethod()")
	public void before() {
		System.out.println("method before");
	}	

	@AfterReturning("myMethod()")
	public void AfterReturning() {
		System.out.println("method after Returning");
	}	
}

UserServiceTest.java:

package com.bjsxt.service;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.bjsxt.model.User;

//Dependency Injection
//Inverse of Control
public class UserServiceTest {

	@Test 
	public void testAdd() throws Exception {
		ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
		UserService service = (UserService)ctx.getBean("userService");
		System.out.println(service.getClass());
		service.add(new User());		
		ctx.destroy();		
	}
}

UserService.java:

package com.bjsxt.service;
import javax.annotation.Resource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;

import com.bjsxt.dao.UserDAO;
import com.bjsxt.model.User;


@Component("userService")
public class UserService {
	
	private UserDAO userDAO;  
	
	public void init() {
		System.out.println("init");
	}
	
	public void add(User user) {
		userDAO.save(user);
	}
	public UserDAO getUserDAO() {
		return userDAO;
	}
	
	@Resource(name="u")
	public void setUserDAO( UserDAO userDAO) {
		this.userDAO = userDAO;
	}	
	public void destroy() {
		System.out.println("destroy");
	}
}

UserDAOImpl.java:

package com.bjsxt.dao.impl;

import org.springframework.stereotype.Component;

import com.bjsxt.dao.UserDAO;
import com.bjsxt.model.User;

@Component("u") 
public class UserDAOImpl implements UserDAO {

	public void save(User user) {
		//Hibernate
		//JDBC
		//XML
		//NetWork
		System.out.println("user saved!");
		//throw new RuntimeException("exeption!");
	}

}

UserDAO.java:

package com.bjsxt.dao;
import com.bjsxt.model.User;
public interface UserDAO {
	public void save(User user);
}

User.java:

package com.bjsxt.dao;
import com.bjsxt.model.User;


public interface UserDAO {
	public void save(User user);
}

结果:

class com.bjsxt.service.UserService
method before
user saved!
method after Returning

LogInterceptor.java的around用法:

package com.bjsxt.aop;

import org.aspectj.lang.ProceedingJoinPoint;
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 LogInterceptor {
	@Pointcut("execution(public * com.bjsxt.dao..*.*(..))")
	public void myMethod(){};
	
	@Before("myMethod()")
	public void before() {
		System.out.println("method before");
	}
	
	@Around("myMethod()")
	public void aroundMethod(ProceedingJoinPoint pjp) throws Throwable {
		System.out.println("method around start");
		pjp.proceed();
		System.out.println("method around end");
	}
	
}

beans.xml: XML catalog里引入 aop的 xsd

<?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"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-2.5.xsd
           http://www.springframework.org/schema/aop
           http://www.springframework.org/schema/aop/spring-aop-2.5.xsd">
	<context:annotation-config />
	<context:component-scan base-package="com.bjsxt"/>
 	<aop:aspectj-autoproxy />
</beans>

UserServiceTest.java:

package com.bjsxt.service;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.bjsxt.model.User;

//Dependency Injection
//Inverse of Control
public class UserServiceTest {

	@Test 
	public void testAdd() throws Exception {
		ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
		
		UserService service = (UserService)ctx.getBean("userService");
		System.out.println(service.getClass());
		service.add(new User());
		service.delete();
		ctx.destroy();
		
	}

}

UserService.java:

package com.bjsxt.service;
import javax.annotation.Resource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;

import com.bjsxt.dao.UserDAO;
import com.bjsxt.model.User;


@Component("userService")
public class UserService {
	
	private UserDAO userDAO;  
	
	public void init() {
		System.out.println("init");
	}
	
	public void add(User user) {
		userDAO.save(user);
	}
	public void delete() {
		userDAO.delete();
	}
	public UserDAO getUserDAO() {
		return userDAO;
	}
	
	@Resource(name="u")
	public void setUserDAO( UserDAO userDAO) {
		this.userDAO = userDAO;
	}	
	public void destroy() {
		System.out.println("destroy");
	}
}

UserDAOImpl.java:

package com.bjsxt.dao.impl;

import org.springframework.stereotype.Component;

import com.bjsxt.dao.UserDAO;
import com.bjsxt.model.User;

@Component("u") 
public class UserDAOImpl implements UserDAO {

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

UserDAO.java　　:

package com.bjsxt.dao;
import com.bjsxt.model.User;
public interface UserDAO {
	public void save(User user);
	public void delete();
}

结果:

class com.bjsxt.service.UserService$$EnhancerByCGLIB$$b6531e3e
method around start
method before
user saved!
method around end
method around start
method before
user delete!
method around end

改成service的话, 因为没有实现接口, 所以需要引入一个包: cglib-nodep-2.1_3.jar

package com.bjsxt.aop;

import org.aspectj.lang.ProceedingJoinPoint;
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 LogInterceptor {
	@Pointcut("execution(public * com.bjsxt.service..*.add(..))")
	public void myMethod(){};
	
	@Before("myMethod()")
	public void before() {
		System.out.println("method before");
	}
	
	@Around("myMethod()")
	public void aroundMethod(ProceedingJoinPoint pjp) throws Throwable {
		System.out.println("method around start");
		pjp.proceed();
		System.out.println("method around end");
	}
	
}

结果:

class com.bjsxt.service.UserService$$EnhancerByCGLIB$$9160c20d
method around start
method before
user saved!
method around end

转载于:https://www.cnblogs.com/wujixing/p/5455533.html