Spring AOP两种实现方式

一. AOP 概念：　　
　　Spring AOP 即Aspect Oriented Programming(面向切面编程), 实现方式分为两种：
　　1. 注解(Annotation)
　　2. 配置(Configure)

二. 应用场景：
　　1. 权限管理；
　　2. 表单验证；
　　3. 事务管理；
　　4. 信息过滤；
　　5. 拦截器；
　　6. 过滤器；
　　7. 日志等等；

三. AOP实现：
　　1. 基于Annotation的实现　　

package com.myframework.xj.security.service;

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.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import com.myframework.xj.credit.CreditException;import com.myframework.xj.security.entity.CheckDetails;
import com.myframework.xj.security.entity.User;

/**
 * 基于注解的AOP实现核查扣款功能
 * @author lvm
 *
 */
@Component
@Aspect
public class CheckServiceAspect {
    
    private static final Logger logger = LoggerFactory.getLogger(CheckServiceAspect.class);
    
    @Autowired
    private CheckDetailsService checkDetailsService;//配置切入点,该方法无方法体,主要为方便同类中其他方法使用此处配置的切入点
    @Pointcut("execution(* com.myframework.xj.security.service.*..(..))")
    public void aspect(){}

    /**
     * 实现代码
     * @param call
     * @return
     * @throws Throwable
     */
    @Around("aspect()")
    public Object aroundCheck(ProceedingJoinPoint call) throws Throwable {
        logger.info("CheckServiceAspect aroundCheck begin...");
        
        Object[] args = call.getArgs();
        //1.当前登录人
        if(args[0] == null || !(args[0] instanceof User))
            throw new CreditException("当前登录人不能为空");
        User user = (User)(args[0]);
        
        //2.查询金额
        CheckDetails details = new CheckDetails();
        if(user.getFund() == null || user.getFund().compareTo(details.getPayment()) <0)
            throw new CreditException("当前登录人账户余额不够");
        try {
            return call.proceed();
        } finally {
            details.setCreatedBy(user);
            checkDetailsService.save(details);
            logger.info("CheckServiceAspect aroundCheck end...");
        }
    }
    
}

　　基于Annotationd的实现需要保证可以被配置文件扫描到　　

<!-- 激活组件扫描功能,在包com.myframework.xj.security.service及其子包下面自动扫描通过注解配置的组件 -->
<context:component-scan base-package="com.myframework.xj.security.service"/>
<!-- 激活自动代理功能 -->
<aop:aspectj-autoproxy proxy-target-class="true"/>

　　2. 基于Configure的实现
　　Java实现代码如下：　　

package com.myframework.xj.security.service;

import org.aspectj.lang.ProceedingJoinPoint;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.myframework.xj.credit.CreditException;
import com.myframework.xj.security.entity.CheckDetails;
import com.myframework.xj.security.entity.User;

/**
 * 根据配置文件实现AOP实现扣款功能
 * @author lvm
 *
 */
public class Aspect {
    
    private static final Logger logger = LoggerFactory.getLogger(CheckAspect.class);
    
    private CheckDetailsService checkDetailsService;    
    
    public void setCheckDetailsService(CheckDetailsService checkDetailsService) {
        this.checkDetailsService = checkDetailsService;
    }
    
    /**
     * 实现代码
     * @param call
     * @return
     * @throws Throwable
     */
    public Object aroundCheck(ProceedingJoinPoint call) throws Throwable {
        
        logger.info("Aspect aroundCheck begin...");
        
        Object[] args = call.getArgs();
        //1.当前登录人
        if(args[0] == null || !(args[0] instanceof User))
            throw new CreditException("当前登录人不能为空");
        User user = (User)(args[0]);
        
        //2.查询金额
        CheckDetails details = new CheckDetails();
        if(user.getFund() == null || user.getFund().compareTo(details.getPayment()) <0)
            throw new CreditException("当前登录人账户余额不够");
        try {
            return call.proceed();
        } finally {
            details.setCreatedBy(user);
            checkDetailsService.save(details);
            logger.info("Aspect aroundCheck end...");
        }
    }
}

　　配置文件如下：　　

<bean id="checkDetailsServiceImpl" class="com.myframework.xj.security.service.CheckDetailsServiceImpl"/>
<bean id="reportServiceImpl" class="com.myframework.xj.credit.service.ReportServiceImpl"/>
<bean id="checkAspectExecutor" class="com.myframework.xj.security.service.CheckAspect">
    <property name="checkDetailsService" ref="checkDetailsServiceImpl"/>
    <property name="reportService" ref="reportServiceImpl"/>
</bean>
<aop:config>
    <aop:aspect id="checkAspect" ref="checkAspectExecutor">
        <aop:pointcut id="checkPointcut" expression="execution(* com.myframework.xj.security.service.CheckDetailsServiceImpl.check*(..))"/>
        <aop:around pointcut-ref="checkPointcut" method="aroundCheck" />
    </aop:aspect>
</aop:config>

四. Annotation和Configure实现比较
　　配置麻烦点 但是可读性好点 
　　注解方便