Spring AOP兩種實現方式

一. AOP 概念：　　
　　Spring AOP 即Aspect Oriented Programming(面向切面編程), 實現方式分為兩種：
　　1. 注解(Annotation)
　　2. 配置(Configure)

二. 應用場景：
　　1. 權限管理；
　　2. 表單驗證；
　　3. 事務管理；
　　4. 信息過濾；
　　5. 攔截器；
　　6. 過濾器；
　　7. 日志等等；

三. AOP實現：
　　1. 基於Annotation的實現　　

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;

/**
 * 基於注解的AOP實現核查扣款功能
 * @author lvm
 *
 */
@Component
@Aspect
public class CheckServiceAspect {
    
    private static final Logger logger = LoggerFactory.getLogger(CheckServiceAspect.class);
    
    @Autowired
    private CheckDetailsService checkDetailsService;//配置切入點,該方法無方法體,主要為方便同類中其他方法使用此處配置的切入點
    @Pointcut("execution(* com.myframework.xj.security.service.*..(..))")
    public void aspect(){}

    /**
     * 實現代碼
     * @param call
     * @return
     * @throws Throwable
     */
    @Around("aspect()")
    public Object aroundCheck(ProceedingJoinPoint call) throws Throwable {
        logger.info("CheckServiceAspect aroundCheck begin...");
        
        Object[] args = call.getArgs();
        //1.當前登錄人
        if(args[0] == null || !(args[0] instanceof User))
            throw new CreditException("當前登錄人不能為空");
        User user = (User)(args[0]);
        
        //2.查詢金額
        CheckDetails details = new CheckDetails();
        if(user.getFund() == null || user.getFund().compareTo(details.getPayment()) <0)
            throw new CreditException("當前登錄人賬戶余額不夠");
        try {
            return call.proceed();
        } finally {
            details.setCreatedBy(user);
            checkDetailsService.save(details);
            logger.info("CheckServiceAspect aroundCheck end...");
        }
    }
    
}

　　基於Annotationd的實現需要保證可以被配置文件掃描到　　

<!-- 激活組件掃描功能,在包com.myframework.xj.security.service及其子包下面自動掃描通過注解配置的組件 -->
<context:component-scan base-package="com.myframework.xj.security.service"/>
<!-- 激活自動代理功能 -->
<aop:aspectj-autoproxy proxy-target-class="true"/>

　　2. 基於Configure的實現
　　Java實現代碼如下：　　

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;

/**
 * 根據配置文件實現AOP實現扣款功能
 * @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;
    }
    
    /**
     * 實現代碼
     * @param call
     * @return
     * @throws Throwable
     */
    public Object aroundCheck(ProceedingJoinPoint call) throws Throwable {
        
        logger.info("Aspect aroundCheck begin...");
        
        Object[] args = call.getArgs();
        //1.當前登錄人
        if(args[0] == null || !(args[0] instanceof User))
            throw new CreditException("當前登錄人不能為空");
        User user = (User)(args[0]);
        
        //2.查詢金額
        CheckDetails details = new CheckDetails();
        if(user.getFund() == null || user.getFund().compareTo(details.getPayment()) <0)
            throw new CreditException("當前登錄人賬戶余額不夠");
        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實現比較
　　配置麻煩點 但是可讀性好點 
　　注解方便