什么是AOP？AOP使用场景？AOP相关概念？Spring AOP组件？如何使用Spring AOP？等等这些问题请参考博文：Spring AOP 实现原理

下面重点介绍如何写事件日志功能，把日志保存到数据库中。 
事件日志是与主业务功能无关的逻辑，用AOP实现是再好不过了，其中因为有些数据库日志表中的字段参数需要传递，所以会用到自定义注解，将这些参数用自定义注解传递过来。

1.自定义注解Operation

package com.jykj.demo.filter;

import java.lang.annotation.Documented;

import java.lang.annotation.ElementType;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;

/**

 * @Descrption该注解描述方法的操作类型和方法的参数意义

 */

@Target(value = ElementType.METHOD)

@Retention(value = RetentionPolicy.RUNTIME)

@Documented

public @interface Operation {

    /**

     * @Description描述操作类型   为必填项,1:登录日志2：操作日志

     */

    int type();

    /**

     * @Description描述操作意义   比如申报通过或者不通过等

     */

    String desc() default ""; 

    /**

     * @Description描述操作方法的参数意义 数组长度需与参数长度一致,否则会参数与描述不一致的情况

     */

    String[] arguDesc() default {};

}

2.切面类EventLogAspect

package com.jykj.demo.filter;

import java.lang.reflect.Method;

import org.aspectj.lang.JoinPoint;

import org.aspectj.lang.reflect.MethodSignature;

import org.springframework.beans.factory.annotation.Autowired;

import com.jykj.demo.service.SysEventService;

//事件日志 切面,凡是带有 @Operation 注解的service方法都将会写日志

public class EventLogAspect {

    @Autowired

    SysEventService sysEventService;

    public void doAfterReturning(JoinPoint jp) {

        System.out.println(

                "log Ending method: " + jp.getTarget().getClass().getName() + "." + jp.getSignature().getName());

        Method proxyMethod = ((MethodSignature) jp.getSignature()).getMethod();

        Method soruceMethod;

        try {

            soruceMethod = jp.getTarget().getClass().getMethod(proxyMethod.getName(), proxyMethod.getParameterTypes());

            Operation oper = soruceMethod.getAnnotation(Operation.class);

            if (oper != null) {

                System.out.println(oper.desc());

                // 解析参数

                sysEventService.insertEventLog(oper.type(),oper.desc()+"("+extractParam(jp.getArgs(),oper.arguDesc())+") 成功");

            }

        } catch (NoSuchMethodException e) {

            e.printStackTrace();

        } catch (SecurityException e) {

            e.printStackTrace();

        }catch (Exception e) {

            e.printStackTrace();

        }

    }

    public void doAfterThrowing(JoinPoint jp, Throwable ex) {

        Method proxyMethod = ((MethodSignature) jp.getSignature()).getMethod();

        Method soruceMethod;

        try {

            soruceMethod = jp.getTarget().getClass().getMethod(proxyMethod.getName(), proxyMethod.getParameterTypes());

            Operation oper = soruceMethod.getAnnotation(Operation.class);

            if (oper != null) {

                System.out.println(oper.desc());

                sysEventService.insertEventLog(oper.type(),oper.desc()+

                        "("+extractParam(jp.getArgs(),oper.arguDesc())+" 出现异常："+ex.getMessage());

            }

        } catch (NoSuchMethodException e) {

            e.printStackTrace();

        } catch (SecurityException e) {

            e.printStackTrace();

        }

    }

    private String extractParam(Object[] objParam, String[] arguDesc) {

        StringBuilder sb = new StringBuilder();

        int len = objParam.length<arguDesc.length?objParam.length:arguDesc.length;//取最小值

        for (int i = 0; i < len; i++) {

            //空字符串将不解析

            if(arguDesc[i]!=null && !arguDesc[i].isEmpty()){

                sb.append(arguDesc[i]+":"+objParam[i]+",");

            }

        }

        String rs = sb.toString();

        return rs.substring(0,rs.length()-1);

    }

}

3.切入点 主业务逻辑类FrmAppsService

package com.jykj.demo.service;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;

import com.jykj.demo.dao.FrmAppsMapper;

import com.jykj.demo.entity.FrmApps;

import com.jykj.demo.filter.Operation;

import com.jykj.demo.mapper.AbstractService;

@Service

public class FrmAppsService {

    @Autowired

    FrmAppsMapper mapper;

    @Operation(type=1,desc="更新框架应用",arguDesc={"","操作类型"})

    public int access(FrmApps app,String action){

        return mapper.access(app,action);

    }

}

4.Spring xml对AOP的配置

    <bean id="aspectEventLog" class="com.jykj.demo.filter.EventLogAspect" />

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

    <!--配置service包下所有类或接口的所有方法-->

    <aop:config proxy-target-class="true">

        <aop:aspect id="EventLogAspect" ref="aspectEventLog">

            <aop:pointcut id="myService"

                expression="execution(* com.jykj.demo.service.*.*(..)) " />

            <aop:after-returning pointcut-ref="myService" method="doAfterReturning"/>

            <aop:after-throwing pointcut-ref="myService" method="doAfterThrowing" throwing="ex"/>

        </aop:aspect>

    </aop:config>

    <!-- 控制器 -->

    <context:component-scan base-package="com.jykj.demo.controller" />

    <!-- service -->

    <context:component-scan base-package="com.jykj.demo.service" />

    <context:component-scan base-package="com.jykj.demo.filter" />

需要注意的是 proxy-target-class=”true” ，如果没有这个，目标类若是实现了接口，将会以JDK代理的方式，否则采用的是CGLib代理的方式，如果启动项目报错了，会报代理类无法转换的问题，这时候把这个配置写上就可以了。

这样就实现了写日志的功能，只要在需要写日志的service类的方法上用自定义注解Operation注解即可

5.输出 （编辑一个记录时）

log Ending method: com.jykj.demo.service.FrmAppsService.access

更新框架应用

log Ending method: com.jykj.demo.service.SysEventService.insertEventLog

另外再附加 在未登录时禁止访问页面的功能 采用拦截器 
SecurityInterceptor类

package com.jykj.demo.filter;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import org.springframework.web.servlet.HandlerInterceptor;

import org.springframework.web.servlet.ModelAndView;

import com.jykj.demo.util.Helper;

public class SecurityInterceptor implements HandlerInterceptor{

    @Override

    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)

            throws Exception {

        HttpSession session = request.getSession();

        if (session.getAttribute(Helper.SESSION_USER) == null) {

            throw new AuthorizationException();

        } else {

            return true;

        }

    }

    @Override

    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,

            ModelAndView modelAndView) throws Exception {

        // TODO Auto-generated method stub

    }

    @Override

    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)

            throws Exception {

        // TODO Auto-generated method stub

    }

}

对应的拦截器的配置 spring-mvc.xml

<mvc:interceptors>

        <mvc:interceptor>

            <mvc:mapping path="/*"/>

            <mvc:exclude-mapping path="/login"/>

            <mvc:exclude-mapping path="/signIn"/>

            <mvc:exclude-mapping path="/register"/>

            <bean class="com.jykj.demo.filter.SecurityInterceptor">

            </bean>

        </mvc:interceptor>

    </mvc:interceptors>

    <!-- bean 处理未登录重定向到登录界面 -->

    <bean id="handlerExceptionResolver"

        class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">

        <property name="exceptionMappings">

            <props>

                <prop key="com.jykj.demo.filter.AuthorizationException">redirect:login</prop>

            </props>

        </property>

    </bean>

异常类AuthorizationException

package com.jykj.demo.filter;

public class AuthorizationException extends Exception{

    private static final long serialVersionUID = 1L;

}

参考博文：Spring Aop 日志拦截应用 
参考博文：基于配置的Spring AOP 
参考博文：Spring AOP 详解