摘要：前言目前系統(tǒng)剛啟動(dòng)，骨架剛剛搭建完成，在項(xiàng)目中，使用了一些切面，做一些業(yè)務(wù)無關(guān)的處理。在現(xiàn)在的項(xiàng)目里面，分別在，調(diào)用，分頁(yè)，處理，均使用到了切面。希望本文的閱讀者也不吝將項(xiàng)目中使用的切面分享出來。

目前系統(tǒng)剛啟動(dòng)，骨架剛剛搭建完成，在項(xiàng)目中，使用了一些切面，做一些業(yè)務(wù)無關(guān)的處理。在本文中，將各個(gè)切面例舉出來，用以加深自己對(duì)切面的理解。記得在初學(xué)切面的時(shí)候，一般文章介紹切面的時(shí)候，主要是日志，消息收集等，其實(shí)在真實(shí)項(xiàng)目中，遠(yuǎn)不止于此。在現(xiàn)在的項(xiàng)目里面，分別在controller，rpc調(diào)用，分頁(yè)，dao處理，均使用到了切面。下面逐個(gè)進(jìn)行說明。希望本文的閱讀者也不吝將項(xiàng)目中使用的切面分享出來。

用于統(tǒng)計(jì)每個(gè)后臺(tái)的controller方法的執(zhí)行時(shí)間，并執(zhí)行打印，切面中用到了TheadLocal。

public class ControllerInterceprot implements HandlerInterceptor{
    private static final Logger log = LoggerFactory.getLogger(ControllerInterceprot.class);

    private static final ThreadLocal startTimeThreadLocal = new NamedThreadLocal("ThreadLocal StartTime");

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        startTimeThreadLocal.set(System.currentTimeMillis());
        String methodName = request.getMethod();
        Long userId = SecurityHelper.getCurrentUserId();
        log.info("start: method: " + methodName + "userId: " + userId +  ", starttime: " + System.currentTimeMillis());
        return true;
    }

    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        long excutionTime = System.currentTimeMillis() - startTimeThreadLocal.get();
        String methodName = request.getMethod();
        Long userId = SecurityHelper.getCurrentUserId();
        if (null == ex){
            log.info("finish: method: " + methodName + "userId: " + userId +  ", excutetime: " + excutionTime);
        }else{
            log.info("exception finish: method: " + methodName + "userId: " + userId +  ", excutetime: " + excutionTime);
        }
        startTimeThreadLocal.set(null);
    }
}

用于對(duì)系統(tǒng)中拋出的異常進(jìn)行統(tǒng)一處理，主要是捕獲異常，多語(yǔ)處理

@ControllerAdvice
public class BizExceptionHandler {
    private static final Logger log = LoggerFactory.getLogger(BizExceptionHandler.class);
    @Autowired
    private BasDbMessageResource messageSource;

    @ExceptionHandler(value = BizException.class)
    @ResponseBody
    public PackVo execute(BizException e, HttpServletRequest request){
        PackVo packVo = new PackVo();
        packVo.setSuccess(false);
        SessionLocaleResolver sessionLocaleResolver = (SessionLocaleResolver) RequestContextUtils.getLocaleResolver(request);
        List messages = e.getClientMessages();
        for(BizClientMessage message : messages){
            packVo.addMsg(message.getCode(),getLocalMessage(message.getCode(),message.getContent(), sessionLocaleResolver.resolveLocale(request)));
        }
        log.warn("BizException", e);
        return packVo;
    }
    @ExceptionHandler(value = IllegalStateException.class)
    @ResponseBody
    public PackVo handleXingException(IllegalStateException e,HttpServletRequest request){
        PackVo packVo = new PackVo();
        packVo.setSuccess(false);
        SessionLocaleResolver sessionLocaleResolver = (SessionLocaleResolver) RequestContextUtils.getLocaleResolver(request);
        packVo.addMsg(BizExceptionCode.SYS_ERR_XING_SERVICE_FAIL,getLocalMessage(BizExceptionCode.SYS_ERR_XING_SERVICE_FAIL,new String[]{e.getMessage()}, sessionLocaleResolver.resolveLocale(request)));
        return packVo;
    }
    @ExceptionHandler(value = Exception.class)
    @ResponseBody
    public PackVo handleSysException(Exception e,HttpServletRequest request){
        e.printStackTrace();
        log.error(e.getMessage());
        PackVo packVo = new PackVo();
        packVo.setSuccess(false);
        SessionLocaleResolver sessionLocaleResolver = (SessionLocaleResolver) RequestContextUtils.getLocaleResolver(request);
        packVo.addMsg(BizExceptionCode.SYS_ERR_COMMON,getLocalMessage(BizExceptionCode.SYS_ERR_COMMON,new String[]{e.getMessage()}, sessionLocaleResolver.resolveLocale(request)));
        return packVo;
    }

    public String getLocalMessage(String code,String[] values,Locale locale){
        log.info("parameter:code=["+code+"] values = ["+values+"]locale=["+locale+"]");
        return messageSource.getMessage(code,values,locale);
    }
}

切在了RPC的接口層，在項(xiàng)目中，所有的RPC方法都規(guī)定在第一個(gè)參數(shù)是ClientInfo對(duì)象，里面封裝了一些用于更新表中的一些公共的字段，比如操作人，語(yǔ)言偏好等。接口會(huì)將ClientInfo放到ThreadLocal中去。

@Component
@Aspect
public class MasterXingInterceptor {
    private static final Log logger = LogFactory.getLog(MasterXingInterceptor.class);

    @Around("execution(* com.best.gwms.master.xing..*.*(..))")
    public Object interceptor(ProceedingJoinPoint pjp) throws Throwable {
        Object[] args = pjp.getArgs();
        if (args != null && args.length > 0) {
            Object firstArg = args[0];
            if (firstArg instanceof ClientInfo) {
                ClientInfo clientInfo = (ClientInfo) firstArg;
                // 把client方法theadlocal里
                MasterStatic.setClientInfoTH(clientInfo);
            }
        }

        try {
            Object ret = pjp.proceed();
            return ret;
        } finally {
            // 把線程池清空掉，以免出現(xiàn)線程池緩存導(dǎo)致的坑
            ThreadLocalUtil.refreshThreadLocal();
        }
    }
}
public class ThreadLocalUtil {

    public static List> TL_LIST = new ArrayList>();

    public static void refreshThreadLocal() {
        for (ThreadLocal tl : TL_LIST) {
            tl.set(null);
        }
    }

    public static void addThreadLocal2List(ThreadLocal tl) {
        TL_LIST.add(tl);
    }
}

public class MasterStatic {
    private static ThreadLocal clientInfoHL = new ThreadLocal();

    static {
        // 放在一個(gè)統(tǒng)一的的方法，便于事務(wù)結(jié)束后統(tǒng)一銷毀（線程池緩存的問題）
        ThreadLocalUtil.addThreadLocal2List(clientInfoHL);
    }

    public static ClientInfo getClientInfoHL() {
        return clientInfoHL.get();
    }

    public static void setClientInfoTH(ClientInfo clientInfo) {
        clientInfoHL.set(clientInfo);
    }

    public static Long getDomainId() {
        return getClientInfoHL() != null ? getClientInfoHL().getDomainId() : null;
    }

    public static Long getUserId() {
        return getClientInfoHL() != null ? getClientInfoHL().getUserId() : null;
    }
}

主要作用有兩個(gè)：1.獲取threadlocal中的clientInfo,切在創(chuàng)建方法，更新方法前，設(shè)置樂觀鎖，創(chuàng)建人，創(chuàng)建時(shí)間，更新人，更新時(shí)間等這些字段，這也要求PO超類，保存公共字段。 2.緩存處理。在get前，查找緩存，如果不命中，再去獲取并更新緩存；在更新后，去更新緩存。

@Aspect
@Component
public class MasterDaoAspectInterceptor {
    private static final Logger log = LoggerFactory.getLogger(MasterDaoAspectInterceptor.class);

    @Autowired
    RedisClient redisClient;

    @Before("execution(* com.best.gwms.common.base.BasDao+.createPo(..)) && (args(po))")
    public void prePersist(AbstractPo po) {
//        po.setCreatorId(0L);
//        po.setDomainId(10000L);
        po.setCreatorId(MasterStatic.getUserId());
        po.setDomainId(MasterStatic.getDomainId());
        po.setLockVersion(0L);
        po.setCreatedTime(new Date());
        po.setUpdatedTime(po.getCreatedTime());
    }

    @Before("execution(* com.best.gwms.common.base.BasDao+.updatePo(..)) && (args(po))")
    // @Before("execution(* com.best.gwms.master.dao..*.updatePo(..)) && (args(po))")
    public void preUpdate(AbstractPo po) {
//        po.setDomainId(10000L);
//        po.setUpdatorId(0L);
        po.setUpdatorId(MasterStatic.getUserId());
        po.setUpdatedTime(new Date());
    }

    /**
     * getpobyid 先從緩存中獲取,若緩存中沒有,則從數(shù)據(jù)庫(kù)中獲取數(shù)據(jù)并存放到緩存中
     *
     * @param pjp
     * @return
     * @throws Throwable
     */
    @Around("execution(* com.best.gwms.common.base.BasDao+.getPoById(..)) )")
    public Object aroundGetPoById(ProceedingJoinPoint pjp) throws Throwable {

        MethodSignature methodSignature = (MethodSignature) pjp.getSignature();
        Method method = methodSignature.getMethod();

        Class c = methodSignature.getReturnType();
        String simpleName = c.getSimpleName();
        Long id = (Long) pjp.getArgs()[0];

        String key = redisClient.buildKey(simpleName, id);

        if (method.isAnnotationPresent(RedisCache.class)) {

            Object value = redisClient.getObject(key);
            if (value != null) {
                return value;
            }
        }

        Object object = pjp.proceed();

        redisClient.setObject(key, object);

        return object;
    }

    /**
     * getpobyid 先從緩存中獲取,若緩存中沒有,則從數(shù)據(jù)庫(kù)中獲取數(shù)據(jù)并存放到緩存中
     *
     * @param pjp
     * @return
     * @throws Throwable
     */
    @Around("execution(* com.best.gwms.common.base.BasDao+.updatePo(..)) )")
    public Object aroundUpdatePo(ProceedingJoinPoint pjp) throws Throwable {
        // 先清理緩存
        MethodSignature methodSignature = (MethodSignature) pjp.getSignature();
        Method method = methodSignature.getMethod();

        AbstractPo po = (AbstractPo) pjp.getArgs()[0];
        String simpleName = po.getClass().getSimpleName();
        Long id = po.getId();

        String key = redisClient.buildKey(simpleName, id);
        if (method.isAnnotationPresent(RedisCache.class)) {
            redisClient.removeValueByKey(key);
        }

        int count = (int) pjp.proceed();
        if (count <= 0) {
            log.warn("OptiMistic Lock Exception:" + simpleName);
            throw new OptLockException(BizExceptionCode.OPT_LOCK_EXCEPTION);
        }

        return count;
    }

    @Around("execution(* com.best.gwms.common.base.BasDao+.createPo(..)) )")
    public Object aroundCreatePo(ProceedingJoinPoint pjp) throws Throwable {
        // 插入記錄的行數(shù)
        Long count = (Long) pjp.proceed();

        if (count.intValue() <= 0) {
            MethodSignature methodSignature = (MethodSignature) pjp.getSignature();
            Method method = methodSignature.getMethod();
            throw new DaoException(BizExceptionCode.DAO_EXCEPTION);
        }
        return count;
    }
}

結(jié)合PageHelper，在切面中處理分頁(yè)相關(guān)的計(jì)算。本類中切的面有點(diǎn)不精確，還是要在方法名上團(tuán)隊(duì)進(jìn)行一些約定。

@Component
@Aspect
public class BasPageInterceptor {

    @Before("execution(* com.best.gwms.master.dao..*.*(..))")
    public void sharePage(JoinPoint jpj){
        //如果DAO的方法是以count開頭，則直接跳過，不進(jìn)行分頁(yè)處理
        if(StringUtils.startsWith(jpj.getSignature().getName(),"count")){
            return;
        }
        Object[] args = jpj.getArgs();
        Integer pageNum = null;
        Integer pageSize= null;
        String orderBy=null;
        for (Object arg : args) {
            if (arg instanceof SearchObject) {
                SearchObject so = (SearchObject) arg;
                orderBy = so.getOrderBy();
                pageNum=so.getPageNo();
                pageSize=so.getPageSize();
                break;
            }
        }
        if (pageNum != null && pageSize != null) {
            if (orderBy == null) {
                PageHelper.startPage(pageNum,pageSize);
                return;
            }
            PageHelper.startPage(pageNum,pageSize,orderBy);
        }
    }
}