应用市场中Java拦截器和切面的使用实例详解

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相信大家对拦截器和切面的概念已经不陌生了，本文我们就看一些在应用市场中，拦截器和切面的使用是怎样的。
拦截器的使用：每次接收到某个请求之前，都会调用此拦截器中的方法，其中preHandle方法如果return true,表示继续调用对应的controller,如果return false，public class CheckLoginInterceptor implements HandlerInterceptor {private Logger logger = Logger.getLogger(CheckLoginInterceptor.class);private static String TOKEN_VALID_MSG ;static{TOKEN_VALID_MSG=JsonUtil.writeObject2JSON(new AMSResultVO(CodeNum.TOKEN_VALID, CodeMessage.TOKEN_VALID));}public Boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {//request.getMethod获取请求是get,post等if ("OPTIONS".equals(request.getMethod())){// 指定允许其他域名访问response.setHeader("Access-Control-Allow-Origin", "*");// 响应类型response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");// 响应头设置response.setHeader("Access-Control-Allow-Headers", "Content-Type, x-requested-with, X-Custom-Header");response.setStatus(204);return true;}// 获取从header中得到的数据String userName = request.getHeader(CommonConsts.PARAM_USER_NAME);String userToken = request.getHeader(CommonConsts.PARAM_USER_TOKEN);Boolean result = true;String method = request.getRequestURI();if(method.equals("/ams/fileUpload")){return true;}if(StringUtil.isEmpty(userName) || StringUtil.isEmpty(userToken)){result = false;} else{result = TokenUtil.validToken(userName, userToken);}// token校验失败if(!result){response.setContentType("text/html;charset=UTF-8");response.getWriter().print(TOKEN_VALID_MSG);response.getWriter().flush();response.getWriter().close();}return result;}public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {}public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {}}复制代码切面的使用：//坏绕通知：需要携带ProceedingJoinPoint类型的参数//环绕通知类似于动态代理的全过程：ProceedingJoinPoint类型的参数可以决定是否执行目标方法//且环绕通知必须有返回值，返回值即目标方法的返回值。@Around("execution(* com.sowell.controller.*Controller.*(..))")public Object aroundMethod(ProceedingJoinPoint pjd) {Object result = null;String methodName = pjd.getSignature().getName();Object args = Arrays.asList(pjd.getArgs());//执行目标方法try {logger.info("request channels begin, param{pageNum:" + methodName + ", pageSize:" + args);//前置通知，表示在此之前的代码会在调用controller之前调用result = pjd.proceed();recordOprationLog(result, methodName, result);//后置通知logger.info("Arround:The method "+ methodName+" ends");}catch (Throwable e) {e.printStackTrace();//异常通知logger.error("Arround:The method "+ methodName+"occurs exception:"+e);//throw new RuntimeException(e);//不抛出异常的话，异常就被上面抓住，执行下去，返回result，result值为null，转换为int}//返回通知logger.info("Arround:The method "+ methodName+" ends with the Result "+ result);return result;}复制代码总结
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