应用市场中Java拦截器和切面的使用实例详解

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 {
	}
}

//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;
}