實現BlockExceptionHandler介面，根據不同的子型別設定不同的異常msg

@Component
public class SentinelExceptionHandler implements BlockExceptionHandler {
    @Override
    public void handle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, BlockException e) throws Exception {
        String msg 
 
= "未知異常";
        int status = 429;

        if(e instanceof FlowException){
            msg = "請求被限流了";
        } else if(e instanceof ParamFlowException){
            msg = "請求被熱點引數限流了";
        } else if(e instanceof DegradeException){
            msg = "請求被降級了";
        } else if(e instanceof AuthorityException){
            msg 
 
= "沒有許可權訪問";
            status = 401;
        }

        httpServletResponse.setContentType("application/json;charset=utf-8");
        httpServletResponse.setStatus(status);
        httpServletResponse.getWriter().println("{msg:" + msg + ",status:" + status + "}");
    }
}