如何处理Promise错误？ JS / Java的

Question

这是我的JavaScript代码，它可以处理您的承诺：

＆＃13;

＆＃13;

this.buy = function(coupon) {
			var flag = confirm("Are you sure you want to buy coupon #"
					+ coupon.id + "?");
			if (flag) {
				var promise = CustomerMockService.buyCoupon(coupon);
				promise.then(function(resp) {
					self.myCoupons = resp.data;
					self.message = "Coupon #" + coupon.id
							+ " has been added to your shopping cart.";
				}, function(err) {
					alert(err.data);
				});
			}
		}

＆＃13;

＆＃13;

＆＃13;

我想在第二个函数（＆＃34;错误＆＃34;）中提醒我从异常中获得的相同消息。 这是抛出所有异常的Java代码：

＆＃13;

＆＃13;

public void purchaseCoupon(Coupon coupon) throws ExistException, OutOfDateException, FacadeException {
		// ==========================================================================
		// check if the customer did'nt already purchased this coupon.
		// ==========================================================================
		ArrayList<Coupon> list = this.getAllPurchasedCoupons();
		for (int i = 0; i < list.size(); i++) {
			if (list.get(i).getId() == coupon.getId())
				throw new ExistException("can't purchase a coupon you already have");
		}
		// ==========================================================================
		// check if the coupon is not out-of-date.
		// ==========================================================================
		if (coupon.getEnd_date().before(new Date()))
			throw new OutOfDateException("The coupon you trying to purchase is out of date.");
		// ==========================================================================
		// check if there is any coupons left to be purchased.
		// ==========================================================================
		if (coupon.getAmount() > 0)
			coupon.setAmount(coupon.getAmount() - 1);
		else
			throw new ExistException("No coupons left");
		// ==========================================================================
		try {
			couponDAODB.updateCoupon(coupon);
			customer_CouponDAODB.createCustomer_Coupon(this.Cust_id, coupon.getId());
		} catch (DAOException e) {
			throw new FacadeException(e.getMessage());
		}
	}

＆＃13;

＆＃13;

＆＃13;

我如何使用＆＃34; err.data＆＃34;只查找异常消息？ 现在警报看起来像：

Answer 1

据我了解，您收到的是html响应，而不是JSON（更为可取）。 您需要在服务器端更改对JSON的响应。

如果不可能，另一个解决方案可以更新错误功能：

function(err) {
  // Make html document from response html string
  var div = document.createElement('div');
  div.innerHTML = err.data;
  // Get html element with error message
  var messageBlock = div.querySelector('h1');
  var message = 'Error on server';
  if (messageBlock) {
    // you can parse you message if it's needed
    message = messageBlock.innerText;
  }
  alert(message); // HTTP Status 500 - ...... can't purchase a coupon...
}

Answer 2

请检查您的架构，我怀疑应该对服务方法进行异常处理，方法和方法不应该是无效的。我建议不要抛出异常，但在该服务方法中捕获它并返回错误（如果发生）。问题是你向java容器抛出异常并且Tomcat处理它并产生标准错误页面。

我的建议是这样的：

public Response purchaseCoupon(Coupon coupon) {
   Response response = new Response(); //some response structure
   try {
     //service logic goes here
     response.setObject(coupon); 
     response.setStatusCode("200");
     response.setSatatusMessage("OK");
   }catch (DAOException | FacadeException e) {
     response.setStatusCode("E001");
     response.setStatusMessage(e.getMessage());
     //additional logging
   }catch (ExistException ex) {
     response.setStatusCode("E010");
     response.setStatusMessage(ex.getMessage());
     //additional logging
   }
  return response;
}