检查HttpWebResponse的null [英] Check null for HttpWebResponse

问题描述

我正在向REST服务发出HTTP post请求，当我收到HttpWebResponse时，我正在检查下面。当我正在做webresponse时，我还应该检查responseStream！= null！= null

I am making HTTP post request to REST service, When I get the HttpWebResponse back, I am doing below check. Should I also check responseStream != null when I am doing webresponse != null

HttpWebResponse webResponse = webRequest.GetResponse() as HttpWebResponse;
if (webResponse != null)
{
    var responseStream = webResponse.GetResponseStream();
    int responseCode = (int)webResponse.StatusCode;
    if (responseStream != null && responseCode == (int)HttpStatusCode.Created)
    {
        cmsStoreWebResponse = ((new  StreamReader(responseStream)).ReadToEnd());`
    }
    else
    {
        this.LogError(string.Format("{0}\n Endpoint: {1}\n {2} {3} {4}", ErrorCodes.IWS_CMSRetrieve_ERROR_001, oagEndpointUrl, ErrorCodes.IWS_CMSStore_ERROR_SERVICE_DOWN, responseStream, responseCode));
        serviceData.Fatal = true;
        serviceData.ErrorCode = ErrorCodes.IWS_EFORMSFORMSETS_001;
        serviceData.ErrorDetails = string.Format("\nEndpoint: {0}\n {1}", oagEndpointUrl, ErrorCodes.RESPONSE_STREAM_NULL);
        throw new FaultException<ServiceExceptionData>(serviceData, new FaultReason(string.Format("\nEndpoint: {0}\n {1}", oagEndpointUrl, ErrorCodes.RESPONSE_STREAM_NULL)));
    }
}
else
{
    this.LogError(string.Format("{0}\n Endpoint: {1}\n {2}",  ErrorCodes.IWS_CMSRetrieve_ERROR_001, oagEndpointUrl, ErrorCodes.IWS_CMSStore_ERROR_SERVICE_DOWN));
    serviceData.Fatal = true;
    serviceData.ErrorCode = ErrorCodes.IWS_EFORMSFORMSETS_001;
    serviceData.ErrorDetails = string.Format("\nEndpoint: {0}\n {1}", oagEndpointUrl, ErrorCodes.RESPONSE_STREAM_NULL);
    throw new FaultException<ServiceExceptionData>(serviceData, new FaultReason(string.Format("\nEndpoint: {0}\n {1}", oagEndpointUrl, ErrorCodes.RESPONSE_STREAM_NULL)));
}

推荐答案

HttpWebResponse.GetResponseStream（）可以返回null，所以是的，你应该检查它是否为空。

HttpWebResponse.GetResponseStream() can return null, so yes, you should check whether it is null or not.

你还应该检查是否 HttpWebResponse.GetResponseStream（）== Stream.Null

所以，像这样：

var webResponseStream = webResponse.GetResponseStream();

if (webResponseStream != null && webResponseStream != Stream.Null)
{
    //do stuff.
}

如果您想知道， webResponseStream！= null 检查是否已将对Stream的引用分配给变量 webResponseStream ，而 webResponseStream！= Stream.Null 检查分配给 webResponseStream 的Stream实例是否包含任何后备数据。

In case you're wondering, webResponseStream != null checks for whether a reference to a Stream has been assigned to the variable webResponseStream, whereas webResponseStream != Stream.Null checks whether or not the Stream instance assigned to webResponseStream contains any backing data.

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