具有 json 字符串的后台任务中的 UWP Httpclient postasync

Question

我只想从我的 UWP 应用中的后台任务 post 一些 json 到 api 并取回响应以读出它。我的后台任务经常失败

Platform::DisconnectedException ^ at memory location 0x077FEE74.

我尝试了很多方法让它与互联网上的东西一起工作，但只是稍微调整了失败。没有代码我可以完美执行后台任务

这里是代码：

public async void Run(IBackgroundTaskInstance taskInstance)
        {
            _deferral = taskInstance.GetDeferral();

HttpClient aClient = new HttpClient();

            aClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            aClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("text/javascript"));



        Uri theUri = new Uri("https://m.xxxx.com/api/v4/session?expand=account,profile)");

StringContent theContent = new StringContent("{ \"keep_login\": true, \"id\": null, \"username\": \"zumbauser\", \"password\": \"zumbapw\" }", Encoding.UTF8, "application/json");


        HttpResponseMessage aResponse = await aClient.PostAsync(theUri, theContent);

        if (aResponse.IsSuccessStatusCode)
        {
            Debug.WriteLine("This is outpuuuuuuuuuuuuuut: " + aResponse.ToString());
        }
        else
        {
            // show the response status code 
            String failureMsg = "HTTP Status: " + aResponse.StatusCode.ToString() + " – Reason: " + aResponse.ReasonPhrase;
        }

_deferral.Complete();
        }

我正在尝试模仿的 Json 看起来像这样：

{"keep_login":null,"id":null,"username":"zumbauser","password":"zumbapw"}

感谢任何帮助！

Answer 1

我知道这听起来可能很傻，但您使用的是哪个 HttpClient？来自 System.Net.Http 的那个还是来自 Windows.Web.Http 的那个？尝试切换到另一个，它可能会有所帮助

Answer 2

最好使用windows.web.http.httpclient for UWP apps since it supports wide range of Languages. See table from the reference

现在是 StringContent。 Windows.Web.HttpClient 作为 HttpStringContent，类似于 System.Net.Http.HttpClient

中的 StringContent

这是一个示例片段，但请务必阅读参考资料。

Uri theUri = new Uri("https://m.xxxx.com/api/v4/session?expand=account,profile)");
HttpStringContent content = new HttpStringContent("{ \"keep_login\": true, \"id\": null, \"username\": \"zumbauser\", \"password\": \"zumbapw\" }", Windows.Storage.Streams.UnicodeEncoding.Utf8, "application/json");
var client = new HttpClient();
HttpResponseMessage response = await client.PostAsync(theUri, content);

所以要完成您的方法，它将是

public async void Run(IBackgroundTaskInstance taskInstance)
{
    _deferral = taskInstance.GetDeferral();
    HttpClient aClient = new HttpClient();
    aClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    aClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("text/javascript"));
    Uri theUri = new Uri("https://m.xxxx.com/api/v4/session?expand=account,profile)");
    HttpStringContent content = new HttpStringContent("{ \"keep_login\": true, \"id\": null, \"username\": \"zumbauser\", \"password\": \"zumbapw\" }", Windows.Storage.Streams.UnicodeEncoding.Utf8, "application/json");
    HttpResponseMessage aResponse = await aClient.PostAsync(theUri, content);
    if (aResponse.IsSuccessStatusCode)
    {
        Debug.WriteLine("This is outpuuuuuuuuuuuuuut: " + aResponse.ToString());
    }
    else
    {
        String failureMsg = "HTTP Status: " + aResponse.StatusCode.ToString() + " – Reason: " + aResponse.ReasonPhrase;
    }
    _deferral.Complete();
}

注意：我在后台任务中对我的一个应用程序进行了同样的尝试，它工作正常。唯一失败的情况是当我尝试发送大量数据时出现可用内存不足错误。

祝你好运，编码愉快。

具有 json 字符串的后台任务中的 UWP Httpclient postasync

UWP Httpclient postasync in background task with json string

json

httpclient

background-task

uwp

windows-10-universal