.NET MAUI安卓端POST带请求内容时抛出System.ObjectDisposedException异常

问题详情 #

开发.NET MAUI应用时，带内容的POST请求函数在Windows平台运行正常，但在Android平台执行时抛出异常：System.ObjectDisposedException: Cannot access a closed Stream。

其中GET、DELETE请求在双平台均能正常运行，不带内容的POST请求（示例代码如下）也可在双平台正常工作，仅带内容的POST请求在Android平台报错。

相关代码 #

带内容的POST请求代码

public async static Task InsertParts(IEnumerable<PartDTO> partsToReport)
{
    using (HttpClient client = GetClient())
    {
        AddAuthorizationHeader(client);
        string url = $"{Url}/endpoint";

        string jsonData = JsonSerializer.Serialize(partsToReport);
        HttpContent content = new StringContent(jsonData, Encoding.UTF8, "application/json");

        var response = await client.PostAsync(url, content);

        if (!(response.IsSuccessStatusCode))
        {
            throw new Exception($"Failed to insert parts: {response.ReasonPhrase}");
        }
    }
}

HttpClient创建代码

public static HttpClient GetClient()
{
#if DEBUG
    HttpClientHandler insecureHandler = new HttpClientHandler();
    insecureHandler.ServerCertificateCustomValidationCallback = HttpClientHandler.DangerousAcceptAnyServerCertificateValidator;
    return new HttpClient(insecureHandler);
#else
    return new HttpClient();
#endif
}

正常运行的无内容POST请求示例

HttpResponseMessage response = await
client.PostAsync($"{Url}/inventory/{id}/{destination}",
null);

解决方案 #

• 复用HttpClient实例：Android平台下频繁创建并销毁HttpClient可能导致请求流被提前关闭。将HttpClient改为静态单例，避免每次请求都创建新实例：

  private static HttpClient _httpClient;
  public static HttpClient GetClient()
  {
      if (_httpClient == null)
      {
  #if DEBUG
          HttpClientHandler insecureHandler = new HttpClientHandler();
          insecureHandler.ServerCertificateCustomValidationCallback = HttpClientHandler.DangerousAcceptAnyServerCertificateValidator;
          _httpClient = new HttpClient(insecureHandler);
  #else
          _httpClient = new HttpClient();
  #endif
      }
      return _httpClient;
  }
  

  同时移除InsertParts方法中的using块，改为直接使用单例HttpClient。

• 显式管理HttpContent生命周期：将StringContent放入using块中，确保其生命周期覆盖整个请求过程：

  string jsonData = JsonSerializer.Serialize(partsToReport);
  using (var content = new StringContent(jsonData, Encoding.UTF8, "application/json"))
  {
      var response = await client.PostAsync(url, content).ConfigureAwait(false);
  
      if (!response.IsSuccessStatusCode)
      {
          throw new Exception($"Failed to insert parts: {response.ReasonPhrase}");
      }
  }
  

• 添加ConfigureAwait(false)：避免Android平台的同步上下文切换导致流被提前释放，在异步调用后添加该配置：

  var response = await client.PostAsync(url, content).ConfigureAwait(false);
  

内容的提问来源于stack exchange，提问作者Dragon Slayer