Question

我正在尝试为Windows Phone 8.1 WinRT应用程序的WebView添加一些缓存。我正在使用新的IUriToStreamResolver为某些网址获取流，这在大多数情况下都可以正常工作。对于某些网址，我得到以下异常：

System.Runtime.InteropServices.COMException（0x80004005）：错误HRESULT已从调用COM组件返回E_FAIL。在System.Threading.Tasks.TaskToAsyncOperationAdapter 1.OnCompleted(AsyncOperationCompletedHandler 1 userCompletionHandler，AsyncStatus asyncStatus）在System.Threading.Tasks.TaskToAsyncInfoAdapter 4.OnCompletedInvoker(AsyncStatus status) at System.Threading.Tasks.TaskToAsyncInfoAdapter 4.TaskCompleted（） ---从抛出异常的先前位置开始的堆栈跟踪结束--- 在System.Threading.Tasks.ExceptionDispatchHelper.b__1（Object edi）在System.Threading.QueueUserWorkItemCallback.WaitCallback_Context（对象状态） at System.Threading.ExecutionContext.RunInternal（ExecutionContext executionContext，ContextCallback callback，Object state，Boolean preserveSyncCtx） at System.Threading.ExecutionContext.Run（ExecutionContext executionContext，ContextCallback callback，Object state，Boolean preserveSyncCtx）在System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem（）在System.Threading.ThreadPoolWorkQueue.Dispatch（）在System.Threading._ThreadPoolWaitCallback.PerformWaitCallback（）

我的UriToStreamResolver使用System.Net.HttpClient从Web获取数据并将相对URL转换为绝对URL。

using System;
using System.Threading.Tasks;
using Windows.Foundation;
using Windows.Storage.Streams;
using Windows.Web;

namespace OfflineBrowser
{
    public sealed class StreamUriWinRTResolver : IUriToStreamResolver
    {
        readonly System.Net.Http.HttpClient _httpClient = new System.Net.Http.HttpClient();
        private readonly string _baseUrl;

    public StreamUriWinRTResolver(string baseUrl)
    {
        _baseUrl = baseUrl;
    }

    public IAsyncOperation<IInputStream> UriToStreamAsync(Uri uri)
    {
        try
        {
            if (uri == null)
            {
                throw new Exception();
            }
            string path = uri.AbsolutePath;
            return GetContent(path).AsAsyncOperation();

        }
        catch (Exception)
        {
            return null;
        }
    }

    private async Task<IInputStream> GetContent(string uriPath)
    {
        try
        {
            var url2 = _baseUrl + uriPath;
            var bytes = await _httpClient.GetByteArrayAsync(new Uri(url2));
            IInputStream inputStream = await GetStreamForByteArray(bytes);
            return inputStream;

        }
        catch (Exception)
        {
            //catch not working.. 
            return null;
        }
    }

    private static async Task<IInputStream> GetStreamForByteArray(byte[] content2)
    {
        var ras = new InMemoryRandomAccessStream();
        var datawriter = new DataWriter(ras);
        datawriter.WriteBytes(content2);
        await datawriter.StoreAsync();
        await datawriter.FlushAsync();
        return ras.GetInputStreamAt(0);
    }
}

}

我称之为：

    private async void Button_Click(object sender, RoutedEventArgs e)
    {
        Uri MyUrl = WebView.BuildLocalStreamUri("MyContent", "/tvgids");
        StreamUriWinRTResolver MyResolver = new StreamUriWinRTResolver("http://www.nu.nl");
        WebView.NavigateToLocalStreamUri(MyUrl, MyResolver);
    }

我尝试捕获异常，但这也不起作用。这可能有什么问题？我在模拟器和真实设备上都遇到了错误。谢谢你的阅读。

WinRT WebView IUriToStreamResolver导致某些URL的COMException

0 个答案: