如何使用 Windows.Web.Http 下载和存储图像？答案

【问题标题】：How to download and store an image using Windows.Web.Http?如何使用 Windows.Web.Http 下载和存储图像？
【发布时间】：2014-11-02 22:15:49
【问题描述】：

如何使用 Windows.Web.Http 从 Internet 下载 jpeg 图像并将其存储在 Windows Store 应用程序中？

我面临的问题是我不知道我必须对图像使用什么 Get...Async 和 Write...Async 方法？文件与字符串有很大不同。

仅限 Windows.Web.Http！

没有第三方解决方案！

如果您提出其他建议，请使用评论部分，而不是答案。谢谢！

…    
using Windows.Storage;
using Windows.Web.Http;

Uri uri = new Uri("http://image.tmdb.org/t/p/w300/" + posterPath);
HttpClient httpClient = new HttpClient();

// I guess I need to use one of the Get...Async methods?
var image = await httpClient.Get…Async(uri);

StorageFolder localFolder = ApplicationData.Current.LocalFolder;
StorageFolder cachedPostersFolder = await localFolder.CreateFolderAsync("cached posters", CreationCollisionOption.OpenIfExists);

StorageFile posterFile = await cachedPostersFolder.CreateFileAsync(posterPath, CreationCollisionOption.ReplaceExisting);

// I guess I need to use one of the Write...Async methods?
await FileIO.Write…Async(posterFile, image);

【问题讨论】：

为什么不使用BackgroundDownloader？

标签： c# windows-phone-8 windows-8 windows-store-apps windows-phone-8.1

【解决方案1】：

您可以使用GetBufferAsync 方法获取缓冲区，然后调用FileIO.WriteBufferAsync 将缓冲区写入文件：

Uri uri = new Uri("http://i.stack.imgur.com/ZfLdV.png?s=128&g=1");
string fileName = "daniel2.png";

StorageFile destinationFile = await KnownFolders.PicturesLibrary.CreateFileAsync(
      fileName, CreationCollisionOption.GenerateUniqueName);


HttpClient client = new HttpClient();

var buffer = await client.GetBufferAsync(uri);
await Windows.Storage.FileIO.WriteBufferAsync(destinationFile, buffer);

【讨论】：

【解决方案2】：

 image1.Source = new BitmapImage(new Uri("http://www.image.com/image.jpg",     UriKind.RelativeOrAbsolute));


       using (var mediaLibrary = new MediaLibrary())
        {
            using (var stream = new MemoryStream())
            {
                var fileName = string.Format("Gs{0}.jpg", Guid.NewGuid());
                bmp.SaveJpeg(stream, bmp.PixelWidth, bmp.PixelHeight, 0, 100);
                stream.Seek(0, SeekOrigin.Begin);
                var picture = mediaLibrary.SavePicture(fileName, stream);
                if (picture.Name.Contains(fileName)) return true;
            }
        }

【讨论】：

【解决方案3】：

这与 John 的答案类似，但是在 WP8.1 中您不能使用 GetBufferAsync。相反，您可以按照我的方式使用 GetStreamAsync：

Uri uri = new Uri(UriString);
string fileName = p4.IconLocation;

HttpClient client = new HttpClient();

var streamImage = await client.GetStreamAsync(uri);

await SaveToLocalFolderAsync(streamImage, fileName);

使用函数：

public async Task SaveToLocalFolderAsync(Stream file, string fileName)
    {
        StorageFolder localFolder = ApplicationData.Current.LocalFolder;
        StorageFile storageFile = await localFolder.CreateFileAsync(fileName, CreationCollisionOption.ReplaceExisting);
        using (Stream outputStream = await storageFile.OpenStreamForWriteAsync())
        {
            await file.CopyToAsync(outputStream);
        }
    }

【讨论】：