我需要帮助从网络服务检索图片。这是一个 GET 请求。
目前我正在检索响应，并且可以将其转换为字节数组，这就是我想要的，但字节数组会使应用程序崩溃，所以我认为内容设置不正确。
我尝试使用以下方式设置响应内容：
response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment") { FileName = filename };
即使我的猜测是它设置错误，或者它在 requestHeader 中设置错误。
有什么想法吗？
using (var client = new HttpClient())
{
client.BaseAddress = new Uri(baseurl.uri);
client.DefaultRequestHeaders.Add("x-access-token", sessionToken);
client.DefaultRequestHeaders
.Accept
.Add(new MediaTypeWithQualityHeaderValue("image/jpeg")
);
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, "");
try
{
Task<HttpResponseMessage> getResponse = client.SendAsync(request);
HttpResponseMessage response = new HttpResponseMessage();
response = await getResponse;
//1. response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment") { FileName = filename };
//2. response.Content.Headers.ContentType =
//new MediaTypeHeaderValue("image/jpeg");//("application/octet-stream");
byte[] mybytearray = null;
if (response.IsSuccessStatusCode)
{
//3.
mybytearray = response.Content.ReadAsByteArrayAsync().Result;
}
var responseJsonString = await response.Content.ReadAsStringAsync();
System.Diagnostics.Debug.WriteLine(responseJsonString);
System.Diagnostics.Debug.WriteLine("GetReportImage ReponseCode: " + response.StatusCode);
return mybytearray;//{byte[5893197]}
}
catch (Exception ex)
{
string message = ex.Message;
return null;
}
}
您可以将图像的 valid 字节数组作为
HttpContent HttpContent contentPost = new
StringContent(JsonConvert.SerializeObject(YourByteArray), Encoding.UTF8,
"application/json");
反序列化结果后，您可以检索字节数组，以与 jpeg 或任何其他格式相同的方式保存。
byte[] imageByteArray = byteArray;
using(Image image = Image.FromStream(new MemoryStream(imageByteArray)))
{
image.Save("NewImage.jpg", ImageFormat.Jpeg);
}
如果您不需要验证文件，您可以像任何其他类型的文件一样获取图片
using var httpClient = new HttpClient();
var streamGot = await httpClient.GetStreamAsync("domain/image.png");
await using var fileStream = new FileStream("image.png", FileMode.Create, FileAccess.Write);
streamGot.CopyTo(fileStream);
这是一个简单的演示 UWP 应用程序，用于下载图像文件。 只需粘贴图像 URL 链接并按下载按钮即可下载所需的图像文件。
主页.xaml
<Page
x:Class="HttpDownloader.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:HttpDownloader"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Grid>
<StackPanel>
<TextBox x:Name="uriInput"
Header="URI:" PlaceholderText="Please provide an uri"
Width="300"
HorizontalAlignment="Center"/>
<Button Content="Dowload"
HorizontalAlignment="Center"
Click="Button_Click"/>
</StackPanel>
</Grid>
</Page>
MainPage.xaml.xs
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Runtime.InteropServices.WindowsRuntime;
using System.Threading.Tasks;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
using System.Net.Http;
using System.Net;
using Windows.Storage.Streams;
using Windows.Storage.Pickers;
using Windows.Storage;
using Windows.Graphics.Imaging;
using System.Threading;
// The Blank Page item template is documented at https://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x409
namespace HttpDownloader
{
/// <summary>
/// An empty page that can be used on its own or navigated to within a Frame.
/// </summary>
public sealed partial class MainPage : Page
{
public MainPage()
{
this.InitializeComponent();
}
private async void Button_Click(object sender, RoutedEventArgs e)
{
HttpClient client = new HttpClient();
string imageUrl = uriInput.Text;
try
{
using (var cancellationTokenSource = new CancellationTokenSource(50000))
{
var uri = new Uri(WebUtility.HtmlDecode(imageUrl));
using (var response = await client.GetAsync(uri, cancellationTokenSource.Token))
{
response.EnsureSuccessStatusCode();
var mediaType = response.Content.Headers.ContentType.MediaType;
string fileName = DateTime.Now.ToString("yyyyMMddhhmmss");
if (mediaType.IndexOf("jpg", StringComparison.OrdinalIgnoreCase) >= 0
|| mediaType.IndexOf("jpeg", StringComparison.OrdinalIgnoreCase) >= 0)
{
fileName += ".jpg";
}
else if (mediaType.IndexOf("png", StringComparison.OrdinalIgnoreCase) >= 0)
{
fileName += ".png";
}
else if (mediaType.IndexOf("gif", StringComparison.OrdinalIgnoreCase) >= 0)
{
fileName += ".gif";
}
else if (mediaType.IndexOf("bmp", StringComparison.OrdinalIgnoreCase) >= 0)
{
fileName += ".bmp";
}
else
{
fileName += ".png";
}
// Get the app's local folder.
StorageFolder localFolder = Windows.Storage.ApplicationData.Current.LocalFolder;
// Create a new subfolder in the current folder.
// Replace the folder if already exists.
string desiredName = "Images";
StorageFolder newFolder = await localFolder.CreateFolderAsync(desiredName, CreationCollisionOption.ReplaceExisting);
StorageFile newFile = await newFolder.CreateFileAsync(fileName, CreationCollisionOption.ReplaceExisting);
using (Stream streamStream = await response.Content.ReadAsStreamAsync())
{
using (Stream streamToWriteTo = File.Open(newFile.Path, FileMode.Create))
{
await streamStream.CopyToAsync(streamToWriteTo);
}
}
}
}
}
catch (Exception ex)
{
Console.WriteLine("Exception occur");
Console.WriteLine(ex.ToString());
}
}
}
}
您将在此文件夹中找到该图像。
Users/[current user name]/AppData/Local/Packages/[Application package name]/LocalState/Images