blocks|key|3024950|text|不需要涉及任何图像类，您可以简单地调用WebClient.DownloadFile|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3024951|string+localFilename+=+@"c:\localpath\tofile.jpg";
using(WebClient+client+=+new+WebClient())
{
++++client.DownloadFile("http://www.example.com/image.jpg",+localFilename);
}|code-block|syntax|javascript|3024952|3024953|更新|BOLD|3024954|由于您需要检查该文件是否存在，如果存在则下载该文件，因此最好在同一请求中执行此操作。下面是一个可以做到这一点的方法：|3024955|private+static+void+DownloadRemoteImageFile(string+uri,+string+fileName)
{
++++HttpWebRequest+request+=+(HttpWebRequest)WebRequest.Create(uri);
++++HttpWebResponse+response+=+(HttpWebResponse)request.GetResponse();

++++//+Check+that+the+remote+file+was+found.+The+ContentType
++++//+check+is+performed+since+a+request+for+a+non-existent
++++//+image+file+might+be+redirected+to+a+404-page,+which+would
++++//+yield+the+StatusCode+"OK",+even+though+the+image+was+not
++++//+found.
++++if+((response.StatusCode+==+HttpStatusCode.OK+%7C%7C+
++++++++response.StatusCode+==+HttpStatusCode.Moved+%7C%7C+
++++++++response.StatusCode+==+HttpStatusCode.Redirect)+&&
++++++++response.ContentType.StartsWith("image",StringComparison.OrdinalIgnoreCase))
++++{

++++++++//+if+the+remote+file+was+found,+download+oit
++++++++using+(Stream+inputStream+=+response.GetResponseStream())
++++++++using+(Stream+outputStream+=+File.OpenWrite(fileName))
++++++++{
++++++++++++byte[]+buffer+=+new+byte[4096];
++++++++++++int+bytesRead;
++++++++++++do
++++++++++++{
++++++++++++++++bytesRead+=+inputStream.Read(buffer,+0,+buffer.Length);
++++++++++++++++outputStream.Write(buffer,+0,+bytesRead);
++++++++++++}+while+(bytesRead+!=+0);
++++++++}
++++}
}|3024956|简而言之，它请求文件，验证响应代码是否为OK、Moved或Redirect之一，以及ContentType是否为图像。如果满足这些条件，则下载该文件。|3024957|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/ez801hhe.aspx^0|J|M|J|M|0|0|0|0|0|2|0|0|0|K|2|N|5|T|8|16|B|0^^$0|@$1|2|3|4|5|6|7|12|8|@$9|13|A|14|B|C]]|D|@$9|15|A|16|1|17]]|E|$]]|$1|F|3|G|5|H|7|18|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|19|8|@]|D|@]|E|$]]|$1|L|3|M|5|6|7|1A|8|@$9|1B|A|1C|B|N]]|D|@]|E|$]]|$1|O|3|P|5|6|7|1D|8|@]|D|@]|E|$]]|$1|Q|3|R|5|H|7|1E|8|@]|D|@]|E|$I|J]]|$1|S|3|T|5|6|7|1F|8|@$9|1G|A|1H|B|C]|$9|1I|A|1J|B|C]|$9|1K|A|1L|B|C]|$9|1M|A|1N|B|C]]|D|@]|E|$]]|$1|U|3|-4|5|6|7|1O|8|@]|D|@]|E|$]]]|V|$W|$5|X|Y|Z|E|$10|11]]]]

There is no need to involve any image classes, you can simply call <a href="http://msdn.microsoft.com/en-us/library/ez801hhe.aspx" rel="noreferrer"><code>WebClient.DownloadFile</code></a>:

<pre><code>string localFilename = @"c:\localpath\tofile.jpg";
using(WebClient client = new WebClient())
{
 client.DownloadFile("http://www.example.com/image.jpg", localFilename);
}
</code></pre>

<hr>

Update 
Since you will want to check whether the file exists and download the file if it does, it's better to do this within the same request. So here is a method that will do that:

<pre><code>private static void DownloadRemoteImageFile(string uri, string fileName)
{
 HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
 HttpWebResponse response = (HttpWebResponse)request.GetResponse();

 // Check that the remote file was found. The ContentType
 // check is performed since a request for a non-existent
 // image file might be redirected to a 404-page, which would
 // yield the StatusCode "OK", even though the image was not
 // found.
 if ((response.StatusCode == HttpStatusCode.OK || 
 response.StatusCode == HttpStatusCode.Moved || 
 response.StatusCode == HttpStatusCode.Redirect) &amp;&amp;
 response.ContentType.StartsWith("image",StringComparison.OrdinalIgnoreCase))
 {

 // if the remote file was found, download oit
 using (Stream inputStream = response.GetResponseStream())
 using (Stream outputStream = File.OpenWrite(fileName))
 {
 byte[] buffer = new byte[4096];
 int bytesRead;
 do
 {
 bytesRead = inputStream.Read(buffer, 0, buffer.Length);
 outputStream.Write(buffer, 0, bytesRead);
 } while (bytesRead != 0);
 }
 }
}
</code></pre>

In brief, it makes a request for the file, verifies that the response code is one of <code>OK</code>, <code>Moved</code> or <code>Redirect</code> and also that the <code>ContentType</code> is an image. If those conditions are true, the file is downloaded.

blocks|key|3239261|text|我在一个项目中使用了Fredrik上面的代码，只做了一些细微的修改，我想分享一下：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3239262|private+static+bool+DownloadRemoteImageFile(string+uri,+string+fileName)
{
++++HttpWebRequest+request+=+(HttpWebRequest)WebRequest.Create(uri);
++++HttpWebResponse+response;
++++try
++++{
++++++++response+=+(HttpWebResponse)request.GetResponse();
++++}
++++catch+(Exception)
++++{
++++++++return+false;
++++}

++++//+Check+that+the+remote+file+was+found.+The+ContentType
++++//+check+is+performed+since+a+request+for+a+non-existent
++++//+image+file+might+be+redirected+to+a+404-page,+which+would
++++//+yield+the+StatusCode+"OK",+even+though+the+image+was+not
++++//+found.
++++if+((response.StatusCode+==+HttpStatusCode.OK+%7C%7C
++++++++response.StatusCode+==+HttpStatusCode.Moved+%7C%7C
++++++++response.StatusCode+==+HttpStatusCode.Redirect)+&&
++++++++response.ContentType.StartsWith("image",+StringComparison.OrdinalIgnoreCase))
++++{

++++++++//+if+the+remote+file+was+found,+download+it
++++++++using+(Stream+inputStream+=+response.GetResponseStream())
++++++++using+(Stream+outputStream+=+File.OpenWrite(fileName))
++++++++{
++++++++++++byte[]+buffer+=+new+byte[4096];
++++++++++++int+bytesRead;
++++++++++++do
++++++++++++{
++++++++++++++++bytesRead+=+inputStream.Read(buffer,+0,+buffer.Length);
++++++++++++++++outputStream.Write(buffer,+0,+bytesRead);
++++++++++++}+while+(bytesRead+!=+0);
++++++++}
++++++++return+true;
++++}
++++else
++++++++return+false;
}|code-block|syntax|javascript|3239263|主要变化包括：|3239264|3239265|对GetResponse()使用try/catch，因为当远程文件返回404|unordered-list-item|3239266|返回boolean|3239267|时，我遇到了异常|3239268|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|L|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

I have used Fredrik's code above in a project with some slight modifications, thought I'd share:

<pre><code>private static bool DownloadRemoteImageFile(string uri, string fileName)
{
 HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
 HttpWebResponse response;
 try
 {
 response = (HttpWebResponse)request.GetResponse();
 }
 catch (Exception)
 {
 return false;
 }

 // Check that the remote file was found. The ContentType
 // check is performed since a request for a non-existent
 // image file might be redirected to a 404-page, which would
 // yield the StatusCode "OK", even though the image was not
 // found.
 if ((response.StatusCode == HttpStatusCode.OK ||
 response.StatusCode == HttpStatusCode.Moved ||
 response.StatusCode == HttpStatusCode.Redirect) &amp;&amp;
 response.ContentType.StartsWith("image", StringComparison.OrdinalIgnoreCase))
 {

 // if the remote file was found, download it
 using (Stream inputStream = response.GetResponseStream())
 using (Stream outputStream = File.OpenWrite(fileName))
 {
 byte[] buffer = new byte[4096];
 int bytesRead;
 do
 {
 bytesRead = inputStream.Read(buffer, 0, buffer.Length);
 outputStream.Write(buffer, 0, bytesRead);
 } while (bytesRead != 0);
 }
 return true;
 }
 else
 return false;
}
</code></pre>

Main changes are:

<ul>
<li>using a try/catch for the GetResponse() as I was running into an exception when the remote file returned 404</li>
<li>returning a boolean</li>
</ul>

blocks|key|3024997|text|++++++++private+static+void+DownloadRemoteImageFile(string+uri,+string+fileName)
++++++++{
++++++++++++HttpWebRequest+request+=+(HttpWebRequest)WebRequest.Create(uri);
++++++++++++HttpWebResponse+response+=+(HttpWebResponse)request.GetResponse();

++++++++++++if+((response.StatusCode+==+HttpStatusCode.OK+%7C%7C
++++++++++++++++response.StatusCode+==+HttpStatusCode.Moved+%7C%7C
++++++++++++++++response.StatusCode+==+HttpStatusCode.Redirect)+&&
++++++++++++++++response.ContentType.StartsWith("image",+StringComparison.OrdinalIgnoreCase))+
++++++++++++{
++++++++++++++++using+(Stream+inputStream+=+response.GetResponseStream())
++++++++++++++++using+(Stream+outputStream+=+File.OpenWrite(fileName))
++++++++++++++++{
++++++++++++++++++++byte[]+buffer+=+new+byte[4096];
++++++++++++++++++++int+bytesRead;
++++++++++++++++++++do
++++++++++++++++++++{
++++++++++++++++++++++++bytesRead+=+inputStream.Read(buffer,+0,+buffer.Length);
++++++++++++++++++++++++outputStream.Write(buffer,+0,+bytesRead);
++++++++++++++++++++}+while+(bytesRead+!=+0);
++++++++++++++++}
++++++++++++}
++++++++}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3024998|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code> private static void DownloadRemoteImageFile(string uri, string fileName)
 {
 HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
 HttpWebResponse response = (HttpWebResponse)request.GetResponse();

 if ((response.StatusCode == HttpStatusCode.OK ||
 response.StatusCode == HttpStatusCode.Moved ||
 response.StatusCode == HttpStatusCode.Redirect) &amp;&amp;
 response.ContentType.StartsWith("image", StringComparison.OrdinalIgnoreCase)) 
 {
 using (Stream inputStream = response.GetResponseStream())
 using (Stream outputStream = File.OpenWrite(fileName))
 {
 byte[] buffer = new byte[4096];
 int bytesRead;
 do
 {
 bytesRead = inputStream.Read(buffer, 0, buffer.Length);
 outputStream.Write(buffer, 0, bytesRead);
 } while (bytesRead != 0);
 }
 }
 }
</code></pre>

blocks|key|3025007|text|也可以使用DownloadData方法|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3025008|++++private+byte[]+GetImage(string+iconPath)
++++{
++++++++using+(WebClient+client+=+new+WebClient())
++++++++{
++++++++++++byte[]+pic+=+client.DownloadData(iconPath);
++++++++++++//string+checkPath+=+Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)+%2B@"\1.png";
++++++++++++//File.WriteAllBytes(checkPath,+pic);
++++++++++++return+pic;
++++++++}
++++}|code-block|syntax|javascript|3025009|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Also possible to use DownloadData method

<pre><code> private byte[] GetImage(string iconPath)
 {
 using (WebClient client = new WebClient())
 {
 byte[] pic = client.DownloadData(iconPath);
 //string checkPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) +@"\1.png";
 //File.WriteAllBytes(checkPath, pic);
 return pic;
 }
 }
</code></pre>

blocks|key|3025019|text|从服务器或网站下载图像并将其存储在本地的最佳实践。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3025020|WebClient+client=new+Webclient();
client.DownloadFile("WebSite+URL","C:\\....image.jpg");
client.Dispose();|code-block|syntax|javascript|3025021|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

The best practice to download an image from Server or from Website and store it locally.

<pre><code>WebClient client=new Webclient();
client.DownloadFile("WebSite URL","C:\\....image.jpg");
client.Dispose();
</code></pre>

blocks|key|298807|text|您可以使用以下代码|type|unstyled|depth|inlineStyleRanges|entityRanges|data|298808|using+(WebClient+client+=+new+WebClient())+{
++++++++++++++++++++Stream+stream+=+client.OpenRead(imgUrl);
++++++++++++++++++++if+(stream+!=+null)+{
++++++++++++++++++++++++Bitmap+bitmap+=+new+Bitmap(stream);
++++++++++++++++++++++++ImageFormat+imageFormat+=+ImageFormat.Jpeg;
++++++++++++++++++++++++if+(bitmap.RawFormat.Equals(ImageFormat.Png))+{
++++++++++++++++++++++++++++imageFormat+=+ImageFormat.Png;
++++++++++++++++++++++++}
++++++++++++++++++++++++else+if+(bitmap.RawFormat.Equals(ImageFormat.Bmp))+{
++++++++++++++++++++++++++++imageFormat+=+ImageFormat.Bmp;
++++++++++++++++++++++++}
++++++++++++++++++++++++else+if+(bitmap.RawFormat.Equals(ImageFormat.Gif))+{
++++++++++++++++++++++++++++imageFormat+=+ImageFormat.Gif;
++++++++++++++++++++++++}
++++++++++++++++++++++++else+if+(bitmap.RawFormat.Equals(ImageFormat.Tiff))+{
++++++++++++++++++++++++++++imageFormat+=+ImageFormat.Tiff;
++++++++++++++++++++++++}

++++++++++++++++++++++++bitmap.Save(fileName,+imageFormat);
++++++++++++++++++++++++stream.Flush();
++++++++++++++++++++++++stream.Close();
++++++++++++++++++++++++client.Dispose();
++++++++++++++++++++}
++++++++++++++++}|code-block|syntax|javascript|298809|项目请访问：github|offset|length|298810|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/ranjit-singh-cc/DownloadImagesByUrl^0|0|0|6|6|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

You can use this code

<pre><code>using (WebClient client = new WebClient()) {
 Stream stream = client.OpenRead(imgUrl);
 if (stream != null) {
 Bitmap bitmap = new Bitmap(stream);
 ImageFormat imageFormat = ImageFormat.Jpeg;
 if (bitmap.RawFormat.Equals(ImageFormat.Png)) {
 imageFormat = ImageFormat.Png;
 }
 else if (bitmap.RawFormat.Equals(ImageFormat.Bmp)) {
 imageFormat = ImageFormat.Bmp;
 }
 else if (bitmap.RawFormat.Equals(ImageFormat.Gif)) {
 imageFormat = ImageFormat.Gif;
 }
 else if (bitmap.RawFormat.Equals(ImageFormat.Tiff)) {
 imageFormat = ImageFormat.Tiff;
 }

 bitmap.Save(fileName, imageFormat);
 stream.Flush();
 stream.Close();
 client.Dispose();
 }
 }
</code></pre>

Project available at: <a href="https://github.com/ranjit-singh-cc/DownloadImagesByUrl" rel="nofollow noreferrer">github</a>

I am trying to download images from the site. The code which I am using is working fine while the image is available. If the image it not available it is creating a problem. How to validate availability of the image?

Code:

Method 1:

<pre><code>WebRequest requestPic = WebRequest.Create(imageUrl);

WebResponse responsePic = requestPic.GetResponse();

Image webImage = Image.FromStream(responsePic.GetResponseStream()); // Error

webImage.Save("D:\\Images\\Book\\" + fileName + ".jpg");
</code></pre>

Method 2:

<pre><code>WebClient client = new WebClient();
Stream stream = client.OpenRead(imageUrl);

bitmap = new Bitmap(stream); // Error : Parameter is not valid.
stream.Flush();
stream.Close();
client.dispose();

if (bitmap != null)
{
 bitmap.Save("D:\\Images\\" + fileName + ".jpg");
}
</code></pre>

Edit:

Stream has the following statements:

<pre><code> Length '((System.Net.ConnectStream)(str)).Length' threw an exception of type 'System.NotSupportedException' long {System.NotSupportedException}
 Position '((System.Net.ConnectStream)(str)).Position' threw an exception of type 'System.NotSupportedException' long {System.NotSupportedException}
 ReadTimeout 300000 int
WriteTimeout 300000 int
</code></pre>

Download image from the site in .NET/C#

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在尝试从网站下载图片。当图像可用时，我使用的代码工作得很好。如果图像不可用，则说明存在问题。如何验证镜像的可用性？代码：方法1：WebRequest requestPic = WebRequest.Create(imageUrl);WebResponse responsePic = requestPic.GetRe...

问在.NET/C#中从站点下载图像
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