从URL路径下载文件的简单方法是什么?
当前回答
你也可以在WebClient类中使用DownloadFileAsync方法。它将具有指定URI的资源下载到本地文件。此外,此方法不会阻塞调用线程。
示例:
webClient.DownloadFileAsync(new Uri("http://www.example.com/file/test.jpg"), "test.jpg");
欲了解更多信息:
http://csharpexamples.com/download-files-synchronous-asynchronous-url-c/
其他回答
这是我的解决方案,效果很好:
public static void DownloadFile(string url, string pathToSaveFile)
{
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
// or: ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;
using (WebDownload client = new WebDownload())
{
client.Headers["User-Agent"] = "User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36";
client.DownloadFile(new Uri(url), pathToSaveFile);
}
}
public class WebDownload : WebClient
{
protected override WebRequest GetWebRequest(Uri address)
{
HttpWebRequest request = (HttpWebRequest)base.GetWebRequest(address);
if (request != null)
{
request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
}
return request;
}
}
using (var client = new WebClient())
{
client.DownloadFile("http://example.com/file/song/a.mpeg", "a.mpeg");
}
使用GetIsNetworkAvailable()检查网络连接,以避免在未连接到网络时创建空文件。
if (System.Net.NetworkInformation.NetworkInterface.GetIsNetworkAvailable())
{
using (System.Net.WebClient client = new System.Net.WebClient())
{
client.DownloadFileAsync(new Uri("http://www.examplesite.com/test.txt"),
"D:\\test.txt");
}
}
如果你需要设置头文件和cookie来下载文件,你需要做一些稍微不同的事情。这里有一个例子……
// Pass in the HTTPGET URL, Full Path w/Filename, and a populated Cookie Container (optional)
private async Task DownloadFileRequiringHeadersAndCookies(string getUrl, string fullPath, CookieContainer cookieContainer, CancellationToken cancellationToken)
{
cookieContainer ??= new CookieContainer(); // TODO: FILL ME AND PASS ME IN
using (var handler = new HttpClientHandler()
{
UseCookies = true,
CookieContainer = cookieContainer, // This will, both, use the cookies passed in, and update/create cookies from the response
ServerCertificateCustomValidationCallback = (message, cert, chain, errors) => true, // use only if it gets angry about the SSL endpoints
AllowAutoRedirect = true,
})
{
using (var client = new HttpClient(handler))
{
SetHeaders(client);
using (var response = await client.GetAsync(getUrl, cancellationToken))
{
if (response.IsSuccessStatusCode)
{
var bytes = await response.Content.ReadAsByteArrayAsync(cancellationToken);
await File.WriteAllBytesAsync(fullPath, bytes, cancellationToken); // This overwrites the file
}
else
{
// TODO: HANDLE ME
throw new FileNotFoundException();
}
}
}
}
}
并且,要添加你需要的header…
private void SetHeaders(HttpClient client)
{
// TODO: SET ME
client.DefaultRequestHeaders.Connection.Add("keep-alive");
client.DefaultRequestHeaders.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) ...");
client.DefaultRequestHeaders.Add("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9, ...");
client.DefaultRequestHeaders.AcceptEncoding.Add(new StringWithQualityHeaderValue("gzip"));
client.DefaultRequestHeaders.AcceptEncoding.Add(new StringWithQualityHeaderValue("deflate"));
client.DefaultRequestHeaders.AcceptLanguage.Add(new StringWithQualityHeaderValue("en-US"));
client.DefaultRequestHeaders.AcceptLanguage.Add(new StringWithQualityHeaderValue("en", .9));
...
}
旁白:你可以通过以下方式填充cookie容器:
循环遍历前一个响应的cookie。 这个响应可以来自HttpAgilityPack,或者WebClient,或者Puppeteer(有很多选项) 手动输入(来自配置值或硬编码值)。
使用System.Net.WebClient.DownloadFile:
string remoteUri = "http://www.contoso.com/library/homepage/images/";
string fileName = "ms-banner.gif", myStringWebResource = null;
// Create a new WebClient instance.
using (WebClient myWebClient = new WebClient())
{
myStringWebResource = remoteUri + fileName;
// Download the Web resource and save it into the current filesystem folder.
myWebClient.DownloadFile(myStringWebResource, fileName);
}
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