本文整理汇总了C#中System.Net.WebClient.TryGetContentLength方法的典型用法代码示例。如果您正苦于以下问题：C# WebClient.TryGetContentLength方法的具体用法？C# WebClient.TryGetContentLength怎么用？C# WebClient.TryGetContentLength使用的例子？那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类System.Net.WebClient的用法示例。
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示例1: InstallPendingUpdate
/// <summary>
/// Installs the given pending update.
/// </summary>
/// <param name="pendingUpdate">The update to install.</param>
/// <param name="downloadProgress">The action to callback with download progress updates.</param>
/// <param name="installerStarted">The action called when the installer has started.</param>
public void InstallPendingUpdate(PendingUpdate pendingUpdate, Action<double> downloadProgress, Action installerStarted)
{
log.Info("Installing update: " + pendingUpdate);
if (pendingUpdate == null)
{
throw new ArgumentNullException("pendingUpdate", "No update pending");
}
var currentProcess = Process.GetCurrentProcess();
var tempDirectory = string.Format(CultureInfo.InvariantCulture, "{0}-{1}-update", currentProcess.ProcessName, currentProcess.Id);
var workingDirectory = Path.GetTempPath().PathCombine(tempDirectory);
var installFile = pendingUpdate.InstallFileName == null
? "AutoUpdate.exe"
: pendingUpdate.InstallFileName;
var installPath = workingDirectory.PathCombine(installFile);
var signatureUri = new Uri(pendingUpdate.UpdateFileUri.ToString() + ".signature");
log.Debug(string.Format(CultureInfo.InvariantCulture, "Working directory:{0} install path:{1}", workingDirectory, installPath));
Directory.CreateDirectory(workingDirectory);
// Allow other processes to read the temp file but not write it
using (var fileStream = new FileStream(installPath, FileMode.Create, FileAccess.Write, FileShare.Read))
{
var buffer = new byte[0x10000];
var webClient = new WebClient();
// TODO: progress updates
// Download the install to the file
log.Info("Downloading install file: " + pendingUpdate.UpdateFileUri);
using (var inputStream = webClient.OpenRead(pendingUpdate.UpdateFileUri))
{
long length;
bool hasLength = webClient.TryGetContentLength(out length);
long totalRead = 0;
var bytesRead = inputStream.Read(buffer, 0, buffer.Length);
while (bytesRead > 0)
{
totalRead += bytesRead;
UpdateProgress(downloadProgress, hasLength, totalRead, length);
fileStream.Write(buffer, 0, bytesRead);
bytesRead = inputStream.Read(buffer, 0, buffer.Length);
}
}
fileStream.Flush();
// Verify the download
log.Info("Verifying install file: " + installPath);
var signature = webClient.DownloadData(signatureUri);
if (!UpdateSettings.UpdateKeys.IsValidSignature(installPath, signature))
{
log.Warn("Invalid signature detected on install file.");
InvalidSignatureDetected(this, new InvalidSignatureEventArgs());
return;
}
}
var psi = new ProcessStartInfo()
{
CreateNoWindow = false,
FileName = installPath,
UseShellExecute = false
};
// Run the installer
// NOTE: There is a possible race condition here if another user somehow manages to write to the update
// file before the new process starts. It would make sense to adjust the install file ACLs before releasing
// the lock on the file.
log.Info("Running install file: " + installPath);
var process = Process.Start(psi);
installerStarted();
process.WaitForExit();
}