.net - 如何使用 Click Once 构建单实例应用程序？

Question

我需要有一个单实例应用程序(根据此 answer )，但需要通过单击一次来部署它。

问题是我要求单击一次不会自动检测更新并尝试在应用程序运行时加载较新的版本。如果它正在运行，那么我需要激活另一个实例。通常，当选择“单击一次”链接时，它所做的第一件事就是尝试查找更新。我想拦截它并在启动正常更新过程之前检查是否有已运行的实例。

有谁知道在“单击一次”部署场景中这是如何实现的？

Answer 1

为了解决这个问题，我们构建了一个原型(prototype)应用程序，它具有以下两个功能。

1. 一台电脑上的多个实例被禁用。单实例应用程序通过 clickonce 进行部署。当用户尝试启动应用程序的第二个实例时，将弹出一条消息，指示“另一个实例已在运行”。

2. 异步检查更新，并安装更新(如果存在)。当用户运行新实例时，如果有可用更新，则会弹出一条消息:“有更新可用”。

构建演示应用程序的过程如下:

第 1 步:使用 Mutex 类检测事件实例应用程序。

namespace ClickOnceDemo
{
    static class Program
    {
        /// summary>
        /// The main entry point for the application.
        /// /summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault( false );
            bool ok;
            var m = new System.Threading.Mutex( true, "Application", out ok );
            if ( !ok )
            {
                MessageBox.Show( "Another instance is already running.", ApplicationDeployment.CurrentDeployment.CurrentVersion.ToString() );
                return;
            }
           Application.Run( new UpdateProgress() );
        }
    }
}

第 2 步:以编程方式处理更新

在此之前，我们应该禁用自动 ClickOnce 更新检查(在“发布 - 更新...”对话框中)。

然后我们创建两个表单:UpdateProgress 和 mainForm，其中 UpdateProgress 表示下载进度，mainForm 表示主应用程序。

当用户运行应用程序时，将首先启动 updateProgress 来检查更新。更新完成后，mainForm 将启动，updateProgress 将被隐藏。

namespace ClickOnceDemo
{
public partial class UpdateProgress : Form
 {
  public UpdateProgress()
        {
            InitializeComponent();
            Text = "Checking for updates...";

            ApplicationDeployment ad = ApplicationDeployment.CurrentDeployment;
            ad.CheckForUpdateCompleted += OnCheckForUpdateCompleted;
            ad.CheckForUpdateProgressChanged += OnCheckForUpdateProgressChanged;

            ad.CheckForUpdateAsync();
       }

        private void OnCheckForUpdateProgressChanged(object sender, DeploymentProgressChangedEventArgs e)
        {
            lblStatus.Text = String.Format( "Downloading: {0}. {1:D}K of {2:D}K downloaded.", GetProgressString( e.State ), e.BytesCompleted / 1024, e.BytesTotal / 1024 );
            progressBar1.Value = e.ProgressPercentage;
        }

        string GetProgressString( DeploymentProgressState state )
        {
            if ( state == DeploymentProgressState.DownloadingApplicationFiles )
            {
                return "application files";
            }
            if ( state == DeploymentProgressState.DownloadingApplicationInformation )
            {
                return "application manifest";
            }
            return "deployment manifest";
        }

        private void OnCheckForUpdateCompleted(object sender, CheckForUpdateCompletedEventArgs e)
        {
            if ( e.Error != null )
            {
                MessageBox.Show( "ERROR: Could not retrieve new version of the application. Reason: \n" + e.Error.Message + "\nPlease report this error to the system administrator." );
                return;
            }
            if ( e.Cancelled )
            {
                MessageBox.Show( "The update was cancelled." );
            }

            // Ask the user if they would like to update the application now.
            if ( e.UpdateAvailable )
            {
                if ( !e.IsUpdateRequired )
                {
                    long updateSize = e.UpdateSizeBytes;
                    DialogResult dr = MessageBox.Show( string.Format("An update ({0}K) is available. Would you like to update the application now?", updateSize/1024), "Update Available", MessageBoxButtons.OKCancel );
                    if ( DialogResult.OK == dr )
                    {
                        BeginUpdate();
                    }
                }
                else
                {
                    MessageBox.Show( "A mandatory update is available for your application. We will install the update now, after which we will save all of your in-progress data and restart your application." );
                    BeginUpdate();
                }
            }
            else
            {
                ShowMainForm();
            }
        }

        // Show the main application form
        private void ShowMainForm()
        {
            MainForm mainForm = new MainForm ();
            mainForm.Show();
            Hide();
        }

        private void BeginUpdate()
        {
            Text = "Downloading update...";
            ApplicationDeployment ad = ApplicationDeployment.CurrentDeployment;
            ad.UpdateCompleted += ad_UpdateCompleted;
            ad.UpdateProgressChanged += ad_UpdateProgressChanged;

            ad.UpdateAsync();
        }

        void ad_UpdateProgressChanged( object sender, DeploymentProgressChangedEventArgs e )
        {
            String progressText = String.Format( "{0:D}K out of {1:D}K downloaded - {2:D}% complete", e.BytesCompleted / 1024, e.BytesTotal / 1024, e.ProgressPercentage );
            progressBar1.Value = e.ProgressPercentage;
            lblStatus.Text = progressText;
        }

        void ad_UpdateCompleted( object sender, AsyncCompletedEventArgs e )
        {
            if ( e.Cancelled )
            {
                MessageBox.Show( "The update of the application's latest version was cancelled." );
                return;
            }
            if ( e.Error != null )
            {
                MessageBox.Show( "ERROR: Could not install the latest version of the application. Reason: \n" + e.Error.Message + "\nPlease report this error to the system administrator." );
                return;
            }

            DialogResult dr = MessageBox.Show( "The application has been updated. Restart? (If you do not restart now, the new version will not take effect until after you quit and launch the application again.)", "Restart Application", MessageBoxButtons.OKCancel );
            if ( DialogResult.OK == dr )
            {
                Application.Restart();
            }
            else
            {
                ShowMainForm();
            }
        }
    }
}

该应用程序运行良好，我们希望它能很好地解决问题。
特别感谢Timothy Walters 提供源代码