(C#) Windows Service，及一个helper类。

(C#) Windows Service - Basic

Using Microsoft Visual Studio or the Microsoft .NET Framework SDK, you can easily create services by creating an application that is installed as a service. This type of application is called a Windows Service. With framework features, you can create services, install them, and start, stop, and otherwise control their behavior.

1. Windows Service Applications

A service can exist in one of three basic states:

- Running
- Paused
- Stopped

The Service can alos reprot the state of a pending command:

- ContinuePending,
- PausePending
- StartPending
- StopPending

These statusesndeicate that a command has been issued , such as a command to pause a running service , but has not been carried out yet.
You can query the Stauts to determine what state a service is in, or use the WaitForStatus to carry out an action when any of these states occurs.

Type of Services

- Win32OwnProcess
- Win32ShareProcess

2. Create Windows Services

如何创建Windows服务

3. 调试Windows Services.

MSDN上面已经将的很详细了，这里简单归纳如下：

1) 添加Installer :  即在Service项目上View Designer，然后在Designer上面的空白区域右击后选择 Add Installer

2) 配置ServiceInstall1 的属性：ServiceName （注意：必须和我们创建的服务的属性中的ServiceName完全一样）

3) 安装服务：Build Solution后，在生成的MyProject.exe目录下面，运行 InstallUtil.exe MyProject.exe 

4) 启动服务，挂起调试： 选择Debug->Attach to Process 后，进行调试。

参考： http://msdn.microsoft.com/zh-cn/library/9k985bc9(v=vs.90).aspx

4.记录使用一个Service helper类来完成 Windows Service的安装和启动。

1). 在WPF的button clieck方法中，安装一个Service

        private void btnRemove_Click(object sender, RoutedEventArgs e)
        {
            this.tbkMessage.Text = "Usb registry service is installing..."; 
            ServiceHelper.StartService();
            this.tbkMessage.Text = "Usb registry service is installed and starting..."; 
        }

2）serviceHelper类.

namespace UsbRegistryCleanUp
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;
    using System.IO;
    using System.Windows.Forms;
    using System.ServiceProcess;
    using System.Configuration.Install; 

    public static class ServiceHelper
    {
        private const string SERVICE_NAME = "UsbRegistryCleaner";
        private const string SERVICE_FILE_NAME = "UsbRegistryCleaner.exe";
        private const string APPLICATION_TITLE = "Usb register cleaner";
        private const string SERVICE_FILE_NOT_EXIST = "Service file does not exist.";
        private const string INSTALL_SERVICE_ERROR = "Error found durring service installatin.";
        private const string UNINSTALL_SERVICE_ERROR = "Error found during service uninstallation.";

        /// <summary>
        /// Get the path of the service file.
        /// </summary>
        /// <returns></returns>
        private static string GetServiceFilePath()
        {
            return Path.Combine(Application.StartupPath, SERVICE_FILE_NAME);
        }

        /// <summary>
        /// Check whether the service file exists or not.
        /// </summary>
        /// <returns></returns>
        private static bool IsServiceFileExists()
        {
            return File.Exists(GetServiceFilePath());
        }

        /// <summary>
        /// Display the error message.
        /// </summary>
        /// <param name="errMsg"></param>
        private static void OOPS(string errMsg)
        {
            MessageBox.Show(errMsg, APPLICATION_TITLE, MessageBoxButtons.OK, MessageBoxIcon.Error);
        }

        /// <summary>
        /// Start service.
        /// </summary>
        public static bool StartService()
        {
            if (!IsWindowsServiceInstalled(SERVICE_NAME))
            {
                if (InstallService() == false)
                    return false;
            }

            ServiceController sc = new ServiceController(SERVICE_NAME);
            if (sc.Status != ServiceControllerStatus.Running)
                sc.Start();

            return true;
        }

        /// <summary>
        /// Stop service.
        /// </summary>
        private static void StopService()
        {
            if (!IsWindowsServiceInstalled(SERVICE_NAME))
            {
                if (InstallService() == false)
                    return;
            }

            ServiceController sc = new ServiceController(SERVICE_NAME);
            if (sc.Status != ServiceControllerStatus.Stopped)
                sc.Stop();
        }

        /// <summary>
        /// Check whether the service has been installed or not.
        /// </summary>
        /// <param name="serviceName"></param>
        /// <returns></returns>
        private static bool IsWindowsServiceInstalled(string serviceName)
        {
            ServiceController[] services = ServiceController.GetServices();
            foreach (ServiceController service in services)
            {
                if (string.Equals(service.ServiceName, serviceName, StringComparison.InvariantCultureIgnoreCase))
                    return true;
            }
            return false;
        }

        /// <summary>
        /// Install service.
        /// </summary>
        /// <returns></returns>
        private static bool InstallService()
        {
            if (!IsServiceFileExists())
            {
                OOPS(SERVICE_FILE_NOT_EXIST);
                return false;
            }

            try
            {
                string[] cmdline = {};
                TransactedInstaller transactedInstaller = new TransactedInstaller();
                AssemblyInstaller assemblyInstaller = new AssemblyInstaller(GetServiceFilePath(), cmdline);
                transactedInstaller.Installers.Add(assemblyInstaller);
                transactedInstaller.Install(new System.Collections.Hashtable());
            }
            catch (Exception ex)
            {
                OOPS(INSTALL_SERVICE_ERROR + ex.Message);
                return false;
            }

            return true;
        }

        /// <summary>
        /// Uninstall the service.
        /// </summary>
        /// <returns></returns>
        public static bool UninstallService()
        {
            if (!IsWindowsServiceInstalled(SERVICE_NAME))
                return true;

            StopService();

            if (!IsServiceFileExists())
            {
                OOPS(SERVICE_FILE_NOT_EXIST);
                return false;
            }

            try
            {
                string[] cmdline = {};
                TransactedInstaller transactedInstaller = new TransactedInstaller();
                AssemblyInstaller assemblyInstaller = new AssemblyInstaller(GetServiceFilePath(), cmdline);
                transactedInstaller.Installers.Add(assemblyInstaller);
                transactedInstaller.Uninstall(null);
            }
            catch (Exception ex)
            {
                OOPS(UNINSTALL_SERVICE_ERROR + ex.Message);
                return false;
            }

            return true;
        }
    }
}