此示例演示如何创建一个 cmdlet，该 cmdlet 允许用户注册 System.IO.FileSystemWatcher引发的事件。 使用此 cmdlet，用户可以注册在特定目录下创建文件时要执行的作。 此示例派生自 Microsoft.PowerShell.Commands.ObjectEventRegistrationBase 基类。
如何使用 Visual Studio 生成示例
安装 Windows PowerShell 2.0 SDK 后，导航到 Events01 文件夹。 默认位置为
C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0\Samples\sysmgmt\WindowsPowerShell\csharp\Events01。双击解决方案（.sln）文件的图标。 这将在 Visual Studio 中打开示例项目Microsoft。
在 生成 菜单中，选择 “生成解决方案”，以在默认
\bin或\bin\debug文件夹中为示例生成库。
如何运行示例
创建以下模块文件夹：
[user]\Documents\WindowsPowerShell\Modules\events01将示例的库文件复制到模块文件夹。
启动 Windows PowerShell。
运行以下命令，将 cmdlet 加载到 Windows PowerShell 中：
Import-Module events01使用 Register-FileSystemEvent cmdlet 注册在 TEMP 目录下创建文件时将写入消息的作。
Register-FileSystemEvent $Env:TEMP Created -Filter "*.txt" -Action { Write-Host "A file was created in the TEMP directory" }在 TEMP 目录下创建一个文件，并注意该作已执行（显示消息）。
这是一个示例输出，通过执行以下步骤来生成。
Id Name State HasMoreData Location Command
-- ---- ----- ----------- -------- -------
1 26932870-d3b... NotStarted False Write-Host "A f...
Set-Content $Env:TEMP\test.txt "This is a test file"
A file was created in the TEMP directory
要求
此示例需要 Windows PowerShell 2.0。
演示
此示例演示了以下内容。
如何编写用于事件注册的 cmdlet
该 cmdlet 派生自 Microsoft.PowerShell.Commands.ObjectEventRegistrationBase 类，该类为 Register-*Event cmdlet 通用的参数提供支持。 派生自 Microsoft.PowerShell.Commands.ObjectEventRegistrationBase 的 Cmdlet 只需定义其特定参数并重写 GetSourceObject 和 GetSourceObjectEventName 抽象方法。
示例
此示例演示如何注册 System.IO.FileSystemWatcher引发的事件。
namespace Sample
{
using System;
using System.IO;
using System.Management.Automation;
using System.Management.Automation.Runspaces;
using Microsoft.PowerShell.Commands;
[Cmdlet(VerbsLifecycle.Register, "FileSystemEvent")]
public class RegisterObjectEventCommand : ObjectEventRegistrationBase
{
/// <summary>The FileSystemWatcher that exposes the events.</summary>
private FileSystemWatcher fileSystemWatcher = new FileSystemWatcher();
/// <summary>Name of the event to which the cmdlet registers.</summary>
private string eventName = null;
/// <summary>
/// Gets or sets the path that will be monitored by the FileSystemWatcher.
/// </summary>
[Parameter(Mandatory = true, Position = 0)]
public string Path
{
get
{
return this.fileSystemWatcher.Path;
}
set
{
this.fileSystemWatcher.Path = value;
}
}
/// <summary>
/// Gets or sets the name of the event to which the cmdlet registers.
/// <para>
/// Currently System.IO.FileSystemWatcher exposes 6 events: Changed, Created,
/// Deleted, Disposed, Error, and Renamed. Check the documentation of
/// FileSystemWatcher for details on each event.
/// </para>
/// </summary>
[Parameter(Mandatory = true, Position = 1)]
public string EventName
{
get
{
return this.eventName;
}
set
{
this.eventName = value;
}
}
/// <summary>
/// Gets or sets the filter that will be user by the FileSystemWatcher.
/// </summary>
[Parameter(Mandatory = false)]
public string Filter
{
get
{
return this.fileSystemWatcher.Filter;
}
set
{
this.fileSystemWatcher.Filter = value;
}
}
/// <summary>
/// Derived classes must implement this method to return the object that generates
/// the events to be monitored.
/// </summary>
/// <returns> This sample returns an instance of System.IO.FileSystemWatcher</returns>
protected override object GetSourceObject()
{
return this.fileSystemWatcher;
}
/// <summary>
/// Derived classes must implement this method to return the name of the event to
/// be monitored. This event must be exposed by the input object.
/// </summary>
/// <returns> This sample returns the event specified by the user with the -EventName parameter.</returns>
protected override string GetSourceObjectEventName()
{
return this.eventName;
}
}
}
