WF从入门到精通（第十三章）：打造自定义活动（二）

WF从入门到精通（第十三章）：打造自定义活动（二）2010-06-03 cnblogs GuoYong.CheFtpGetFileActivity类
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Net;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Workflow.ComponentModel;
using System.Workflow.ComponentModel.Compiler;
using System.Workflow.ComponentModel.Design;
using System.Workflow.Activities;
using System.Drawing;
namespace FtpActivity
{
  [Designer（typeof（FtpGetFileActivityDesigner）, typeof（IDesigner））]
  [ToolboxBitmap（typeof（FtpGetFileActivity）, "FtpImage.bmp"）]
  [ToolboxItem（typeof（FtpGetFileActivityToolboxItem））]
  [ActivityValidator（typeof（FtpGetFileActivityValidator））]
  public sealed class FtpGetFileActivity : System.Workflow.ComponentModel.Activity
  {
    public static DependencyProperty FtpUrlProperty = DependencyProperty.Register（"FtpUrl", typeof（System.String）, typeof（FtpGetFileActivity））;
    [Description（"Please provide the full URL for the file to download."）]
    [DesignerSerializationVisibility（DesignerSerializationVisibility.Visible）]
    [ValidationOption（ValidationOption.Required）]
    [Browsable（true）]
    [Category（"FTP Parameters"）]
    public string FtpUrl
    {
      get
      {
        return （（string）（base.GetValue（FtpGetFileActivity.FtpUrlProperty）））;
      }
      set
      {
        Uri tempUri = null;
        if （Uri.TryCreate（value, UriKind.Absolute, out tempUri））
        {
          if （tempUri.Scheme == Uri.UriSchemeFtp）
          {
            base.SetValue（FtpGetFileActivity.FtpUrlProperty, tempUri.AbsoluteUri）;
          }
        }
        else
        {
          // Not a valid FTP URI
          throw new ArgumentException（"The value assigned to the FtpUrl property is not a valid FTP URI."）;
        }
      }
    }
    public static DependencyProperty FtpUserProperty = DependencyProperty.Register（"FtpUser", typeof（System.String）, typeof（FtpGetFileActivity））;
    [Description（"Please provide the FTP user account name."）]
    [DesignerSerializationVisibility（DesignerSerializationVisibility.Visible）]
    [ValidationOption（ValidationOption.Optional）]
    [Browsable（true）]
    [Category（"FTP Parameters"）]
    public string FtpUser
    {
      get
      {
        return （（string）（base.GetValue（FtpGetFileActivity.FtpUserProperty）））;
      }
      set
      {
        base.SetValue（FtpGetFileActivity.FtpUserProperty, value）;
      }
    }
    public static DependencyProperty FtpPasswordProperty = DependencyProperty.Register（"FtpPassword", typeof（System.String）, typeof（FtpGetFileActivity））;
    [Description（"Please provide the FTP user account password."）]
    [DesignerSerializationVisibility（DesignerSerializationVisibility.Visible）]
    [ValidationOption（ValidationOption.Optional）]
    [Browsable（true）]
    [Category（"FTP Parameters"）]
    public string FtpPassword
    {
      get
      {
        return （（string）（base.GetValue（FtpGetFileActivity.FtpPasswordProperty）））;
      }
      set
      {
        base.SetValue（FtpGetFileActivity.FtpPasswordProperty, value）;
      }
    }
    private const string AnonymousUser = "anonymous";
    private const string AnonymousPassword = "someone@example.com";
     protected override ActivityExecutionStatus Execute（
      ActivityExecutionContext executionContext）
    {
      // Retrieve the file.
      GetFile（）;
      // Work complete, so close.
      return ActivityExecutionStatus.Closed;
    }
    private void GetFile（）
    {
      // Create the Uri. We check the validity again
      // even though we checked it in the property
      // setter since binding may have taken place.
      // Binding shoots the new value directly to the
      // dependency property, skipping our local
      // getter/setter logic. Note that if the URL
      // is very malformed, the Uri constructor will
      // throw.
      Uri requestUri = new Uri（FtpUrl）;
      if （requestUri.Scheme ！= Uri.UriSchemeFtp）
      {
        // Not a valid FTP URI
        throw new ArgumentException（"The value assigned to the FtpUrl property is not a valid FTP URI."）;
      } // if
      string fileName =
        Path.GetFileName（requestUri.AbsolutePath）;
      if （String.IsNullOrEmpty（fileName））
      {
        // No file to retrieve.
        return;
      } // if
      Stream bitStream = null;
      FileStream fileStream = null;
      StreamReader reader = null;
      try
      {
        // Open the connection
        FtpWebRequest request =
          （FtpWebRequest）WebRequest.Create（requestUri）;
        // Establish the authentication credentials
        if （！String.IsNullOrEmpty（FtpUser））
        {
          request.Credentials =
            new NetworkCredential（FtpUser, FtpPassword）;
        } // if
        else
        {
          request.Credentials =
            new NetworkCredential（AnonymousUser,
            ！String.IsNullOrEmpty（FtpPassword） ？
            FtpPassword : AnonymousPassword）;
        } // else
        // Make the request and retrieve response stream
        FtpWebResponse response =
          （FtpWebResponse）request.GetResponse（）;
        bitStream = response.GetResponseStream（）;
        // Create the local file
        fileStream = File.Create（fileName）;
        // Read the stream, dumping bits into local file
        byte[] buffer = new byte[1024];
        Int32 bytesRead = 0;
        while （（bytesRead = bitStream.Read（buffer, 0, buffer.Length）） > 0）
        {
          fileStream.Write（buffer, 0, bytesRead）;
        } // while
      } // try
      finally
      {
        // Close the response stream
        if （reader ！= null） reader.Close（）;
        else if （bitStream ！= null） bitStream.Close（）;
        // Close the file
        if （fileStream ！= null） fileStream.Close（）;
      } // finally
    }
  }
}
其中接下来要做的一个更重要的事情是创建一个自定义验证器。尽管你可以使用该FTP活动了，因为它现在已经存在，但此时它是不完整的引入到工作流视图设计器中的。它所缺少的是属性验证。我们就来看看怎样添加一个验证器。