基于ASP.NET AJAX的WebPart开发与部署(2)

　 using System;
using System.Collections.Generic;
using System.Text;
using System.Web;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Serialization;
using System.Web.UI;
using Microsoft.SharePoint.WebPartPages;
using Microsoft.SharePoint.Utilities;
using System.Web.UI.WebControls;
using System.Drawing;
下面是AjaxBaseWebPart类的实现部分：
　 /// <summary>
/// A base class that implements all the functionality required to use ASP.net Ajax extensions inside WSS
/// </summary>
[XmlRoot(Namespace = "Deps.AjaxBaseWebpart")]
public abstract class AjaxBaseWebpart : Microsoft.SharePoint.WebPartPages.WebPart
{
/*
* The idea and the code behind this base web part was taken from Erics blog post at:
* http://www.capdes.com/2007/02/ajaxbasepart_easy_aspnet_20_aj.html
* This basically manages the presence and configuration of the ScriptManager
* which is required by ASP.net ajax extensions to handle postbacks, ect. This web part also includes
* a common method for handling errors.
*/
#region Declarations
private string _ValidationGroupId;
private ValidationSummary _ErrorContainer;
private ScriptManager _AjaxManager;
#endregion

#region Constructor
public AjaxBaseWebpart()
{

}
#endregion

#region Methods
/// <summary>
/// Used to provide a common way to display errors to the user of the current web part.
/// </summary>
/// <param name="message">Description of the error that occured.</param>
public void RegisterError(string message)
{
if (this.Controls.Contains(_ErrorContainer))
{
//this way of generating a unique control id is used in some of the OOB web parts
int uniqueCounter;
if (HttpContext.Current.Items["GetUniqueControlId"] != null)
{
uniqueCounter = (int)HttpContext.Current.Items["GetUniqueControlId"];
}
else
{
uniqueCounter = 0;
}
uniqueCounter++;
HttpContext.Current.Items["GetUniqueControlId"] = uniqueCounter;

//create a custom validator to register the current error message with the ValidationSummary control
CustomValidator cv = new CustomValidator();
cv.ID = string.Concat("_Error_", uniqueCounter);
cv.ValidationGroup = _ValidationGroupId;
cv.Display = ValidatorDisplay.None;
cv.IsValid = false;
cv.ErrorMessage = message;

this.Controls.Add(cv);
}
else
{
//if RegisterError is called before the CreateChildControls override in AjaxBasePart then transfer the user to an error page using the SPUtility
SPUtility.TransferToErrorPage("The CreateChildControls function of the AjaxBasePart has not been called. You probably need to add \"base.CreateChildControls()\" to the top of your CreateChildControls override.");
}
}
/// <summary>
/// Needs to be called to ensure that the ValidationSummary control is registered on the page. Any child web parts will need to have base.CreateChildControls() at the top of their own CreateChildControls override.
/// </summary>
protected override void CreateChildControls()
{
base.CreateChildControls();

if (!this.Controls.Contains(_ErrorContainer))
{
_ValidationGroupId = Guid.NewGuid().ToString();

_ErrorContainer = new ValidationSummary();
_ErrorContainer.ID = "_ErrorContainer";
_ErrorContainer.ValidationGroup = _ValidationGroupId;
_ErrorContainer.BorderStyle = BorderStyle.Solid;
_ErrorContainer.BorderWidth = Unit.Pixel(3);
_ErrorContainer.BorderColor = Color.Red;

this.Controls.Add(_ErrorContainer);
}
}
#endregion

#region Events
/// <summary>
/// Oninit fires before page load. Modifications to the page that are necessary to support Ajax are done here.
/// </summary>
protected override void OnInit(EventArgs e)
{
base.OnInit(e);

//get the existing ScriptManager if it exists on the page
_AjaxManager = ScriptManager.GetCurrent(this.Page);

if (_AjaxManager == null)
{
//create new ScriptManager and EnablePartialRendering
_AjaxManager = new ScriptManager();
_AjaxManager.EnablePartialRendering = true;

// Fix problem with postbacks and form actions (DevDiv 55525)
Page.ClientScript.RegisterStartupScript(typeof(AjaxBaseWebpart), this.ID, "_spOriginalFormAction = document.forms[0].action;", true);

//tag:"form" att:"onsubmit" val:"return _spFormOnSubmitWrapper()" blocks async postbacks after the first one
//not calling "_spFormOnSubmitWrapper()" breaks all postbacks
//returning true all the time, somewhat defeats the purpose of the _spFormOnSubmitWrapper() which is to block repetitive postbacks, but it allows MS AJAX Extensions to work properly
//its a hack that hopefully has minimal effect
if (this.Page.Form != null)
{
string formOnSubmitAtt = this.Page.Form.Attributes["onsubmit"];
if (!string.IsNullOrEmpty(formOnSubmitAtt) && formOnSubmitAtt == "return _spFormOnSubmitWrapper();")
{
this.Page.Form.Attributes["onsubmit"] = "_spFormOnSubmitWrapper();";
}

//add the ScriptManager as the first control in the Page.Form
//I don't think this actually matters, but I did it to be consistent with how you are supposed to place the ScriptManager when used declaritevly
this.Page.Form.Controls.AddAt(0, _AjaxManager);
}
}
}
#endregion

#region Properties
/// <summary>
/// Exposes the Page's script manager. The value is not set until after OnInit
/// </summary>
[WebPartStorage(Storage.None)]
public ScriptManager AjaxManager
{
get { return _AjaxManager; }
set { _AjaxManager = value; }
}
#endregion
}