在我的ASP.NET网络表单中，说我有类似的东西：
<asp:Literal ID="Literal1" runat="server" Text="abc"></asp:Literal>
现在说我改变后面代码中的文本。该控件已启用viewstate，因此新文本值在整个回发过程中持续存在，这正是我想要的。但在某些情况下，我想将控件重置回原始值（即“abc”），而不必在后面的代码中对其进行硬编码。因此，在不禁用viewstate的情况下，有没有什么方法可以检索控件在首次加载屏幕时的原始值？
由于
答案 0 :(得分：0)
我不知道如何使用viewstate。但您可以为站点创建一个基页，其中包含跟踪更改的选项，并在加载页面时存储默认值。还有一个班级来做实际的检查。
例如：
更改跟踪器：
/// <summary>
/// Class to Track changes in a web page
/// </summary>
[Serializable]
public class ChangeTracker : IDisposable
{
//- MEMBER VARIABLES --------------------------------------------------------------------------------------------------------
#region Members
private bool m_ChangesMade = false;
private Dictionary<string, object> m_OriginalValues = new Dictionary<string, object>();
private Dictionary<string, object> m_ChangedValues = new Dictionary<string, object>();
private List<string> m_ControlsToIgnore = new List<string>();
#endregion Members
//- PROPERTIES --------------------------------------------------------------------------------------------------------------
#region Properties
/// <summary>
/// Gets or Sets the Controls to Ignore (ClientID array)
/// </summary>
public List<string> ControlsToIgnore
{
get { return m_ControlsToIgnore; }
set { m_ControlsToIgnore = value; }
}
/// <summary>
/// Gets or Sets the Dictionay of Changed Values
/// </summary>
public Dictionary<string, object> ChangedValues
{
get { return m_ChangedValues; }
set { m_ChangedValues = value; }
}
/// <summary>
/// Gets or Sets the Dictionay of Original Values
/// </summary>
public Dictionary<string, object> OriginalValues
{
get { return m_OriginalValues; }
set { m_OriginalValues = value; }
}
/// <summary>
/// Gets or Sets Whether changes have been made to the control collection
/// </summary>
public bool ChangesMade
{
get
{
try
{
return m_ChangesMade;
}
catch (Exception)
{
throw;
}
}
set { m_ChangesMade = value; }
}
#endregion Properties
#region Constructor
/// <summary>
/// Constructor (required for serialization)
/// </summary>
public ChangeTracker()
{
}
#endregion Constructor
#region Methods
/// <summary>
/// Adds all relivant controls recursively to the list
/// </summary>
/// <param name="oControl">The control to add</param>
private void AddControls(Control oControl)
{
try
{
if (oControl != null)
{
//Check whether the control shoudl be ignored
if (!this.ControlsToIgnore.Contains(oControl.ClientID))
{
//loop recursively
foreach (Control aControl in oControl.Controls)
{
this.AddControls(aControl);
}
if (oControl is IEditableTextControl)
{
if (this.OriginalValues.ContainsKey(oControl.ClientID))
{
this.OriginalValues[oControl.ClientID] = (oControl as IEditableTextControl).Text;
}
else
{
this.OriginalValues.Add(oControl.ClientID, (oControl as IEditableTextControl).Text);
}
}
if (oControl is ICheckBoxControl)
{
if (this.OriginalValues.ContainsKey(oControl.ClientID))
{
this.OriginalValues[oControl.ClientID] = (oControl as ICheckBoxControl).Checked;
}
else
{
this.OriginalValues.Add(oControl.ClientID, (oControl as ICheckBoxControl).Checked);
}
}
}
}
else
{
throw new ArgumentNullException("oControl");
}
}
catch (Exception)
{
throw;
}
}
/// <summary>
/// Checks the controls for changes
/// </summary>
/// <param name="oControl">The control to check</param>
private void CheckControl(Control oControl)
{
try
{
//Check the control should not be ignored
if (!this.ControlsToIgnore.Contains(oControl.ClientID))
{
//loop recursively
foreach (Control aControl in oControl.Controls)
{
this.CheckControl(aControl);
}
if (oControl is IEditableTextControl)
{
if (this.OriginalValues.ContainsKey(oControl.ClientID))
{
if (this.OriginalValues[oControl.ClientID].ToString() != (oControl as IEditableTextControl).Text)
{
if (!this.ChangedValues.ContainsKey(oControl.ClientID))
{
this.ChangedValues.Add(oControl.ClientID, (oControl as IEditableTextControl).Text);
}
else
{
this.ChangedValues[oControl.ClientID] = (oControl as IEditableTextControl).Text;
}
this.ChangesMade = true;
}
}
}
if (oControl is ICheckBoxControl)
{
if (this.OriginalValues.ContainsKey(oControl.ClientID))
{
if ((bool)this.OriginalValues[oControl.ClientID] != (oControl as ICheckBoxControl).Checked)
{
if (!this.ChangedValues.ContainsKey(oControl.ClientID))
{
this.ChangedValues.Add(oControl.ClientID, (oControl as ICheckBoxControl).Checked);
}
else
{
this.ChangedValues[oControl.ClientID] = (oControl as ICheckBoxControl).Checked;
}
this.ChangesMade = true;
}
}
}
}
}
catch (Exception)
{
throw;
}
}
/// <summary>
/// Stores the default values
/// </summary>
///<param name="oControl">The control to store</param>
public void StoreDefaultValues(Control oControl)
{
try
{
//Reset the Original Values collection
this.OriginalValues = new Dictionary<string, object>();
this.ChangesMade = false;
//Add all relevant controls
this.AddControls(oControl);
}
catch (Exception)
{
throw;
}
}
/// <summary>
/// Checks the form for changes
/// </summary>
///<param name="oControl">The control to check for changes</param>
public void CheckForChanges(Control oControl)
{
try
{
//Instantiate changed values
this.ChangedValues = new Dictionary<string, object>();
//Reset changes made flag
this.ChangesMade = false;
//Check controls for changes
this.CheckControl(oControl);
}
catch (Exception)
{
throw;
}
}
/// <summary>
/// Dispose of the object
/// </summary>
public void Dispose()
{
try
{
m_ChangedValues = null;
m_ControlsToIgnore = null;
m_OriginalValues = null;
}
catch (Exception)
{
throw;
}
}
#endregion Methods
}
基本网页：
/// <summary>
/// Adds Extra functionality to a web page
/// </summary>
public class WebPage : System.Web.UI.Page
{
#region Properties
/// <summary>
/// Gets or Sets the Change Tracker
/// </summary>
protected ChangeTracker ChangeTracker
{
get
{
if (Session[String.Format("ChangeTracker{0}", this.ClientID)] == null)
{
Session[String.Format("ChangeTracker{0}", this.ClientID)] = new ChangeTracker();
}
return Session[String.Format("ChangeTracker{0}", this.ClientID)] as ChangeTracker;
}
set
{
Session[String.Format("ChangeTracker{0}", this.ClientID)] = value;
}
}
/// <summary>
/// Gets or Sets whether changes have been made
/// </summary>
protected bool ChangesTracked
{
get
{
if (ViewState["ChangesTracked"] == null)
{
ViewState["ChangesTracked"] = false;
}
return (bool)ViewState["ChangesTracked"];
}
set
{
ViewState["ChangesTracked"] = value;
}
}
#endregion Properties
#region Events
/// <summary>
/// Stores the value of the controls after the load completes
/// </summary>
/// <param name="e">order</param>
protected override void OnLoadComplete(EventArgs e)
{
try
{
base.OnLoadComplete(e);
//Dont store on postback
if (!Page.IsPostBack)
{
//Check whether to track changes
if (this.ChangesTracked)
{
//Store the default values
this.ChangeTracker.StoreDefaultValues(this);
}
}
}
catch (Exception)
{
throw;
}
}
#endregion Events
}
用法（例如在保存事件上）：
//Check for changes
base.ChangeTracker.CheckForChanges(this);
//If changes have been made, flag as dirty
if (base.ChangeTracker.ChangesMade)
{
//Do stuff
}
正如您所看到的，当页面加载完成时会存储初始值，因此它们都可用于比较，或者在您的情况下，可以重置为原始值。
答案 1 :(得分：0)
您可以尝试使用Page_Init方法从控件中获取文本。视图状态稍后将在页面处理管道中恢复到控制树。因此，如果您访问Page_Init中的文本并将值存储在某个合适的位置，则可以从标记（aspx）文件中获取值。