ClientID,UniqueID

[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden), WebSysDescription("Control_ClientID"), Browsable(false)]
public virtual string ClientID
{
    get
    {
        this.EnsureID();
        string uniqueID = this.UniqueID;
        if ((uniqueID != null) && (uniqueID.IndexOf(this.IdSeparator) >= 0))
        {
            return uniqueID.Replace(this.IdSeparator, '_');         }
        return uniqueID;
    }
}
 

 //ClientID就是将UniqueID中的IdSeparator （其值为:”$”）替换为”_”。
[Browsable(false), WebSysDescription("Control_UniqueID"), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
public virtual string UniqueID
{
    get
    {
        if (this._cachedUniqueID == null)
        {
            Control namingContainer = this.NamingContainer;
            if (namingContainer == null)
            {
                return this._id;
            }
            if (this._id == null)
            {
                this.GenerateAutomaticID(); 
            }
            if (this.Page == namingContainer)
            {
                this._cachedUniqueID = this._id;
            }
            else
            {
                string uniqueIDPrefix = namingContainer.GetUniqueIDPrefix();
                if (uniqueIDPrefix.Length == 0)
                {
                    return this._id;
                }
                this._cachedUniqueID = uniqueIDPrefix + this._id;
            }
        }
        return this._cachedUniqueID;
    }
}
 如果控件的ID为空,则对控件自动编号this.GenerateAutomaticID();如果当前的控件容器是Page或者为null,则UniqueID就是控件的ID.否则 取得父控件UniqueID+分隔符($)作为当前控件的UniqueID前缀. internal virtual string GetUniqueIDPrefix()
{
    this.EnsureOccasionalFields();
    if (this._occasionalFields.UniqueIDPrefix == null)
    {
        string uniqueID = this.UniqueID;
        if (!string.IsNullOrEmpty(uniqueID))
        {
            this._occasionalFields.UniqueIDPrefix = uniqueID + this.IdSeparator;
        }
        else
        {
            this._occasionalFields.UniqueIDPrefix = string.Empty;
        }
    }
    return this._occasionalFields.UniqueIDPrefix;
}