简陋的会计凭证金额输入控件 [转]

using System;
using System.ComponentModel;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace Voucher
{
    [DefaultProperty("jText")]
    [ToolboxData(@"<{0}:VoucherInput jText = ‘000‘  
    runat=‘server‘></{0}:VoucherInput>")
    ]
    public class VoucherInput : WebControl, INamingContainer
    {
      
        private TextBox _TextBox;

        #region 属性
        [
        Bindable(true),
        Category("Appearance"),
        DefaultValue(""),
        Description("金额")
        ]
        public string jText
        {
            get
            {
                EnsureChildControls();
                return _TextBox.Text;
            }
            set
            {
                EnsureChildControls();
                _TextBox.Text = value;
            }
        }

        #endregion Properties delegated to child controls

        #region 方法
        protected override void CreateChildControls()
        {
            Controls.Clear();
            _TextBox = new TextBox();
            _TextBox.ID = "TextBox1";
            _TextBox.MaxLength = 15;
            _TextBox.Width = 120;
            _TextBox.Height = 20;
            _TextBox.Attributes.Add("onkeypress", "keyPress()");
            _TextBox.Style.Add(HtmlTextWriterStyle.BackgroundImage, "url(Images/text.gif)");
            _TextBox.Style.Add(HtmlTextWriterStyle.Direction, "rtl");
            _TextBox.Style.Add(HtmlTextWriterStyle.BorderWidth, "0");

            this.Controls.Add(_TextBox);

        }

        protected override void Render(HtmlTextWriter writer)
        {
            AddAttributesToRender(writer);
            _TextBox.RenderControl(writer);
            writer.Write("<script language=javascript>function keyPress(){if(!(event.keyCode>=48&&event.keyCode<=57 ||event.keyCode==46||event.keyCode==45)){event.keyCode = 0;}}</script>");
        }
        #endregion Overriden methods

    }
}