同事写的，收录一下，方法如下：

    /// <summary>
    /// 防止重复提交
    /// </summary>
    /// <param name="imaButtons">按键集合</param>
    /// <param name="clientID">页面有JS验证的组件</param>
    public void RepeatSubmitCheckForRC( List<ImageButton> imaButtons)
    {
        foreach (ImageButton button in imaButtons)
        {
            StringBuilder sb = new StringBuilder();
            sb.Append("if (typeof(Page_ClientValidate) == 'function') { if (Page_ClientValidate() == false) { return false; }};");
            if (button.ID != "saveButton")
            {
                sb.Append("if(!contentRequiredValidator()){return false};");//富文本编辑为空验证
            }
            sb.Append("this.disabled  = true;");
            sb.Append(this.Page.ClientScript.GetPostBackEventReference(button, ""));
            sb.Append(";");
            button.Attributes.Add("onclick", sb.ToString());
        }
    }

调用方法的时候

        List<ImageButton> imaButtons = new List<ImageButton>();
        imaButtons.Add(sumbitButton);
        imaButtons.Add(saveButton);
        RepeatSubmitCheckForRC(imaButtons);