一、业务需求

    目前使用DevExpress控件开发的项目中，需要对表格（GirdView）的指定列或多列内容进行转为百分比显示（比如：将0.39转为39%以此类推）。

二、需求分析

实现对表格列的内容转为百分比有3种思路：

①直接对指定列的数据进行百分比处理，即（获取到指定列的数据，然后乘以100在添加百分比（%）符号）；

②直接使用GridView自带的【DisplayFormat.FormatString】内容进行设置进行百分比显示（P2表示保留小数点后2位的百分比【比如：0.3956转为39.56%】）；

③直接给数字后面添加百分比符号（比如：39转为39%）

三、实现方法

这里以使用GridView自带的【DisplayFormat.FormatString】内容进行设置进行百分比显示和直接给数字后面添加百分比符号（比如：39转为39%）进行实现说明：

3.1、必须先将需要转为百分比的列值转为数字格式

注意：转换格式方法必须在dataTable数据附值前

            //设置列数据类型为double
            dt.Columns[列名称].DataType = typeof(数据类型);

            //比如：设置线宽数据类型为double
            dt.Columns["TRIAL_LINEWIDTH"].DataType = typeof(double);

3.2、转换指定列或多列为百分比的代码

        /// <summary>
        /// 设置表格所有单元格都保留2位小数
        /// </summary>
        /// <param name="gridView">gridView组件</param>
        public static void ResreserveTwoBit(GridView gridView)
        {
            if (gridView != null && gridView.Columns.Count > 0)
            {
                int count = gridView.Columns.Count;
                for (int i = 0; i < count; i++)
                {
                    gridView.Columns[i].DisplayFormat.FormatType = FormatType.Numeric;
                    gridView.Columns[i].DisplayFormat.FormatString = "F2";

                }
            }
        }

        /// <summary>
        /// 设置表格指定单元格都保留2位小数
        /// </summary>
        /// <param name="gridView">gridView组件</param>
        /// <param name="startColumnIndex">开始列索引</param>
        /// <param name="endColumnIndex">结束列索引</param>
        public static void ResreserveTwoBit(GridView gridView, int startColumnIndex, int endColumnIndex)
        {
            if (gridView != null && gridView.Columns.Count > 0 &&
                startColumnIndex > 0 && endColumnIndex > 0 &&
                endColumnIndex <= gridView.Columns.Count)
            {
                //int count = gridView.Columns.Count;
                for (int i = startColumnIndex; i <= endColumnIndex; i++)
                {
                    gridView.Columns[i].DisplayFormat.FormatType = FormatType.Numeric;
                    gridView.Columns[i].DisplayFormat.FormatString = "F2";

                }
            }
        }

        /// <summary>
        /// 设置表格指定单元格都保留2位小数
        /// </summary>
        /// <param name="gridView">gridView组件</param>
        /// <param name="startColumnIndex">开始列索引</param>
        /// <param name="endColumnIndex">结束列索引</param>
        public static void ResreserveTwoBit(GridView gridView, string columnName)
        {
            if (gridView != null && gridView.Columns.Count > 0 && !string.IsNullOrEmpty(columnName))
            {
                gridView.Columns[columnName].DisplayFormat.FormatType = FormatType.Numeric;
                gridView.Columns[columnName].DisplayFormat.FormatString = "F2";
            }
        }

        /// <summary>
        /// 设置表格指定单元格都使用百分比
        /// </summary>
        /// <param name="gridView">gridView组件</param>
        /// <param name="startColumnIndex">开始列索引</param>
        /// <param name="endColumnIndex">结束列索引</param>
        public static void SetPercentage(GridView gridView, int startColumnIndex, int endColumnIndex)
        {
            if (gridView != null && gridView.Columns.Count > 0 &&
                startColumnIndex > 0 && endColumnIndex > 0 &&
                endColumnIndex <= gridView.Columns.Count)
            {
                //int count = gridView.Columns.Count;
                for (int i = startColumnIndex; i <= endColumnIndex; i++)
                {
                    gridView.Columns[i].DisplayFormat.FormatType = FormatType.Numeric;
                    gridView.Columns[i].DisplayFormat.FormatString = "P2";

                }
            }
        }

        /// <summary>
        /// 设置表格指定单元格都使用百分比
        /// </summary>
        /// <param name="gridView">gridView组件</param>
        /// <param name="columnName">列名称</param>
        public static void SetPercentage(GridView gridView, string columnName)
        {
            if (gridView != null && gridView.Columns.Count > 0 && !string.IsNullOrEmpty(columnName))
            {
                gridView.Columns[columnName].DisplayFormat.FormatType= FormatType.Numeric;
                gridView.Columns[columnName].DisplayFormat.FormatString = "P2";
            }
        }

        /// <summary>
        /// 设置表格指定单元格都使用百分比
        /// </summary>
        /// <param name="gridView">gridView组件</param>
        /// <param name="columnName">列名称</param>
        /// <param name="keepDecimalPlaces">保留的小数位数（默认保留2位）</param>
        public static void SetPercentage(GridView gridView, string columnName,string keepDecimalPlaces="P2")
        {
            if (gridView != null && gridView.Columns.Count > 0 && !string.IsNullOrEmpty(columnName) && !string.IsNullOrEmpty(keepDecimalPlaces))
            {
                gridView.Columns[columnName].DisplayFormat.FormatType = FormatType.Numeric;
                gridView.Columns[columnName].DisplayFormat.FormatString = keepDecimalPlaces;
            }
        }

        /// <summary>
        /// 给表格指定单元格都保留2位小数后添加%号
        /// </summary>
        /// <param name="gridView"></param>
        /// <param name="startColumnIndex"></param>
        /// <param name="endColumnIndex"></param>
        public static void SetResreserveTwoBitAndPercentageChar(GridView gridView, int startColumnIndex, int endColumnIndex)
        {
            if (gridView != null && gridView.Columns.Count > 0 &&
               startColumnIndex > 0 && endColumnIndex > 0 &&
               endColumnIndex <= gridView.Columns.Count)
            {
                for (int i = startColumnIndex; i <= endColumnIndex; i++)
                {
                    gridView.Columns[i].DisplayFormat.FormatType = FormatType.Numeric;
                    gridView.Columns[i].DisplayFormat.FormatString = $"{0:N2}'%'";

                }
            }
        }

        /// <summary>
        /// 给表格指定单元格都保留2位小数后添加%号
        /// </summary>
        /// <param name="gridView"></param>
        /// <param name="columnName">列名称</param>
        public static void SetResreserveTwoBitAndPercentageChar(GridView gridView, string columnName)
        {
            if (gridView != null && gridView.Columns.Count > 0 && !string.IsNullOrEmpty(columnName))
            {
                gridView.Columns[columnName].DisplayFormat.FormatType = FormatType.Numeric;
                gridView.Columns[columnName].DisplayFormat.FormatString = $"{0:N2}'%'";
            }
        }

        /// <summary>
        /// 给表格指定单元格都添加%符号，不做运算
        /// </summary>
        /// <param name="gridView"></param>
        /// <param name="columnName"></param>
        public static void SetPercentageChar(GridView gridView, string columnName)
        {
            if (gridView != null && gridView.Columns.Count > 0 && !string.IsNullOrEmpty(columnName))
            {
                gridView.Columns[columnName].DisplayFormat.FormatType = FormatType.Numeric;
                gridView.Columns[columnName].DisplayFormat.FormatString = $"{0}'%'";
            }
        }