LINQ返回DataTable类型 list转dataset 转换为JSON对象

using System.Web.Script.Serialization;
using System.Collections.Generic;
using System.Reflection;
using System.Data;
using System;

namespace CommonCode
{
    public class Common
    {
        /// <summary>
        /// LINQ返回DataTable类型
        /// </summary>
        public static DataTable ToDataTable<T>(IEnumerable<T> varlist)
        {
            DataTable dtReturn = new DataTable();
            // column names
            PropertyInfo[] oProps = null;

            if (varlist == null)
                return dtReturn;
            foreach (T rec in varlist)
            {
                if (oProps == null)
                {
                    oProps = ((Type)rec.GetType()).GetProperties();
                    foreach (PropertyInfo pi in oProps)
                    {
                        Type colType = pi.PropertyType;
                        if ((colType.IsGenericType) && (colType.GetGenericTypeDefinition() == typeof(Nullable<>)))
                        {
                            colType = colType.GetGenericArguments()[];
                        }
                        dtReturn.Columns.Add(new DataColumn(pi.Name, colType));
                    }
                }
                DataRow dr = dtReturn.NewRow();
                foreach (PropertyInfo pi in oProps)
                {
                    dr[pi.Name] = pi.GetValue(rec, null) == null ? DBNull.Value : pi.GetValue(rec, null);
                }
                dtReturn.Rows.Add(dr);
            }
            return dtReturn;
        }

        /// <summary>
        /// list转dataset
        /// </summary>
        public static DataSet ConvertToDataSet<T>(IList<T> list)
        {
            if (list == null || list.Count <= )
                return null;
            DataSet ds = new DataSet();
            DataTable dt = new DataTable(typeof(T).Name);
            DataColumn column;
            DataRow row;
            System.Reflection.PropertyInfo[] myPropertyInfo =
                typeof(T).GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance);
            foreach (T t in list)
            {
                if (t == null) continue;
                row = dt.NewRow();

                for (int i = , j = myPropertyInfo.Length; i < j; i++)
                {
                    System.Reflection.PropertyInfo pi = myPropertyInfo[i];
                    String name = pi.Name;

                    if (dt.Columns[name] == null)
                    {
                        if (pi.PropertyType.UnderlyingSystemType.ToString() == "System.Nullable`1[System.Int32]")
                        {
                            column = new DataColumn(name, typeof(Int32));
                            dt.Columns.Add(column);
                            //row[name] = pi.GetValue(t, new object[] {i});//PropertyInfo.GetValue(object,object[])
                            if (pi.GetValue(t, null) != null)
                                row[name] = pi.GetValue(t, null);
                            else
                                row[name] = System.DBNull.Value;
                        }
                        else if (pi.PropertyType.UnderlyingSystemType.ToString() == "System.Nullable`1[System.DateTime]")
                        {
                            column = new DataColumn(name, typeof(DateTime));
                            dt.Columns.Add(column);
                            if (pi.GetValue(t, null) != null)
                                row[name] = pi.GetValue(t, null);
                            else
                                row[name] = System.DBNull.Value;
                        }
                        else
                        {
                            column = new DataColumn(name, pi.PropertyType);
                            dt.Columns.Add(column);
                            row[name] = pi.GetValue(t, null);
                        }
                    }
                }
                dt.Rows.Add(row);
            }
            ds.Tables.Add(dt);
            return ds;
        }
        public delegate object[] CreateRowDelegate<T>(T t);

        public static string Serialize(DataTable dt)
        {
            List<Dictionary<string, object>> list = new List<Dictionary<string, object>>();
            foreach (DataRow dr in dt.Rows)
            {
                Dictionary<string, object> result = new Dictionary<string, object>();
                foreach (DataColumn dc in dt.Columns)
                {
                    result.Add(dc.ColumnName, dr[dc].ToString());
                }
                list.Add(result);
            }
            int count = ;
            try
            {
                count = Convert.ToInt32(dt.TableName);
            }
            catch (System.Exception ex)
            {
                count = dt.Rows.Count;
            }
            string strReturn = "";
            if (count == )
            {
                strReturn = "{\"totalCount\":0,\"data\":[]}";
            }
            else
            {
                strReturn = ConventToJson(list, count);
            }
            return strReturn;
        }

        /// <summary>
        /// 转换为JSON对象
        /// </summary>
        public static string ConventToJson<T>(List<T> list, int count)
        {
            JavaScriptSerializer serializer = new JavaScriptSerializer();
            string strJson = serializer.Serialize(list);
            strJson = strJson.Substring();
            strJson = strJson.Insert(, "{totalCount:" + count + ",data:[");
            strJson += "}";
            return strJson;
        }

        /// <summary>
        /// 不需要分页
        /// </summary>
        public static string Serialize(DataTable dt, bool flag)
        {
            JavaScriptSerializer serializer = new JavaScriptSerializer();
            List<Dictionary<string, object>> list = new List<Dictionary<string, object>>();
            foreach (DataRow dr in dt.Rows)
            {
                Dictionary<string, object> result = new Dictionary<string, object>();
                foreach (DataColumn dc in dt.Columns)
                {
                    result.Add(dc.ColumnName, dr[dc].ToString());
                }
                list.Add(result);
            }
            return serializer.Serialize(list);
        }
    }
}