C# json Helper

using System;
using System.Collections.Generic;
using System.Data;
using System.Text;

namespace Common
{
public class JsonHelper
{

/// <summary>
/// DataTable 转 Json
/// </summary>
/// <param name="dt">DataTable</param>
/// <param name="fromCount">来自的行数</param>
/// <param name="totalCountStr">总行数</param>
/// <param name="tbname">表名</param>
/// <returns></returns>
public static string DT2JSON(DataTable dt, string tbname)
{
StringBuilder jsonBuilder = new StringBuilder();
jsonBuilder.Append("{\"" + tbname + "\":[");
for (int i = 0; i < dt.Rows.Count; i++)
{
if (i > 0)
jsonBuilder.Append(",");
jsonBuilder.Append("{");
jsonBuilder.Append("\"no\":\"" + i + "\",");
for (int j = 0; j < dt.Columns.Count; j++)
{
if (j > 0)
jsonBuilder.Append(",");
if (dt.Columns[j].DataType.Equals(typeof(DateTime)) && dt.Rows[i][j].ToString() != "")
jsonBuilder.Append("\"" + dt.Columns[j].ColumnName.ToLower() + "\": \"" + Convert.ToDateTime(dt.Rows[i][j].ToString()).ToString("yyyy-MM-dd HH:mm:ss") + "\"");
else if (dt.Columns[j].DataType.Equals(typeof(String)))
jsonBuilder.Append("\"" + dt.Columns[j].ColumnName.ToLower() + "\": \"" + dt.Rows[i][j].ToString().Replace("\\", "\\\\").Replace("\'", "\\\'").Replace("\t", " ").Replace("\r", " ").Replace("\n", "<br/>") + "\"");
else
jsonBuilder.Append("\"" + dt.Columns[j].ColumnName.ToLower() + "\": \"" + dt.Rows[i][j].ToString() + "\"");
}
jsonBuilder.Append("}");
}
jsonBuilder.Append("]}");
return jsonBuilder.ToString();

}
}
}