c#写的操作JSON的类

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

namespace ZGZY.Common
{
    /// <summary>
    /// JSON帮助类
    /// </summary>
    public class JsonHelper
    {
        #region 通用方法
        /// <summary>
        /// 格式化字符型、日期型、布尔型
        /// </summary>
        public static string StringFormat(string str, Type type)
        {
            if (type == typeof(string))
            {
                str = StringFilter(str);
                str = "\"" + str + "\"";
            }
            else if (type == typeof(DateTime) || type == typeof(DateTime?))
            {
                str = "\"" + str + "\"";
            }

            else if (type == typeof(bool))
            {
                str = str.ToLower();
            }
            else if (type == typeof(Guid))
            {
                str = "\"" + str + "\"";
            }
            else if (type != typeof(string) && string.IsNullOrEmpty(str))
            {
                str = "\"" + str + "\"";
            }
            return str;
        }

        /// <summary>
        /// 过滤字符串
        /// </summary>
        public static string StringFilter(string str)
        {
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < str.Length; i++)
            {
                char c = str.ToCharArray()[i];
                switch (c)
                {
                    case '\"':
                        sb.Append("\\\""); break;
                    case '\\':
                        sb.Append("\\\\"); break;