Convert DataSet, string, DataTable, and objects in C# to Json

/// <summary>
   /// 提供方法将其他类型转换为Json
   /// </summary>
   public static class ConvertToJson
   {

       #region 私有方法
       /// <summary>
       /// 过滤特殊字符
       /// </summary>
       /// <param name="s">字符串</param>
       /// <returns>json字符串</returns>
       private static string String2Json(String s)
       {
           StringBuilder sb = new StringBuilder();
           for (int i = 0; i < s.Length; i++)
           {
               char c = s.ToCharArray()[i];
               switch (c)
               {
                   case &#39;\"&#39;:
                       sb.Append("\\\""); break;
                   case &#39;\\&#39;:
                       sb.Append("\\\\"); break;
                   case &#39;/&#39;:
                       sb.Append("\\/"); break;
                   case &#39;\b&#39;:
                       sb.Append("\\b"); break;
                   case &#39;\f&#39;:
                       sb.Append("\\f"); break;
                   case &#39;\n&#39;:
                       sb.Append("\\n"); break;
                   case &#39;\r&#39;:
                       sb.Append("\\r"); break;
                   case &#39;\t&#39;:
                       sb.Append("\\t"); break;
                   default:
                       sb.Append(c); break;
               }
           }
           return sb.ToString();
       }
       /// <summary>
       /// 格式化字符型、日期型、布尔型
       /// </summary>
       /// <param name="str"></param>
       /// <param name="type"></param>
       /// <returns></returns>
       private static string StringFormat(string str, Type type)
       {
           if (type == typeof(string))
           {
               str = String2Json(str);
               str = "\"" + str + "\"";
           }
           else if (type == typeof(DateTime))
           {
               str = "\"" + str + "\"";
           }
           else if (type == typeof(bool))
           {
               str = str.ToLower();
           }
           else if (type != typeof(string) && string.IsNullOrEmpty(str))
           {
               str = "\"" + str + "\"";
           }
           return str;
       }

       #endregion

       #region list转换成JSON
       /// <summary>
       /// list转换为Json
       /// </summary>
       /// <typeparam name="T"></typeparam>
       /// <param name="list"></param>
       /// <returns></returns>
       public static string ListToJson<T>(IList<T> list)
       {
           object obj = list[0];
           return ListToJson<T>(list, obj.GetType().Name);
       }
       /// <summary>
       /// list转换为json
       /// </summary>
       /// <typeparam name="T"></typeparam>
       /// <param name="list"></param>
       /// <param name="JsonName"></param>
       /// <returns></returns>
       private static string ListToJson<T>(IList<T> list, string JsonName)
       {
           StringBuilder Json = new StringBuilder();
           if (string.IsNullOrEmpty(JsonName))
               JsonName = list[0].GetType().Name;
           Json.Append("{\"" + JsonName + "\":[");
           if (list.Count > 0)
           {
               for (int i = 0; i < list.Count; i++)
               {
                   T obj = Activator.CreateInstance<T>();
                   PropertyInfo[] pi = obj.GetType().GetProperties();
                   Json.Append("{");
                   for (int j = 0; j < pi.Length; j++)
                   {
                       Type type = pi[j].GetValue(list[i], null).GetType();
                       Json.Append("\"" + pi[j].Name.ToString() + "\":" + StringFormat(pi[j].GetValue(list[i], null).ToString(), type));
                       if (j < pi.Length - 1)
                       {
                           Json.Append(",");
                       }
                   }
                   Json.Append("}");
                   if (i < list.Count - 1)
                   {
                       Json.Append(",");
                   }
               }
           }
           Json.Append("]}");
           return Json.ToString();
       }
       #endregion

       #region 对象转换为Json
       /// <summary>
       /// 对象转换为json
       /// </summary>
       /// <param name="jsonObject">json对象</param>
       /// <returns>json字符串</returns>
       public static string ToJson(object jsonObject)
       {
           string jsonString = "{";
           PropertyInfo[] propertyInfo = jsonObject.GetType().GetProperties();
           for (int i = 0; i < propertyInfo.Length; i++)
           {
               object objectValue = propertyInfo[i].GetGetMethod().Invoke(jsonObject, null);
               string value = string.Empty;
               if (objectValue is DateTime || objectValue is Guid || objectValue is TimeSpan)
               {
                   value = "&#39;" + objectValue.ToString() + "&#39;";
               }
               else if (objectValue is string)
               {
                   value = "&#39;" + ToJson(objectValue.ToString()) + "&#39;";
               }
               else if (objectValue is IEnumerable)
               {
                   value = ToJson((IEnumerable)objectValue);
               }
               else
               {
                   value = ToJson(objectValue.ToString());
               }
               jsonString += "\"" + ToJson(propertyInfo[i].Name) + "\":" + value + ",";
           }
           jsonString.Remove(jsonString.Length - 1, jsonString.Length);
           return jsonString + "}";
       }

       #endregion

       #region 对象集合转换为json
       /// <summary>
       /// 对象集合转换为json
       /// </summary>
       /// <param name="array">对象集合</param>
       /// <returns>json字符串</returns>
       public static string ToJson(IEnumerable array)
       {
           string jsonString = "{";
           foreach (object item in array)
           {
               jsonString += ToJson(item) + ",";
           }
           jsonString.Remove(jsonString.Length - 1, jsonString.Length);
           return jsonString + "]";
       }
       #endregion

       #region 普通集合转换Json
       /// <summary>
       /// 普通集合转换Json
       /// </summary>
       /// <param name="array">集合对象</param>
       /// <returns>Json字符串</returns>
       public static string ToArrayString(IEnumerable array)
       {
           string jsonString = "[";
           foreach (object item in array)
           {
               jsonString = ToJson(item.ToString()) + ",";
           }
           jsonString.Remove(jsonString.Length - 1, jsonString.Length);
           return jsonString + "]";
       }
       #endregion

       #region  DataSet转换为Json
       /// <summary>
       /// DataSet转换为Json
       /// </summary>
       /// <param name="dataSet">DataSet对象</param>
       /// <returns>Json字符串</returns>
       public static string ToJson(DataSet dataSet)
       {
           string jsonString = "{";
           foreach (DataTable table in dataSet.Tables)
           {
               jsonString += "\"" + table.TableName + "\":" + ToJson(table) + ",";
           }
           jsonString = jsonString.TrimEnd(&#39;,&#39;);
           return jsonString + "}";
       }
       #endregion

       #region Datatable转换为Json
       /// <summary>
       /// Datatable转换为Json
       /// </summary>
       /// <param name="dt">Datatable对象</param>
       /// <returns>Json字符串</returns>
       public static string ToJson(DataTable dt)
       {
           StringBuilder jsonString = new StringBuilder();
           jsonString.Append("[");
           DataRowCollection drc = dt.Rows;
           for (int i = 0; i < drc.Count; i++)
           {
               jsonString.Append("{");
               for (int j = 0; j < dt.Columns.Count; j++)
               {
                   string strKey = dt.Columns[j].ColumnName;
                   string strValue = drc[i][j].ToString();
                   Type type = dt.Columns[j].DataType;
                   jsonString.Append("\"" + strKey + "\":");
                   strValue = StringFormat(strValue, type);
                   if (j < dt.Columns.Count - 1)
                   {
                       jsonString.Append(strValue + ",");
                   }
                   else
                   {
                       jsonString.Append(strValue);
                   }
               }
               jsonString.Append("},");
           }
           jsonString.Remove(jsonString.Length - 1, 1);
           jsonString.Append("]");
           return jsonString.ToString();
       }
       /// <summary>
       /// DataTable转换为Json
       /// </summary>
       public static string ToJson(DataTable dt, string jsonName)
       {
           StringBuilder Json = new StringBuilder();
           if (string.IsNullOrEmpty(jsonName))
               jsonName = dt.TableName;
           Json.Append("{\"" + jsonName + "\":[");
           if (dt.Rows.Count > 0)
           {
               for (int i = 0; i < dt.Rows.Count; i++)
               {
                   Json.Append("{");
                   for (int j = 0; j < dt.Columns.Count; j++)
                   {
                       Type type = dt.Rows[i][j].GetType();
                       Json.Append("\"" + dt.Columns[j].ColumnName.ToString() + "\":" + StringFormat(dt.Rows[i][j].ToString(), type));
                       if (j < dt.Columns.Count - 1)
                       {
                           Json.Append(",");
                       }
                   }
                   Json.Append("}");
                   if (i < dt.Rows.Count - 1)
                   {
                       Json.Append(",");
                   }
               }
           }
           Json.Append("]}");
           return Json.ToString();
       }

       #endregion

       #region DataReader转换为Json
       /// <summary>
       /// DataReader转换为Json
       /// </summary>
       /// <param name="dataReader">DataReader对象</param>
       /// <returns>Json字符串</returns>
       public static string ToJson(DbDataReader dataReader)
       {
           StringBuilder jsonString = new StringBuilder();
           jsonString.Append("[");
           while (dataReader.Read())
           {
               jsonString.Append("{");
               for (int i = 0; i < dataReader.FieldCount; i++)
               {
                   Type type = dataReader.GetFieldType(i);
                   string strKey = dataReader.GetName(i);
                   string strValue = dataReader[i].ToString();
                   jsonString.Append("\"" + strKey + "\":");
                   strValue = StringFormat(strValue, type);
                   if (i < dataReader.FieldCount - 1)
                   {
                       jsonString.Append(strValue + ",");
                   }
                   else
                   {
                       jsonString.Append(strValue);
                   }
               }
               jsonString.Append("},");
           }
           dataReader.Close();
           jsonString.Remove(jsonString.Length - 1, 1);
           jsonString.Append("]");
           return jsonString.ToString();
       }
       #endregion
   }

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