DataSet 转换到JSON

在CSDN上下载的代码，放到文章里，是为了保存以后用，希望不会侵权哦

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

/// <summary>
///tojson 的摘要说明
/// </summary>
public class Converter
{
private static void WriteDataRow(StringBuilder sb, DataRow row)
{
sb.Append("{");
foreach (DataColumn column in row.Table.Columns)
{
sb.AppendFormat("\"{0}\":", column.ColumnName);
WriteValue(sb, row[column]);
sb.Append(",");
}
// Remove the trailing comma.
if (row.Table.Columns.Count > 0)
{
--sb.Length;
}
sb.Append("}");
}

private static void WriteDataColumn(StringBuilder sb, DataColumn column)
{
sb.Append("{");
sb.AppendFormat("\"{0}\":", column.ColumnName);
sb.AppendFormat("\"{0}\"", column.DataType.ToString().Remove(0,7));
sb.Append("}");
}

private static void WriteDataSet(StringBuilder sb, DataSet ds)
{
sb.Append("{\"" + ds.DataSetName +"\":{");
foreach (DataTable table in ds.Tables)
{
sb.AppendFormat("\"'{0}\":", table.TableName);
WriteDataTable(sb, table);
sb.Append(",");
}
// Remove the trailing comma.
if (ds.Tables.Count > 0)
{
--sb.Length;
}
sb.Append("}}");
}

private static void WriteDataTable(StringBuilder sb, DataTable table)
{
sb.Append("{\"Columns\":[");

foreach (DataColumn col in table.Columns)
{
WriteDataColumn(sb, col);
sb.Append(",");
}

--sb.Length;
sb.Append("]},");

sb.Append("{\"Rows\":[");

foreach (DataRow row in table.Rows)
{
WriteDataRow(sb, row);
sb.Append(",");
}
// Remove the trailing comma.
if (table.Rows.Count > 0)
{
--sb.Length;
}
sb.Append("]}");
}

private static void WriteEnumerable(StringBuilder sb, IEnumerable e)
{
bool hasItems = false;
sb.Append("[");
foreach (object val in e)
{
WriteValue(sb, val);
sb.Append(",");
hasItems = true;
}
// Remove the trailing comma.
if (hasItems)
{
--sb.Length;
}
sb.Append("]");
}

private static void WriteHashtable(StringBuilder sb, Hashtable e)
{
bool hasItems = false;
sb.Append("{");
foreach (string key in e.Keys)
{
sb.AppendFormat("\"{0}\":", key.ToLower());
WriteValue(sb, e[key]);
sb.Append(",");
hasItems = true;
}
// Remove the trailing comma.
if (hasItems)
{
--sb.Length;
}
sb.Append("}");
}

private static void WriteString(StringBuilder sb, string s)
{
sb.Append("\"");
foreach (char c in s)
{
switch (c)
{
case '\"':
sb.Append("\\\"");
break;
case '\\':
sb.Append("\\\\");
break;
case '\b':
sb.Append("\\b");
break;
case '\f':
sb.Append("\\f");
break;
case '\n':
sb.Append("\\n");
break;
case '\r':
sb.Append("\\r");
break;
case '\t':
sb.Append("\\t");
break;
default:
sb.Append(c);
break;
}
}
sb.Append("\"");
}

public static void WriteValue(StringBuilder sb, object val)
{
if (val == null || val == System.DBNull.Value)
{
sb.Append("null");
}
else if (val is string || val is Guid)
{
WriteString(sb, val.ToString());
}
else if (val is bool)
{
sb.Append(val.ToString().ToLower());
}
else if (val is double ||
val is float ||
val is long ||
val is int ||
val is short ||
val is byte ||
val is decimal)
{
sb.AppendFormat("{0}", val);
}
else if (val.GetType().IsEnum)
{
sb.Append((int)val);
}
else if (val is DateTime)
{
sb.Append("\"");
sb.Append(((DateTime)val).ToString("yyyy-MM-dd HH:mm:ss"));
sb.Append("\"");
}
else if (val is DataSet)
{
WriteDataSet(sb, val as DataSet);
}
else if (val is DataTable)
{
WriteDataTable(sb, val as DataTable);
}
else if (val is DataRow)
{
WriteDataRow(sb, val as DataRow);
}
else if (val is Hashtable)
{
WriteHashtable(sb, val as Hashtable);
}
else if (val is IEnumerable)
{
WriteEnumerable(sb, val as IEnumerable);
}
}

public static string Convert2Json(object o)
{
StringBuilder sb = new StringBuilder();
WriteValue(sb, o);
return sb.ToString();
}
}