C#实现DataSet数据转换为Json的代码

/// <summary>
/// DataSet对象转换为Josn
/// </summary>
/// <param name="ds"></param>
/// <returns></returns>
public static string GetJsonString(DataSet ds)
{
    string json = string.Empty;
    IList<Hashtable> mList = new List<Hashtable>();
    try
    {
foreach (DataRow row in ds.Tables[0].Rows)
{
    Hashtable ht = new Hashtable();
    foreach (DataColumn col in ds.Tables[0].Columns)
    {
ht.Add(col.ColumnName, row[col.ColumnName]);
    }
    mList.Add(ht);
}
json = javascriptConvert.SerializeObject(mList);
    }
    catch (Exception ex)
    {
string error = ex.Message;
    }
    return json;
}

public static string CreateJsonByDataTable(DataTable dt)
{
    StringBuilder jsonString = new StringBuilder();
    if (dt != null && dt.Rows.Count > 0)
    {
jsonString.Append("[");
for (int i = 0; i < dt.Rows.Count; i++)
{
    jsonString.Append("{");
    for (int j = 0; j < dt.Columns.Count; j++)
    {
if (j < dt.Columns.Count - 1)
{
    jsonString.Append(""" + dt.Columns[j].ColumnName.ToString() + "":" + """ + dt.Rows[i][j].ToString() + "",");
}
else if (j == dt.Columns.Count - 1)
{
    jsonString.Append(""" + dt.Columns[j].ColumnName.ToString() + "":" + """ + dt.Rows[i][j].ToString() + """);
}
    }
    if (i == dt.Rows.Count - 1)
    {
jsonString.Append("}");
    }
    else
    { //www.jb200.com
jsonString.Append("},");
    }
}
jsonString.Append("]");
return jsonString.ToString();
    }
    else
    {
return string.Empty;
    }
}