LINQ返回DataTable类型 list转dataset 转换为JSON对象

using System.Web.Script.Serialization;
using System.Collections.Generic;
using System.Reflection;
using System.Data;
using System;

namespace CommonCode
{
public class Common
{
/// <summary>
/// LINQ返回DataTable类型
/// </summary>
public static DataTable ToDataTable<T>(IEnumerable<T> varlist)
{
DataTable dtReturn = new DataTable();
// column names
PropertyInfo[] oProps = null;

if (varlist == null)
return dtReturn;
foreach (T rec in varlist)
{
if (oProps == null)
{
oProps = ((Type)rec.GetType()).GetProperties();
foreach (PropertyInfo pi in oProps)
{
Type colType = pi.PropertyType;
if ((colType.IsGenericType) && (colType.GetGenericTypeDefinition() == typeof(Nullable<>)))
{
colType = colType.GetGenericArguments()[0];
}
dtReturn.Columns.Add(new DataColumn(pi.Name, colType));
}
}
DataRow dr = dtReturn.NewRow();
foreach (PropertyInfo pi in oProps)
{
dr[pi.Name] = pi.GetValue(rec, null) == null ? DBNull.Value : pi.GetValue(rec, null);
}
dtReturn.Rows.Add(dr);
}
return dtReturn;
}

/// <summary>
/// list转dataset
/// </summary>
public static DataSet ConvertToDataSet<T>(IList<T> list)
{
if (list == null || list.Count <= 0)
return null;
DataSet ds = new DataSet();
DataTable dt = new DataTable(typeof(T).Name);
DataColumn column;
DataRow row;
System.Reflection.PropertyInfo[] myPropertyInfo =
typeof(T).GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance);
foreach (T t in list)
{
if (t == null) continue;
row = dt.NewRow();

for (int i = 0, j = myPropertyInfo.Length; i < j; i++)
{
System.Reflection.PropertyInfo pi = myPropertyInfo[i];
String name = pi.Name;

if (dt.Columns[name] == null)
{
if (pi.PropertyType.UnderlyingSystemType.ToString() == "System.Nullable`1[System.Int32]")
{
column = new DataColumn(name, typeof(Int32));
dt.Columns.Add(column);
//row[name] = pi.GetValue(t, new object[] {i});//PropertyInfo.GetValue(object,object[])
if (pi.GetValue(t, null) != null)
row[name] = pi.GetValue(t, null);
else
row[name] = System.DBNull.Value;
}
else if (pi.PropertyType.UnderlyingSystemType.ToString() == "System.Nullable`1[System.DateTime]")
{
column = new DataColumn(name, typeof(DateTime));
dt.Columns.Add(column);
if (pi.GetValue(t, null) != null)
row[name] = pi.GetValue(t, null);
else
row[name] = System.DBNull.Value;
}
else
{
column = new DataColumn(name, pi.PropertyType);
dt.Columns.Add(column);
row[name] = pi.GetValue(t, null);
}
}
}
dt.Rows.Add(row);
}
ds.Tables.Add(dt);
return ds;
}
public delegate object[] CreateRowDelegate<T>(T t);

public static string Serialize(DataTable dt)
{
List<Dictionary<string, object>> list = new List<Dictionary<string, object>>();
foreach (DataRow dr in dt.Rows)
{
Dictionary<string, object> result = new Dictionary<string, object>();
foreach (DataColumn dc in dt.Columns)
{
result.Add(dc.ColumnName, dr[dc].ToString());
}
list.Add(result);
}
int count = 0;
try
{
count = Convert.ToInt32(dt.TableName);
}
catch (System.Exception ex)
{
count = dt.Rows.Count;
}
string strReturn = "";
if (count == 0)
{
strReturn = "{\"totalCount\":0,\"data\":[]}";
}
else
{
strReturn = ConventToJson(list, count);
}
return strReturn;
}

/// <summary>
/// 转换为JSON对象
/// </summary>
public static string ConventToJson<T>(List<T> list, int count)
{
JavaScriptSerializer serializer = new JavaScriptSerializer();
string strJson = serializer.Serialize(list);
strJson = strJson.Substring(1);
strJson = strJson.Insert(0, "{totalCount:" + count + ",data:[");
strJson += "}";
return strJson;
}

/// <summary>
/// 不需要分页
/// </summary>
public static string Serialize(DataTable dt, bool flag)
{
JavaScriptSerializer serializer = new JavaScriptSerializer();
List<Dictionary<string, object>> list = new List<Dictionary<string, object>>();
foreach (DataRow dr in dt.Rows)
{
Dictionary<string, object> result = new Dictionary<string, object>();
foreach (DataColumn dc in dt.Columns)
{
result.Add(dc.ColumnName, dr[dc].ToString());
}
list.Add(result);
}
return serializer.Serialize(list);
}
}
}