using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Linq;using System.Reflection;using System.Text;using System.Threading.Tasks;namespace Xmh.DBUnit{    /// 
    ///  将DataTable转换为List，将List转换为DataTable的实现类    /// 
    public static class DataTableHelper    {        public static DataTable ConvertTo
     
      (IList
      
        list)        {            DataTable table = CreateTable
       
        ();            Type entityType = typeof(T);            PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(entityType);            foreach (T item in list)            {                DataRow row = table.NewRow();                foreach (PropertyDescriptor prop in properties)                    row[prop.Name] = prop.GetValue(item);                table.Rows.Add(row);            }            return table;        }        public static IList
        
          ConvertTo
         
          (IList
          
            rows) { IList
           
             list = null; if (rows != null) { list = new List
            
             (); foreach (DataRow row in rows) { T item = CreateItem
             
              (row); list.Add(item); } } return list; } public static IList
              
                ConvertTo
               
                (DataTable table) { if (table == null) return null; List
                
                  rows = new List
                 
                  (); foreach (DataRow row in table.Rows) rows.Add(row); return ConvertTo
                  
                   (rows); } //Convert DataRow into T Object public static T CreateItem
                   
                    (DataRow row) { string columnName; T obj = default(T); if (row != null) { obj = Activator.CreateInstance
                    
                     (); foreach (DataColumn column in row.Table.Columns) { columnName = column.ColumnName; //Get property with same columnName PropertyInfo prop = obj.GetType().GetProperty(columnName); try { Type type = prop.PropertyType; //判断type类型是否为泛型，因为nullable是泛型类, if (type.IsGenericType && type.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))//判断convertsionType是否为nullable泛型类 { //如果type为nullable类，声明一个NullableConverter类，该类提供从Nullable类到基础基元类型的转换 System.ComponentModel.NullableConverter nullableConverter = new System.ComponentModel.NullableConverter(type); //将type转换为nullable对的基础基元类型 type = nullableConverter.UnderlyingType; } //Get value for the column object value = (row[columnName].GetType() == typeof(DBNull)) ? null : row[columnName]; //Set property value if (prop.CanWrite) //判断其是否可写 prop.SetValue(obj, (value == null ? null : Convert.ChangeType(value, type)), null); } catch { throw; //Catch whatever here } } } return obj; } public static DataTable CreateTable
                     
                      () { Type entityType = typeof(T); DataTable table = new DataTable(entityType.Name); PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(entityType); foreach (PropertyDescriptor prop in properties) table.Columns.Add(prop.Name, prop.PropertyType); return table; } public static List
                      
                        ToList
                       
                        (this DataTable dt) where T : class, new() { Type t = typeof(T); PropertyInfo[] propertys = t.GetProperties(); List
                        
                          lst = new List
                         
                          (); string typeName = string.Empty; foreach (DataRow dr in dt.Rows) { T entity = new T(); foreach (PropertyInfo pi in propertys) { typeName = pi.Name; if (dt.Columns.Contains(typeName)) { if (!pi.CanWrite) continue; object value = dr[typeName]; if (value == DBNull.Value) continue; if (pi.PropertyType == typeof(string)) { pi.SetValue(entity, value.ToString(), null); } else if (pi.PropertyType == typeof(int) || pi.PropertyType == typeof(int?)) { pi.SetValue(entity, int.Parse(value.ToString()), null); } else if (pi.PropertyType == typeof(DateTime?) || pi.PropertyType == typeof(DateTime)) { pi.SetValue(entity, DateTime.Parse(value.ToString()), null); } else if (pi.PropertyType == typeof(float)) { pi.SetValue(entity, float.Parse(value.ToString()), null); } else if (pi.PropertyType == typeof(double)) { pi.SetValue(entity, double.Parse(value.ToString()), null); } else { pi.SetValue(entity, value, null); } } } lst.Add(entity); } return lst; } }}