/// <summary>
/// DataTable转List<Model>通用类【实体转换辅助类】
/// </summary>
public class ModelConvertHelper<T> where T : new()
{
public static IList<T> ConvertToModel(DataTable dt)
{
// 定义集合
IList<T> ts = new List<T>();
// 获得此模型的类型
Type type = typeof(T);
string tempName = "";
foreach (DataRow dr in dt.Rows)
{
T t = new T();
// 获得此模型的公共属性
PropertyInfo[] propertys = t.GetType().GetProperties();
foreach (PropertyInfo pi in propertys)
{
tempName = pi.Name; // 检查DataTable是否包含此列
if (dt.Columns.Contains(tempName))
{
// 判断此属性是否有Set
if (!pi.CanWrite) continue;
object value = dr[tempName];
if (value != DBNull.Value)
pi.SetValue(t, value, null);
}
}
ts.Add(t);
}
return ts;
}
}
//方法二：使用emit实现
public static List<TResult> ToList<TResult>(this DataTable dt) where TResult : class, new()
{
List<TResult> list = new List<TResult>();
if (dt == null) return list;
DataTableEntityBuilder<TResult> eblist = DataTableEntityBuilder<TResult>.CreateBuilder(dt.Rows[0]);
foreach(DataRow info in dt.Rows) list.Add(eblist.Build(info));
dt.Dispose(); dt = null;
return list;
}
public class DataTableEntityBuilder<Entity>
{
private static readonly MethodInfo getValueMethod = typeof(DataRow).GetMethod("get_Item", new Type[] { typeof(int) });
private static readonly MethodInfo isDBNullMethod = typeof(DataRow).GetMethod("IsNull", new Type[] { typeof(int) });
private delegate Entity Load(DataRow dataRecord);
private Load handler;
private DataTableEntityBuilder() { }
public Entity Build(DataRow dataRecord) {
return handler(dataRecord);
}
public static DataTableEntityBuilder<Entity> CreateBuilder(DataRow dataRecord) {
DataTableEntityBuilder<Entity> dynamicBuilder = new DataTableEntityBuilder<Entity>();
DynamicMethod method = new DynamicMethod("DynamicCreateEntity", typeof(Entity), new Type[] { typeof(DataRow) }, typeof(Entity), true);
ILGenerator generator = method.GetILGenerator();
LocalBuilder result = generator.DeclareLocal(typeof(Entity));
generator.Emit(OpCodes.Newobj, typeof(Entity).GetConstructor(Type.EmptyTypes));
generator.Emit(OpCodes.Stloc, result);
for (int i = 0; i < dataRecord.ItemArray.Length; i++) {
PropertyInfo propertyInfo = typeof(Entity).GetProperty(dataRecord.Table.Columns[i].ColumnName);
Label endIfLabel = generator.DefineLabel();
if (propertyInfo != null && propertyInfo.GetSetMethod() != null) {
generator.Emit(OpCodes.Ldarg_0);
generator.Emit(OpCodes.Ldc_I4, i);
generator.Emit(OpCodes.Callvirt, isDBNullMethod);
generator.Emit(OpCodes.Brtrue, endIfLabel);
generator.Emit(OpCodes.Ldloc, result);
generator.Emit(OpCodes.Ldarg_0);
generator.Emit(OpCodes.Ldc_I4, i);
generator.Emit(OpCodes.Callvirt, getValueMethod);
generator.Emit(OpCodes.Unbox_Any, propertyInfo.PropertyType);
generator.Emit(OpCodes.Callvirt, propertyInfo.GetSetMethod());
generator.MarkLabel(endIfLabel);
}
}
generator.Emit(OpCodes.Ldloc, result);
generator.Emit(OpCodes.Ret);
dynamicBuilder.handler = (Load)method.CreateDelegate(typeof(Load));
return dynamicBuilder;
}
}