エンティティ・クラスの値の動的入力
6963 ワード
/// <summary>
///
/// </summary>
/// <typeparam name="T"></typeparam>
public class DynamicEntityBuilder<T>
{
private static readonly MethodInfo getValueMethod = typeof(IDataRecord).GetMethod("get_Item", new Type[] { typeof(int) });
private static readonly MethodInfo isDBNullMethod = typeof(IDataRecord).GetMethod("IsDBNull", new Type[] { typeof(int) });
private delegate T Load(IDataRecord dataRecord);
private Load handler;
private DynamicEntityBuilder() { }
public T Build(IDataRecord dataRecord)
{
return handler(dataRecord);
}
public static DynamicEntityBuilder<T> CreateBuilder(IDataRecord dataRecord)
{
DynamicEntityBuilder<T> dynamicBuilder = new DynamicEntityBuilder<T>();
DynamicMethod method = new DynamicMethod("DynamicCreate", typeof(T), new Type[] { typeof(IDataRecord) }, typeof(T), true);
ILGenerator generator = method.GetILGenerator();
LocalBuilder result = generator.DeclareLocal(typeof(T));
generator.Emit(OpCodes.Newobj, typeof(T).GetConstructor(Type.EmptyTypes));
generator.Emit(OpCodes.Stloc, result);
for (int i = 0; i < dataRecord.FieldCount; i++)
{
PropertyInfo propertyInfo = typeof(T).GetProperty(dataRecord.GetName(i));
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, dataRecord.GetFieldType(i));
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;
}
}使用
public ERole Select(int roleID)
{
ERole entity = new ERole();
string sql = string.Format("select * from Role with(nolock) where roleid = {0}",roleID);
DbCommand cmd = Db.EsfCrmReader.GetSqlStringCommand(sql);
using (IDataReader dataReader = Db.EsfCrmReader.ExecuteReader(cmd))
{
if (dataReader.Read())
{
entity = DynamicEntityBuilder<ERole>.CreateBuilder(dataReader).Build(dataReader);
}
}
return entity;
}