120 lines
4.4 KiB
C#
120 lines
4.4 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Text;
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using System.Reflection.Emit;
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using System.Reflection;
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using CYQ.Data.Table;
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namespace CYQ.Data.Tool
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{
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/// <summary>
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/// 快速转换类[数据量越大[500条起],性能越高]
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/// </summary>
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internal class FastToT<T>
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{
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public delegate T EmitHandle(MDataRow row);
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/// <summary>
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/// 构建一个ORM实体转换器
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/// </summary>
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/// <typeparam name="T">转换的目标类型</typeparam>
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/// <param name="schema">表数据架构</param>
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public static EmitHandle Create(MDataTable schema)
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{
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Type tType = typeof(T);
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Type rowType = typeof(MDataRow);
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DynamicMethod method = new DynamicMethod("RowToT", tType, new Type[] { rowType }, tType);
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MethodInfo getValue = rowType.GetMethod("GetItemValue", BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic, null, new Type[] { typeof(int) }, null);
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ILGenerator gen = method.GetILGenerator();//开始编写IL方法。
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gen.DeclareLocal(tType);
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gen.DeclareLocal(typeof(object));
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gen.DeclareLocal(typeof(bool)); //分别定义了一个Type t,object o,bool b;
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gen.Emit(OpCodes.Newobj, tType.GetConstructor(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic, null, new Type[] { }, null));
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gen.Emit(OpCodes.Stloc_0);//t= new T();
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int ordinal = -1;
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List<FieldInfo> fileds = new List<FieldInfo>();
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fileds.AddRange(tType.GetFields(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public));
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if (tType.BaseType.Name != "Object" && tType.BaseType.Name != "OrmBase")
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{
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FieldInfo[] items = tType.BaseType.GetFields(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
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foreach (FieldInfo item in items)
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{
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bool isAdd = true;
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foreach (FieldInfo f in fileds)//这里检测去重复。
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{
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if (item.Name == f.Name)
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{
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isAdd = false;
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break;
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}
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}
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if (isAdd)
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{
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fileds.Add(item);
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}
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}
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}
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foreach (FieldInfo field in fileds)
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{
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string fieldName = field.Name;
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if(fieldName[0]=='<')
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{
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fieldName=fieldName.Substring(1,fieldName.IndexOf('>')-1);
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}
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ordinal = schema.Columns.GetIndex(fieldName.TrimStart('_'));
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if (ordinal == -1)
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{
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ordinal = schema.Columns.GetIndex(fieldName);
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}
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if (ordinal > -1)
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{
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Label retFalse = gen.DefineLabel();//定义标签；goto;
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gen.Emit(OpCodes.Ldarg_0);
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gen.Emit(OpCodes.Ldc_I4, ordinal);
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gen.Emit(OpCodes.Call, getValue);//Call GetItemValue(ordinal);
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gen.Emit(OpCodes.Stloc_1); // o=GetItemValue(ordinal);
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gen.Emit(OpCodes.Ldloc_1);
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gen.Emit(OpCodes.Ldnull);
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gen.Emit(OpCodes.Ceq);// if (o==null)
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gen.Emit(OpCodes.Stloc_2); //b=o==null;
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gen.Emit(OpCodes.Ldloc_2);
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gen.Emit(OpCodes.Brtrue_S, retFalse);//为null值，跳过
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gen.Emit(OpCodes.Ldloc_0);//实体对象
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gen.Emit(OpCodes.Ldloc_1);//属性的值
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EmitCastObj(gen, field.FieldType);//类型转换
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gen.Emit(OpCodes.Stfld, field);//对实体赋值 System.Object.FieldSetter(String typeName, String fieldName, Object val)
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gen.MarkLabel(retFalse);//继续下一个循环
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}
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}
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gen.Emit(OpCodes.Ldloc_0);
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gen.Emit(OpCodes.Ret);
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return method.CreateDelegate(typeof(EmitHandle)) as EmitHandle;
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}
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private static void EmitCastObj(ILGenerator il, Type targetType)
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{
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if (targetType.IsValueType)
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{
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il.Emit(OpCodes.Unbox_Any, targetType);
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}
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else
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{
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il.Emit(OpCodes.Castclass, targetType);
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}
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}
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}
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}
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