自己动手写ORM框架(六):实现查询功能FindById方法(五)
//将值设置到对象中
setter(obj, value);
}
public static object GetFieldValue(object obj, FieldInfo field)
{
//创建Set委托
GetHandler getter = DynamicMethodCompiler.CreateGetHandler(obj.GetType(), field);
//获取字段值
return getter(obj);
}
}
}
DynamicMethodCompiler代码：
using System;
using System.Collections.Generic;
using System.Text;
using System.Reflection;
using System.Reflection.Emit;
namespace System.Orm.Common
{
//定义GetHandler委托
public delegate object GetHandler(object source);
//定义SetHandler委托
public delegate void SetHandler(object source, object value);
//定义InstantiateObjectHandler委托
public delegate object InstantiateObjectHandler();
public sealed class DynamicMethodCompiler
{
// DynamicMethodCompiler
private DynamicMethodCompiler() { }
// 创建InstantiateObject委托
internal static InstantiateObjectHandler CreateInstantiateObjectHandler(Type type)
{
ConstructorInfo constructorInfo = type.GetConstructor(BindingFlags.Public |
BindingFlags.NonPublic | BindingFlags.Instance, null, new Type[0], null);
if (constructorInfo == null)
{
throw new ApplicationException(string.Format("The type {0} must declare an empty constructor (the constructor may be private, internal, protected, protected internal, or public).", type));
}
DynamicMethod dynamicMethod = new DynamicMethod("InstantiateObject",
MethodAttributes.Static |
MethodAttributes.Public, CallingConventions.Standard, typeof(object),
null, type, true);
ILGenerator generator = dynamicMethod.GetILGenerator();
generator.Emit(OpCodes.Newobj, constructorInfo);
generator.Emit(OpCodes.Ret);
return (InstantiateObjectHandler)dynamicMethod.CreateDelegate
(typeof(InstantiateObjectHandler));
}
// 创建Get委托
internal static GetHandler CreateGetHandler(Type type, PropertyInfo propertyInfo)
{
MethodInfo getMethodInfo = propertyInfo.GetGetMethod(true);
DynamicMethod dynamicGet = CreateGetDynamicMethod(type);
ILGenerator getGenerator = dynamicGet.GetILGenerator();
getGenerator.Emit(OpCodes.Ldarg_0);
getGenerator.Emit(OpCodes.Call, getMethodInfo);
BoxIfNeeded(getMethodInfo.ReturnType, getGenerator);
getGenerator.Emit(OpCodes.Ret);
return (GetHandler)dynamicGet.CreateDelegate(typeof(GetHandler));
}
// 创建Get委托
internal static GetHandler CreateGetHandler(Type type, FieldInfo fieldInfo)
{
DynamicMethod dynamicGet = CreateGetDynamicMethod(type);
ILGenerator getGenerator = dynamicGet.GetILGenerator();
getGenerator.Emit(OpCodes.Ldarg_0);
getGenerator.Emit(OpCodes.Ldfld, fieldInfo);
BoxIfNeeded(fieldInfo.FieldType, getGenerator);
getGenerator.Emit(OpCodes.Ret);
return (GetHandler)dynamicGet.CreateDelegate(typeof(GetHandler));