我的应用程序基于设置动态加载dll
从数据库(文件,类和方法名称).为了方便,加快和减少使用反射我想要一个缓存….
从数据库(文件,类和方法名称).为了方便,加快和减少使用反射我想要一个缓存….
遵循使用：
MethodInfo.Invoke
没有什么表现(Reflection Performance – Create Delegate (Properties C#))
我想翻译任何对方法的调用.我想到了会这样工作的东西：
public static T Create<T>(Type type,string methodName) // or public static T Create<T>(MethodInfo info) // to use like this: var action = Create<Action<object>>(typeof(Foo),"AnySetValue");
一个要求是所有的参数,可以是对象.
我正在试图处理表达,到目前为止我有这样的事情：
private void Sample()
{
var assembly = Assembly.GetAssembly(typeof(Foo));
Type customType = assembly.GetType("Foo");
var actionMethodInfo = customType.GetMethod("AnyMethod");
var funcMethodInfo = customType.GetMethod("AnyGetString");
var otherActionMethod = customType.GetMethod("AnySetValue");
var otherFuncMethodInfo = customType.GetMethod("OtherGetString");
var foo = Activator.CreateInstance(customType);
var actionAccessor = (Action<object>)BuildSimpleAction(actionMethodInfo);
actionAccessor(foo);
var otherAction = (Action<object,object>)BuildOtherAction(otherActionMethod);
otherAction(foo,string.Empty);
var otherFuncAccessor = (Func<object,object>)BuildFuncAccessor(funcMethodInfo);
otherFuncAccessor(foo);
var funcAccessor = (Func<object,object,object>)BuildOtherFuncAccessor(otherFuncMethodInfo);
funcAccessor(foo,string.Empty);
}
static Action<object> BuildSimpleAction(MethodInfo method)
{
var obj = Expression.Parameter(typeof(object),"o");
Expression<Action<object>> expr =
Expression.Lambda<Action<object>>(
Expression.Call(
Expression.Convert(obj,method.DeclaringType),method),obj);
return expr.Compile();
}
static Func<object,object> BuildFuncAccessor(MethodInfo method)
{
var obj = Expression.Parameter(typeof(object),"o");
Expression<Func<object,object>> expr =
Expression.Lambda<Func<object,object>>(
Expression.Convert(
Expression.Call(
Expression.Convert(obj,typeof(object)),obj);
return expr.Compile();
}
static Func<object,object> BuildOtherFuncAccessor(MethodInfo method)
{
var obj = Expression.Parameter(typeof(object),"o");
var value = Expression.Parameter(typeof(object));
Expression<Func<object,object>>(
Expression.Call(
Expression.Convert(obj,method,Expression.Convert(value,method.GetParameters()[0].ParameterType)),obj,value);
return expr.Compile();
}
static Action<object,object> BuildOtherAction(MethodInfo method)
{
var obj = Expression.Parameter(typeof(object),"o");
var value = Expression.Parameter(typeof(object));
Expression<Action<object,object>> expr =
Expression.Lambda<Action<object,object>>(
Expression.Call(
Expression.Convert(obj,value);
return expr.Compile();
}
public class Foo
{
public void AnyMethod() {}
public void AnySetValue(string value) {}
public string AnyGetString()
{ return string.Empty; }
public string OtherGetString(string value)
{ return string.Empty; }
}
有没有办法简化这段代码？ (我相信可以创建一个只使用泛型的方法..)当你有3,4,5,任何参数像我一样？
我在想,如果有这样的话呢？
但是我会有更多的参数(在动作或函数中),这个参数(第一个参数)要执行一个对象.
这可能吗？
解决方法
我已经做了一个满足您所有要求的示例程序(我想！)
class Program
{
class MyType
{
public MyType(int i) { this.Value = i; }
public void SetValue(int i) { this.Value = i; }
public void SetSumValue(int a,int b) { this.Value = a + b; }
public int Value { get; set; }
}
public static void Main()
{
Type type = typeof(MyType);
var mi = type.GetMethod("SetValue");
var obj1 = new MyType(1);
var obj2 = new MyType(2);
var action = DelegateBuilder.BuildDelegate<Action<object,int>>(mi);
action(obj1,3);
action(obj2,4);
Console.WriteLine(obj1.Value);
Console.WriteLine(obj2.Value);
// Sample passing a default value for the 2nd param of SetSumValue.
var mi2 = type.GetMethod("SetSumValue");
var action2 = DelegateBuilder.BuildDelegate<Action<object,int>>(mi2,10);
action2(obj1,3);
action2(obj2,4);
Console.WriteLine(obj1.Value);
Console.WriteLine(obj2.Value);
// Sample without passing a default value for the 2nd param of SetSumValue.
// It will just use the default int value that is 0.
var action3 = DelegateBuilder.BuildDelegate<Action<object,int>>(mi2);
action3(obj1,3);
action3(obj2,4);
Console.WriteLine(obj1.Value);
Console.WriteLine(obj2.Value);
}
}
DelegateBuilder类：
public class DelegateBuilder
{
public static T BuildDelegate<T>(MethodInfo method,params object[] missingParamValues)
{
var queueMissingParams = new Queue<object>(missingParamValues);
var dgtMi = typeof(T).GetMethod("Invoke");
var dgtRet = dgtMi.ReturnType;
var dgtParams = dgtMi.GetParameters();
var paramsOfDelegate = dgtParams
.Select(tp => Expression.Parameter(tp.ParameterType,tp.Name))
.ToArray();
var methodParams = method.GetParameters();
if (method.IsStatic)
{
var paramsToPass = methodParams
.Select((p,i) => CreateParam(paramsOfDelegate,i,p,queueMissingParams))
.ToArray();
var expr = Expression.Lambda<T>(
Expression.Call(method,paramsToPass),paramsOfDelegate);
return expr.Compile();
}
else
{
var paramThis = Expression.Convert(paramsOfDelegate[0],method.DeclaringType);
var paramsToPass = methodParams
.Select((p,i + 1,queueMissingParams))
.ToArray();
var expr = Expression.Lambda<T>(
Expression.Call(paramThis,paramsOfDelegate);
return expr.Compile();
}
}
private static Expression CreateParam(ParameterExpression[] paramsOfDelegate,int i,ParameterInfo callParamType,Queue<object> queueMissingParams)
{
if (i < paramsOfDelegate.Length)
return Expression.Convert(paramsOfDelegate[i],callParamType.ParameterType);
if (queueMissingParams.Count > 0)
return Expression.Constant(queueMissingParams.Dequeue());
if (callParamType.ParameterType.IsValueType)
return Expression.Constant(Activator.CreateInstance(callParamType.ParameterType));
return Expression.Constant(null);
}
}
怎么运行的
核心是BuildDelegate方法：
static T BuildDelegate< T>(MethodInfo方法)
> T是要创建的委托类型.
方法是要由生成的委托调用的方法的MethodInfo.
示例调用：var action = BuildDelegate< Action< object,int>>(mi);
参数规则：
>如果传递的方法是一个实例方法,生成的委托的第一个参数将接受包含方法本身的对象的实例.所有其他参数将被传递给该方法.>如果传递的方法是一个静态方法,那么生成的委托的所有参数将被传递给该方法.>缺少参数将传递默认值.>额外的参数将被丢弃.
