如何从一个静态方法调用一个实例类方法与反射 [英] How to call an instance class method from a static method with reflection

问题描述

 命名空间ClassLibraryB {
 public class Class1 {
 public void Add（int ii，int jj）
 {
 i = ii; 
 j = jj; 
 result = i + j; 
} 
 public void Add2（）
 {
 result = i + j; 
} 
} 
} 
  

这被静态调用，并给出我一个答案

  ClassLibraryB.Class1 objB = new ClassLibraryB.Class1（）; 
 objB.Add（4，16）; 
 objB.Add2（）; 
 kk = objB.result; 
 textBox1.Text + =Addition =+ kk.ToString（）+\r\\\
; 
  

但是，当我尝试使用下面的dll调用它失败，因为它不是静态的

  Assembly testAssembly = Assembly.LoadFile（strDLL）; 
键入calcType = testAssembly.GetType（ClassLibraryB.Class1）; 
 object calcInstance = Activator.CreateInstance（calcType）; 
 PropertyInfo numberPropertyInfo = calcType.GetProperty（i）; 
 numberPropertyInfo.SetValue（calcInstance，5，null）; 
 PropertyInfo numberPropertyInfo2 = calcType.GetProperty（j）; 
 numberPropertyInfo2.SetValue（calcInstance，15，null）; 
 int value2 =（int）numberPropertyInfo.GetValue（calcInstance，null）; 
 int value3 =（int）numberPropertyInfo2.GetValue（calcInstance，null）; 
 calcType.InvokeMember（Add2，BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.Public，
 null，null，null）; 
 PropertyInfo numberPropertyInfo3 = calcType.GetProperty（result）; 
 int value4 =（int）numberPropertyInfo3.GetValue（calcInstance，null）; 
  

我只需要知道我必须对dll类做什么修改才能调用这里

解决方案

您必须将类型的实例传递给 InvokeMember

  calcType.InvokeMember（Add2，flags，null，calcInstance，null）; 
  

---

如果您正在创建一个插件，一个包含插件的接口声明的类库（dll）
$ b $ >

包含接口（插件）实现的类库（dll）

可执行文件（exe）加载插件

接口DLL由其他两个组件引用。您需要三个程序集，因为插件不应该知道您的应用程序，应用程序不应该知道除了其界面之外的插件。这使得插件可互换和不同的应用程序可以使用相同的插件。

---

接口装配 Calculator.Contracts.dll

  public interface ICalculator 
 {
 int Add（int a，int b）; 
} 
  

---

插件实现 Calculator.dll

  public class Calculator：ICalculator 
 {
 public int Add（int a，int b）
 {
 return a + b; 
} 
} 
  

---

现在，您可以加载插件并在应用程序（exe）中以类型方式使用它：

  Assembly asm = Assembly .LoadFrom（strDLL）; 
 string calcInterfaceName = typeof（ICalculator）.FullName; 
 foreach（type as in asm.GetExportedTypes（））{
 Type interfaceType = type.GetInterface（calcInterfaceName）; 
 if（interfaceType！= null&& 
（type.Attributes& TypeAttributes.Abstract）！= TypeAttributes.Abstract）{
 
 ICalculator calculator =（ICalculator）Activator .CreateInstance（类型）; 
 int result = calculator.Add（2，7）; 
} 
} 
  

namespace ClassLibraryB {
    public class Class1 {
        public void Add(int ii, int jj)
        {
            i = ii;
            j = jj;
            result = i + j;
        }
        public void Add2()
        {
            result =  i + j;
        }
    }
}

This gets called statically and gives me an answer

ClassLibraryB.Class1 objB = new ClassLibraryB.Class1();
objB.Add(4, 16);
objB.Add2();
kk = objB.result;
textBox1.Text += "Addition =" + kk.ToString() + "\r\n";

However when I try to call the dll using below it fails with since it is not static

Assembly testAssembly = Assembly.LoadFile(strDLL);
Type calcType = testAssembly.GetType("ClassLibraryB.Class1");
object calcInstance = Activator.CreateInstance(calcType);
PropertyInfo numberPropertyInfo = calcType.GetProperty("i");
numberPropertyInfo.SetValue(calcInstance, 5, null);
PropertyInfo numberPropertyInfo2 = calcType.GetProperty("j");
numberPropertyInfo2.SetValue(calcInstance, 15, null);
int value2 = (int)numberPropertyInfo.GetValue(calcInstance, null);
int value3 = (int)numberPropertyInfo2.GetValue(calcInstance, null);
calcType.InvokeMember("Add2",BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.Public,
    null, null, null);
PropertyInfo numberPropertyInfo3 = calcType.GetProperty("result");
int value4 = (int)numberPropertyInfo3.GetValue(calcInstance, null);

I just need to know exactly what changes I have to make to the dll class to be able to call it here

解决方案

You must pass an instance of the type to InvokeMember

calcType.InvokeMember("Add2", flags, null, calcInstance, null);

---

If you are creating a plug-in, the right thing to do is to have three assemblies.

1. A class library (dll) containing an interface declaration of the plug-in
2. A class library (dll) containing an implementation of the interface (the plug-in)
3. An executable (exe) loading the plug-in

The interface DLL is referenced by the two other components. You need three assemblies because the plug-in should not know anything about your application and the application should not know anything about your plug-in other than its interface. This makes the plug-ins interchangeable and different applications can use the same plug-in.

---

Interface Assembly Calculator.Contracts.dll

public interface ICalculator
{
    int Add(int a, int b);
}

---

Plug-in implementation Calculator.dll

public class Calculator : ICalculator
{
    public int Add(int a, int b)
    {
        return a + b;
    }
}

---

Now you can load the plug-in and use it in a typed way in the application (exe):

Assembly asm = Assembly.LoadFrom(strDLL);
string calcInterfaceName = typeof(ICalculator).FullName;
foreach (Type type in asm.GetExportedTypes()) {
    Type interfaceType = type.GetInterface(calcInterfaceName);
    if (interfaceType != null &&
        (type.Attributes & TypeAttributes.Abstract) != TypeAttributes.Abstract) {

        ICalculator calculator = (ICalculator)Activator.CreateInstance(type);
        int result = calculator.Add(2, 7);
    }
}

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