c# - 如何获取数组字段的 FieldInfo？

Question

我正在尝试从结构中获取数组值的字段信息。到目前为止，我有以下内容，但我不知道如何获取我想要的信息。

    [StructLayout(LayoutKind.Sequential)]
    public struct Test
    {
        public byte Byte1;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst=3)]
        public Test2[] Test1;
    }

    BindingFlags struct_field_flags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance | BindingFlags.DeclaredOnly;
    FieldInfo[] all_struct_fields = typeof(Test).GetFields(struct_field_flags);
    foreach (FieldInfo struct_field in all_struct_fields)
    {
        if(struct_field.FieldType.IsArray)
        {
           // Get FieldInfo for each value in the Test1 array within Test structure
        }
    }

如果我这样做了:

 Type array_type = struct_field.FieldType.GetElementType();

这将返回 Test2 类型，但我不想要数组的类型，我想要该结构的 FieldInfo 或字段，以便我可以在其中设置值。

Answer 1

很抱歉最初的错误答案。我懒得创建自己的 Test2 类型，所以我使用了一个字符串。这是正确答案(希望如此):

我用下面的代码做了你想做的:

class Program
{
    static void Main(string[] args)
    {
        object sampleObject = GetSampleObject();
        FieldInfo[] testStructFields = typeof(Test).GetFields();

        foreach (FieldInfo testStructField in testStructFields)
        {
            if (testStructField.FieldType.IsArray)
            {
                // We can cast to ILIst because arrays implement it and we verfied that it is an array in the if statement
                System.Collections.IList sampleObject_test1 = (System.Collections.IList)testStructField.GetValue(sampleObject);
                // We can now get the first element of the array of Test2s:
                object sampleObject_test1_Element0 = sampleObject_test1[0];

                // I hope this the FieldInfo that you want to get:
                FieldInfo myValueFieldInfo = sampleObject_test1_Element0.GetType().GetField("MyValue");

                // Now it is possible to read and write values
                object sampleObject_test1_Element0_MyValue = myValueFieldInfo.GetValue(sampleObject_test1_Element0);
                Console.WriteLine(sampleObject_test1_Element0_MyValue); // prints 99
                myValueFieldInfo.SetValue(sampleObject_test1_Element0, 55);
                sampleObject_test1_Element0_MyValue = myValueFieldInfo.GetValue(sampleObject_test1_Element0);
                Console.WriteLine(sampleObject_test1_Element0_MyValue); // prints 55
            }
        }
    }

    static object GetSampleObject()
    {
        Test sampleTest = new Test();
        sampleTest.Test1 = new Test2[5];
        sampleTest.Test1[0] = new Test2() { MyValue = 99 };
        object sampleObject = sampleTest;
        return sampleObject;
    }
}

[StructLayout(LayoutKind.Sequential)]
public struct Test2
{
    public int MyValue;
}

[StructLayout(LayoutKind.Sequential)]
public struct Test
{
    public byte Byte1;
    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
    public Test2[] Test1;
}

这是最重要的一行:

FieldInfo myValueFieldInfo = sampleObject_test1_Element0.GetType().GetField("MyValue");

它应该为您提供您正在谈论的 FieldInfo。