问题
I'm developing an app that works with data block classes inheritied from a base class and I am trying to use Reflection to drill down to properties/fields in my data block class. Since all the data block classes are derived/inherited from the base class (which contains a Size property) I can use a general variable of type base class to create an object in my app easily enough; I can also get/set properties at a top level. My problem occurs when the property is a field - I do not know how to get to the next level in the field to get to the base properties and/or fields, if applicable.
My BaseClass:
namespace MyBase {
public class BaseClass {
private int _size;
public BaseClass() { }
public BaseClass(int size) {
_size = size;
}
public int Size() {
return _size;
}
}
}
Data block class #1:
namespace DataBlock_class {
//Data block class #1: (contains simple properties - will be used later)
public class RecordBlock1_class : MyBase.BaseClass {
public byte Char { get; set; }
public byte Color { get; set; }
public RecordBlock1_class() : base(2) {
Char = 0;
Color = 0;
}
}
//Data block class #2: (contains simple properties)
public RecordBlock2_class : MyBase.BaseClass {
public bool Boolean1 { get; set; }
public byte Byte1 { get; set; }
public short Short1 { get; set; }
public ushort UShort1 { get; set; }
public RecordBlock2_class() : base(11) {
Boolean1 = false;
Byte1 = 0;
Short1 = 0;
UShort1 = 0;
}
}
//Data block class #3: (contains simple properties & fields)
public RecordBlock3_class : MyBase.BaseClass {
public int Int1 { get; set; }
public uint UInt1 { get; set; }
public RecordBlock1_class[] ArrayField1 { get; set; } // array of 12
public RecordBlock1_class[] ArrayField2 { get; set; } // array of 12
public RecordBlock1_class[] ArrayField3 { get; set; } // array of 12
public RecordBlock2_class() : base(34) {
Int1 = 0;
UInt1 = 0;
ArrayField1 = new RecordBlock1_class[12];
for(int x = 0; x < 12; x++) {
ArrayField1[x] = new RecordBlock1_class();
}
ArrayField2 = new RecordBlock1_class[12];
for(int x = 0; x < 12; x++) {
ArrayField2[x] = new RecordBlock1_class();
}
ArrayField3 = new RecordBlock1_class[12];
for(int x = 0; x < 12; x++) {
ArrayField3[x] = new RecordBlock1_class();
}
}
}
}
Since all my data block classes derive/inherit from MyBase.BaseClass, I can use this for my variable - I do not what type of data block class I will be processing at run time.
in my C# app, I have the following block of code:
string CSharpQualifiedName = "<this could be any of the data block classes above>";
// DataBlock_class.RecordBlock1_class
// DataBlock_class.RecordBlock2_class
// DataBlock_class.RecordBlock3_class
Using my MyBase.BaseClass variable, I can then instantiate a MyBase.BaseClass object:
MyBase.BaseClass baseClass = null;
Type baseClassType = Type.GetType(CSharpQualifiedName);
if(baseClassType == null) {
foreach(Assembly asm in AppDomain.CurrentDomain.GetAsseblies()) {
baseClassType= asm.GetType(CSharpQualifiedName);
if(baseClassType != null) {
baseClass = Activator.CreateInstance(baseClassType) as MyBase.BaseClass;
break;
}
}
}
Dealing with the first two data block classes are easy enough - I can using PropertyInfo to get/set values.
string fieldProperty = "<any property in the class>";
PropertyInfo pi = baseClass.GetType().GetProperty(fieldProperty);
Now, my proplem/issue is RecordBlock3_class - How do I get to one of the items in any of array fields/properties AND then to the Char/Color property in RecordBlock1_class???
I can use FieldInto to get to the ArrayFieldX fields, but I'm lost after that?
FieldInfo fi = baseClass.GetType().GetField(fieldProperty);
Any assistance/advice is greatly appreicated!! I will say one more thing, the data block classes can get a bit more complex as users create more nested class structures.
回答1:
You can get element type of the array property by Reflection also, and then get its properties normally:
string fieldProperty = "ArrayField1";
System.Reflection.PropertyInfo pi = baseClass.GetType().GetProperty(fieldProperty);
if (pi.PropertyType.IsArray)
{
Type elementType = pi.PropertyType.GetElementType();
System.Reflection.PropertyInfo pi2 = elementType.GetProperty("Color");
}
Based on that, you can write simple yet more generic function that is traversing nested properties (to use also fields, simply modify below code):
static System.Reflection.PropertyInfo GetProperty(Type type, string propertyPath)
{
System.Reflection.PropertyInfo result = null;
string[] pathSteps = propertyPath.Split('/');
Type currentType = type;
for (int i = 0; i < pathSteps.Length; ++i)
{
string currentPathStep = pathSteps[i];
result = currentType.GetProperty(currentPathStep);
if (result.PropertyType.IsArray)
{
currentType = result.PropertyType.GetElementType();
}
else
{
currentType = result.PropertyType;
}
}
return result;
}
and then you can 'query' objects with 'paths':
PropertyInfo pi = GetProperty(c1.GetType(), "ArrayField1/Char");
PropertyInfo pi2 = GetProperty(c2.GetType(), "Color");
If you want to get values of object in this way, a method will be similar:
static object GetPropertyValue(object obj, string propertyPath)
{
System.Reflection.PropertyInfo result = null;
string[] pathSteps = propertyPath.Split('/');
object currentObj = obj;
for (int i = 0; i < pathSteps.Length; ++i)
{
Type currentType = currentObj.GetType();
string currentPathStep = pathSteps[i];
var currentPathStepMatches = Regex.Match(currentPathStep, @"(\w+)(?:\[(\d+)\])?");
result = currentType.GetProperty(currentPathStepMatches.Groups[1].Value);
if (result.PropertyType.IsArray)
{
int index = int.Parse(currentPathStepMatches.Groups[2].Value);
currentObj = (result.GetValue(currentObj) as Array).GetValue(index);
}
else
{
currentObj = result.GetValue(currentObj);
}
}
return currentObj;
}
And then you can get values queries, including arrays, for example:
var v = GetPropertyValue(baseClass, "ArrayField1[5]/Char");
Of course both methods requires some polishing of error handling etc.
来源：https://stackoverflow.com/questions/19936888/c-sharp-developing-net3-5-using-reflection-to-get-set-values-to-nested-properti