是否可以通过反思设置私有财产？

Question

我可以通过反思设置私有财产吗？

public abstract class Entity
{
    private int _id;
    private DateTime? _createdOn;
    public virtual T Id
    {
        get { return _id; }
        private set { ChangePropertyAndNotify(ref _id, value, x => Id); }
    }
    public virtual DateTime? CreatedOn
    {
        get { return _createdOn; }
        private set { ChangePropertyAndNotify(ref _createdOn, value, x => CreatedOn); }
    }
}

我已经尝试了以下它并不起作用,其中t代表一种类型Entity:

var t = typeof(Entity);
var mi = t.GetMethod("set_CreatedOn", BindingFlags.Instance | BindingFlags.NonPublic);

我想我可以做到这一点,但我无法解决这个问题.

Answer 1

是的:

/// <summary>
/// Returns a _private_ Property Value from a given Object. Uses Reflection.
/// Throws a ArgumentOutOfRangeException if the Property is not found.
/// </summary>
/// <typeparam name="T">Type of the Property</typeparam>
/// <param name="obj">Object from where the Property Value is returned</param>
/// <param name="propName">Propertyname as string.</param>
/// <returns>PropertyValue</returns>
public static T GetPrivatePropertyValue<T>(this object obj, string propName)
{
    if (obj == null) throw new ArgumentNullException("obj");
    PropertyInfo pi = obj.GetType().GetProperty(propName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
    if (pi == null) throw new ArgumentOutOfRangeException("propName", string.Format("Property {0} was not found in Type {1}", propName, obj.GetType().FullName));
    return (T)pi.GetValue(obj, null);
}

/// <summary>
/// Returns a private Property Value from a given Object. Uses Reflection.
/// Throws a ArgumentOutOfRangeException if the Property is not found.
/// </summary>
/// <typeparam name="T">Type of the Property</typeparam>
/// <param name="obj">Object from where the Property Value is returned</param>
/// <param name="propName">Propertyname as string.</param>
/// <returns>PropertyValue</returns>
public static T GetPrivateFieldValue<T>(this object obj, string propName)
{
    if (obj == null) throw new ArgumentNullException("obj");
    Type t = obj.GetType();
    FieldInfo fi = null;
    while (fi == null && t != null)
    {
        fi = t.GetField(propName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
        t = t.BaseType;
    }
    if (fi == null) throw new ArgumentOutOfRangeException("propName", string.Format("Field {0} was not found in Type {1}", propName, obj.GetType().FullName));
    return (T)fi.GetValue(obj);
}

/// <summary>
/// Sets a _private_ Property Value from a given Object. Uses Reflection.
/// Throws a ArgumentOutOfRangeException if the Property is not found.
/// </summary>
/// <typeparam name="T">Type of the Property</typeparam>
/// <param name="obj">Object from where the Property Value is set</param>
/// <param name="propName">Propertyname as string.</param>
/// <param name="val">Value to set.</param>
/// <returns>PropertyValue</returns>
public static void SetPrivatePropertyValue<T>(this object obj, string propName, T val)
{
    Type t = obj.GetType();
    if (t.GetProperty(propName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance) == null)
        throw new ArgumentOutOfRangeException("propName", string.Format("Property {0} was not found in Type {1}", propName, obj.GetType().FullName));
    t.InvokeMember(propName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.SetProperty | BindingFlags.Instance, null, obj, new object[] { val });
}

/// <summary>
/// Set a private Property Value on a given Object. Uses Reflection.
/// </summary>
/// <typeparam name="T">Type of the Property</typeparam>
/// <param name="obj">Object from where the Property Value is returned</param>
/// <param name="propName">Propertyname as string.</param>
/// <param name="val">the value to set</param>
/// <exception cref="ArgumentOutOfRangeException">if the Property is not found</exception>
public static void SetPrivateFieldValue<T>(this object obj, string propName, T val)
{
    if (obj == null) throw new ArgumentNullException("obj");
    Type t = obj.GetType();
    FieldInfo fi = null;
    while (fi == null && t != null)
    {
        fi = t.GetField(propName, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
        t = t.BaseType;
    }
    if (fi == null) throw new ArgumentOutOfRangeException("propName", string.Format("Field {0} was not found in Type {1}", propName, obj.GetType().FullName));
    fi.SetValue(obj, val);
}

Answer 2

t.GetProperty("CreatedOn")
    .SetValue(obj, new DateTime(2009, 10, 14), null);

编辑:由于该属性本身是公共的,你显然不需要BindingFlags.NonPublic用来找到它.SetValue尽管setter具有较少的可访问性,但仍然可以按照您的预期进行调用.

Answer 3

您可以通过代码从派生类型访问私有setter

public static void SetProperty(object instance, string propertyName, object newValue)
{
    Type type = instance.GetType();

    PropertyInfo prop = type.BaseType.GetProperty(propertyName);

    prop.SetValue(instance, newValue, null);
}

Answer 4

这些都不适合我，而且我的属性名称是唯一的，所以我只使用了这个：

public static void SetPrivatePropertyValue<T>(T obj, string propertyName, object newValue)
{
    // add a check here that the object obj and propertyName string are not null
    foreach (FieldInfo fi in obj.GetType().GetFields(BindingFlags.Instance | BindingFlags.NonPublic))
    {
        if (fi.Name.ToLower().Contains(propertyName.ToLower()))
        {
            fi.SetValue(obj, newValue);
            break;
        }
    }
}