5

我用一个静态方法编写了一个类，该方法将属性值从一个对象复制到另一个对象。它不关心每个对象是什么类型，只关心它们具有相同的属性。它可以满足我的需要，因此我不会对其进行进一步设计，但是您会做出哪些改进？

这是代码：

public class ShallowCopy
{
    public static void Copy<From, To>(From from, To to)
        where To : class
        where From : class
    {
        Type toType = to.GetType();
        foreach (var propertyInfo in from.GetType().GetProperties(BindingFlags.GetProperty | BindingFlags.Public | BindingFlags.Instance))
        {
            toType.GetProperty(propertyInfo.Name).SetValue(to, propertyInfo.GetValue(from, null), null);
        }
    }
}

我使用它如下：

EmployeeDTO dto = GetEmployeeDTO();
Employee employee = new Employee();
ShallowCopy.Copy(dto, employee);
4

4 回答 4

6

你的 DTO 是可序列化的吗？我希望如此，在这种情况下：

MemberInfo[] sm = FormatterServices.GetSerializableMembers(typeof(From));
object[] data = FormatterServices.GetObjectData(from, sm);
FormatterServices.PopulateObjectMembers(to, sm, data);

但请注意，我并不真正同意这种一般方法。我希望签订一份强有力的合同，以便在每个 DTO 实施的 DTO 上进行复制。

于 2009-01-22T17:09:43.033 回答
4

  • Change your type parameter names to comply with naming conventions, e.g. TFrom and TTo, or TSource and TDest (or TDestination).

  • Do most of your work in a generic type instead of in just a generic method. That allows you to cache the properties, as well as allowing type inference. Type inference is important on the "TFrom" parameter, as it will allow anonymous types to be used.

  • You could potentially make it blindingly fast by dynamically generating code to do the property copying and keeping it in a delegate which is valid for the "from" type. Or potentially generate it for every from/to pair, which would mean the actual copying wouldn't need to use reflection at all! (Preparing the code would be a one-time hit per pair of types, but hopefully you wouldn't have too many pairs.)

于 2009-01-22T17:22:25.753 回答
2

在返回之前创建新实例To并调用该Copy()方法的新方法可能很有用。

像这样：

public static To Create<From, To>(From from)
    where To : class, new()
    where From : class
{
    var to = new To();
    Copy(from, to);
    return to;
}
于 2009-01-22T17:07:17.377 回答
1

Decide what you want to do if passed objects of types that share some properties but not all. Check for the existence of the property in the From object in the To object before trying to set it's value. Do the "right thing" when you come to a property that doesn't exist. If all of the public properties need to be identical, then you will need to check if you've set all of them on the To object and handle the case where you haven't appropriately.

I'd also suggest that you may want to use attributes to decorate the properties that need to be copied and ignore others. This would allow you to go back and forth between the two different objects more easily and continue to maintain some public properties that are derived rather than stored on your business object.

于 2009-01-22T17:14:28.110 回答