用xpo實現dc技術的關鍵點-XPO是如何處理接口類型與真實類型的對應關系的

文章出處

https://www.devexpress.com/Support/Center/Question/Details/Q487000/xpodatamodel-and-model-interfaces

代碼來自于上面的網址,這個代碼功能是xpo解析類型信息時,可以有個中轉.

這也成了xaf中dc機制的一個關鍵點,即,接口信息需要有一個真實的對應類型信息才行.

也說是說,接口類型只是一個公開給程序員的信息,ta必須對應一個真實的classinfo,這個classinfo用于xpo解析真實的表\字段\表達式等其他元數據時使用.

 public class InterfaceAsForcedAliasHelper {
            public InterfaceAsForcedAliasHelper() { }
            public InterfaceAsForcedAliasHelper(ReflectionDictionary dictionary)
                : this() {
                Help(dictionary);
            }
            public void Help(ReflectionDictionary dictionary) {
                dictionary.CanGetClassInfoByTypeHandler += new EventHandler<CanGetClassInfoByTypeEventArgs>(canGet);
                dictionary.ResolveClassInfoByTypeHandler += new EventHandler<ResolveClassInfoByTypeEventArgs>(resolve);
            }
            Dictionary<Type, Type> map = new Dictionary<Type, Type>();
            public void Map(Type interfaceType, Type actualClassInfoType) {
                map.Add(interfaceType, actualClassInfoType);
            }
            void canGet(object sender, CanGetClassInfoByTypeEventArgs e) {
                if(e.CanGetClassInfo.HasValue)
                    return;
                if(map.ContainsKey(e.ClassType))
                    e.CanGetClassInfo = true;
            }
            void resolve(object sender, ResolveClassInfoByTypeEventArgs e) {
                if(e.ClassInfo != null)
                    return;
                Type mapType;
                if(map.TryGetValue(e.ClassType, out mapType)) {
                    if(mapType != null && mapType != e.ClassType) {
                        e.ClassInfo = e.Dictionary.QueryClassInfo(mapType);
                    }
                }
            }
        }

            ReflectionDictionary myDictionary = new ReflectionDictionary();
            InterfaceAsForcedAliasHelper helper = new InterfaceAsForcedAliasHelper(myDictionary);
            helper.Map(typeof(IInterfaceAsForcedAliasTestPerson), typeof(InterfaceAsForcedAliasTestPerson));
            IDataLayer dl = new SimpleDataLayer(myDictionary, new InMemoryDataStore());