Activator.CreateInstance

最新推荐文章于 2021-02-07 14:38:17 发布

原创最新推荐文章于 2021-02-07 14:38:17 发布 · 625 阅读

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本文介绍了一个使用C#实现的泛型工厂模式案例，通过一个私有字典存储类型映射，提供了两种方法来创建指定类型的实例，一种不带参数，另一种接受参数数组。此外，还展示了如何根据不同数据库项类型创建相应的子类实例。

   private Dictionary<Type, Type> m_ObjectType = new Dictionary<Type, Type>();


   public T CreateNewInstance<T>() where T : class
        {
            if (m_ObjectType.ContainsKey(typeof(T)))
            {
                Type insType = m_ObjectType[typeof(T)];
                return Activator.CreateInstance(insType) as T;
            }
            else
            {
                throw new Exception("未知的类型"+ typeof(T).ToString());
            }
        }

        public T CreateNewInstance<T>(params object[] args) where T:class
        {
            if (m_ObjectType.ContainsKey(typeof(T)))
            {
                Type insType = m_ObjectType[typeof(T)];
                return Activator.CreateInstance(insType, args) as T;
            }
            else
            {
                throw new Exception("未知的类型" + typeof(T).ToString());
            }
        }

   public IDatabaseItem CreateNewDatabaseItem(string name, string description, 
    DatabaseItemType tt, IDatabaseItem parent)
        {
            switch (tt)
            {
                case DatabaseItemType.Database:
                    return CreateNewInstance<DatabaseItem>(name, parent);
                case DatabaseItemType.Field:
                    return CreateNewInstance<DatabaseFieldItem>(name, description, 
                      parent);
                case DatabaseItemType.Server:
                    return CreateNewInstance<DatabaseServerItem>(name);
                case DatabaseItemType.Table:
                    return CreateNewInstance<DatabaseTableItem>(name, parent);
                default:
                    throw new Exception("未知的数据库类型");
            }
        }