NBear实例讲解

Nbear的接口主要是调用ObjectConvertor类的3大类方法：ToObject,ToList,ToDataTable。

主要功能：不同类型的对象可以通过类型属性的映射,进行转换，包括类与接口。对于两种类型毫无继承关系,且两种类型的数据需要转换时，Nbear是很有用的。

另外Nbear是开源代码,在类型转换的过程中,主要使用 System.Reflection.Emit;反射来取值并赋值到新对象。使用IL编程一定程度上提高了程序的效率。

要研究IL的网友，可以认真研究一下其源码。

  public interface IUser
    {

        string Name
        {
            get;
            set;
        }

        int Age
        {
            get;
            set;
        }

    }

    public class User : IUser
    {
        //需要无参数构造函数
        public User()
        {
        }
        public User(string name, int age, bool isvisible)
        {
            this.Name=name;
            this.Age=age;
            this.IsVisible=isvisible;
        }

        public string Name
        {
            get;
            set;
        }

        public int Age
        {
            get;
            set;
        }
        public bool IsVisible
        {
            get;
            set;
        }

    }

   using NBear.Mapping;
    using NBearLiteDemo.Model;
    class Program
    {
        //ObjectConvertor类:: ToObject；ToList；ToDataTable
        static void Main(string[] args)
        {
         
           
            User user=new User("Jefftary", 24, true);
            User[] users=new User[] { user,new User("Jackbaby",19,true)};
          
            User outputObject1 = ObjectConvertor.ToObject<User>(user);            
            User outputObject2 = ObjectConvertor.ToObject<IUser, User>(user);   
          
            //User-Others
            DataRow outputObject3 = ObjectConvertor.ToObject<DataRow>(user);                   
            Hashtable outputObject4 = ObjectConvertor.ToObject<Hashtable>(user);                
            NameValueCollection outputObject5 = ObjectConvertor.ToObject<NameValueCollection>(user);                
            Dictionary<string, object> outputObject6 = ObjectConvertor.ToObject<Dictionary<string, object>>(user);               
              
            //Others->User
            User outputObject31 = ObjectConvertor.ToObject<User>(outputObject3);
            User outputObject41 = ObjectConvertor.ToObject<User>(outputObject4);
            User outputObject51 = ObjectConvertor.ToObject<User>(outputObject5);     
            User outputObject61 = ObjectConvertor.ToObject<User>(outputObject5);

            object[] list=new object[] { outputObject1, outputObject2, outputObject3, outputObject4, outputObject5, outputObject6 };
            object[] list2=new object[] { outputObject31, outputObject41, outputObject51, outputObject61 };

             //Array->List<User>
            List<User> userList = ObjectConvertor.ToList<IUser, User>(users);

             //Array->DataTable->List<User>->DataTable
            DataTable userTable = ObjectConvertor.ToDataTable(users, typeof(User));
            List<User> userList1 = ObjectConvertor.ToList<DataRow, User>(userTable);
            List<User> userList2 = ObjectConvertor.ToList<IDataReader, User>(userTable);
            DataTable  userTable2=ObjectConvertor.ToDataTable(userList, typeof(User));
             

            ShowList(list,"[Object]",true);
            ShowList(list2, "[Object-Parse]", true);

            ShowList(users, "[Array]");

            ShowList(userTable, "[ToDataTable(users, typeof(User))]");
            ShowList(userList, "[ToList<IUser, User>(users)]");
           
            ShowList(userList1, "[ToList<DataRow, User>(userTable)]");
            ShowList(userList2, "[ToList<IDataReader, User>(userTable)]");            
            ShowList(userTable2, "[ToDataTable(userList, typeof(User))]");
       

            var th=Type.GetTypeHandle(3);
            
            Console.WriteLine(th);
            Console.ReadKey();
        }
        
        static void Show(object obj,bool showType=true)
        {  
            string printFormat="{0}:\r\n\t\t{1}\t{2}\t{3}\r\n";
            if(!showType)
                printFormat="\trow:\t{1}\t{2}\t{3}";

            Type type=obj.GetType(); 
            if (type.Equals(typeof(User)))
            {
                var user=obj as User;
                Console.WriteLine(string.Format(printFormat, type, user.Name, user.Age, user.IsVisible));
            }
            else
            {   
                //反射获取索引器 this[Name]
                var prop = type.GetProperty("Item", new Type[] { typeof(string) });
                if (prop!=null)
                {
                    //DataRow,Hashtable,Dictionary,NameValueCollection
                    var name= prop.GetGetMethod().Invoke(obj, new object[] { "Name" });
                    var age= prop.GetGetMethod().Invoke(obj, new object[] { "Age" });
                    var visible= prop.GetGetMethod().Invoke(obj, new object[] { "IsVisible" });
                    Console.WriteLine("this[Name]:");
                    Console.WriteLine(string.Format(printFormat, type, name, age, visible));
                }
            }
            
            //else if (type.Equals(typeof(NameValueCollection)))
            //{
            //    var nv=obj as NameValueCollection;

            //    Console.WriteLine(string.Format(printFormat, type, nv["Name"], nv["Age"], nv["IsVisible"]));
            //}
            //else if (type.Equals(typeof(DataRow)))
            //{
            //    var dr=obj as DataRow;
            //    Console.WriteLine(string.Format(printFormat, type, dr["Name"].ToString(), dr["Age"].ToString(), dr["IsVisible"].ToString()));

            //}
            //else if (typeof(IDataReader).IsAssignableFrom(type))
            //{
            //    var rd=obj as IDataReader;
            //    Console.WriteLine(string.Format(printFormat, type, rd["Name"].ToString(), rd["Age"].ToString(), rd["IsVisible"].ToString()));

            //}
            //else if (type.Equals(typeof(Dictionary<string, object>)))
            //{
            //    var dc=obj as Dictionary<string, object>;
            //    Console.WriteLine(string.Format(printFormat, type, dc["Name"].ToString(), dc["Age"].ToString(), dc["IsVisible"].ToString()));
            //}
            //else if (type.Equals(typeof(Hashtable)))
            //{
            //    var ht=obj as Hashtable;
            //    Console.WriteLine(string.Format(printFormat, type, ht["Name"].ToString(), ht["Age"].ToString(), ht["IsVisible"].ToString()));

            //}
        }

        static void ShowList(object obj,string title="",bool showType=false)
        {
            Console.WriteLine(string.Format("----------------------------{0}------------------------",title));
            Type  type=obj.GetType();
            if (type.Equals(typeof(DataTable)))
            {
                var tb=obj as DataTable;
                //for (int i=0; i<tb.Rows.Count; i++)
                //    Show(tb.Rows[i],showType);
                IDataReader reader=tb.CreateDataReader();
                while (reader.Read())
                {
                    Show(reader, showType);
                }            


            }
            else if(type.IsGenericType && typeof(IEnumerable<>).MakeGenericType(typeof(object)).IsAssignableFrom(type))
            {
                var list=obj as IEnumerable<object>;
                foreach (var item in list)
                {
                    Show(item, showType);
                }
            }
            else if (type.IsArray)
            {
                var ary=obj as Array;
                foreach (var item in ary)
                {
                    Show(item,showType);
                }
            }
        }
    

    }