序列化与HashCode..

在前一个文章序列化对象 :)中,我提到了
在这里,我使用了序列化,因为序列化的一个好处就是可以还原原始的HashCode,
即,序列化前的对象的GetHashCode()的返回值和序列化后还原的GetHashCode()的返回值是一样的:)

但是,我今天刚刚试了一下,发现不是这样的..示例代码如下:

using System;
using System.IO;
using System.Text;
using System.Collections;
using System.Runtime.Serialization.Formatters.Binary;

namespace TestForMapfile_Write
{
    /**//// <summary>
    /// Summary description for Class1.
    /// </summary>
    class Class1
    {
        /**//// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main(string[] args)
        {
            Console.WriteLine("please input p / c or x / y: ");
            SharedMemory sm = new SharedMemory();
            SharedMemory smClient;
            SharedMemory smHT;
            Client client;
            object obj;
            switch( Console.ReadLine()) 
            {            
                case "p":
                case "P":                
                    sm.Create( 10240,"Tiger");
                    client = new Client();
                    Console.WriteLine( client.GetHashCode());
                    client = new Client();
                    client.email = "tiger@msn.com";
                    client.id = 0;
                    client.name = "tiger";
                    sm.CopyFrom( Ser(client).ToArray());
                    Console.WriteLine( client.GetHashCode());
                    Console.WriteLine("ok");
                    Console.ReadLine();
                    break;
                case "c":
                case "C":
                    sm.Open( 10240,"Tiger");
                    MemoryStream ms = new MemoryStream( sm.CopyTo(0));
                    obj = Deser(ms);
                    Console.WriteLine( obj.GetHashCode());
                    Console.WriteLine("ok");
                    Console.ReadLine();
                    break;

                case "x":
                case "X":
                    smHT = new SharedMemory(10234,"smht");
                    smClient = new SharedMemory(10234,"smClient");
                    Hashtable ht = new Hashtable();
                    obj = new Client(1,"tiger","hh");
                    smClient.CopyFrom( Ser(obj).ToArray());
                    ht.Add( obj,1);
                    obj = new Client( 2,"unrule","unruldem");
                    smClient.CopyFrom( Ser(obj).ToArray());
                    ht.Add( obj,2);
                    smHT.CopyFrom( Ser(ht).ToArray());
                    Console.WriteLine("OK");
                    Console.ReadLine();
                    break;
                case "y":
                case "Y":
                    smHT = new SharedMemory();
                    smHT.Open(10234,"smht");
                    obj = Deser( new MemoryStream( smHT.CopyTo(0)));
                    smClient = new SharedMemory();
                    smClient.Open( 10234,"smClient");
                    object obj1 = Deser( new MemoryStream( smClient.CopyTo(0)));
                    if( ((Hashtable)obj).ContainsKey( (Client)obj1)){
                        Console.WriteLine("win");
                    }
                    else{
                        Console.WriteLine("Fail");
                    }
                    foreach( DictionaryEntry  i in (Hashtable)obj){
                        Console.WriteLine( ((Client)i.Key).id);
                    }
                    Console.ReadLine();
                    break;
            }
        }

        public static MemoryStream Ser(object obj){
            MemoryStream ms = new MemoryStream();
            BinaryFormatter formatter = new BinaryFormatter();
            formatter.Serialize(ms,obj);
            return ms;
        }

        public static object Deser(MemoryStream ms){
            BinaryFormatter formatter = new BinaryFormatter();
            return formatter.Deserialize(ms);
        }
    }

    [Serializable]
    class Client{
        public int id;
        public string name;
        public string email;

        public Client(){}
        public Client(int ID,string Name,string Email){
            id = ID;
            name = Name;
            email = Email;
        }
    }
}

注意:使用的时候加入前面的.NET中使用Mapping File 的API :)中提到了SharedMemory类
运行时分别运行两个,一个输入X,一个输入Y

这里,我把两个Client对象放到一个Hashtable中,再分别把这些个对象序列化,通过MappingFile传给另一个EXE程序.
再反序列化.结果,输出的是Fail,但是Hashtable中确实是有原始的Client对象..

结论:
通过这个例子,我发现,HashCode是和程序运行相关的,是相对于这个程序在当前运行期是唯一的.
所以了,我们如果想要把一个对象做为Hashtable中的Key同时把这个对象和这个Hashtable传给其它的应用程序(比如上面示例中的Client和Hashtalbe).请注意其对象的HashCode.:)

如果一定要传Hashtable过去.那么只要这个Hashtable的Key是.NET内置的数据类型,那照样可以正常使用:)

so,我前面文章中提到的那个结论(最上面有写)是错的.希望大家在使用中注意一下子.Have a good luck~