.NET 中的序列化
序列化(serialization)就是把对象的当前状态(字段及其值)转换数据流,可以把得到的数据流存放到文件、数据库、内存或其它地方;然后在我们需要时,使用反序列化(deserialization)将对象恢复。在.Net中,要序列化一个对象,可以使用属性将类的元素标为可序列化的(Serializable)和不可被序列化的(NonSerialized)。通过SoapFormatter(基于XML)和BinaryFormatter可以得到不同的数据流格式。
一、可序列化(Serializable)和不可序列化(NonSerialized)属性
如果允许一个类序列化,需要在类上标记[Serializeble]属性
[Serializable] //通过标记该属性,说明此类可以被序列化
public class User
{
private int id;
private string name;
[NonSerialized] //标记该属性后,email字段将不会被序列化
private string email;
public User(int id, string name, string email)
{
this.id = id;
this.name = name;
this.email = email;
}
}
public class User
{
private int id;
private string name;
[NonSerialized] //标记该属性后,email字段将不会被序列化
private string email;
public User(int id, string name, string email)
{
this.id = id;
this.name = name;
this.email = email;
}
}
如果一个可序列化的类包含了对另一个类的引用,那么被引用的类也必须支持序列化
[Serializable] //通过标记该属性,说明此类可以被序列化
public class User
{
private int id;
private string name;
private Contact contact; //引用了一个类
public User(int id, string name, string email)
{
this.id = id;
this.name = name;
this.email = email;
}
}
[Serializable]
public class Contact
{
private string email;
private string qq;
private string msn
}
public class User
{
private int id;
private string name;
private Contact contact; //引用了一个类
public User(int id, string name, string email)
{
this.id = id;
this.name = name;
this.email = email;
}
}
[Serializable]
public class Contact
{
private string email;
private string qq;
private string msn
}
二、SoapFormatter和BinaryFormatter
下面的代码分别使用SoapFormatter和BinaryFormatter将User类序列化到文件中:
namespace SerializApp
{
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters.Soap;
using System.Runtime.Serialization.Formatters.Binary;
class Program
{
static void Main(string[] args)
{
User user = new User(1001, "netflu", "netflu@msn.com");
FileStream mySoap = File.Create(@"C:\Soap_user.txt");
new SoapFormatter().Serialize(mySoap, user);
mySoap.Close();
FileStream myBinary = File.Create(@"C:\Binary_user.dat");
new BinaryFormatter().Serialize(myBinary, user);
myBinary.Close();
}
}
[Serializable]
public class User
{
private int id;
private string name;
[NonSerialized]
private string email;
public User(int id, string name, string email)
{
this.id = id;
this.name = name;
this.email = email;
}
}
}
{
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters.Soap;
using System.Runtime.Serialization.Formatters.Binary;
class Program
{
static void Main(string[] args)
{
User user = new User(1001, "netflu", "netflu@msn.com");
FileStream mySoap = File.Create(@"C:\Soap_user.txt");
new SoapFormatter().Serialize(mySoap, user);
mySoap.Close();
FileStream myBinary = File.Create(@"C:\Binary_user.dat");
new BinaryFormatter().Serialize(myBinary, user);
myBinary.Close();
}
}
[Serializable]
public class User
{
private int id;
private string name;
[NonSerialized]
private string email;
public User(int id, string name, string email)
{
this.id = id;
this.name = name;
this.email = email;
}
}
}
使用SoapFormatter得到的数据流(Soap_user.txt):
<SOAP-ENV:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:clr="http://schemas.microsoft.com/soap/encoding/clr/1.0" SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
<SOAP-ENV:Body>
<a1:User id="ref-1" xmlns:a1="http://schemas.microsoft.com/clr/nsassem/SerializApp/SerializApp%2C%20Version%3D1.0.0.0%2C%20Culture%3Dneutral%2C%20PublicKeyToken%3Dnull">
<id>1001</id>
<name id="ref-3">netflu</name>
</a1:User>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
<SOAP-ENV:Body>
<a1:User id="ref-1" xmlns:a1="http://schemas.microsoft.com/clr/nsassem/SerializApp/SerializApp%2C%20Version%3D1.0.0.0%2C%20Culture%3Dneutral%2C%20PublicKeyToken%3Dnull">
<id>1001</id>
<name id="ref-3">netflu</name>
</a1:User>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
使用BinaryFormatter得到的数据流(Binary_user.dat):
BSerializApp, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null SerializApp.User idname ? netflu
通过对SoapFormatter和BinaryFormatter输出的数据流进行观察,可以发现他们各有优缺点,Soap的可读性高,而Binary的数据量小。
三、自定义序列化
如果要精确控制对象的序列化,需要实现ISerializable接口
//ISerializable接口原型
public interface ISerializable
{
void GetObjectData(System.Runtime.Serialization.SerializationInfo info, System.Runtime.Serialization.StreamingContext context)
}
public interface ISerializable
{
void GetObjectData(System.Runtime.Serialization.SerializationInfo info, System.Runtime.Serialization.StreamingContext context)
}
以下是一个实现了ISerializable接口的类:
[Serializable]
public class User : ISerializable
{
private int id;
private string name;
private string email;
public User(int id, string name, string email)
{
this.id = id;
this.name = name;
this.email = email;
}
private User(SerializationInfo info, StreamingContext context)
{
this.id = info.GetInt32("id");
this.name = info.GetString("name");
this.email = info.GetString("email");
}
ISerializable 成员
}
public class User : ISerializable
{
private int id;
private string name;
private string email;
public User(int id, string name, string email)
{
this.id = id;
this.name = name;
this.email = email;
}
private User(SerializationInfo info, StreamingContext context)
{
this.id = info.GetInt32("id");
this.name = info.GetString("name");
this.email = info.GetString("email");
}
ISerializable 成员
}
主要通过SerializationInfo对象提供的AddValue方法通过键值对来保存一个值,然后通过一系列GetValue方法来取出值。