【转】编写高质量代码改善C#程序的157个建议——建议57：实现ISerializable的子类型应负责父类的序列化

建议57：实现ISerializable的子类型应负责父类的序列化

我们将要实现的继承自ISerializable的类型Employee有一个父类Person，假设Person没有实现序列化，而现在子类Employee却需要满足序列化的场景。不过序列化器并没有默认处理Person类型对象，这些事情只能由我们自己做。

以下是一个不妥的实现，序列化器只发现和处理了Employee中Salary字段：

    class Program
    {
        static void Main()
        {
            Employee  liming = new Employee() { Name = "liming", Salary = 2000 };
            BinarySerializer.SerializeToFile(liming, @"c:", "person.txt");
            Employee limingCopy = BinarySerializer.DeserializeFromFile<Employee>(@"c:person.txt");
            Console.WriteLine(string.Format("姓名：{0}", limingCopy.Name));
            Console.WriteLine(string.Format("薪水：{0}", limingCopy.Salary));
        }
    }
    
    public class Person
    {
        public string Name { get; set; }
    }

    [Serializable]
    public class Employee : Person, ISerializable
    {
        public int Salary { get; set; }

        public Employee()
        {
        }

        protected Employee(SerializationInfo info, StreamingContext context)
        {
            Salary = info.GetInt32("Salary");
        }

        public override void GetObjectData(SerializationInfo info, StreamingContext context)
        {
            info.AddValue("Salary", Salary);
        }
    }

序列化工具类：

    public class BinarySerializer
    {
        //将类型序列化为字符串
        public static string Serialize<T>(T t)
        {
            using (MemoryStream stream = new MemoryStream())
            {
                BinaryFormatter formatter = new BinaryFormatter();
                formatter.Serialize(stream, t);
                return System.Text.Encoding.UTF8.GetString(stream.ToArray());
            }
        }

        //将类型序列化为文件
        public static void SerializeToFile<T>(T t, string path, string fullName)
        {
            if (!Directory.Exists(path))
            {
                Directory.CreateDirectory(path);
            }
            string fullPath = Path.Combine(path, fullName);
            using (FileStream stream = new FileStream(fullPath, FileMode.OpenOrCreate))
            {
                BinaryFormatter formatter = new BinaryFormatter();
                formatter.Serialize(stream, t);
                stream.Flush();
            }
        }

        //将字符串反序列化为类型
        public static TResult Deserialize<TResult>(string s) where TResult : class
        {
            byte[] bs = System.Text.Encoding.UTF8.GetBytes(s);
            using (MemoryStream stream = new MemoryStream(bs))
            {
                BinaryFormatter formatter = new BinaryFormatter();
                return formatter.Deserialize(stream) as TResult;
            }
        }

        //将文件反序列化为类型
        public static TResult DeserializeFromFile<TResult>(string path) where TResult : class
        {
            using (FileStream stream = new FileStream(path, FileMode.Open))
            {
                BinaryFormatter formatter = new BinaryFormatter();
                return formatter.Deserialize(stream) as TResult;
            }
        }
    }

View Code

看见，Name字段并没有正确处理。这需要我们修改类型Employee中受保护的构造方法GetObjectData方法，为它加入父类字段的处理：

[Serializable] public class Employee : Person, ISerializable { public int Salary { get; set; } public Employee() { } protected Employee(SerializationInfo info, StreamingContext context) { Name = info.GetString("Name"); Salary = info.GetInt32("Salary"); } public void GetObjectData(SerializationInfo info, StreamingContext context) { info.AddValue("Name", Name); info.AddValue("Salary", Salary); } }

上面的例子中Person类未被设置成支持序列化。现在，假设Person类已经实现了ISerializable接口，那么这个问题处理起来会相对容易，在子类Employee中，我们只需要调用父类受保护的构造方法和GetObjectData方法就可以了。如下所示：

[Serializable] public class Person : ISerializable { public string Name { get; set; } public Person() { } protected Person(SerializationInfo info, StreamingContext context) { Name = info.GetString("Name"); } public virtual void GetObjectData(SerializationInfo info, StreamingContext context) { info.AddValue("Name", Name); } } [Serializable] public class Employee : Person, ISerializable { public int Salary { get; set; } public Employee() { } protected Employee(SerializationInfo info, StreamingContext context) : base(info, context) { Salary = info.GetInt32("Salary"); } public override void GetObjectData(SerializationInfo info, StreamingContext context) { base.GetObjectData(info, context); info.AddValue("Salary", Salary); } }

【转】编写高质量代码改善C#程序的157个建议——建议57：实现ISerializable的子类型应负责父类的序列化

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