WCF 序列化機制全比較：DataContract、Xml、JSON、Soap、Binary 五大序列化器特性與效能

WCF 透過序列化將物件圖轉換為傳輸格式，支援多種序列化器，各有適用場景。本文詳細比較 DataContractSerializer、XmlSerializer、DataContractJsonSerializer、SoapFormatter、BinaryFormatter 五大序列化器的特性、輸出格式與效能特徵。

五大序列化器快速比較

實體類別定義與屬性標記

DataContract / DataMember

[DataContract(Namespace = "https://webabcd.cnblogs.com/")]
public class DataContractSerializerObject {
    [DataMember(Name = "UniqueID", Order = 0)] public Guid ID { get; set; }
    [DataMember(Order = 1)] public string Name { get; set; }
    [DataMember(Order = 2)] public int Age { get; set; }
    [DataMember(Order = 3)] public DateTime Time { get; set; }
}

• Namespace：XML 命名空間
• Name：序列化後的元素名稱
• Order：序列化順序 (字母序預設)
• IsRequired、EmitDefaultValue 等進階選項

XmlSerializer 屬性

[XmlRoot(Namespace = "https://webabcd.cnblogs.com/")]
public class XmlSerializerObject {
    [XmlElement(ElementName = "UniqueID", Order = 0)] public Guid ID { get; set; }
    [XmlElement(Order = 1)] public string Name { get; set; }
    [XmlElement(Order = 2)] public int Age { get; set; }
    [XmlElement(Order = 3)] public DateTime Time { get; set; }
}

JSON 序列化

[DataContract(Namespace = "https://webabcd.cnblogs.com/")]
public class DataContractJsonSerializerObject {
    [DataMember(Name = "UniqueID", Order = 0)] public Guid ID { get; set; }
    [DataMember(Order = 1)] public string Name { get; set; }
    [DataMember(Order = 2)] public int Age { get; set; }
    [DataMember(Order = 3)] public DateTime Time { get; set; }
}

Soap/Binary Formatter：只需 [Serializable]

[Serializable]
public class SoapFormatterObject {
    public Guid ID { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
    public DateTime Time { get; set; }
}

序列化/反序列化程式碼範例

DataContractSerializer

var obj = new DataContractSerializerObject { 
    ID = Guid.NewGuid(), Name = "DataContractSerializer", Age = 28, Time = DateTime.Now 
};
var serializer = new DataContractSerializer(typeof(DataContractSerializerObject));

// 序列化
var ms = new MemoryStream();
serializer.WriteObject(ms, obj);
ms.Position = 0;
string xml = new StreamReader(ms).ReadToEnd();

// 反序列化
var buffer = Encoding.UTF8.GetBytes(xml);
var ms2 = new MemoryStream(buffer);
var obj2 = serializer.ReadObject(ms2) as DataContractSerializerObject;

XmlSerializer

var serializer = new XmlSerializer(typeof(XmlSerializerObject));
serializer.Serialize(ms, obj); // 序列化
var obj2 = serializer.Deserialize(ms2) as XmlSerializerObject; // 反序列化

SoapFormatter

var formatter = new SoapFormatter();
formatter.Serialize(ms, obj);
string soap = Encoding.UTF8.GetString(ms.GetBuffer());
var obj2 = formatter.Deserialize(ms2) as SoapFormatterObject;

BinaryFormatter

var formatter = new BinaryFormatter();
formatter.Serialize(ms, obj);
byte[] binary = ms.GetBuffer(); // 二進位位元組陣列
var obj2 = formatter.Deserialize(ms2) as BinaryFormatterObject;

DataContractJsonSerializer

var serializer = new DataContractJsonSerializer(typeof(DataContractJsonSerializerObject));
serializer.WriteObject(ms, obj);
string json = new StreamReader(ms).ReadToEnd();
var obj2 = serializer.ReadObject(ms2) as DataContractJsonSerializerObject;

實際輸出格式比較

DataContractSerializer (XML)

<DataContractSerializerObject xmlns="https://webabcd.cnblogs.com/" xmlns:i="https://www.w3.org/2001/XMLSchema-instance">
  <UniqueID>86148742-ef08-4d78-acab-ce393ea8b885</UniqueID>
  <Name>DataContractSerializer</Name>
  <Age>28</Age>
  <Time>2008-04-24T09:06:23.875+08:00</Time>
</DataContractSerializerObject>

XmlSerializer (XML)

<?xml version="1.0"?>
<XmlSerializerObject xmlns:xsi="..." xmlns:xsd="..." xmlns="https://webabcd.cnblogs.com/">
  <UniqueID>15efa47f-9532-4e91-8c00-3097ea976106</UniqueID>
  <Name>XmlSerializer</Name>
  <Age>28</Age>
  <Time>2008-04-24T09:06:24.109375+08:00</Time>
</XmlSerializerObject>

SoapFormatter (SOAP XML)

<SOAP-ENV:Envelope ...>
  <SOAP-ENV:Body>
    <a1:SoapFormatterObject id="ref-1" ...>
      <_x003C_ID_x003E_k__BackingField>...</_x003C_ID_x003E_k__BackingField>
      <_x003C_Name_x003E_k__BackingField>ShowSoapFormatter</_x003C_Name_x003E_k__BackingField>
      ...
    </a1:SoapFormatterObject>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

BinaryFormatter (二進位，Base64 顯示)

AAEAAAD/////AQAAAAAAAAAMAgAAAFdDRi5TZXJ2aWNlTGliLCBWZXJzaW9uPTEuMC4wLjAsIEN1bHR1cmU9bmV1dHJhbCwgUHVibGljS2V5VG9rZW49bnVsbAUBAAAIQ1dGLlNlcnZpY2VMaWIuU2VyaWFsaXphdGlvbi5CaW5hcnlGb3JtYXR0ZXJPYmplY3QEAAAAHgQAAAAJAwAAAAcICQg=

DataContractJsonSerializer (JSON)

{"UniqueID":"f4173d7d-9555-4dcb-8db7-62b85315d3f1","Name":"DataContractJsonSerializer","Age":28,"Time":"\/Date(1208999184531+0800)\/"}

關鍵差異深度分析

版本容忍度

• DataContract/JSON：IsRequired=false (預設) 允許缺少欄位；EmitDefaultValue=false 可省略預設值；支援 OnSerializing/OnDeserialized 回調
• XmlSerializer：需標記 XmlElement(IsNullable=true) 或使用 DefaultValue 屬性
• Soap/Binary：嚴格要求欄位完全相容，新增/移除欄位會導致反序列化失敗

效能特徵

• BinaryFormatter：體積最小、速度最快，但輸出不可讀、跨平台差
• DataContractSerializer：針對 WCF 優化，流式處理、支援 XML 讀寫器
• XmlSerializer：啟動時需動態生成序列化組件 (sgen.exe 可預編譯)
• SoapFormatter：冗長 SOAP 封裝，效能最差，已淘汰

安全性考量

• BinaryFormatter/SoapFormatter：極度危險，反序列化任意型別可導致 RCE (CVE-2017-0213 等)，生產環境嚴禁使用
• DataContract/JSON/Xml：僅反序列化已知型別，相對安全

選型建議

現代化替代方案

.NET Core / .NET 5+ 建議使用：

• System.Text.Json：高效能 JSON，內建支援，取代 DataContractJsonSerializer
• MessagePack、Protobuf：二進位高效能，跨語言支援佳
• XmlSerializer 仍支援但不再是首選

序列化器的選擇直接影響服務的互通性、效能、安全性與維護性，應根據傳輸協定、客戶端類型與版本演進策略綜合評估。