Java 自定义序列化

Question

我有一个对象，其中包含一些我想要序列化的不可序列化字段。它们来自一个我无法更改的单独 API，因此不能将它们设为可序列化。主要问题是 Location 类。它包含四个我需要的可以序列化的东西，都是整数。如何使用 read/writeObject 来创建可以执行以下操作的自定义序列化方法:

// writeObject:
List<Integer> loc = new ArrayList<Integer>();
loc.add(location.x);
loc.add(location.y);
loc.add(location.z);
loc.add(location.uid);
// ... serialization code

// readObject:
List<Integer> loc = deserialize(); // Replace with real deserialization
location = new Location(loc.get(0), loc.get(1), loc.get(2), loc.get(3));
// ... more code

我该怎么做？

Answer 1

Java 支持 Custom Serialization .阅读自定义默认协议(protocol)部分。

引用:

There is, however, a strange yet crafty solution. By using a built-in feature of the serialization mechanism, developers can enhance the normal process by providing two methods inside their class files. Those methods are:

• private void writeObject(ObjectOutputStream out) throws IOException;
• private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException;

在这种方法中，如果需要，您可以将其序列化为其他形式，例如您说明的位置的 ArrayList 或 JSON 或其他数据格式/方法，然后在 readObject() 上重新构建它

在您的示例中，您添加以下代码:

private void writeObject(ObjectOutputStream oos)
throws IOException {
    // default serialization 
    oos.defaultWriteObject();
    // write the object
    List loc = new ArrayList();
    loc.add(location.x);
    loc.add(location.y);
    loc.add(location.z);
    loc.add(location.uid);
    oos.writeObject(loc);
}

private void readObject(ObjectInputStream ois)
throws ClassNotFoundException, IOException {
    // default deserialization
    ois.defaultReadObject();
    List loc = (List)ois.readObject(); // Replace with real deserialization
    location = new Location(loc.get(0), loc.get(1), loc.get(2), loc.get(3));
    // ... more code

}