可序列化的非可序列化父类的子类

Question

我正在使用android/java中的Location子类序列化打砖块

位置不可序列化.我有一个名为FALocation的第一个子类,它没有任何实例变量.我已声明它可序列化.

然后我有一个名为Waypoint的第二个类看起来像这样:

public class Waypoint extends FALocation implements Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    /* Class variables *******************************************************/
    private static int CLASS_VERSION=1; //Used to version parcels

    /* Instance variables ****************************************************/
    private transient String type=DataHelper.PT_TYPE_US;
    private transient String country; 
    private transient String name=null;
    private transient String description=null;
    private transient int elevation = 0;
    private transient int population = 0; // Afterthought, added to match the DB structure

    /* Constructors **********************************************************/    
    public Waypoint() {
        super();
    }

    public Waypoint(double lat, double lon, String name, String description) {
        super(lat, lon);
        this.setName(name);
        this.setDescription(description);
    }

    public Waypoint(Location l) {
        super(l);
    }

    public Waypoint(String provider) {
        super(provider);
    }


    /* Implementing serializable */
    private void writeObject(java.io.ObjectOutputStream out) throws IOException {
        Log.v("DroidFA", "Serialising \"%s\" (v%d).", Waypoint.class.getSimpleName(), CLASS_VERSION);
        out.writeInt(CLASS_VERSION);

        out.writeObject(type);
        out.writeObject(country);
        out.writeObject(name);
        out.writeObject(description);
        out.writeInt(elevation);
        out.writeInt(population);
    }

    private void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException {

        int serialClassVersion = in.readInt();
        Log.v("DroidFA", "Deserialising \"%s\" (v%d).", Waypoint.class.getSimpleName(),serialClassVersion);

        type = (String) in.readObject();
        country = (String) in.readObject();
        name = (String) in.readObject();
        description = (String) in.readObject();
        elevation = in.readInt();
        population = in.readInt();
    }
}

序列化工作正常.

Deseriamization产生跟随异常(leg对象包含一个航点):

10-05 13:50:35.259: WARN/System.err(7867): java.io.InvalidClassException: android.location.Location; IllegalAccessException
10-05 13:50:35.267: WARN/System.err(7867):     at java.io.ObjectInputStream.resolveConstructorClass(ObjectInputStream.java:2010)
10-05 13:50:35.267: WARN/System.err(7867):     at java.io.ObjectInputStream.readNewObject(ObjectInputStream.java:2095)
10-05 13:50:35.267: WARN/System.err(7867):     at java.io.ObjectInputStream.readNonPrimitiveContent(ObjectInputStream.java:929)
10-05 13:50:35.267: WARN/System.err(7867):     at java.io.ObjectInputStream.readObject(ObjectInputStream.java:2285)
10-05 13:50:35.278: WARN/System.err(7867):     at java.io.ObjectInputStream.readObject(ObjectInputStream.java:2240)
10-05 13:50:35.278: WARN/System.err(7867):     at com.droidfa.navigation.Leg.readObject(Leg.java:262)
.../...

Answer 1

是否绝对有必要序列化位置？也许你可以将它标记为瞬态,并在反序列化对象后动态获取它.(无论如何,从文档中):

问:如果A类没有实现Serializable但是子类B实现了Serializable,那么当B被序列化时,A类的字段会被序列化吗？

答:只写出并恢复Serializable对象的字段.仅当对象具有将初始化非可序列化超类型字段的无参数构造函数时,才可以恢复该对象.如果子类可以访问超类的状态,它可以实现writeObject和readObject来保存和恢复该状态.

因此,如果子类可以访问其非可序列化超类的字段,则可以使用writeObject和readObject协议来实现序列化.否则,将存在无法序列化的字段.