Question

我想序列化android.net.Uri类型的对象的状态。

下面是我的带有writeObject和readObject方法的模型类

public class ReminderObject implements Serializable {
private boolean isReminderOn;
private int fromHours, toHours;
private int interval;
private ArrayList<CharSequence> daysToRepeat;
private Uri toneToPlay;
private AdvanceSettingsObject adv;

public ReminderObject(boolean isReminderOn, int fromHours, int toHours,
        int interval, ArrayList<CharSequence> daysToRepeat, Uri toneToPlay,
        AdvanceSettingsObject adv) {
    super();
    this.isReminderOn = isReminderOn;
    this.fromHours = fromHours;
    this.toHours = toHours;
    this.interval = interval;
    this.daysToRepeat = daysToRepeat;
    this.toneToPlay = toneToPlay;
    this.adv = adv;
} 
/*
getters and setters
*/
    public void writeObject(ObjectOutputStream op){
    try {
        op.defaultWriteObject();
        op.writeChars(toneToPlay.toString());
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}
public void readObject(ObjectInputStream in){
    try{
        in.defaultReadObject();
        toneToPlay = Uri.parse(in.readUTF());
    }catch(Exception e){

    }
}

}

MainActivity的代码段：

try {
        ObjectOutputStream os = new ObjectOutputStream(new     FileOutputStream(Environment.getExternalStorageDirectory().getAbsolutePath()+"/ReminderData.txt")    );
        os.writeObject(reminder); // Getting above mentioned Exception here
        Log.i("TAG","reminder serialized");
        ObjectInputStream is = new ObjectInputStream(new FileInputStream(Environment.getExternalStorageDirectory().getAbsolutePath()+"/ReminderData.txt"));
        ReminderObject reminderRead = (ReminderObject) is.readObject();
        if(reminderRead!=null)
            Log.i("TAG", "Deserialized Reminder object is : "+reminderRead.toString());
        else{
            Log.i("TAG", "Null received");
        }
    } catch(ClassNotFoundException cnf){
        cnf.printStackTrace();
    } catch (FileNotFoundException e) {     
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

面临异常：

03-31 23:47:59.246: W/System.err(12681): java.io.NotSerializableException: android.net.Uri$HierarchicalUri 03-31 23:47:59.246: W/System.err(12681): at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1364) 03-31 23:47:59.246: W/System.err(12681): at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1671) 03-31 23:47:59.246: W/System.err(12681): at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1517) 03-31 23:47:59.246: W/System.err(12681): at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1481) 03-31 23:47:59.246: W/System.err(12681): at java.io.ObjectOutputStream.writeFieldValues(ObjectOutputStream.java:979) 03-31 23:47:59.246: W/System.err(12681): at java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:368) 03-31 23:47:59.246: W/System.err(12681): at java.io.ObjectOutputStream.writeHierarchy(ObjectOutputStream.java:1074) 03-31 23:47:59.246: W/System.err(12681): at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1404) 03-31 23:47:59.246: W/System.err(12681): at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1671) 03-31 23:47:59.246: W/System.err(12681): at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1517) 03-31 23:47:59.246: W/System.err(12681): at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1481) 03-31 23:47:59.246: W/System.err(12681): at com.navkar.navkarreminder.SetReminderActivity.scheduleReminder(SetReminderActivity.java:595)

请求帮助。

Answer 1

我认为问题是您保存问题的数据成员。

private Uri toneToPlay是非序列化数据类型，您无法将其序列化。

Answer 2

URI private Uri toneToPlay不可序列化。因此，有另一种方法，您可以将数据类型URI更改为String，并将URI转换为字符串，将字符串转换为URI，反之亦然。

Uri to String

Uri uri;
String stringUri;
stringUri = uri.toString();

字符串到Uri

Uri uri;
String stringUri;
uri = Uri.parse(stringUri);

Answer 3

请考虑使用java.net.URI类。这具有几乎相同的功能，但它是 Serializable 。您可以轻松地从Uri转换为URI（和向后）：

Uri to URI ：new URI(uri.toString())

URI到Uri ：Uri.parse(uri.toString())

Answer 4

一种可能的解决方案是，当我们仍然希望让Uri成为成员（例如，为了方便起见）并序列化类时，就是使Uri transient并序列化Uri String（用@King of群众显示）。

通过这种方式，我们不会更改POJO的公共接口，也不会序列化Uri，从而创建了一种惰性方式。

带有Uri的可序列化POJO看起来像这样：

class MediaFile implements Serializable {

    private static final long serialVersionUID = -420L;    

    @Nullable
    private transient Uri mFileUri;

    @NonNull
    private String mFileUriString;

    MediaFile(@NonNull Uri fileUri) {
        this.mFileUriString = fileUri.toString();
    }

    @NonNull
    public getFileUri() {
        if (mFileUri == null) {
            mFileUri = Uri.parse(mFileUriString);
        }
        return mFileUri;
    }


}

对于Kotlin：

class MediaFile(uri: Uri) : Serializable {
    private val mUriString = uri.toString();
    @Transient private val mUri by lazy { Uri.parse(mUriString) }
}

序列化android.net.Uri对象

4 个答案: