问序列化可绘制文件时出现问题

EN

public class MyObject implements Serializable {

    private static final long serialVersionUID = 1L;
    public String name;
    public String lastName;
    public Drawable photo;

    public MyObject() {
    }

    public MyObject(String name, String lastName, Drawable photo) {

        this.name = name;
        this.lastName = lastName;
        this.photo = photo;
    }
}

02-02 23:06:10.825: WARN/System.err(13891): java.io.NotSerializableException: android.graphics.drawable.BitmapDrawable

public static void saveArrayList(ArrayList<MyObject> arrayList, Context context) {

    final File file = new File(context.getCacheDir(), FILE_NAME);
    FileOutputStream outputStream = null;
    ObjectOutputStream objectOutputStream = null;

    try {
        outputStream = new FileOutputStream(file);
        objectOutputStream  = new ObjectOutputStream(outputStream);

        objectOutputStream.writeObject(arrayList);
    }

    catch(Exception e) {
        e.printStackTrace();
    }
    finally {
        try {
            if(objectOutputStream != null) {
                objectOutputStream.close();
            }
            if(outputStream != null) {
                outputStream.close();
            }
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }
}