android - Parcelable 从数组中获取巨大的无限项目直到 OOM

Question

我正在使用 Parcelable 在 fragment 之间进行通信。一切都运行良好，但有时当 Android 终止应用程序进程以释放内存并且用户返回到应用程序时，Parcelable 从数组中获取大量项目，例如几百万个项目而不是 2-3 个，当然它会抛出 OOM。我想 CREATOR 有问题，但我无法处理它。parcelable 的代码由父类(super class)和子类以及我感兴趣的项目类组成:

基类:

 public abstract class BaseRs implements Parcelable {

private String token;
private String msgAlert;
private String simpleMsg;
private AdsObj adsObj;    
private Map<String, String> mapSettings;

//getters & setters

public BaseRs() {
}


protected BaseRs(Parcel in) {
    token = in.readString();
    msgAlert = in.readString();
    simpleMsg = in.readString();
    adsObj = in.readParcelable(AdsObj.class.getClassLoader());
    mapSettings = MapParcelable.readParcelable(in);
}

@Override
public void writeToParcel(Parcel dest, int flags) {
    dest.writeString(token);
    dest.writeString(msgAlert);
    dest.writeString(simpleMsg);
    dest.writeParcelable(adsObj, flags);
    MapParcelable.writeToParcel(dest, mapSettings);
 }

}

子类

public class GetSalesItemsRs extends BaseRs {

private SaleCoinItem[] coinPacksArray;

//getters+ setters


protected GetSalesItemsRs(Parcel in) {
    super(in);
    coinPacksArray = in.createTypedArray(SaleCoinItem.CREATOR);
}

@Override
public void writeToParcel(Parcel dest, int flags) {
    super.writeToParcel(dest, flags);
    dest.writeTypedArray(coinPacksArray, flags);
}

@Override
public int describeContents() {
    return 0;
}

public static final Creator<GetSalesItemsRs> CREATOR = new Creator<GetSalesItemsRs>() {
    @Override
    public GetSalesItemsRs createFromParcel(Parcel in) {
        return new GetSalesItemsRs(in);
    }

    @Override
    public GetSalesItemsRs[] newArray(int size) {
        return new GetSalesItemsRs[size];
    }
    };
}

和我感兴趣的对象

public class SaleCoinItem implements Parcelable {

private int amount;
private double price;
private int sortOrder;

//getters & setters

protected SaleCoinItem(Parcel in) {
    amount = in.readInt();
    price = in.readDouble();
    sortOrder = in.readInt();
}

@Override
public void writeToParcel(Parcel dest, int flags) {
    dest.writeInt(amount);
    dest.writeDouble(price);
    dest.writeInt(sortOrder);
}

@Override
public int describeContents() {
    return 0;
}

public static final Creator<SaleCoinItem> CREATOR = new Creator<SaleCoinItem>() {
    @Override
    public SaleCoinItem createFromParcel(Parcel in) {
        return new SaleCoinItem(in);
    }

    @Override
    public SaleCoinItem[] newArray(int size) {
        return new SaleCoinItem[size];


       }
    };
}

parcel Map 的功能 - 也许这里是错误 ;)

public class MapParcelable {

public static void writeToParcel(Parcel out, Map<String, String> map) {
    if (map != null) {
        out.writeInt(map.size());
        for (Map.Entry<String, String> entry : map.entrySet()) {
            out.writeString(entry.getKey());
            out.writeString(entry.getValue());
        }
    }
}

public static Map<String, String> readParcelable(Parcel parcel) {
    Map<String, String> map = new HashMap<String, String>();
    int size = parcel.readInt();
    for (int i = 0; i < size; i++) {
        String key = parcel.readString();
        String value = parcel.readString();
        map.put(key, value);
    }

    return map;


   }

}

我在 onCreateView 方法中获取了 parcelable obj :

GetSalesItemsRs mGetSalesItemsRs = getArguments().getParcelable(KEY_PARCEL);

Answer 1

我认为问题在于，如果 Map 为 null，则您不会将大小字段写入 Parcel，但当您读取它时，您总是会读取大小字段，并且它最终可能会读取一些随机值。所以或者你把代码改成

if (map != null) {
    out.writeInt(map.size());
    for (Map.Entry<String, String> entry : map.entrySet()) {
        out.writeString(entry.getKey());
        out.writeString(entry.getValue());
    }
}else{
    out.writeInt(0);
}

并且在重新创建类时永远不会得到空值，或者您创建另一个 bool 字段“hasMap”并始终写入那个