FirebaseException:无法使用NodeUtilities.NodeFromJSON中的类解析节点

Question

我在Java中使用Firebase.当用户的信息必须更新时,以下简单代码始终正常工作:

final FirebaseBean_User userObject = new FirebaseBean_User(uuid, name, timestamp, points, gamesPlayed, gamesWon);
mFirebaseUser.setValue(userObject, System.currentTimeMillis());

我使用当前时间戳作为优先级值,以便我可以获得最近在线的所有用户的列表.

但是,当用户离线时,我想将其标记为离线.因此,我在中间又添加了一条简单的线:

final FirebaseBean_User userObject = new FirebaseBean_User(uuid, name, timestamp, points, gamesPlayed, gamesWon);
mFirebaseUser.onDisconnect().setValue(userObject, USER_PRIORITY_OFFLINE); // best practice: always call onDisconnect() before the actual setValue() operation to prevent ghost data
mFirebaseUser.setValue(userObject, System.currentTimeMillis());

突然这段代码停止了工作.我得到以下异常,其中引起的行(465)是中间的新行:

FATAL EXCEPTION: main
com.firebase.client.FirebaseException: Failed to parse node with class class com.my.package.MultiplayerService$FirebaseBean_User
    at com.firebase.client.snapshot.NodeUtilities.NodeFromJSON(NodeUtilities.java:130)
    at com.firebase.client.OnDisconnect.setValue(OnDisconnect.java:81)
    at com.my.package.MultiplayerService.updateUserInformation(MultiplayerService.java:465)
    at com.my.package.MultiplayerService.access$4(MultiplayerService.java:461)
    at com.my.package.MultiplayerService$1.onDataChange(MultiplayerService.java:83)
    at com.firebase.client.core.ValueListenerContainer$1.run(ValueListenerContainer.java:50)
    at android.os.Handler.handleCallback(Handler.java:605)
    at android.os.Handler.dispatchMessage(Handler.java:92)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:4514)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
    at dalvik.system.NativeStart.main(Native Method)

为什么会这样？我做错了吗？我的意思是,setValue()之前工作得很好,现在唯一的变化是我也打电话给它onDisconnect(),它停止工作.

(如果之前在该参考点有数据,则无关紧要.)

以下是用于参考的类:

private static class FirebaseBean_User {

    private String uuid;
    private String name;
    private int lastlogin;
    private double points;
    private int gamesplayed;
    private int gameswon;

    private FirebaseBean_User() { }

    public FirebaseBean_User(String uuid, String name, int lastlogin, double points, int gamesplayed, int gameswon) {
        this.uuid = uuid;
        this.name = name;
        this.lastlogin = lastlogin;
        this.points = points;
        this.gamesplayed = gamesplayed;
        this.gameswon = gameswon;
    }

    public String getUuid() {
        return uuid;
    }

    public String getName() {
        return name;
    }

    public int getLastlogin() {
        return lastlogin;
    }

    public double getPoints() {
        return points;
    }

    public int getGamesplayed() {
        return gamesplayed;
    }

    public int getGameswon() {
        return gameswon;
    }

    @Override
    public boolean equals(Object o) {
        return (o instanceof FirebaseBean_User && ((FirebaseBean_User) o).getUuid() == this.uuid);
    }

}

Answer 1

在 com.firebase.client.snapshot.NodeUtilities 类中，这似乎是一个 JSON 解析问题。

我没有找到关于此类的任何文档，但根据我使用其他序列化/解析引擎的经验，我怀疑问题出在您的FirebaseBean_User类上，因为缺少空的可访问（如公共）构造函数。

大多数解析引擎最终都会调用该Class<?>.newInstance()方法，从而实例化调用空构造函数的对象。

所以，尝试改变：

private FirebaseBean_User() { }

为了：

public FirebaseBean_User() { }