使用gson保存数据和mediaplayer服务获取错误

时间：2016-12-31 16:46:21

标签： android arraylist android-service android-sharedpreferences gson

我正在关注音频播放器的this教程。我可以在服务中播放歌曲。但是当我尝试使用gson保存歌曲并将arraylist发送到服务但是当我点击列表时项目应用程序崩溃错误

FATAL EXCEPTION: main
              Process: com.example.neelay.level95, PID: 15133
              java.lang.RuntimeException: Unable to start service com.example.neelay.level95.MediaPlayerService@79fde5a with Intent { cmp=com.example.neelay.level95/.MediaPlayerService }: java.lang.RuntimeException: Failed to invoke private android.net.Uri() with no args
                  at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3034)
                  at android.app.ActivityThread.access$2200(ActivityThread.java:153)
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1449)
                  at android.os.Handler.dispatchMessage(Handler.java:102)
                  at android.os.Looper.loop(Looper.java:148)
                  at android.app.ActivityThread.main(ActivityThread.java:5441)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:738)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:628)
               Caused by: java.lang.RuntimeException: Failed to invoke private android.net.Uri() with no args
                  at com.google.gson.internal.ConstructorConstructor$3.construct(ConstructorConstructor.java:111)
                  at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:210)
                  at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:129)
                  at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:220)
                  at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:41)
                  at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:82)
                  at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:61)
                  at com.google.gson.Gson.fromJson(Gson.java:887)
                  at com.google.gson.Gson.fromJson(Gson.java:852)
                  at com.google.gson.Gson.fromJson(Gson.java:801)
                  at com.example.neelay.level95.StorageUtil.loadAudio(StorageUtil.java:42)
                  at com.example.neelay.level95.MediaPlayerService.onStartCommand(MediaPlayerService.java:106)
                  at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3017)
                  at android.app.ActivityThread.access$2200(ActivityThread.java:153) 
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1449) 
                  at android.os.Handler.dispatchMessage(Handler.java:102) 
                  at android.os.Looper.loop(Looper.java:148) 
                  at android.app.ActivityThread.main(ActivityThread.java:5441) 
                  at java.lang.reflect.Method.invoke(Native Method) 
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:738) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:628) 
               Caused by: java.lang.InstantiationException: Can't instantiate abstract class android.net.Uri
                  at java.lang.reflect.Constructor.newInstance(Native Method)
                  at com.google.gson.internal.ConstructorConstructor$3.construct(ConstructorConstructor.java:108)
                  at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:210) 
                  at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:129) 
                  at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:220) 
                  at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:41) 
                  at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:82) 
                  at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:61) 
                  at com.google.gson.Gson.fromJson(Gson.java:887) 
                  at com.google.gson.Gson.fromJson(Gson.java:852) 
                  at com.google.gson.Gson.fromJson(Gson.java:801) 
                  at com.example.neelay.level95.StorageUtil.loadAudio(StorageUtil.java:42) 
                  at com.example.neelay.level95.MediaPlayerService.onStartCommand(MediaPlayerService.java:106) 
                  at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3017) 
                  at android.app.ActivityThread.access$2200(ActivityThread.java:153) 
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1449) 
                  at android.os.Handler.dispatchMessage(Handler.java:102) 
                  at android.os.Looper.loop(Looper.java:148) 
                  at android.app.ActivityThread.main(ActivityThread.java:5441) 
                  at java.lang.reflect.Method.invoke(Native Method) 
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:738) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:628) 

我收到错误的服务错误

 @Override
public int onStartCommand(Intent intent, int flags, int startId) {
    try {

        //Load data from SharedPreferences
        StorageUtil storage = new StorageUtil(getApplicationContext());
        audioList = storage.loadAudio();
        audioIndex = storage.loadAudioIndex();

        if (audioIndex != -1 && audioIndex < audioList.size()) {
            //index is in a valid range
            activeAudio = audioList.get(audioIndex);
        } else {
            stopSelf();
        }
    } catch (NullPointerException e) {
        stopSelf();
    }

    //Request audio focus
    if (requestAudioFocus() == false) {
        //Could not gain focus
        stopSelf();
    }

    if (mediaSessionManager == null) {
        try {
            initMediaSession();
            initMediaPlayer();
        } catch (RemoteException e) {
            e.printStackTrace();
            stopSelf();
        }
        buildNotification(PlaybackStatus.PLAYING);
    }

    //Handle Intent action from MediaSession.TransportControls
    handleIncomingActions(intent);
    return super.onStartCommand(intent, flags, startId);
}
在songutil类中显示错误的

错误

 public ArrayList<Songfileinfo> loadAudio() {
    preferences = context.getSharedPreferences(STORAGE, Context.MODE_PRIVATE);
    Gson gson = new Gson();
    String json = preferences.getString("audioArrayList", null);
    Type type = new TypeToken<ArrayList<Songfileinfo>>() {
    }.getType();
    return gson.fromJson(json, type);
}

我只能知道我在第106行的服务类中遇到错误 audioList = storage.loadAudio();和第41行的songutil课程 return gson.fromJson(json, type);但我怎么能解决这个问题，任何帮助都会有所帮助。现在当我从songfileinfo中删除一些代码时，我能够播放这首歌是代码

public class Songfileinfo implements Serializable {
private String title,album,artist,file_uri;

// private Uri album_art;   //私人长期; 

public Songfileinfo(String data, String title, String album, String artist) {
    this.file_uri = data;
    this.title = title;
    this.album = album;
    this.artist = artist;
}

public Songfileinfo() {

}

public String getTitle() {
    return title;
}

public void setTitle(String title) {
    this.title = title;
}

public String getAlbum() {
    return album;
}

public void setAlbum(String album) {
    this.album = album;
}

public String getArtist() {
    return artist;
}

public void setArtist(String artist) {
    this.artist = artist;
}

public String getFile_uri() {
    return file_uri;
}

public void setFile_uri(String file_uri) {
    this.file_uri = file_uri;
}

}

但是当我添加代码时，它仍然会崩溃

private Uri album_art;
private long duration;
 public Uri getAlbum_art() {
    return album_art;
}

public void setAlbum_art(Uri album_art) {
    this.album_art = album_art;
}

public long getDuration() {
    return duration;
}

public void setDuration(long duration) {
    this.duration = duration;
}

任何原因如果它被崩溃我也会在构造函数中添加它。

2 个答案:

答案 0 :(得分：1)

基本上Gson使用java反射从json构建数据对象。它需要一个空构造函数。您正在数据对象中使用Uri。所以只需将Uri中的地址保存为字符串。这将解决问题。

答案 1 :(得分：0)

我认为问题出在这里; 

String json = preferences.getString("audioArrayList", null);

如果prefs中没有audioArrayList，则默认返回null。 

gson.fromJson(json, type);

变得混乱。顺便说一下，我通常会为类型的json String设置我所期望的任何类。使用

的任何具体原因 
Type type = new TypeToken<ArrayList<Songfileinfo>>()

...

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