Question

我在尝试初始化数据库时遇到错误。我正在使用Android Room，我想使用RoomDatabaseBuilder来执行回调并填充我的数据库。

我在Activity类中执行getDatabase方法，但后来我使用dao从数据库获取信息，应用程序崩溃。这是我与Android Room的第一次联系，也许我正在伪造一些重要的事情。有人可以帮我这个吗？

数据库类：

static RoomDatabase.Callback rdc = new RoomDatabase.Callback() {

    @Override
    public void onOpen(@NonNull SupportSQLiteDatabase db) {
        super.onOpen(db);
        Log.d(TAG, "Debug: onOpen");

        //Borramos todos los sonidos de la base de datos
        INSTANCE.soundsDao().deleteAllSounds(); // Instance is "private static DatabaseSounds INSTANCE;"

崩溃的活动线来源：

db = DatabaseSounds.getDatabase(getApplicationContext());
   AsyncTask task = new LoadGridAsyncTask().execute(); **

   private class LoadGridAsyncTask extends AsyncTask<Void, Void, Integer> {

        @Override
        protected Integer doInBackground(Void... voids) {
            //Extraemos el listado de sonidos y los convertimos a DTO
            List<EntitySounds> listSounds = db.soundsDao().getAll(); **** THIS is the line of crash

这是错误

java.lang.RuntimeException: An error occurred while executing doInBackground()
        at android.os.AsyncTask$3.done(AsyncTask.java:325)
        at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:354)
        at java.util.concurrent.FutureTask.setException(FutureTask.java:223)
        at java.util.concurrent.FutureTask.run(FutureTask.java:242)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:243)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
        at java.lang.Thread.run(Thread.java:761)
     Caused by: java.lang.IllegalStateException: getDatabase called recursively
        at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:203)
        at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:163)
        at android.arch.persistence.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.getWritableSupportDatabase(FrameworkSQLiteOpenHelper.java:96)
        at android.arch.persistence.db.framework.FrameworkSQLiteOpenHelper.getWritableDatabase(FrameworkSQLiteOpenHelper.java:54)
        at android.arch.persistence.room.RoomDatabase.compileStatement(RoomDatabase.java:244)
        at android.arch.persistence.room.SharedSQLiteStatement.createNewStatement(SharedSQLiteStatement.java:65)
        at android.arch.persistence.room.SharedSQLiteStatement.getStmt(SharedSQLiteStatement.java:72)
        at android.arch.persistence.room.SharedSQLiteStatement.acquire(SharedSQLiteStatement.java:87)
        at com.genaut.myapp.database.dao.DaoSounds_Impl.deleteAllSounds(DaoSounds_Impl.java:140)
        at com.genaut.myapp.database.DatabaseSounds$1.onOpen(DatabaseSounds.java:57)
        at com.genaut.myapp.database.DatabaseSounds_Impl$1.onOpen(DatabaseSounds_Impl.java:65)
        at android.arch.persistence.room.RoomOpenHelper.onOpen(RoomOpenHelper.java:111)
        at android.arch.persistence.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.onOpen(FrameworkSQLiteOpenHelper.java:149)
        at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:266)
        at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:163)
        at android.arch.persistence.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.getWritableSupportDatabase(FrameworkSQLiteOpenHelper.java:96)
        at android.arch.persistence.db.framework.FrameworkSQLiteOpenHelper.getWritableDatabase(FrameworkSQLiteOpenHelper.java:54)
        at android.arch.persistence.room.RoomDatabase.query(RoomDatabase.java:233)
        at com.genaut.myapp.database.dao.DaoSounds_Impl.getAll(DaoSounds_Impl.java:155)
        at com.genaut.myapp.Home$LoadGridAsyncTask.doInBackground(Home.java:83)
        at com.genaut.myapp.Home$LoadGridAsyncTask.doInBackground(Home.java:78)
        at android.os.AsyncTask$2.call(AsyncTask.java:305)
        at java.util.concurrent.FutureTask.run(FutureTask.java:237)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:243) 
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133) 
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607) 
        at java.lang.Thread.run(Thread.java:761)

这是Dao方法：

@Query("SELECT * FROM entitysounds")
    List<EntitySounds> getAll();

Answer 1

然后我使用dao从数据库中获取信息

这不起作用，因为Room尚未设置。之一：

在b或
请勿在{{1}}内使用Room，而是使用RoomDatabase.Callback作为RoomDatabase.Callback参数提供的SupportSQLiteDatabase以及其他回调方法
< / LI>

Answer 2

在新的单独线程中运行

Executors.newSingleThreadExecutor().execute {
    INSTANCE.soundsDao().deleteAllSounds(); 
}

Answer 3

我的朋友，我遇到类似的问题。但是对我来说，问题是我从两个不同的类中获取数据库。从第二个类中删除第二个初始化后，它就起作用了。

Answer 4

之所以会这样，是因为已经有onOpen()被调用时调用了回调的getDatabase。

然后在第INSTANCE.soundsDao().deleteAllSounds()行，如果您在deleteAllSounds()（SoundsDao_Impl s的Impl生成文件）中查看Dao的实现，则可以看到它调用{{ 1}}，它将调用__db.beginTransaction()。

这是抛出mOpenHelper.getWritableDatabase()的地方Exception。

可以将该修复程序getDatabase called recursively放在此参考文献中的另一个线程中：https://medium.com/androiddevelopers/7-pro-tips-for-room-fbadea4bfbd1

INSTANCE.soundsDao().deleteAllSounds()

此处参考：https://gist.github.com/florina-muntenescu/697e543652b03d3d2a06703f5d6b44b5

getDatabase使用Room递归调用

4 个答案: