Question

我正在尝试创建一个应用。应用正在模拟器中打开。但是，当我尝试在真实设备中打开应用程序时，它崩溃了。关于我的问题，我尝试了许多解决方案。但我无法解决我的问题。我添加了DatabaseHelper，Logcat。我在AndroidManifest.xml中添加了android.permission，但未能获得解决方案。应用程序无法打开。申请已终止。不开放。请建议解决此问题。

我在实际设备上运行该应用程序之前删除了该应用程序。但是问题仍然存在。

DatabaseHelper.java

public class DatabaseHelper extends SQLiteOpenHelper {
    private static DatabaseHelper mInstance = null;


    String DB_PATH = null;
    private static String DB_NAME = "kriyayoga.db";
    private static SQLiteDatabase myDataBase;
    private  final Context myContext;
    private  static  final int DATABASE_VERSION = 1;

    public static synchronized DatabaseHelper getInstance(Context context) {

        if (mInstance == null) {
            mInstance = new DatabaseHelper(context.getApplicationContext());
        }
        return mInstance;
    }

    public DatabaseHelper(Context context) {
        super(context, DB_NAME, null, DATABASE_VERSION);
        this.myContext = context;
        this.DB_PATH = "/data/data/" + context.getPackageName() + "/" + "databases/";
        //this.DB_PATH = this.myContext.getDatabasePath(DB_NAME).getAbsolutePath();
        Log.e("Path 1", DB_PATH);

    }


    public void createDataBase() throws IOException {
        boolean dbExist = checkDataBase();
        if (dbExist) {
        } else {
            this.getReadableDatabase();
            try {
                copyDataBase();
            } catch (IOException e) {
                throw new Error("Error copying database");
            }
        }
    }

    private boolean checkDataBase() {
        File dbFile = myContext.getDatabasePath(DB_NAME);
        return dbFile.exists();
    }

    private void copyDataBase() throws IOException {
        InputStream myInput = myContext.getAssets().open(DB_NAME);
        String outFileName = DB_PATH + DB_NAME;
        OutputStream myOutput = new FileOutputStream(outFileName);
        byte[] buffer = new byte[1024];
        int length;
        while ((length = myInput.read(buffer)) > 0) {
            myOutput.write(buffer, 0, length);
        }
        myOutput.flush();
        myOutput.close();
        myInput.close();

    }

    public void openDataBase() throws SQLException {
        String myPath = DB_PATH + DB_NAME;
        myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

    }

    @Override
    public synchronized void close() {
        if (myDataBase != null)
            myDataBase.close();
        super.close();
    }


    @Override
    public void onCreate(SQLiteDatabase db) {
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        if (newVersion > oldVersion)
            try {
                copyDataBase();
            } catch (IOException e) {
                e.printStackTrace();

            }
    }

    @Override
    public void onOpen(SQLiteDatabase db) {
        onCreate(db);
    }

}

Logcat 问题显示在ListNavAdapter.java

E/SQLiteLog: (1) no such table: yoga
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
    android.database.sqlite.SQLiteException: no such table: yoga (code 1 SQLITE_ERROR): , while compiling: SELECT heading FROM yoga ORDER BY _id
        at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
        at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:946)
        at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:527)
        at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
        at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
        at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
        at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:46)
        at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1408)
        at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1347)
        at com.priyanka.kriyayoga.ListNavAdapter.onViewCreated(ListNavAdapter.java:81)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1471)
        at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1784)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1852)
        at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:802)
        at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2625)
        at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2411)
        at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2366)
        at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2273)
        at android.support.v4.app.FragmentManagerImpl.dispatchStateChange(FragmentManager.java:3273)
        at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:3229)
        at android.support.v4.app.FragmentController.dispatchActivityCreated(FragmentController.java:201)
        at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:620)
        at android.support.v7.app.AppCompatActivity.onStart(AppCompatActivity.java:178)
        at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1395)
        at android.app.Activity.performStart(Activity.java:7293)
        at android.app.ActivityThread.handleStartActivity(ActivityThread.java:3196)
        at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:180)
        at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:165)
        at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:142)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:70)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2011)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:224)
        at android.app.ActivityThread.main(ActivityThread.java:7135)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:537)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:876)

当我在真实设备上运行应用程序时，它会显示运行时异常

应用程序崩溃。

在我添加的 AndroidManifest.xml 中

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

在 ListNavAdapter 中，我曾经获取数据

SQLiteDatabase sqLiteDatabase = DatabaseHelper.getInstance(this.getContext()).getReadableDatabase();
 Cursor cursor1 = sqLiteDatabase.rawQuery("SELECT heading FROM yoga ORDER BY _id", new String[]{});

Answer 1

您的问题很可能是您尝试使用的设备是Android 9+。使用9+时，默认值已从日记模式更改为WAL（预写日志）。

在复制结果之前使用 getWritableDatabase （或 getReadableDatabase ，如果它们可以以可写方式打开数据库，则它们都以可写方式打开数据库）在正在创建的 -wal 和 -shm 文件中。复制数据库后，将保留-wal和-shm文件。打开复制的数据库时，SQLite将打开 -wal 文件，并且发现差异，因为 -wal 文件属于被覆盖的数据库文件，而不是复制的数据库文件。。为了提供可用的数据库，然后用有效的因此空的数据库文件覆盖损坏的数据库文件，并解释为什么表似乎已消失。

从历史上看（我认为我看不到其他原因） getWritableDatabase 用于解决无法打开文件的ENONENT错误，这是因为在首次运行App时，数据库目录在data / data / package_name目录中不存在（因此文件副本失败）。

以下更改将通过在需要时创建数据库目录（效率更高）来避免此问题。

第一次更改：-

private boolean checkDataBase() {
    File dbFile = myContext.getDatabasePath(DB_NAME);
    return dbFile.exists();
}

成为：-

private boolean checkDataBase() {
    File dbFile = myContext.getDatabasePath(DB_NAME);
    if (dbFile.exists()) return true;
    if (!dbFile.getParentFile().exists()) {
        dbfile.getParentFile().mkdirs();
    }
    return false;
}

然后在 createDataBase 方法中删除或注释行 this.getReadableDatabase() 。

注意，以上代码是本内代码，尚未运行或测试，因此可能包含错误。

android.database.sqlite.SQLiteException：否此类表格：Yoga（代码1 SQLITE_ERROR）：

1 个答案: