Question

我遇到了SQLite数据库的问题。它只是工作正常，但当我添加扩展＆＃34; .db＆＃34;使用数据库名称，整个应用程序崩溃。它没有构建任何数据库。我想知道是否有人可以提供帮助！我需要查看数据库但不能使用扩展名。

public class DataBaseHelper extends SQLiteOpenHelper {
private Context mycontext;

private static String DB_NAME = "newsapp.db";
public SQLiteDatabase myDataBase;
private String DB_PATH = "/data/data/"
        + "com.news.mint"
        + "/databases/";

public DataBaseHelper(Context context) throws IOException {
    super(context, DB_NAME, null, 1);
    this.mycontext = context;
    boolean dbexist = checkdatabase();
    if (dbexist ) {

        opendatabase();
    } else {

        createdatabase();
    }
}

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() {
    // SQLiteDatabase checkdb = null;
    boolean checkdb = false;
    try {
        String myPath = DB_PATH + DB_NAME;
        File dbfile = new File(myPath);

        checkdb = dbfile.exists();
    } catch (SQLiteException e) {

    }
    return checkdb;
}

private void copydatabase() throws IOException {
    // Open your local db as the input stream
    InputStream myinput = mycontext.getAssets().open(DB_NAME);

    // Path to the just created empty db
    String outfilename = DB_PATH + DB_NAME;

    // Open the empty db as the output stream
    OutputStream myoutput = new FileOutputStream(outfilename);

    // transfer byte to inputfile to outputfile
    byte[] buffer = new byte[1024];
    int length;
    while ((length = myinput.read(buffer)) > 0) {
        myoutput.write(buffer, 0, length);
    }

    // Close the streams
    myoutput.flush();
    myoutput.close();
    myinput.close();
}

public void opendatabase() throws SQLException {
    // Open the database
    String mypath = DB_PATH + DB_NAME;
    myDataBase = SQLiteDatabase.openDatabase(mypath, null,
            SQLiteDatabase.OPEN_READWRITE);
}

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

}

@Override
public void onCreate(SQLiteDatabase arg0) {
    // TODO Auto-generated method stub

}

@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
    // TODO Auto-generated method stub

}


}

LogCat：

    09-23 14:34:10.895: E/AndroidRuntime(7477): FATAL EXCEPTION: main
09-23 14:34:10.895: E/AndroidRuntime(7477): android.database.sqlite.SQLiteException: no such table: primary_keywords (code 1): , while compiling: SELECT stock_Symbol from primary_keywords where stock_id = '22628'
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:1013)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:624)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1314)
 09-23 14:34:10.895: E/AndroidRuntime(7477):    at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1253)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at com.newsmint.databasemanagementsystem.QueryManager.getDataLocal(QueryManager.java:36)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at com.newsmint.stockmint.NewsActivityFragment.init(NewsActivityFragment.java:74)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at com.newsmint.stockmint.NewsActivityFragment.onResume(NewsActivityFragment.java:147)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.support.v4.app.Fragment.performResume(Fragment.java:1543)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:963)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:440)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.os.Handler.handleCallback(Handler.java:615)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.os.Handler.dispatchMessage(Handler.java:92)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.os.Looper.loop(Looper.java:137)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at android.app.ActivityThread.main(ActivityThread.java:4921)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at java.lang.reflect.Method.invokeNative(Native Method)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at java.lang.reflect.Method.invoke(Method.java:511)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
09-23 14:34:10.895: E/AndroidRuntime(7477):     at dalvik.system.NativeStart.main(Native Method)
09-23 14:56:47.185: E/SQLiteLog(7870): (1) no such table: top_news

Answer 1

    @Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
    // TODO Auto-generated method stub


   db.execSQL("DROP TABLE IF EXISTS " +"your table name");

}

Answer 2

我认为

copydatabase（）因目录而失败 /data/data/com.news.mint/databases/当时不存在抛出与故障单中的异常不同的异常。

为了使它工作，你应该做两件事：

将数据库创建逻辑从DataBaseHelper-Constructor移至

@Override
public SQLiteDatabase openOrCreateDatabase(final String name,
        final int mode, final SQLiteDatabase.CursorFactory factory) {

你应该替换

String myPath = DB_PATH + DB_NAME;
File dbfile = new File(myPath);

带

...
File dbfile = context.getDatabasePath(DB_NAME)

// create directory if it does not exist. Else copydatabase will fail because directory does not exist yet.
if (!dbfile.getParentFile().exists()) {
    dbfile.getParentFile().mkdirs();
}

在测试此代码之前，您应手动删除数据库（或卸载应用程序）

/data/data/com.news.mint/databases/newsapp.db

强制执行新的数据库创建

Answer 3

嗯，它没有用扩展来解决它，但我现在能够使用Questoid sqlitebrowser查看数据库，该数据库适用于没有扩展名的数据库。

使用扩展名为.db的Sqlite数据库时，应用程序崩溃

3 个答案: