无法打开Android设备上我的数据库，但可以在模拟器 [英] Cannot open my database on the android device, but can on the emulator

问题描述

任何人能解释什么问题？
我开发我的应用程序，它使用我自己的数据库。所有工作正常，但有一天我开始接到在

Can anyone explain what's the problem? I developed my application which uses my own database. All worked fine, but in one day I began to receive the error at

long rowsCount = DatabaseUtils.queryNumEntries(myDataBase, table);

该错误是

android.database.sqlite.SQLiteDatabaseCorruptException：数据库磁盘映像格式不正确：，在编译：SELECT COUNT（*）FROM字

android.database.sqlite.SQLiteDatabaseCorruptException: database disk image is malformed: , while compiling: SELECT count(*) FROM words

在最奇怪我收到的错误只在我的设备（LG P500），以及程序工作正常，在模拟器上。

The strangest in that I receive the error only on my device (lg p500), and the program works fine on the emulator.

我的code与数据库相关的：

My code related to the database:

dbHelper = new MySQLiteHelper(context);
    try {
        dbHelper.createDataBase();
    }catch(IOException ioe) 
    {
        throw new Error("Unable to create database");
    }
...
dbHelper.openDataBase();
long tableSize = dbHelper.countTableRows(MySQLiteHelper.TABLE_WORDS); //The error appears
...

MySQLiteHelper code：

MySQLiteHelper code:

public class MySQLiteHelper extends SQLiteOpenHelper {

private static final String DATABASE_NAME = "words.db";
private static final int DATABASE_VERSION = 1;
private static final String DB_PATH = "/data/data/ru.my.program/databases";
public static final String TABLE_WORDS = "words";
public static final String COLUMN_ID = "_id";
public static final String COLUMN_WORD = "word";
private final Context myContext;

public SQLiteDatabase myDataBase;

public MySQLiteHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
    myContext = context;
}

@Override
public void onCreate(SQLiteDatabase database) {
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {  
}

public void createDataBase() throws IOException{         
    boolean dbExist = checkDataBase(); 
    if(dbExist){
        //do nothing - database already exist
    }else{ 
        //By calling this method and empty database will be created into the default system path
        //of your application so we are gonna be able to overwrite that database with our database.
        this.getReadableDatabase(); 
        this.close();
        try 
        {
            copyDataBase(); 
        }
        catch(IOException e)
        { 
            throw new Error("Error copying database"); 
        }
    }
}

private boolean checkDataBase(){    
    File dbFile = new File(DB_PATH + "/" + DATABASE_NAME);
    return dbFile.exists();

}

private void copyDataBase() throws IOException{      
    //Open your local db as the input stream
    InputStream myinput = myContext.getAssets().open(DATABASE_NAME);

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

    //Open the empty db as the output stream
    OutputStream myoutput = new FileOutputStream("/data/data/ru.my.program/databases/words.db");

    // 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{
    String myPath = DB_PATH + "/" +DATABASE_NAME;
    myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS|SQLiteDatabase.OPEN_READONLY);
    Log.i(MySQLiteHelper.class.getName(), "Open DB");
}

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

}
public long countTableRows(String table)
{
    long rowsCount = DatabaseUtils.queryNumEntries(myDataBase, table);
    return rowsCount;
}

我已经同检查数据库与DDMS设备上，并相信它是在一个适当的位置复制它，因为资产。

I have checked up the database on the device with the DDMS and was convinced that it is copied in a proper place and it same, as in assets.

我已经检查数据库具有android_metadata表区域=ru_RU。

I have checked that the database has android_metadata table with locale="ru_RU".

我已签，我在字表有列_id。

I have checked that I have the column "_id" in the "words" table.

我试图手动删除应用程序文件夹（与数据库），但它并没有帮助。

I tried to remove the application folder (with the database) manually, but it hasn't helped.

我甚至尝试重新命名我的应用程序包...

I even tried to rename my application package...

推荐答案

我已经重新创建数据库文件后问题已经消失。
看来数据库文件应该有一个更表sqlite_sequence。该表应该包含两列：名称和序列。 名为这些表中的行量表的名称，已创建（不含android_metadata），序列。

The problem has disappeared after I have recreated the database file. It seems that the database file should have one more table "sqlite_sequence". The table should contain two columns: name and seq. "name" for names of tables, which you have created (excluding android_metadata), "seq" for amount of rows in these tables.

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