無法打開資產文件夾中的sqlite文件複製到設備

Question

這是我的第一個應用程序Android。我在這件事上看到了一些問題，但沒有人爲我解決問題。

我的資產文件夾中的數據庫，fmdb.sqlite命名。我以前從這個鏈接的代碼示例： http://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/

當我到了，應該讓流在資產文件夾（copyDataBase法）的源碼文件中的行，我得到一個異常「java.io.FileNotFoundException： fmdb.sqlite」。

誰能告訴我我做錯了什麼？這是我的班。

public class DatabaseOpener extends SQLiteOpenHelper { 

// If you change the database schema, you must increment the database version. 
public static final int DATABASE_VERSION = 1; 

//The Android's default system path of your application database. 
public static String DB_PATH; 

public static String DB_NAME = "fmdb.sqlite"; 

private SQLiteDatabase myDataBase; 

private final Context myContext; 



public DatabaseOpener(Context context) throws IOException { 
    super(context, DB_NAME, null, DATABASE_VERSION); 
    myContext = context; 
} 

/** 
* Check if the database already exists to avoid re-copying the file each time you open the application. 
* @return true if it exists, false if it doesn't 
*/ 
    private boolean checkDataBase(){ 

     SQLiteDatabase checkDB = null; 

     try{ 
     String myPath = DB_PATH; 
     checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); 

     }catch(SQLiteException e){ 

     //database does't exist yet. 

     } 

     if(checkDB != null){ 

     checkDB.close(); 

    } 

    return checkDB != null ? true : false; 
    } 

    /** 
    * Creates a empty database on the system and rewrites it with your own database. 
    * */ 
    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(); 

      try { 

      copyDataBase(); 

      } catch (IOException e) { 

      throw new Error("Error copying database"); 

      } 
     } 

    } 

    /** 
    * Copies your database from your local assets-folder to the just created empty database in the 
    * system folder, from where it can be accessed and handled. 
    * This is done by transfering bytestream. 
    * */ 
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; 

    //Open the empty db as the output stream 
    OutputStream myOutput = new FileOutputStream(outFileName); 

    //transfer bytes from the inputfile to the 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 SQLiteDatabase openDataBase() throws SQLException{ 

    //Open the database 
    String myPath = DB_PATH;// + DB_NAME; 
    myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); 

    return myDataBase; 
} 

@Override 
public synchronized void close() { 

    if(myDataBase != null) 
    myDataBase.close(); 

    super.close(); 

} 



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

} 

@Override 
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
    // TODO Auto-generated method stub 

} 

}

編輯2 這裏是logcat的。我卸載並重新運行該程序。現在是關於打開數據庫文件寫作，我非常感謝你的幫助！

09-29 17:59:19.540: W/SQLiteAssetHelper(27063): copying database from assets... 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): Couldn't open fmdb.sqlite for writing (will try read-only): 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): com.readystatesoftware.sqliteasset.SQLiteAssetHelper$SQLiteAssetException: Missing databases/fmdb.sqlite file (or .zip, .gz archive) in assets, or target folder not writable 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at android.content.res.AssetManager.openAsset(Native Method) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at android.content.res.AssetManager.open(AssetManager.java:315) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at android.content.res.AssetManager.open(AssetManager.java:289) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at com.readystatesoftware.sqliteasset.SQLiteAssetHelper.copyDatabaseFromAssets(SQLiteAssetHelper.java:436) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at com.readystatesoftware.sqliteasset.SQLiteAssetHelper.createOrOpenDatabase(SQLiteAssetHelper.java:400) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at com.readystatesoftware.sqliteasset.SQLiteAssetHelper.getWritableDatabase(SQLiteAssetHelper.java:176) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at com.readystatesoftware.sqliteasset.SQLiteAssetHelper.getReadableDatabase(SQLiteAssetHelper.java:254) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at com.friendlymeter.dal.MyDatabase.getSample(MyDatabase.java:27) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at com.friendlymeter.app.MainActivity$2.onClick(MainActivity.java:105) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at android.view.View.performClick(View.java:4204) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at android.view.View$PerformClick.run(View.java:17355) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at android.os.Handler.handleCallback(Handler.java:725) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at android.os.Handler.dispatchMessage(Handler.java:92) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at android.os.Looper.loop(Looper.java:137) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at android.app.ActivityThread.main(ActivityThread.java:5041) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at java.lang.reflect.Method.invokeNative(Native Method) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at java.lang.reflect.Method.invoke(Method.java:511) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 09-29 17:59:19.689: E/SQLiteAssetHelper(27063): at dalvik.system.NativeStart.main(Native Method) 09-29 17:59:19.709: E/SQLiteLog(27063): (14) cannot open file at line 30176 of [00bb9c9ce4] 09-29 17:59:19.709: E/SQLiteLog(27063): (14) os_unix.c:30176: (2) open(/data/data/com.friendlymeter.app/databases/fmdb.sqlite) - 09-29 17:59:19.909: D/dalvikvm(27063): GC_CONCURRENT freed 130K, 9% free 2652K/2904K, paused 9ms+15ms, total 171ms 09-29 17:59:20.019: E/SQLiteDatabase(27063): Failed to open database '/data/data/com.friendlymeter.app/databases/fmdb.sqlite'. 09-29 17:59:20.019: E/SQLiteDatabase(27063): android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.database.sqlite.SQLiteConnection.nativeOpen(Native Method) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:209) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:193) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.database.sqlite.SQLiteConnectionPool.openConnectionLocked(SQLiteConnectionPool.java:463) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:185) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:177) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.database.sqlite.SQLiteDatabase.openInner(SQLiteDatabase.java:804) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.database.sqlite.SQLiteDatabase.open(SQLiteDatabase.java:789) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:694) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:669) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at com.readystatesoftware.sqliteasset.SQLiteAssetHelper.getReadableDatabase(SQLiteAssetHelper.java:264) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at com.friendlymeter.dal.MyDatabase.getSample(MyDatabase.java:27) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at com.friendlymeter.app.MainActivity$2.onClick(MainActivity.java:105) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.view.View.performClick(View.java:4204) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.view.View$PerformClick.run(View.java:17355) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.os.Handler.handleCallback(Handler.java:725) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.os.Handler.dispatchMessage(Handler.java:92) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.os.Looper.loop(Looper.java:137) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at android.app.ActivityThread.main(ActivityThread.java:5041) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at java.lang.reflect.Method.invokeNative(Native Method) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at java.lang.reflect.Method.invoke(Method.java:511) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 09-29 17:59:20.019: E/SQLiteDatabase(27063): at dalvik.system.NativeStart.main(Native Method) 

Answer 1

我同意100％，CommonsWare的評論。最簡單的方法是使用SQLiteAssetHelper。我會發布這個答案，但這是從上面的鏈接粘貼100％複製。這是你使用這個庫所需要知道的一切。

SQLiteAssetHelper旨在作爲在可替換的下降爲框架的SQLiteOpenHelper。請熟悉該課程的行爲和生命週期。

擴展SQLiteAssetHelper，你通常會做SQLiteOpenHelper，提供的構造與數據庫名稱和版本號：

public class MyDatabase extends SQLiteAssetHelper { 

    private static final String DATABASE_NAME = "northwind.db"; 
    private static final int DATABASE_VERSION = 1; 

    public MyDatabase(Context context) { 
     super(context, DATABASE_NAME, null, DATABASE_VERSION); 
    } 
} 

SQLiteAssetHelper依靠資產文件和文件夾的命名規則。您的資產文件夾將位於您的項目根目錄下，如果您使用的是默認的Gradle項目結構，則位於src/main下。至少，您必須提供以下信息：

一個數據庫內的資產文件夾 SQLite數據庫的數據庫文件夾中的文件名，你在代碼中提供的數據庫名稱相匹配的內部（包括文件擴展名，如果有的話） 對於示例上述項目將包含以下內容：

assets/databases/northwind.db 該庫的早期版本要求將數據庫資源壓縮到ZIP歸檔中。這不再是一項要求，但仍然受到支持。仍然以Gingerbread（API 10）或更低版本爲目標的應用程序應繼續提供壓縮存檔，以確保大型數據庫文件在打包過程中不被損壞。更友好的Linux支持GZIP格式。使用上述示例的命名約定如下：

ZIP：assets/databases/northwind.db.zip（一個SQLite數據庫文件必須是歸檔中的唯一文件） GZIP：assets/databases/northwind。 db.gz 將從資產中提取數據庫並將其複製到應用程序的專用數據目錄中。如果您更喜歡將數據庫文件存儲在其他位置（例如外部存儲），則可以使用備用構造函數指定存儲路徑。只要應用程序需要訪問數據庫，就必須確保此路徑可用並可寫。

super(context, DATABASE_NAME, context.getExternalFilesDir(null).getAbsolutePath(), null, DATABASE_VERSION); 

該數據庫由可使用的第一次或者getReadableDatabase（）或getWritableDatabase（）被調用。

如果您沒有提供正確命名的文件，該類將拋出SQLiteAssetHelperException。

此實現不支持SQLiteOpenHelper方法onConfigure，onCreate和onDowngrade，並且已聲明爲final。

編輯

幫助請求，現在給出。首先你必須在assets文件夾裏面放一個databases文件夾。它必須命名爲databases,拼寫完整並區分大小寫。這是圖書館查找數據庫的地方。接下來你必須把sqliteassethelper-2.0.1.jar放在你的libs文件夾裏面。現在只需編寫代碼。

以下是一些示例代碼。

public class MyDatabase extends SQLiteAssetHelper { 

    private static String DATABASE_NAME = "your_database_name.sqlite"; // must have file extension 
    private static int DATABASE_VERSION = 1; 

    public static final String SAMPLE_TABLE = "your_table_name"; 

    public static final String SAMPLE_COLUMN= "your_column_name"; 

    public MyDatabase(Context context) { 
     super(context, DATABASE_NAME, null, DATABASE_VERSION); 
    } 

    /** 
    * Returns a sample string. 
    * @return sample - a sample string from your database table 
    */ 
    public String getSample() { 
     SQLiteDatabase database = this.getReadableDatabase(); 
     String[] columnsArray = { SAMPLE_COLUMN }; 
     Cursor cursor = database.query(true, SAMPLE_TABLE, columnsArray, null, null, null, null, null, null); 
     if (cursor != null) { 
      cursor.moveToFirst(); 
     } 

     String sample = cursor.getString(cursor.getColumnIndex(SAMPLE_COLUMN)); 

     cursor.close(); 
     database.close(); 

     return sample; 
    } 
} 

然後你把它在你的應用程序是這樣

public void databaseTest() { 
    MyDatabase db = new MyDatabase(YourActivity.this); 
    String sample = db.getSample(); 
    Log.v("SAMPLE", sample); 
    db.close(); 
} 

如果你有什麼事讓我知道

Answer 2

行 - 我終於得到它與我張貼最初的代碼工作。該解決方案不需要使用SQLiteAssetHelper（儘管它確實減少了必須編寫的代碼量 - 感謝@javascript爲您的GREAT HELP）。我拿了一箇舊的sqlite數據庫，並運行它的應用程序 - 它在閱讀時沒有拋出異常。雖然我的原始文件已經在所有的sqlite管理工具中打開（所以沒有損壞），但我決定創建一個新的數據庫文件。

我用來測試代碼和應用程​​序數據庫的舊數據庫之間的區別是（除了架構）文件擴展名。舊的數據庫擴展名爲「.db」，應用程序數據庫爲「.sqlite」。所以我用「.db」EXTENSION創建了一個新的數據庫，創建了它的所有表格，然後 - 應用程序成功地將文件從assets文件夾複製到模擬器中的數據庫文件夾。

希望這可以幫助別人，這是一直很無奈:)