Question

这是我在Android上的第一个申请。我在这个问题上看到了一些问题，但没有人能为我解决问题。

我在assets文件夹中有一个名为fmdb.sqlite的数据库。我使用了这个链接的代码示例： http://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/

当我到达应该获取资源文件夹（copyDataBase方法）中sqlite文件的流的行时，我得到一个异常＆＃34; java.io.FileNotFoundException：fmdb.sqlite＆＃34;。

谁能告诉我我做错了什么？这是我的课。

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

}

}

编辑2 这是LogCat。我卸载并重新运行程序。现在它是关于打开db文件写的，我真的很感谢你的帮助！

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％的CommonsWare评论。最简单的方法是使用SQLiteAssetHelper。我会将此作为答案发布，但这是从上面的链接100％复制粘贴。为了使用这个库，您需要知道的全部内容。

SQLiteAssetHelper旨在作为框架的SQLiteOpenHelper的替代品。请熟悉该类的行为和生命周期。

像通常执行SQLiteOpenHelper一样扩展SQLiteAssetHelper，为构造函数提供数据库名称和版本号：

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依赖于资产文件和文件夹命名约定。您的资源文件夹将位于项目根目录下，或者如果您使用默认的gradle项目结构，则位于src / main下。至少，您必须提供以下内容：

资产内的数据库文件夹数据库文件夹中的SQLite数据库，其文件名与您在代码中提供的数据库名称相匹配（包括文件扩展名，如果有）对于上面的示例，项目将包含以下内容：

资产/数据库/ northwind.db 此库的早期版本要求在ZIP存档中压缩数据库资产。这不再是必需的，但仍然受到支持。仍然以Gingerbread（API 10）或更低版本为目标的应用程序应继续提供压缩存档，以确保在打包过程中大型数据库文件不会损坏。还支持更友好的Linux GZIP格式。使用上面示例的命名约定如下：

ZIP：assets / databases / northwind.db.zip（单个SQLite数据库文件必须是归档中的唯一文件） GZIP：assets / databases / northwind.db.gz 数据库将从资产中提取出来并复制到应用程序的私有数据目录中。如果您希望将数据库文件存储在其他位置（例如外部存储），则可以使用备用构造函数来指定存储路径。每当应用程序需要访问数据库时，您必须确保此路径可用且可写。

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

第一次调用getReadableDatabase（）或getWritableDatabase（）时，数据库可供使用。

如果您没有提供适当命名的文件，该类将抛出SQLiteAssetHelperException。

此实现不支持onConfigure，onCreate和onDowngrade上的SQLiteOpenHelper方法，并且已声明为final。

修改

请求帮助，现在给出。首先，必须将databases文件夹放在assets文件夹中。必须将其命名为databases，拼写完全且区分大小写。那是库查找数据库的地方。接下来，必须将sqliteassethelper-2.0.1.jar放入libs文件夹中。现在只需编写代码。

以下是一些示例代码。

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; } }

然后你在你的应用程序中调用它

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

如果您还需要其他信息，请告诉我

Answer 2

好的 - 我终于使用了我发布的原始代码。该解决方案不需要使用SQLiteAssetHelper（虽然它确实减少了必须编写的代码量 - 感谢@javascript为您的GREAT帮助）。我拿了一个旧的sqlite db并用它运行应用程序 - 它在阅读时没有任何异常。虽然我的原始文件已在所有sqlite管理工具中打开（因此没有损坏），但我决定创建一个新的数据库文件。

我用来测试代码的旧数据库和应用程序数据库之间的区别是（架构除外）文件扩展名。旧的数据库扩展名为＆＃34; .db＆＃34;，应用程序数据库为＆＃34; .sqlite＆＃34;。所以我用THE＆＃34; .db＆＃34;创建了一个新数据库。 EXTENSION，在其中创建所有表格 - 瞧 - 应用程序成功将文件从assets文件夹复制到模拟器中的数据库文件夹。

希望这有助于某人，这真的很令人沮丧：）

无法在assets文件夹中打开sqlite文件来复制到设备

2 个答案: