SQLite 无法在频繁 "SELECT" 查询时打开数据库文件（代码 14）

Question

我有以下 class "Singleton" 来处理 SQLite 连接并确保整个连接有 1 个实例 process/app:

public class DBController {
  private static DBController instance = new DBController();
  private static DBHelper dbHelper;
  public static DBController getInstance()
  {
    return instance;
  }
  public SQLiteDatabase dbOpen(Context context)
  {
    if(dbHelper == null)
        dbHelper = new DBHelper(context);
    return dbHelper.getWritableDatabase();
  }
}

和 DBHelper class 本身：

public class DBHelper extends SQLiteOpenHelper {

  public DBHelper(Context context) {
    super(context, "database.db", null, 1);
  }
  @Override
  public void onCreate(SQLiteDatabase db) {
    final String position = "CREATE TABLE test (" +
            "test TEXT NOT NULL);";
    db.execSQL(position);
  }
}

当我经常尝试"SELECT"来自数据库的一些信息时，我收到以下错误：

SQLiteLog: (14) cannot open file at line 31278 of [2ef4f3a5b1]
SQLiteLog: (14) os_unix.c:31278: (24) open(/data/user/0/uz.mycompany.myapp/databases/database.db-journal) - 
SQLiteLog: (14) cannot open file at line 31278 of [2ef4f3a5b1]
SQLiteLog: (14) os_unix.c:31278: (24) open(/data/user/0/uz.mycompany.myapp/databases/database.db-journal) - 
SQLiteLog: (14) statement aborts at 29: [SELECT * FROM test WHERE test='testdata1'] unable to open database file
SQLiteQuery: exception: unable to open database file (code 14); query: SELECT * FROM test WHERE test='testdata1'
android.database.sqlite.SQLiteCantOpenDatabaseException: unable to open database file (code 14)

我正在运行以下代码执行查询：

public String getData(Context context)
{
    SQLiteDatabase _db = dbOpen(context);
    Cursor c = _db.rawQuery("SELECT * FROM test WHERE test='testdata1'", null);
    return getDataFromCursor(c).get(0); //gets data from cursor and returns first one
}

我如何manage/improve我的数据库连接到overcome/avoid这个问题？

Answer 1

在对这些东西执行任何查询之前（你应该打开你的数据库）。完成任务后关闭数据库。

private DBHelper dbHelper = new DBHelper(context);

try {
    _db = dbHelper.getWritableDatabase();
} catch (SQLException s) {
    new Exception("Error with DB Open");
}

// 然后现在写你的查询....然后关闭数据库。

_db.close();

你可以看看我的git link1 git link2

Answer 2

你的代码re-opens数据库每次dbOpen()被调用。

SQLite 数据库对象非常轻量级；继续关闭并 re-opening 它真的没有意义。

您已经有了单身人士；只需在此处存储一个 SQLiteDatabase 引用。

Answer 3

另外，我认为游标太多，因此打开的游标也可能导致相同的结果 "unable to open database file error"。（在下面的代码中，shoplistcursor中有507行，所以就结束了1500 个游标 used/reused 总共 )

我收到了同样的信息。根据 :-

10-29 19:57:00.901 12845-12845/mjt.shopper E/SQLiteLog: (14) cannot open file at line 30046 of [9491ba7d73]
10-29 19:57:00.901 12845-12845/mjt.shopper E/SQLiteLog: (14) os_unix.c:30046: (24) open(/data/data/mjt.shopper/databases/Shopper-journal) - 
10-29 19:57:00.901 12845-12845/mjt.shopper E/SQLiteLog: (14) cannot open file at line 30046 of [9491ba7d73]
10-29 19:57:00.901 12845-12845/mjt.shopper E/SQLiteLog: (14) os_unix.c:30046: (24) open(/data/data/mjt.shopper/databases/Shopper-journal) - 
10-29 19:57:00.901 12845-12845/mjt.shopper E/SQLiteLog: (14) statement aborts at 24: [SELECT *  FROM productusage WHERE productailseref = 60 AND productproductref = 75 ;] unable to open database file
10-29 19:57:00.902 12845-12845/mjt.shopper E/SQLiteQuery: exception: unable to open database file (code 14); query: SELECT *  FROM productusage WHERE productailseref = 60 AND productproductref = 75 ;
10-29 19:57:00.902 12845-12845/mjt.shopper D/AndroidRuntime: Shutting down VM
10-29 19:57:00.903 12845-12845/mjt.shopper E/AndroidRuntime: FATAL EXCEPTION: main

错误的代码是：-

 SQLiteDatabase db = getWritableDatabase();
        Cursor shoplistcursor = getAllRowsFromTable(SHOPLIST_TABLE_NAME);
        Cursor productcsr;
        Cursor aislecsr;
        Cursor prdusecsr;
        while(shoplistcursor.moveToNext()) {
            productcsr = getProductFromProductId(shoplistcursor.getLong(shoplistcursor.getColumnIndex(SHOPLIST_COLUMN_PRODUCTREF)));
            aislecsr = getAisleFromAisleId(shoplistcursor.getLong(shoplistcursor.getColumnIndex(SHOPLIST_COLUMN_AISLEREF)));
            prdusecsr = getProductUsage(shoplistcursor.getLong(shoplistcursor.getColumnIndex(SHOPLIST_COLUMN_AISLEREF)),
                    shoplistcursor.getLong(shoplistcursor.getColumnIndex(SHOPLIST_COLUMN_PRODUCTREF)));
            if (productcsr.getCount() < 1 | aislecsr.getCount() < 1 | prdusecsr.getCount() < 1) {
                deleteShopListEntry(shoplistcursor.getLong(shoplistcursor.getColumnIndex(SHOPLIST_COLUMN_ID)));
            } 
            if(shoplistcursor.isLast()) {
                prdusecsr.close();
                aislecsr.close();
                productcsr.close();
            }
        }
        shoplistcursor.close();
        db.close();
}

解决方法是在每次迭代时关闭游标。根据 :-

 SQLiteDatabase db = getWritableDatabase();
        Cursor shoplistcursor = getAllRowsFromTable(SHOPLIST_TABLE_NAME);
        Cursor productcsr;
        Cursor aislecsr;
        Cursor prdusecsr;
        while(shoplistcursor.moveToNext()) {
            productcsr = getProductFromProductId(shoplistcursor.getLong(shoplistcursor.getColumnIndex(SHOPLIST_COLUMN_PRODUCTREF)));
            aislecsr = getAisleFromAisleId(shoplistcursor.getLong(shoplistcursor.getColumnIndex(SHOPLIST_COLUMN_AISLEREF)));
            prdusecsr = getProductUsage(shoplistcursor.getLong(shoplistcursor.getColumnIndex(SHOPLIST_COLUMN_AISLEREF)),
                    shoplistcursor.getLong(shoplistcursor.getColumnIndex(SHOPLIST_COLUMN_PRODUCTREF)));
            if (productcsr.getCount() < 1 | aislecsr.getCount() < 1 | prdusecsr.getCount() < 1) {
                productcsr.close();
                aislecsr.close();
                prdusecsr.close();
                deleteShopListEntry(shoplistcursor.getLong(shoplistcursor.getColumnIndex(SHOPLIST_COLUMN_ID)));
            } else {
                productcsr.close();
                aislecsr.close();
                prdusecsr.close();
            }
        }
        shoplistcursor.close();
        db.close();
    }

Answer 4

我正在使用游标进行大型查询，其中游标在 800 毫秒内通过三个单独的 'QUERY' 访问数据库超过 1350 次。所以我得到了错误（android.database.sqlite.SQLiteCantOpenDatabaseException：无法打开数据库文件（代码 14））。我通过在开始新查询之前关闭游标来解决它。这解决了我的问题。希望它能处理比我的更大的查询。

String data_query = "SELECT * FROM test WHERE id= " + c_id + " AND memberId = " + memberId;           
Cursor cu_cu = userHelper.getData(data_query);
float cu_cu_count = cu_cu.getCount();
System.out.println("ALL ANSWER COUNT : " + cu_cu_count);
cu_cu.close();

Answer 5

在你的申请中class

public static SQLiteDatabase database;

@Override
public void onCreate() {
    super.onCreate();

    SQLiteOpenHelper helper = Database.getInstance(getApplicationContext());

    if (database == null) {
        database = helper.getWritableDatabase();
    } else {
        if (!database.isOpen()) {
            database = helper.getWritableDatabase();
        }
    }
}

在您的查询中class

 public DataSources() {
    database = ApplicationController.database;
 }

这样你就创建了一个可写的数据库对象一次

SQLite 无法在频繁 "SELECT" 查询时打开数据库文件（代码 14）

SQLite unable to open database file (code 14) on frequent "SELECT" query

sqlite

singleton

android

android-sqlite