的Android SQLite的泄露

Question

我有問題與SQL處理

A SQLiteConnection object for database '/data/data/.../databases/queueManager' was leaked! Please fix your application to end transactions in progress properly and to close the database when it is no longer needed. 

從Androidhive教程中取出並定製我的使用

表看起來像

+ ----------------------------------------------------------- + 
: DATABASE_ID : DATABASE_QID : DATABASE_QUEUE : DATABASE_DATE : 
+ ----------------------------------------------------------- + 

代碼

DBQueue searchDBqid(int id) { 
     SQLiteDatabase db = this.getReadableDatabase(); 

     String selectQuery = "SELECT * FROM " + TABLE_QUEUE + " WHERE " + DATABASE_QID + " = " + id; 

      Cursor cursornum = db.rawQuery(selectQuery, null); 
      int dk = cursornum.getCount(); 
      cursornum.close(); 

      if (dk >0) { 
       Cursor cursor = db.query(TABLE_QUEUE, new String[] { DATABASE_ID, 
         DATABASE_QID, DATABASE_QUEUE, DATABASE_DATE }, DATABASE_QID + "=?", 
         new String[] { String.valueOf(id) }, null, null, null, null); 

       if (cursor != null) cursor.moveToFirst(); 

       DBQueue dbqueue = new DBQueue(Integer.parseInt(cursor.getString(0)), 
         cursor.getString(1), cursor.getString(2), cursor.getString(3)); 
       return dbqueue; 
      } 

     db.close(); 
     return null; 
    } 

    DBQueue getDBQueue(int id) { 
     SQLiteDatabase db = this.getReadableDatabase(); 

     Cursor cursor = db.query(TABLE_QUEUE, new String[] { DATABASE_ID, 
       DATABASE_QID, DATABASE_QUEUE }, DATABASE_ID + "=?", 
       new String[] { String.valueOf(id) }, null, null, null, null); 
     if (cursor != null) 
      cursor.moveToFirst(); 

     DBQueue dbqueue = new DBQueue(Integer.parseInt(cursor.getString(0)), 
       cursor.getString(1), cursor.getString(2), cursor.getString(3)); 
     return dbqueue; 
    } 


    public String getAllqid() { 
     Time today = new Time(Time.getCurrentTimezone()); 
     today.setToNow(); 

     String selectQuery = "SELECT * FROM " + TABLE_QUEUE + " WHERE " + DATABASE_DATE + " = '" + today.format("%d %m %Y") + "'"; 

     SQLiteDatabase db = this.getWritableDatabase(); 
     Cursor cursor = db.rawQuery(selectQuery, null); 

     StringBuilder sb = new StringBuilder();  
     if (cursor.moveToFirst()) { 
      do { 
       if (sb.length() > 0) sb.append(','); 
       sb.append(cursor.getString(1)); 
      } while (cursor.moveToNext()); 
     } 

     String result = sb.toString(); 
     return result; 
    } 
    public void deleteDatedDBQueue() { 
     Time today = new Time(Time.getCurrentTimezone()); 
     today.setToNow(); 
     String selectQuery = "SELECT * FROM " + TABLE_QUEUE + " WHERE " + DATABASE_DATE + " != '" + today.format("%d %m %Y") + "'"; ; 

     SQLiteDatabase db = this.getWritableDatabase(); 
     Cursor cursor = db.rawQuery(selectQuery, null); 

     if (cursor.moveToFirst()) { 
      do { 
       db.delete(TABLE_QUEUE, DATABASE_ID + " = ?", 
         new String[] { String.valueOf(Integer.parseInt(cursor.getString(0))) }); 
      } while (cursor.moveToNext()); 
     } 
     db.close(); 
    } 
    public int getDBQueueCount() { 
     String countQuery = "SELECT * FROM " + TABLE_QUEUE; 
     SQLiteDatabase db = this.getReadableDatabase(); 
     Cursor cursor = db.rawQuery(countQuery, null); 
     cursor.close(); 

     return cursor.getCount(); 
    } 
} 

有人可以請告訴我如何解決這個泄漏？

全碼：http://ijailbreak.me/databasehandler.txt

Answer 1

，當你完成它的每個Cursor應該被關閉。傳統的方式來做到這一點是：

Cursor cursor = db.query(...); 
try { 
    // read data from the cursor in here 
} finally { 
    cursor.close(); 
} 

但是現在，隨着try-with-resources，它可以更簡潔：

try (Cursor cursor = db.query(...)) { 
    // read data from the cursor in here 
} 

Answer 2

您忘記關閉幾次你的光標，請確保您始終關閉遊標當你完成。

例如，第二查詢不關閉遊標，我已經TODO'd它清晰

你也不要關閉SQLiteDatabase一旦你在getDBQueue，getAllqid和getDBQueueCount做，如果你改變你的設計讓你的SQLiteOpenHelper單身，那麼你不會需要關閉SQLiteDatabase，避免泄漏

DBQueue searchDBqid(int id) { 
     SQLiteDatabase db = this.getReadableDatabase(); 

     String selectQuery = "SELECT * FROM " + TABLE_QUEUE + " WHERE " + DATABASE_QID + " = " + id; 

      Cursor cursornum = db.rawQuery(selectQuery, null); 
      int dk = cursornum.getCount(); 
      cursornum.close(); 

      if (dk >0) { 

       // TODO: Close this cursor! 
       Cursor cursor = db.query(TABLE_QUEUE, new String[] { DATABASE_ID, 
         DATABASE_QID, DATABASE_QUEUE, DATABASE_DATE }, DATABASE_QID + "=?", 
         new String[] { String.valueOf(id) }, null, null, null, null); 

       if (cursor != null) cursor.moveToFirst(); 

       DBQueue dbqueue = new DBQueue(Integer.parseInt(cursor.getString(0)), 
         cursor.getString(1), cursor.getString(2), cursor.getString(3)); 
       return dbqueue; 
      } 

     db.close(); 
     return null; 
    } 

Answer 3

第一次打開的數據庫和最後把這個代碼。

@Override 
     protected void onDestroy() { 
      // TODO Auto-generated method stub 
     mdb.close(); 
     super.onDestroy(); 
     } 

Answer 4

每次打開一個數據庫時間（讀或寫），以及使用的存儲器資源已經通過使用被解除分配光標「.close（）;」後它的使用在每個數據庫功能 例如結束：

if (cursor != null) cursor.moveToFirst(); 

       DBQueue dbqueue = new DBQueue(Integer.parseInt(cursor.getString(0)), 
         cursor.getString(1), cursor.getString(2), cursor.getString(3)); 
       return dbqueue; 
      } 
cursor.close(); 

     db.close(); 
     return null; 
    } 

DBQueue getDBQueue(int id) { 
     SQLiteDatabase db = this.getReadableDatabase(); 

     Cursor cursor = db.query(TABLE_QUEUE, new String[] { DATABASE_ID, 
       DATABASE_QID, DATABASE_QUEUE }, DATABASE_ID + "=?", 
       new String[] { String.valueOf(id) }, null, null, null, null); 
     if (cursor != null) 
      cursor.moveToFirst(); 

     DBQueue dbqueue = new DBQueue(Integer.parseInt(cursor.getString(0)), 
       cursor.getString(1), cursor.getString(2), cursor.getString(3)); 
cursor.close(); 
db.close(); 
     return dbqueue; 
    } 

等.... !!