Question

我制作了一款包含3项活动的应用。在fisrt活动（导入）中，我只是将一些值导入sqlite数据库。

这是我的DatabaseHelper类：

   public class DatabaseHelper_bp extends SQLiteOpenHelper {

    private static final String DATABASE_NAME = "bpDB";
    private static final int DATABASE_VERSION = 1;

    // Database creation sql statement
    private static final String DATABASE_CREATE = "create table bp_import ( _id integer primary key, datetime text not null, systolic text not null, diastolic text not null, pulses text not null, notes text not null);";

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

    // Method is called during creation of the database
    @Override
    public void onCreate(SQLiteDatabase database) {
        database.execSQL(DATABASE_CREATE);
    }

    // Method is called during an upgrade of the database,
    @Override
    public void onUpgrade(SQLiteDatabase database, int oldVersion,
            int newVersion) {
        Log.w(DatabaseHelper_bp.class.getName(),
                "Upgrading database from version " + oldVersion + " to "
                        + newVersion + ", which will destroy all old data");
        database.execSQL("DROP TABLE IF EXISTS bp_import");
        onCreate(database);
    }
}

我的DAO课程用于我的度量/值：

    public class BpDAO {

    private DatabaseHelper_bp dbHelper;

    private SQLiteDatabase database;
    /**
     * bp table related constants.
     */
    public final static String bp_TABLE = "bp_import";
    public final static String bp_ID = "_id";
    public final static String bp_DT = "datetime";
    public final static String bp_SYS = "systolic";
    public final static String bp_DIA = "diastolic";
    public final static String bp_PUL = "pulses";
    public final static String bp_NOT = "notes";

    /**
     * 
     * @param context
     */
    public BpDAO(Context context) {
        dbHelper = new DatabaseHelper_bp(context);
        database = dbHelper.getWritableDatabase();
    }

    /**
     * \ Creates a new blood pressure measure
     * 
     * @param datetime
     * @param systolic
     * @param diastolic
     * @param pulses
     * @param notes
     * @return
     */
    public long importBP(String datetime, String systolic, String diastolic,
            String pulses, String notes) {
        ContentValues values = new ContentValues();
        values.put(bp_DT, datetime);
        values.put(bp_SYS, systolic);
        values.put(bp_DIA, diastolic);
        values.put(bp_PUL, pulses);
        values.put(bp_NOT, notes);
        return database.insert(bp_TABLE, null, values);
    }

    public void close() {
           database.close();
    }

    /**
     * Fetch all bp
     * 
     * @return
     */
    public Cursor fetchAll_bp() {
        Cursor mCursor = database.query(true, bp_TABLE, new String[] { bp_SYS,
                bp_DIA, bp_DT, bp_ID }, null, null, null, null, null, null);
        if (mCursor != null) {
            mCursor.moveToFirst();
        }
        return mCursor;
    }
}

在第二个活动（历史记录）中，我有一个由数据库填充的List，所有ok enter image description here

以下是2活动（历史）的代码：

public class HistoryActivity extends ListActivity {

private BpDAO dao;

private SimpleCursorAdapter dbAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    dao = new BpDAO(this);
    Cursor bpList = dao.fetchAll_bp();
    String[] from = new String[] { BpDAO.bp_SYS, BpDAO.bp_DIA, BpDAO.bp_DT };
    int[] target = new int[] { R.id.bpSysHolder, R.id.bpDiaHolder,
            R.id.bpDtHolder };
    dbAdapter = new SimpleCursorAdapter(this, R.layout.history_bp, bpList,
            from, target);
    setListAdapter(dbAdapter);
}

@Override
public void onListItemClick(ListView l, View view, int position, long id) {
    // TODO Auto-generated method stub
    super.onListItemClick(l, view, position, id);
    Log.d("BPT", "Selected bp id =" + id);
            // log says that i have selected an item with id : 11 

    Cursor selectedBpDetails = (Cursor) l.getItemAtPosition(position);

    String bp_DT = selectedBpDetails.getString(selectedBpDetails
            .getColumnIndex(BpDAO.bp_DT));
    String bp_SYS = selectedBpDetails.getString(selectedBpDetails
            .getColumnIndex(BpDAO.bp_SYS));
    String bp_DIA = selectedBpDetails.getString(selectedBpDetails
            .getColumnIndex(BpDAO.bp_DIA));
    String bp_PUL = selectedBpDetails.getString(selectedBpDetails
            .getColumnIndex(BpDAO.bp_PUL));
    String bp_NOT = selectedBpDetails.getString(selectedBpDetails
            .getColumnIndex(BpDAO.bp_NOT));

    Log.d("BPT", "Selected bp details = { date=" + bp_DT + ", systolic="
            + bp_SYS + ", diastolic=" + bp_DIA + ", pulses=" + bp_PUL
            + ", notes=" + bp_NOT + " }");

    Intent intent = new Intent(HistoryActivity.this, FromHistory.class);
    intent.putExtra("bp_SYS", bp_SYS);
    intent.putExtra("bp_DIA", bp_DIA);
    intent.putExtra("bp_DT", bp_DT);
    intent.putExtra("bp_PUL", bp_PUL);
    intent.putExtra("bp_NOT", bp_NOT);
    startActivity(intent);
}

}

当我点击列表项时，我开始一个新的活动，我从数据库中显示该度量的所有信息。

但我有logcat：

1.close() was never explicitly called on database
2.android.database.sqlite.DatabaseObjectNotClosedException: Application did not close the cursor or database object that was opened here
3.E/System(561): java.lang.IllegalStateException: Don't have database lock!

我已经看到了其他一些问题，但未能找到如何根据我的情况关闭它。

Answer 1

完成光标后，您需要close()

示例：

selectedBpDetails.close();

Answer 2

您可以通过调用数据close()来直接关闭数据，也可以覆盖活动的onDestroy方法，然后在执行此方法时关闭你打开过的光标。

public class HistoryActivity extends ListActivity {
    // ...
    Cursor bpList;
    // ...

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // ...
        bpList = dao.fetchAll_bp();
        // ...
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        bpList.close();
    }

    @Override
    public void onListItemClick(ListView l, View view, int position, long id) {
        // ...
        Cursor selectedBpDetails = (Cursor) l.getItemAtPosition(position);
        // ...
        selectedBpDetails.close();
    }

    // ...
}

Answer 3

（当你完成游标时，你应该关闭游标，正如其他人指出的那样，但是......）该错误告诉您需要关闭SQLiteDatabase。将此方法添加到BpDAO类：

public void close() {
    database.close();
}

每当您在任何活动中创建新的BpDAO对象时，您需要致电close()，您可以在完成后或onDestroy()内完成此操作：

@Override
protected void onDestroy() {
    super.onDestroy();
    dao.close();
}

sqlite + listview + new活动：从未在数据库上显式调用close（）？

3 个答案: