java - sqlite + listview + 新 Activity : close() was never explicitly called on database?

Question

我制作了一个包含 3 个 Activity 的应用程序。在第一个 Activity (导入)中，我只是将一些值导入到 sqlite 数据库中。

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);
    }
}

以及我的 DAO 类用于我的度量/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 Activity (历史记录)中，我有一个由数据库填充的列表，一切正常

这是2个Activity(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);
}

}

当我单击列表项时，我会启动一个新 Activity ，显示数据库中该度量的所有信息。

但是我在 logcat 中有:

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!

我看到了一些其他问题，但没有找到适合我的情况关闭它的方法。

Answer 1

(正如其他人指出的那样，当您完成游标后，您应该关闭游标，但是......)
该错误告诉您需要关闭 SQLiteDatabase。将此方法添加到您的 BpDAO 类中:

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

每当您在任何需要调用 close() 的 Activity 中创建新的 BpDAO 对象时，您都可以在完成后或在 中执行此操作>onDestroy():

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