Question

我创建了一个由警报管理器每5秒调用一次的服务。我的服务使用dbHandler类中的方法来添加，更新，检查更新的信息并检查数据库中数据的可用性。将数据插入表后，下次再次调用我的服务时，它仍然没有结果，并且再次输出相同的数据。服务检查和添加数据的日志：

dbHandler onCreate：

    @Override
public void onCreate(SQLiteDatabase db){

    String query = "CREATE TABLE " + tableN + "(" +
            column_id + " INTEGER PRIMARY KEY," +
            column_name + " TEXT ," +
            column_desc + " TEXT ," +
            column_activity + " TEXT ," +
            column_contact + " TEXT " +

            ");";
    db.execSQL(query);

}

检查数据并将数据添加到数据库的方法

public void add_n(nDatabse tuple) {
    ContentValues values = new ContentValues();
    values.put(column_id, tuple.get_id());
    values.put(column_name, tuple.get_name());
    values.put(column_desc, tuple.get_description());
    values.put(column_activity, tuple.get_activity());
    values.put(column_contact, tuple.get_contact());
    SQLiteDatabase db = getWritableDatabase();



    //Inserting in Database

    db.insert(tableN, null, values);

    //checking Entry of Database
    String query = "SELECT * FROM " + tableN + " WHERE " + column_id + " = " + tuple.get_id() + " ";
    Cursor c = db.rawQuery(query, null);
    if (c.getCount() > 0) {
        c.moveToFirst();
        Log.d( " After Adding Data...",c.getString(1));}

    db.close();
}

检查可用性

public boolean checkNotAvailable(nDatabse tuple) {

    SQLiteDatabase db = getWritableDatabase();
    String query = "SELECT * FROM " + tableN + " WHERE " + column_id + " = " + tuple.get_id() + " ";

    Cursor c = db.rawQuery(query, null);
    //Log.d("as",toString().valueOf(tuple.get_id()));
    if (c.getCount() == 0) {
        Log.d("NO ENTRY", toString().valueOf(tuple.get_id()));
        return true;
    }
    db.close();
    return false;

}

从服务

调用方法

                //doing 5 times    
                dbHandler dbH = new dbHandler(this, null, null, 1);
                if (dbH.checkNotAvailable(n))
                    dbH.add_n(n);

Log.d在每次服务电话上重复输出

        D/NO ENTRY: 0
        D/ After Adding Data...: Name 1
        D/NO ENTRY: 1
        D/ After Adding Data...: Name 2
        D/NO ENTRY: 2
        D/ After Adding Data...: Name 3
        D/NO ENTRY: 3
        D/ After Adding Data...: Name 4
        D/NO ENTRY: 4
        D/ After Adding Data...: Name 5

Answer 1

问题是，我将null传递给dbhandler构造函数并且没有指定数据库的名称，这可能导致形成在服务停止时清除的临时数据库。

退出服务后数据库值将被清除

1 个答案: