SQLite數據庫常用操作

SQLite數據庫常用操作

1. 創建一個DBHleper繼承SQLiteOpenHelper
2. 在構造方法裏傳入數據庫名稱，和版本名稱
   private DBHelper(Context context) {
super(context, DB_NAME, null, VERSION);
}
3. 重寫父類方法onCrate()創建表
   public void onCreate(SQLiteDatabase db) {
db.execSQL(SQL_CREATE);
}
4. 重寫父類方法Update方法更新表
   public void onUpgrade(SQLiteDatabase db, int i, int i1) {
db.execSQL(SQL_DROP);
db.execSQL(SQL_CREATE);
}

數據庫增刪改查

    public class ThreadDaoImpl implements ThreadDao {
    private DBHelper dbHelper = null;
    public ThreadDaoImpl(Context context) {
        dbHelper = DBHelper.getInstance(context);
    }

    @Override
    public synchronized void insertThread(ThreadInfo threadInfo) {
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        db.execSQL("insert into thread_info(thread_id,url,icon,name,start,end,finished,file_length) values(?,?,?,?,?,?,?,?)",
                new Object[]{threadInfo.getId(), threadInfo.getUrl(),threadInfo.getIcon(),threadInfo.getName(), threadInfo.getStart(), threadInfo.getEnd(), threadInfo.getFinished(),threadInfo.getLength()});
        db.close();
    }

    @Override
    public synchronized void deleteThread(String url) {
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        db.execSQL("delete from thread_info where url=?",
                new Object[]{url});
        db.close();
    }

    @Override
    public synchronized void updateThread(String url, int thread_id, long finished) {
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        db.execSQL("update thread_info set finished =? where url=? and thread_id=?",
                new Object[]{finished, url, thread_id});
       // db.close();
    }

    @Override
    public synchronized List<ThreadInfo> getThreads(String url) {
        SQLiteDatabase db = dbHelper.getReadableDatabase();
        List<ThreadInfo> threadInfos = new ArrayList<>();
        Cursor cursor = db.rawQuery("select * from thread_info where url=?", new String[]{url});
        while (cursor.moveToNext()){
            ThreadInfo threadInfo = new ThreadInfo();
            threadInfo.setId(cursor.getInt(cursor.getColumnIndex("thread_id")));
            threadInfo.setUrl(cursor.getString(cursor.getColumnIndex("url")));
            threadInfo.setStart(cursor.getInt(cursor.getColumnIndex("start")));
            threadInfo.setEnd(cursor.getInt(cursor.getColumnIndex("end")));
            threadInfo.setFinished(cursor.getInt(cursor.getColumnIndex("finished")));
            threadInfo.setLength(cursor.getInt(cursor.getColumnIndex("file_length")));
            threadInfos.add(threadInfo);
        }
        cursor.close();
        db.close();
        return threadInfos;
    }

    @Override
    public List<ThreadInfo> getAllThreads() {
        SQLiteDatabase db = dbHelper.getReadableDatabase();
        List<ThreadInfo> threadInfos = new ArrayList<>();
        Cursor cursor = db.rawQuery("select * from thread_info where thread_id=?", new String[]{"0"});
        while (cursor.moveToNext()){
            ThreadInfo threadInfo = new ThreadInfo();
            threadInfo.setId(cursor.getInt(cursor.getColumnIndex("thread_id")));
            threadInfo.setUrl(cursor.getString(cursor.getColumnIndex("url")));
            threadInfo.setIcon(cursor.getString(cursor.getColumnIndex("icon")));
            threadInfo.setName(cursor.getString(cursor.getColumnIndex("name")));
            threadInfo.setStart(cursor.getInt(cursor.getColumnIndex("start")));
            threadInfo.setEnd(cursor.getInt(cursor.getColumnIndex("end")));
            threadInfo.setFinished(cursor.getInt(cursor.getColumnIndex("finished")));
            threadInfo.setLength(cursor.getInt(cursor.getColumnIndex("file_length")));
            threadInfos.add(threadInfo);
        }
        cursor.close();
        db.close();
        return threadInfos;
    }

    @Override
    public synchronized boolean isExists(String url, int thread_id) {
        SQLiteDatabase db = dbHelper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from thread_info where url=? and thread_id=?", new String[]{url,thread_id+""});
        boolean exists=cursor.moveToNext();
        cursor.close();
        db.close();
        return exists;
    }
}