如何把AutoCompleteTextView连接到数据库

AutoCompleteTextView可以根据输入的文字来显示提示, 它的Adapter可以是一个list, 也可以动态的提取数据库数据.
写了一个例子来展示, 建立一个数据库来储存人名, 只要在AutoCompleteTextView里面输入2个字母就会显示匹配下拉单.
这是一个定制的CursorAdapter, newView会返回一个包含cursor里文字的view, bindView把cursor的数据绑定在view里, convertToString会把view的数据转换为AutoCompleteTextView显示的文字, runQueryOnBackgroundThread方法会查询数据库.

   private class MyCursorAdpter extends CursorAdapter {
        private int columnIndex;
        
        public MyCursorAdpter(Context context, Cursor c, int col) {
            super(context, c);
            this.columnIndex = col;
        }
        @Override
        public View newView(Context context, Cursor cursor, ViewGroup parent) {
            final LayoutInflater inflater = LayoutInflater.from(context);
            final TextView view = (TextView) inflater.inflate(
                    android.R.layout.simple_dropdown_item_1line, parent, false);
            view.setText(cursor.getString(columnIndex));
            return view;
        }
        @Override
        public void bindView(View view, Context context, Cursor cursor) {
            ((TextView) view).setText(cursor.getString(columnIndex));
        }
        
        @Override
        public String convertToString(Cursor cursor) {
            return cursor.getString(columnIndex);
        }
        @Override
        public Cursor runQueryOnBackgroundThread(CharSequence constraint) {
            if (constraint != null) {
                String selection = "name like \'" + constraint.toString() +"%\'";
                return sqlite.query("test", columns, selection, null, null, null, null);
            }
            else {
                return null;
            }
        }
    }

建立数据库, 以及添加数据, 使用CursorAdapter的数据库必须包含_id项.

    private void createDatas() {
        String createTable = "create table test (name varchar(255), _id varchar(255))";
        sqlite.execSQL(createTable);
        
        ContentValues values = new ContentValues();
        values.put("name", "nicole");
        values.put("_id", "0");
        sqlite.insert("test", null, values);
        
        values.put("name", "nicolas");
        values.put("_id", "1");
        sqlite.insert("test", null, values);
        
        values.put("name", "jean");
        values.put("_id", "2");
        sqlite.insert("test", null, values);
        
        values.put("name", "jennyfer");
        values.put("_id", "3");
        sqlite.insert("test", null, values);
    }