AutoCompleteTextView绑定数据库，模糊匹配方法 使用CursorAdapter

通过CursorAdapter这个适配器，AutoCompleteTextView可以直接与sqlite数据库绑定，而不用在程序中预先添加匹配数据。并且，通过sql的like关键字，可以实现模糊查询，非首字母查询。 贴上代码：

SQLiteDatabase sqlite = this.openOrCreateDatabase("data", 0, null);
//连接数据库
AutoCompleteTextView actv=(AutoCompleteTextView) findViewById(R.id.actv);
//不解释
actv.setThreshold(1);
//输入一个字符即开始匹配
String[] trainColumns = new String[] {"train_no", "id as _id" };
//欲查询匹配的列放第一,查询结果必须有_id列，因我的表中没有，所以把id as成_id,实践证明，其实随便哪个字段都可以as _id，不用主键，这里也可以train_no as _id.
trainAdpter trainadpter = new trainAdpter(this, null, 0);
//实例化自定义的适配器，代码在下面
actv.setAdapter(trainadpter);
//绑定适配器

private class trainAdpter extends CursorAdapter {
        private int columnIndex;

        public trainAdpter(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);
            return view;
        }

        @Override
        public void bindView(View view, Context context, Cursor cursor) {
            ((TextView) view).setText(cursor.getString(columnIndex));
        }

        @Override
        public String convertToString(Cursor cursor) {
            Log.i("info", " convertToString ");
            return cursor.getString(columnIndex);
        }

        @Override
        public Cursor runQueryOnBackgroundThread(CharSequence constraint) {
            if (constraint != null) {
                String selection = "train_no like \'%" + constraint.toString() + "%\' limit 100";
                System.out.println(selection);
                return sqlite.query("train", trainColumns, selection, null, null, null, null);
                //从表train查询
            } else {
                return null;
            }
        }
    }