给我一个Android 日历控件代码

好的，下面是一个简单的 Android 日历控件的代码示例：

public class CalendarView extends LinearLayout {

    private static final String TAG = CalendarView.class.getSimpleName();

    private TextView tvMonthYear;
    private GridView gvCalendar;
    private Calendar currentDate = Calendar.getInstance();
    private List<Date> dates = new ArrayList<>();
    private SimpleDateFormat dateFormat = new SimpleDateFormat("MMMM yyyy", Locale.getDefault());
    private CalendarGridAdapter adapter;

    public CalendarView(Context context) {
        super(context);
    }

    public CalendarView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        initControl(context, attrs);
    }

    public CalendarView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        initControl(context, attrs);
    }

    private void initControl(Context context, AttributeSet attrs) {
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        inflater.inflate(R.layout.calendar_view, this);
        tvMonthYear = findViewById(R.id.tv_month_year);
        gvCalendar = findViewById(R.id.gv_calendar);
        gvCalendar.setOnItemClickListener((parent, view, position, id) -> {
            Date date = (Date) parent.getItemAtPosition(position);
            Log.d(TAG, "Selected date: " + date.toString());
        });
        adapter = new CalendarGridAdapter(context, dates, currentDate);
        gvCalendar.setAdapter(adapter);
        refreshCalendar();
    }

    private void refreshCalendar() {
        dates.clear();
        Calendar monthCalendar = (Calendar) currentDate.clone();
        monthCalendar.set(Calendar.DAY_OF_MONTH, 1);
        int firstDayOfWeek = monthCalendar.get(Calendar.DAY_OF_WEEK) - 1;
        monthCalendar.add(Calendar.DAY_OF_MONTH, -firstDayOfWeek);
        while (dates.size() < 42) {
            dates.add(monthCalendar.getTime());
            monthCalendar.add(Calendar.DAY_OF_MONTH, 1);
        }
        adapter.notifyDataSetChanged();
        tvMonthYear.setText(dateFormat.format(currentDate.getTime()));
    }

    public void setPreviousMonth() {
        currentDate.add(Calendar.MONTH, -1);
        refreshCalendar();
    }

    public void setNextMonth() {
        currentDate.add(Calendar.MONTH, 1);
        refreshCalendar();
    }

    private static class CalendarGridAdapter extends ArrayAdapter<Date> {

        private final LayoutInflater inflater;
        private final Calendar currentCalendar;
        private final Calendar todayCalendar;

        public CalendarGridAdapter(@NonNull Context context, List<Date> dates, Calendar currentCalendar) {
            super(context, R.layout.calendar_day, dates);
            this.currentCalendar = currentCalendar;
            this.todayCalendar = Calendar.getInstance();
            inflater = LayoutInflater.from(context);
        }

        @NonNull
        @Override
        public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
            Date date = getItem(position);
            if (convertView == null) {
                convertView = inflater.inflate(R.layout.calendar_day, parent, false);
            }
            TextView tvDay = convertView.findViewById(R.id.tv_day);
            tvDay.setText(String.valueOf(date.getDate()));
            if (date.getMonth() != currentCalendar.get(Calendar.MONTH)) {
                tvDay.setTextColor(Color.GRAY);
            } else if (date.equals(todayCalendar.getTime())) {
                tvDay.setTextColor(Color.RED);
            } else {
                tvDay.setTextColor(Color.BLACK);
            }
            return convertView;
        }
    }
}

这个控件使用了一个 GridView 来显示日历，每个单元格就是一个日期。在构造函数中，我们初始化了一些必要的变量和控件，设置了 GridView 的适配器，以及调用了 refreshCalendar() 来刷新日历。

refreshCalendar() 方法是核心方法，用于计算当前月份的所有日期，并将其添加到 dates 列表中，然后通知适配器进行更新。

其他一些方法，如 setPreviousMonth() 和 setNextMonth()，用于在用户点击前一个月和后一个月按钮时切换到相应的月份。

这只是一个简单的示例，您可以根据自己的需求进行更改和扩展。