今天分享一个日历选择控件，可以定义日期可选、选择范围、按月分组展示。这个日历无非就是把每个日期的数据通过系统的日历查询出来，然后用recyclerview展示即可，数据模型里可以定义哪些可选以及选定状态等等。思路就是这样了，先看看效果：

日历效果

首先定义好数据来源，即从系统的calendar获取日期列表，这里因为是要按月分组，所以我选择用一个key为月份的时间戳value为对应月份的所有日期list的map来接收查询出来的日历，在展示的时候把map转为分组的list即可：

import android.annotation.SuppressLint;

import androidx.annotation.NonNull;

import java.text.ParseException;

import java.text.SimpleDateFormat;

import java.util.ArrayList;

import java.util.Calendar;

import java.util.Date;

import java.util.LinkedHashMap;

/**

* 日历工具类

* @author ly

* date 2020/4/24 9:52

*/

public class CalendarUtils {

public final static String YEAR = "yyyy";

public final static String YEAR_MONTH = "yyyy年MM月";

public final static String MONTH_DAY = "MM-dd";

public final static String DATE = "yyyy-MM-dd";

public final static String TIME = "HH:mm";

public final static String MONTH_DAY_TIME = "MM月dd日 hh:mm";

public final static String DATE_TIME_SECOND = "yyyy-MM-dd HH:mm:ss";

public final static String DATE_TIME = "yyyy-MM-dd HH:mm";

public final static String DATE1_TIME = "yyyy/MM/dd HH:mm";

public static @NonNull

LinkedHashMap> getMonthMap(Calendar initialCalendar, int monthNum) {

return getMonthMap(initialCalendar, monthNum, Integer.MAX_VALUE);

}

public static @NonNull

LinkedHashMap> getMonthByLimit(Calendar initialCalendar, int validSelNumLimit) {

return getMonthMap(initialCalendar, Integer.MAX_VALUE, validSelNumLimit);

}

/**

* 以月为单位，获取每个月的日期列表

*

* @param initialCalendar 初始选中的日期

* @param validSelNumLimit 最大有效选中数量

* @return 返回一个key为当前loop月的时间戳，value为当前月的所有日期list的有序map

* @author ly on 2020/4/25 11:37

*/

public static @NonNull

LinkedHashMap> getMonthMap(Calendar initialCalendar, int monthNum, int validSelNumLimit) {

//key：当前loop月的时间戳 value：当前月的所有日期list

LinkedHashMap> dateMap = new LinkedHashMap<>();

ArrayList dateInMonthList = new ArrayList<>();

if (initialCalendar == null)

initialCalendar = Calendar.getInstance();

Calendar c = Calendar.getInstance();

//设置开始遍历的date

//也可以不使用下面的set，直接c.setTime(initialCalendar.getTime())，只是第一个月的数据可能不足那个月的最大天数(ui不美观)

//告诉calendar从指定月的第一天开始，而不是精确到某一天

c.set(initialCalendar.get(Calendar.YEAR), initialCalendar.get(Calendar.MONTH), 1);

int loopMonthCount = 0;

int validDateNum = 0;//有效的可选日期数量

while (loopMonthCount < monthNum) {

// 获取当前月最大天数

int maxDayNum = c.getActualMaximum(Calendar.DATE);

int month = c.get(Calendar.MONTH);

DateInfo dateInfo = new DateInfo();

dateInfo.year = c.get(Calendar.YEAR);

dateInfo.month = month + 1;

dateInfo.day = c.get(Calendar.DAY_OF_MONTH);

dateInfo.timestamp = c.getTimeInMillis();

dateInfo.week = c.get(Calendar.DAY_OF_WEEK);

dateInfo.isSelected = initialCalendar.get(Calendar.MONTH) == c.get(Calendar.MONTH) && initialCalendar.get(Calendar.DATE) == c.get(Calendar.DATE);

//是否为可选的日期

boolean isAvailableDate = (dateInfo.isSelected || c.after(initialCalendar)) && dateInfo.week != Calendar.SUNDAY && dateInfo.week != Calendar.SATURDAY;

if (isAvailableDate)

validDateNum++;

dateInfo.canSelect = isAvailableDate && validDateNum <= validSelNumLimit;

if (dateInMonthList.isEmpty()) {//在每一月的第一周前面补空data

for (int j = 0; j < dateInfo.week - 1; j++) {

DateInfo d = new DateInfo();

dateInMonthList.add(0, d);

}

}

dateInMonthList.add(dateInfo);

if (maxDayNum == dateInfo.day) {//每loop到月底put一次

dateMap.put(dateInfo.timestamp, new ArrayList<>(dateInMonthList));

dateInMonthList.clear();

if (validDateNum < validSelNumLimit) {

loopMonthCount++;

} else {

break;//达到最大可选数后自动跳出looper

}

}

//条件满足时一直add天数即可

c.add(Calendar.DATE, 1);

}

return dateMap;

}

public static @NonNull

LinkedHashMap> getMonthMap(String startDate, String endDate) {

//key：当前loop月的时间戳 value：当前月的所有日期list

LinkedHashMap> dateMap = new LinkedHashMap<>();

ArrayList dateInMonthList = new ArrayList<>();

long startTimestamp = getMillisecondByFormat(startDate, DATE);

long endTimestamp = getMillisecondByFormat(endDate, DATE);

if (endTimestamp < startTimestamp || startTimestamp <= 0)

return dateMap;

Calendar start = Calendar.getInstance();

start.setTimeInMillis(startTimestamp);

Calendar end = Calendar.getInstance();

end.setTimeInMillis(endTimestamp);

Calendar c = Calendar.getInstance();

//设置开始遍历的date

//也可以不使用下面的set，直接c.setTime(initialCalendar.getTime())，只是第一个月的数据可能不足那个月的最大天数(ui不美观)

//告诉calendar从指定月的第一天开始，而不是精确到某一天

c.set(start.get(Calendar.YEAR), start.get(Calendar.MONTH), 1);

boolean needLoop = true;

while (needLoop) {

// 获取当前月最大天数

int maxDayNum = c.getActualMaximum(Calendar.DATE);

int month = c.get(Calendar.MONTH);

DateInfo dateInfo = new DateInfo();

dateInfo.year = c.get(Calendar.YEAR);

dateInfo.month = month;

dateInfo.day = c.get(Calendar.DAY_OF_MONTH);

dateInfo.timestamp = c.getTimeInMillis();

dateInfo.week = c.get(Calendar.DAY_OF_WEEK);

//此处理想条件应为 start.getTimeInMillis()==c.getTimeInMillis()，但开始时间戳和查询出来的时间戳不相等(就算是同一天)

//先用这个判断着

dateInfo.isSelected = start.get(Calendar.YEAR) == c.get(Calendar.YEAR) && start.get(Calendar.MONTH) == c.get(Calendar.MONTH) && start.get(Calendar.DATE) == c.get(Calendar.DATE);

boolean isEnd = end.get(Calendar.MONTH) == c.get(Calendar.MONTH) && end.get(Calendar.DATE) == c.get(Calendar.DATE);

dateInfo.canSelect = (dateInfo.isSelected || c.after(start)) && (c.before(end) || isEnd) && dateInfo.week != Calendar.SUNDAY && dateInfo.week != Calendar.SATURDAY;

if (dateInMonthList.isEmpty()) {//在每一月的第一周前面补空data

for (int j = 0; j < dateInfo.week - 1; j++) {

DateInfo d = new DateInfo();

dateInMonthList.add(0, d);

}

}

dateInMonthList.add(dateInfo);

if (maxDayNum == dateInfo.day) {//每loop到月底put一次

dateMap.put(dateInfo.timestamp, new ArrayList<>(dateInMonthList));

dateInMonthList.clear();

needLoop = c.before(end);//每到月底判断一下，是否还需继续loop

}

//条件满足时一直add天数即可

c.add(Calendar.DATE, 1);

}

return dateMap;

}

/**

* 获取当前日期一周的日期

*/

@SuppressLint("SimpleDateFormat")

public static ArrayList getWeek(String date) {

ArrayList result = new ArrayList<>();

Calendar c = Calendar.getInstance();

try {

c.setTime(new SimpleDateFormat("yyyy-MM-dd").parse(date));

} catch (ParseException e) {

e.printStackTrace();

}

c.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY); //获取本周一的日期

for (int i = 0; i < 7; i++) {

DateInfo entity = new DateInfo();

entity.timestamp = c.getTimeInMillis();

entity.day = c.get(Calendar.DATE);

entity.week = c.get(Calendar.DAY_OF_WEEK);

c.add(Calendar.DATE, 1);

result.add(entity);

}

return result;

}

/**

* 获取系统当前日期

*/

public static String getCurrDate(String format) {

@SuppressLint("SimpleDateFormat") SimpleDateFormat formatter = new SimpleDateFormat(format);

Date curDate = new Date(System.currentTimeMillis());//获取当前时间

return formatter.format(curDate);

}

/**

* String类型的日期时间转化为毫秒(1970-)类型.

*

* @param strDate String形式的日期时间

* @param format 格式化字符串，如："yyyy-MM-dd HH:mm:ss"

* @author LY 2015-9-16 上午11:40:26

*/

public static long getMillisecondByFormat(String strDate, String format) {

@SuppressLint("SimpleDateFormat") SimpleDateFormat mSimpleDateFormat = new SimpleDateFormat(format);

Date date = null;

try {

date = mSimpleDateFormat.parse(strDate);

} catch (ParseException e) {

e.printStackTrace();

}

if (date == null) return 0;

return date.getTime();

}

/**

* 毫秒----> format格式的日期

*

* @author LY 2015-9-18 下午3:41:32

*/

public static String getDateByMillisecond(long milliseconds, String format) {

Date d = new Date(milliseconds);

@SuppressLint("SimpleDateFormat") SimpleDateFormat f = new SimpleDateFormat(format);

return f.format(d);

}

public static String getCurDateByFormat(String format) {

return getDateByMillisecond(System.currentTimeMillis(), format);

}

public static String getNextMonthByFormat(String format) {

Calendar c = Calendar.getInstance();

c.setTimeInMillis(System.currentTimeMillis());

c.add(Calendar.MONTH, 1);

Date d = c.getTime();

@SuppressLint("SimpleDateFormat") SimpleDateFormat f = new SimpleDateFormat(format);

return f.format(d);

}

}

日历的数据entity，注意一下canSelect我这里的业务需求是周末不可选，其他在范围内的日期可选，可以根据自己的需求来定制。DateInfo：

import com.robot.common.utils.CalendarUtils;

import java.util.Calendar;

/**

* @author ly

* date 2020/4/24 9:52

*/

public class DateInfo {

public long timestamp; //时间戳

public int year;

public int month;

public int day;

public int week;//一周中第几天，非中式

//是否选中

public boolean isSelected;

//日期是否可选

public boolean canSelect;

/**

* 根据美式周末到周一 返回

*/

public String getWeekName() {

String name = "";

switch (week) {

case Calendar.SUNDAY:

name = "周日";

break;

case Calendar.MONDAY:

name = "周一";

break;

case Calendar.TUESDAY:

name = "周二";

break;

case Calendar.WEDNESDAY:

name = "周三";

break;

case Calendar.THURSDAY:

name = "周四";

break;

case Calendar.FRIDAY:

name = "周五";

break;

case Calendar.SATURDAY:

name = "周六";

break;

default:

break;

}

return name;

}

public String getDay() {

if (day > 0) {

return String.valueOf(day);

} else {

return "";

}

}

public int getMonth() {

return month + 1;

}

public String getDate() {

return CalendarUtils.getDateByMillisecond(timestamp, CalendarUtils.DATE);

}

}

最后就是负责展示的类了，很简单。这里是dialog来实现的：

import android.app.Activity;

import android.view.Gravity;

import android.view.ViewGroup;

import android.widget.TextView;

import androidx.annotation.NonNull;

import androidx.recyclerview.widget.GridLayoutManager;

import androidx.recyclerview.widget.RecyclerView;

import com.chad.library.adapter.base.BaseSectionQuickAdapter;

import com.chad.library.adapter.base.BaseViewHolder;

import com.chad.library.adapter.base.entity.SectionEntity;

import java.util.ArrayList;

import java.util.LinkedHashMap;

import java.util.List;

/**

* @author ly

* date 2019/8/1 17:36

*/

public class SelDateDialog extends BaseDialog {

private SectionAdapter mAdapter;

private OnDateSelectedListener onDateSelectedListener;

private List dateList = new ArrayList<>();

private LinkedHashMap> monthMap;

private RecyclerView rv;

private int selPosition;

private DateInfo selDateInfo;

public SelDateDialog(@NonNull Activity activity, OnDateSelectedListener onDateSelectedListener) {

super(activity);

this.onDateSelectedListener = onDateSelectedListener;

mAdapter = new SectionAdapter(dateList);

mAdapter.setOnItemClickListener((adapter, view, position) -> {

SectionEntity item = mAdapter.getItem(position);

if (item == null || item.t == null)//item.t=null可能是点到了header 不做处理

return;

selPosition = position;

mAdapter.selectOne(position);

selDateInfo = item.t;

if (onDateSelectedListener != null) {

onDateSelectedListener.onDateSelect(selDateInfo);

}

// dismiss();

});

}

@Override

public int getLayoutResId() {

return R.layout.dialog_sel_date;

}

@Override

public void initViews() {

if (getWindow() != null) {

getWindow().getAttributes().width = ScreenUtil.getScreenWidth();

getWindow().getAttributes().height = (int) (ScreenUtil.getScreenHeight() * 0.7);

getWindow().setGravity(Gravity.BOTTOM);

getWindow().setWindowAnimations(com.robot.common.R.style.bottom_enter_anim);

}

setCanceledOnTouchOutside(true);

setCancelable(true);

findViewById(R.id.m_tv_dialog_sel_date_cancel).setOnClickListener(view -> {

dismiss();

});

rv = findViewById(R.id.m_rv_dialog_calendar);

rv.setLayoutManager(new GridLayoutManager(getContext(), 7));

mAdapter.bindToRecyclerView(rv);

rv.smoothScrollToPosition(selPosition);

}

public void setData(String startDate, String endDate) {

if (!dateList.isEmpty()) {

dateList.clear();

mAdapter.notifyDataSetChanged();

}

// LinkedHashMap> month = CalendarUtils.getMonthByLimit(selCalendar, 30);

monthMap = CalendarUtils.getMonthMap(startDate, endDate);

for (Long aLong : monthMap.keySet()) {

DateSection sectionTitle = new DateSection(true, CalendarUtils.getDateByMillisecond(aLong, CalendarUtils.YEAR_MONTH));

dateList.add(sectionTitle);

ArrayList monthDateList = monthMap.get(aLong);

if (monthDateList != null)

for (DateInfo dateInfo : monthDateList) {

dateList.add(new DateSection(dateInfo));

if (dateInfo.isSelected) {

selDateInfo = dateInfo;

if (onDateSelectedListener != null)

onDateSelectedListener.onDateSelect(selDateInfo);

}

}

}

DateSection sectionFooter = new DateSection(true, "后续日期暂不可订");

dateList.add(sectionFooter);

}

public LinkedHashMap> getMonthMap() {

return monthMap;

}

public DateInfo getSelDateInfo() {

return selDateInfo;

}

public void selectOne(DateInfo dateInfo) {

if (dateInfo != null && dateList != null) {

for (int i = 0; i < dateList.size(); i++) {

DateSection dateSection = dateList.get(i);

DateInfo info = dateSection.t;

if (info != null) {

info.isSelected = dateInfo.timestamp == info.timestamp;

if (info.isSelected)

selPosition = i;

}

}

mAdapter.notifyDataSetChanged();

if (rv != null)

rv.smoothScrollToPosition(selPosition);

}

}

static class SectionAdapter extends BaseSectionQuickAdapter {

private int itemW;

SectionAdapter(List data) {

super(R.layout.dialog_sel_date_item, R.layout.dialog_sel_date_title, data);

itemW = ScreenUtil.getScreenWidth() / 7;

}

void selectOne(int position) {

for (int i = 0; i < mData.size(); i++) {

SectionEntity entity = mData.get(i);

DateInfo dateInfo = entity.t;

if (dateInfo != null)

dateInfo.isSelected = position == i;

}

notifyDataSetChanged();

}

@Override

protected void convertHead(BaseViewHolder helper, final DateSection item) {

helper.setText(R.id.m_tv_dialog_sel_date_title, item.header);

}

@Override

protected void convert(BaseViewHolder helper, DateSection item) {

DateInfo dateInfo = item.t;

TextView tv = helper.getView(R.id.m_tv_dialog_sel_date);

tv.setText(dateInfo.getDay());

helper.itemView.setEnabled(dateInfo.canSelect);

tv.setBackgroundResource(dateInfo.isSelected ? R.mipmap.ic_date_item_sel : R.color.transparent);

if (dateInfo.canSelect) {

if (dateInfo.isSelected) {

tv.setTextColor(0xffffffff);

} else {

tv.setTextColor(mContext.getResources().getColor(R.color.black_text1));

}

} else {

tv.setTextColor(0xffC3C3DC);

}

ViewGroup.LayoutParams layoutParams = helper.itemView.getLayoutParams();

layoutParams.width = itemW;

layoutParams.height = itemW;

}

}

private static class DateSection extends SectionEntity {

DateSection(boolean isHeader, String header) {

super(isHeader, header);

}

DateSection(DateInfo dateInfo) {

super(dateInfo);

}

}

public interface OnDateSelectedListener {

void onDateSelect(@NonNull DateInfo dateInfo);

}

}

布局也贴一下，dialog_sel_date：

xmlns:tools="http://schemas.android.com/tools"

android:id="@+id/ll_dialog_share_confirm"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_gravity="bottom"

android:background="@drawable/shape_white_tr16b0"

android:gravity="bottom"

android:orientation="vertical">

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:orientation="horizontal">

android:id="@+id/m_tv_dialog_sel_date_cancel"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:padding="@dimen/list_lr_margin"

android:src="@mipmap/ic_close"

android:text="取消" />

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_centerInParent="true"

android:gravity="center"

android:text="选择日期"

android:textColor="#ff282832"

android:textSize="17sp" />

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:orientation="horizontal"

android:paddingTop="8dp"

android:paddingBottom="15dp">

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_weight="1"

android:gravity="center"

android:text="日"

android:textColor="#fffa496a"

android:textSize="12sp" />

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_weight="1"

android:gravity="center"

android:text="一"

android:textColor="@color/black_text1"

android:textSize="12sp" />

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_weight="1"

android:gravity="center"

android:text="二"

android:textColor="@color/black_text1"

android:textSize="12sp" />

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_weight="1"

android:gravity="center"

android:text="三"

android:textColor="@color/black_text1"

android:textSize="12sp" />

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_weight="1"

android:gravity="center"

android:text="四"

android:textColor="@color/black_text1"

android:textSize="12sp" />

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_weight="1"

android:gravity="center"

android:text="五"

android:textColor="@color/black_text1"

android:textSize="12sp" />

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_weight="1"

android:gravity="center"

android:text="六"

android:textColor="#fffa496a"

android:textSize="12sp" />

android:id="@+id/m_rv_dialog_calendar"

android:layout_width="match_parent"

android:layout_height="0dp"

android:layout_weight="1"

android:overScrollMode="never"

tools:listitem="@layout/m_dialog_item_sel_scenic" />

dialog_sel_date_item:

xmlns:tools="http://schemas.android.com/tools"

android:id="@+id/m_tv_dialog_sel_date"

style="@style/text_black"

android:layout_gravity="center"

android:gravity="center"

android:textSize="16sp"

tools:text="10" />

m_tv_dialog_sel_date_title:

xmlns:tools="http://schemas.android.com/tools"

android:id="@+id/m_tv_dialog_sel_date_title"

style="@style/text_black"

android:layout_width="match_parent"

android:background="#F3F3FA"

android:gravity="center"

android:paddingTop="6dp"

android:paddingBottom="6dp"

android:textSize="14sp"

tools:text="2020.3"/>

接着在需要用这个日历的地方创建上面的Dialog，传入开始及结束日期show即可：

SelDateDialog selDateDialog = new SelDateDialog(this, dateInfo -> showToast(dateInfo.getDate()));

selDateDialog.setData("2020-07-06", "2020-08-06");

selDateDialog.show();

最后，我想说一下，github上有很多的开源日历库，那些库大多功能繁多，如果app对日历依赖性强，需求稍微复杂那我还是建议用开源库的，毕竟不用花时间造轮子。但是简单的需求(就如本例)就没必要用那些库了，而且还要看文档学他的使用方式，还不如自己动手写了。所以视情况而定，不要动不动就接第三方库，不利于自己能力的提升。