Android自定义实现日历控件

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:padding="20sp"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <relativelayout
        android:id="@+id/titlerl"
        android:layout_width="match_parent"
        android:layout_height="30dp">
        <textview
            android:id="@+id/lasttv"
            android:text="上一月"
            android:layout_alignparentleft="true"
            android:gravity="center"
            android:layout_width="wrap_content"
            android:layout_height="30dp"></textview>
        <textview
            android:id="@+id/monthtv"
            android:text="十一月"
            android:gravity="center"
            android:layout_centerhorizontal="true"
            android:layout_width="wrap_content"
            android:layout_height="30dp"></textview>
        <textview
            android:id="@+id/nexttv"
            android:text="下一月"
            android:gravity="center"
            android:layout_alignparentright="true"
            android:layout_width="wrap_content"
            android:layout_height="30dp"></textview>
    </relativelayout>
    <linearlayout
        android:id="@+id/weekll"
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <textview
            android:id="@+id/tv7"
            android:text="日"
            android:gravity="center"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="30dp"></textview>
        <textview
            android:id="@+id/tv1"
            android:text="一"
            android:gravity="center"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="30dp"></textview>
        <textview
            android:id="@+id/tv2"
            android:text="二"
            android:gravity="center"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="30dp"></textview>
        <textview
            android:id="@+id/tv3"
            android:text="三"
            android:gravity="center"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="30dp"></textview>
        <textview
            android:id="@+id/tv4"
            android:text="四"
            android:gravity="center"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="30dp"></textview>
        <textview
            android:id="@+id/tv5"
            android:text="五"
            android:gravity="center"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="30dp"></textview>
        <textview
            android:id="@+id/tv6"
            android:text="六"
            android:gravity="center"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="30dp"></textview>
    </linearlayout>
    <gridview
        android:id="@+id/calendarcv"
        android:numcolumns="7"
        android:layout_width="match_parent"
        android:layout_height="match_parent"></gridview>
</linearlayout>

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <textview
        android:id="@+id/itemtv"
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="match_parent"></textview>
</linearlayout>

<androidx.constraintlayout.widget.constraintlayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".mainactivity">
    <com.aye.newcalendar.newcalendar
        android:id="@+id/calendarnc"
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="match_parent"></com.aye.newcalendar.newcalendar>
</androidx.constraintlayout.widget.constraintlayout>

public class newcalendar extends linearlayout {
    private textview lasttv,nexttv,datetv;
    private gridview calendargv;

    private calendar calendar=calendar.getinstance();  //日历控件初始化
    //重写三个构造方法
    public newcalendar(context context) {
        super(context);
    }
    public newcalendar(context context, @nullable attributeset attrs) {
        super(context, attrs);
        initcontrol(context);  //绑定控件
    }
    public newcalendar(context context, @nullable attributeset attrs, int defstyleattr) {
        super(context, attrs, defstyleattr);
        initcontrol(context);  //绑定控件
    }
    private void initcontrol(context context){
        bindcontrol(context);  //绑定控件
        bindcontrolevent();   //绑定控件事件
    }

    //绑定控件事件方法
    private void bindcontrolevent() {
        rendercalendar();
        //“下一月”点击事件
        nexttv.setonclicklistener(new onclicklistener() {
            @override
            public void onclick(view v) {
                calendar.add(calendar.month,+1);   //月份+1
                rendercalendar();
            }
        });
        //“上一个”点击事件
        lasttv.setonclicklistener(new onclicklistener() {
            @override
            public void onclick(view v) {
                calendar.add(calendar.month,-1);   //月份-1
                rendercalendar();
            }
        });
    }

    private void rendercalendar() {
        simpledateformat sdf = new simpledateformat("mmm yyy");  //日期格式化
        datetv.settext(sdf.format(calendar.gettime()));  //设置月份
        arraylist<date> cells = new arraylist<>();
        calendar calendar1 = (calendar) calendar.clone();  //克隆日历对象
        calendar1.set(calendar.day_of_month, 1);  //置于当月第一天;
        int prevdays = calendar1.get(calendar.day_of_week) - 1;  //获取上个月最后一天是星期几
        calendar1.add(calendar.day_of_month, -prevdays);  //第一天

        int maxcount = 6 * 7;  //设置每个月最大天数
        //循环存入集合中
        while (cells.size() < maxcount) {
            cells.add(calendar1.gettime());
            calendar1.add(calendar.day_of_month, 1);  //日期+1
        }
        //设置适配器
        calendargv.setadapter(new calendaradapter(getcontext(),cells));
    }
    
    
    //适配器
    private class calendaradapter extends arrayadapter<date>{
        layoutinflater layoutinflater;
        public calendaradapter(@nonnull context context,arraylist<date> days) {
            super(context, r.layout.item_layout,days);
            layoutinflater=layoutinflater.from(context);
        }
        @nonnull
        @override
        public view getview(int position, @nullable view convertview, @nonnull viewgroup parent) {
            date date=getitem(position);
            viewholder viewholder;
            if (convertview==null){  //初始化绑定
                convertview=layoutinflater.inflate(r.layout.item_layout,parent,false);
                viewholder=new viewholder();
                viewholder.itemtv=convertview.findviewbyid(r.id.itemtv);
                convertview.settag(viewholder);
            }
            viewholder= (viewholder) convertview.gettag();
            int day=date.getdate();
            viewholder.itemtv.settext(string.valueof(day));  //赋值

        return convertview;
        }
        class viewholder{
            textview itemtv;
        }
    }
    private void bindcontrol(context context) {
        layoutinflater inflater=layoutinflater.from(context);
        inflater.inflate(r.layout.calendar_layout,this);

        lasttv=findviewbyid(r.id.lasttv);
        nexttv=findviewbyid(r.id.nexttv);
        datetv=findviewbyid(r.id.datetv);
        calendargv=findviewbyid(r.id.calendargv);
    }
}

date now=new date();
boolean isthesamemonth=false;  //是否与当前月份相同
//判断显示的日期月份与当前月份相同
 if (date.getmonth()==now.getmonth()) {  //月份相同
                isthesamemonth = true;
            }
            //若显示的日期月份与当前月份相同,则设置字体颜色是黑色
            if (isthesamemonth) {
                viewholder.itemtv.settextcolor(color.parsecolor("#000000"));
            }
            //设置当前日期字体为红色
            if (now.getdate()==date.getdate()&&now.getmonth()==date.getmonth()&&now.getyear()==date.getyear()){
                viewholder.itemtv.settextcolor(color.parsecolor("#ff0000"));
            }

//长按事件接口
public interface newcalendarlistener{
        void onitemclick(date date);
    }

        //适配器长按事件
        calendargv.setonitemlongclicklistener(new adapterview.onitemlongclicklistener() {
            @override
            public boolean onitemlongclick(adapterview<?> parent, view view, int position, long id) {
                if (listener==null){
                    return false;
                }else {
                    //获取长按的位置，传入onitemclick方法中
                    listener.onitemclick((date) parent.getitematposition(position));
                    return true;
                }
            }
        });

@override
protected void oncreate(bundle savedinstancestate) {
        super.oncreate(savedinstancestate);
        setcontentview(r.layout.activity_main);
        newcalendar calendar=findviewbyid(r.id.calendarnc);
        calendar.listener=this;
    }
    //mainactivity实现长按事件接口
    @override
    public void onitemclick(date date) {
        dateformat df= simpledateformat.getdateinstance();
        toast.maketext(this,df.format(date),toast.length_short).show();
    }