自定义时间选择控件（仿ios滚动效果）

1.先上自定义的控件：

/**
 * 滚轮选择器
 * author lh
 * data 2016/8/20 17:26
 */
public class wheelview extends view {

    public static final string tag = "wheelview";

    /**
     * 自动回滚到中间的速度
     */
    public static final float speed = 2;

    /**
     * 除选中item外，上下各需要显示的备选项数目
     */
    public static final int show_size = 1;

    private context context;

    private list itemlist;
    private int itemcount;

    /**
     * item高度
     */
    private int itemheight = 50;

    /**
     * 选中的位置，这个位置是mdatalist的中心位置，一直不变
     */
    private int currentitem;

    private paint selectpaint;
    private paint mpaint;
    // 画背景图中单独的画笔
    private paint centerlinepaint;

    private float centery;
    private float centerx;

    private float mlastdowny;
    /**
     * 滑动的距离
     */
    private float mmovelen = 0;
    private boolean isinit = false;
    private selectlistener mselectlistener;
    private timer timer;
    private mytimertask mtask;

    handler updatehandler = new handler() {

        @override
        public void handlemessage(message msg) {
            if (math.abs(mmovelen) < speed) {
                // 如果偏移量少于最少偏移量
                mmovelen = 0;
                if (null != timer) {
                    timer.cancel();
                    timer.purge();
                    timer = null;
                }
                if (mtask != null) {
                    mtask.cancel();
                    mtask = null;
                    performselect();
                }
            } else {
                // 这里mmovelen / math.abs(mmovelen)是为了保有mmovelen的正负号，以实现上滚或下滚
                mmovelen = mmovelen - mmovelen / math.abs(mmovelen) * speed;
            }
            invalidate();
        }

    };

    public wheelview(context context) {
        super(context);
        init(context);
    }

    public wheelview(context context, attributeset attrs) {
        super(context, attrs);
        init(context);
    }

    public void setonselectlistener(selectlistener listener) {
        mselectlistener = listener;
    }

    public void setwheelstyle(int style) {
        itemlist = wheelstyle.getitemlist(context, style);
        if (itemlist != null) {
            itemcount = itemlist.size();
            resetcurrentselect();
            invalidate();
        } else {
            log.i(tag, "item is null");
        }
    }

    public void setwheelitemlist(list itemlist) {
        this.itemlist = itemlist;
        if (itemlist != null) {
            itemcount = itemlist.size();
            resetcurrentselect();
        } else {
            log.i(tag, "item is null");
        }
    }

    private void resetcurrentselect() {
        if (currentitem < 0) {
            currentitem = 0;
        }
        while (currentitem >= itemcount) {
            currentitem--;
        }
        if (currentitem >= 0 && currentitem < itemcount) {
            invalidate();
        } else {
            log.i(tag, "current item is invalid");
        }
    }

    public int getitemcount() {
        return itemcount;
    }
    /**
     * 选择选中的item的index
     * author lh
     * data 2016/9/4 11:09
     */
    public void setcurrentitem(int selected) {
        currentitem = selected;
        resetcurrentselect();
    }

    public int getcurrentitem() {
        return currentitem;
    }

    @override
    protected void onmeasure(int widthmeasurespec, int heightmeasurespec) {
        super.onmeasure(widthmeasurespec, heightmeasurespec);
        int mviewheight = getmeasuredheight();
        int mviewwidth = getmeasuredwidth();
        centerx = (float) (mviewwidth / 2.0);
        centery = (float) (mviewheight / 2.0);

        isinit = true;
        invalidate();
    }


    private void init(context context) {
        this.context = context;

        timer = new timer();
        itemlist = new arraylist<>();

        mpaint = new paint(paint.anti_alias_flag);
        mpaint.setstyle(style.fill);
        mpaint.settextalign(align.center);
        mpaint.setcolor(getresources().getcolor(r.color.wheel_unselect_text));
        int size1 = (int) (supportdisplay.getlayoutscale()*22+0.5);
        mpaint.settextsize(size1);

        selectpaint = new paint(paint.anti_alias_flag);
        selectpaint.setstyle(style.fill);
        selectpaint.settextalign(align.center);
        selectpaint.setcolor(getresources().getcolor(r.color.color_1a1a1a));
        int size2 = (int) (supportdisplay.getlayoutscale()*24+0.5);
        selectpaint.settextsize(size2);

        centerlinepaint = new paint(paint.anti_alias_flag);
        centerlinepaint.setstyle(style.fill);
        centerlinepaint.settextalign(align.center);
        centerlinepaint.setcolor(getresources().getcolor(r.color.wheel_unselect_text));

        // 绘制背景
        setbackground(null);
    }

    @override
    protected void ondraw(canvas canvas) {
        super.ondraw(canvas);
        if (isinit) {
            drawdata(canvas);
        }
    }

    private void drawdata(canvas canvas) {
        // 先绘制选中的text再往上往下绘制其余的text
        if (!itemlist.isempty()) {
            // 绘制中间data
            drawcentertext(canvas);
            // 绘制上方data
            for (int i = 1; i < show_size + 1; i++) {
                drawothertext(canvas, i, -1);
            }
            // 绘制下方data
            for (int i = 1; i < show_size + 1; i++) {
                drawothertext(canvas, i, 1);
            }
        }
    }

    private void drawcentertext(canvas canvas) {
        // text居中绘制，注意baseline的计算才能达到居中，y值是text中心坐标
        float y = centery + mmovelen;
        fontmetricsint fmi = selectpaint.getfontmetricsint();
        float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0));
        canvas.drawtext(itemlist.get(currentitem), centerx, baseline, selectpaint);
    }

    /**
     * 绘制文本
     * author lh
     * data 2016/9/4 11:10
     * @param canvas   画布
     * @param position 距离mcurrentselected的差值
     * @param type     1表示向下绘制，-1表示向上绘制
     */
    private void drawothertext(canvas canvas, int position, int type) {
        int index = currentitem + type * position;
        if (index >= itemcount) {
            index = index - itemcount;
        }
        if (index < 0) {
            index = index + itemcount;
        }
        string text = itemlist.get(index);

        int itemheight = getheight() / (show_size * 2 + 1);
        float d = itemheight * position + type * mmovelen;
        float y = centery + type * d;

        fontmetricsint fmi = mpaint.getfontmetricsint();
        float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0));
        canvas.drawtext(text, centerx, baseline, mpaint);
    }

    @override
    public void setbackground(drawable background) {
        background = new drawable() {
            @override
            public void draw(canvas canvas) {
                itemheight = getheight() / (show_size * 2 + 1);
                int width = getwidth();

                canvas.drawline(0, itemheight, width, itemheight, centerlinepaint);
                canvas.drawline(0, itemheight * 2, width, itemheight * 2, centerlinepaint);

                centerlinepaint.setcolor(getresources().getcolor(r.color.wheel_bg));
                rect toprect = new rect(0, 0, width, itemheight);
                canvas.drawrect(toprect, centerlinepaint);
                rect bottomrect = new rect(0, itemheight * 2, width, itemheight * 3);
                canvas.drawrect(bottomrect, centerlinepaint);
            }

            @override
            public void setalpha(int alpha) {

            }

            @override
            public void setcolorfilter(colorfilter cf) {

            }

            @override
            public int getopacity() {
                return 0;
            }
        };
        super.setbackground(background);
    }

    @override
    public boolean ontouchevent(motionevent event) {
        switch (event.getactionmasked()) {
            case motionevent.action_down:
                dodown(event);
                break;
            case motionevent.action_move:
                domove(event);
                break;
            case motionevent.action_up:
                doup();
                break;
            default:
                break;
        }
        return true;
    }

    private void dodown(motionevent event) {
        if (mtask != null) {
            mtask.cancel();
            mtask = null;
        }
        mlastdowny = event.gety();
    }

    private void domove(motionevent event) {

        mmovelen += (event.gety() - mlastdowny);
        if (mmovelen > itemheight / 2) {
            // 往下滑超过离开距离
            mmovelen = mmovelen - itemheight;
            currentitem--;
            if (currentitem < 0) {
                currentitem = itemcount - 1;
            }
        } else if (mmovelen < -itemheight / 2) {
            // 往上滑超过离开距离
            mmovelen = mmovelen + itemheight;
            currentitem++;
            if (currentitem >= itemcount) {
                currentitem = 0;
            }
        }

        mlastdowny = event.gety();
        invalidate();
    }

    private void doup() {
        // 抬起手后mcurrentselected的位置由当前位置move到中间选中位置
        if (math.abs(mmovelen) < 0.0001) {
            mmovelen = 0;
            return;
        }
        if (mtask != null) {
            mtask.cancel();
            mtask = null;
        }
        if (null == timer) {
            timer = new timer();
        }
        mtask = new mytimertask(updatehandler);
        timer.schedule(mtask, 0, 10);
    }

    class mytimertask extends timertask {
        handler handler;

        public mytimertask(handler handler) {
            this.handler = handler;
        }

        @override
        public void run() {
            handler.sendmessage(handler.obtainmessage());
        }

    }

    private void performselect() {
        if (mselectlistener != null) {
            mselectlistener.onselect(currentitem, itemlist.get(currentitem));
        } else {
            log.i(tag, "null listener");
        }
    }

    public interface selectlistener {
        void onselect(int index, string text);
    }

}

/**
 * 时间选择样式
 * author lh
 * data 2016/9/4 11:05
 */
public class wheelstyle {

    public static final int minyear = 1980;
    public static final int maxyear = 2020;

    /**
     * wheel style hour
     */
    public static final int style_hour = 1;
    /**
     * wheel style minute
     */
    public static final int style_minute = 2;
    /**
     * wheel style year
     */
    public static final int style_year = 3;
    /**
     * wheel style month
     */
    public static final int style_month = 4;
    /**
     * wheel style day
     */
    public static final int style_day = 5;
    /**
     * wheel style simple day
     */
    public static final int style_simple_day = 6;
    /**
     * wheel style set warn
     */
    public static final int style_set_warn = 7;
    /**
     * wheel style work answer
     */
    public static final int style_work_answer = 8;

    private wheelstyle() {
    }

    public static list getitemlist(context context, int style) {
        if (style == style_hour) {
            return createhourstring();
        } else if (style == style_minute) {
            return createminutestring();
        } else if (style == style_year) {
            return createyearstring();
        } else if (style == style_month) {
            return createmonthstring();
        } else if (style == style_day) {
            return createdaystring();
        } else if (style == style_simple_day) {
            return createsimpledaystring();
        } else if (style == style_set_warn) {
            return createsetwarntimestring();
        } else {
            throw new illegalargumentexception("style is illegal");
        }
    }

    private static list createhourstring() {
        list wheelstring = new arraylist<>();
        for (int i = 0; i < 24; i++) {
            wheelstring.add(string.format("%02d" + "时", i));
        }
        return wheelstring;
    }

    private static list createminutestring() {
        list wheelstring = new arraylist<>();
        for (int i = 0; i < 60; i++) {
            wheelstring.add(string.format("%02d" + "分", i));
        }
        return wheelstring;
    }

    private static list createyearstring() {
        list wheelstring = new arraylist<>();
        for (int i = minyear; i <= maxyear; i++) {
            wheelstring.add(integer.tostring(i));
        }
        return wheelstring;
    }

    private static list createmonthstring() {
        list wheelstring = new arraylist<>();
        for (int i = 1; i <= 12; i++) {
            wheelstring.add(string.format("%02d" + "月", i));
        }
        return wheelstring;
    }

    private static list createdaystring() {
        list wheelstring = new arraylist<>();
        for (int i = 1; i <= 31; i++) {
            wheelstring.add(string.format("%02d" + "日", i));
        }
        return wheelstring;
    }

    private static list createsimpledaystring() {
        list wheelstring = new arraylist<>();
        wheelstring.add("一天后");
        wheelstring.add("两天后");
        wheelstring.add("三天后");
        return wheelstring;
    }

    private static list createsetwarntimestring() {
        list wheelstring = new arraylist<>();
        wheelstring.add("30分钟");
        wheelstring.add("60分钟");
        wheelstring.add("90分钟");
        wheelstring.add("120分钟");
        return wheelstring;
    }
    /**
     * 计算闰月
     *
     * @param month
     * @return
     */
    private static boolean isleapmonth(int month) {
        return month == 1 || month == 3 || month == 5 || month == 7
                || month == 8 || month == 10 || month == 12;
    }

    /**
     * 计算闰年
     *
     * @param year
     * @return
     */
    private static boolean isleapyear(int year) {
        return (year % 4 == 0 && year % 100 != 0) || year % 400 == 0;
    }
}

5.获取当前选择的项也很简单mwheelview.getcurrentitem();就能获取到控件的当前选择的项。获取到所在的项以后剩下的就是逻辑操作了。