Android自定义WheelView滚轮，并在此基础上自定义日期选择器

项目需求，需要根据UI自定义日期选择器（Android自带的DatePicker极丑）。

所以自定义了WheelView，并在此基础上自定义日期选择器。

参考1.WheelView TimePicker CityPicker 滚轮（联动）选择器

        2.使用第三方WheelView制作日期选择器

        3.WheelPicker(推荐参考，功能强大)

自定义WheelView代码如下：

/**
 * WheelView滚轮
 *
 */
public class WheelView extends View {
    /**
     * 控件宽度
     */
    private float controlWidth;
    /**
     * 控件高度
     */
    private float controlHeight;
    /**
     * 是否滑动中
     */
    private boolean isScrolling = false;
    /**
     * 选择的内容
     */
    private ArrayList itemList = new ArrayList<>();
    /**
     * 设置数据
     */
    private ArrayList dataList = new ArrayList<>();
    /**
     * 按下的坐标
     */
    private int downY;
    /**
     * 按下的时间
     */
    private long downTime = 0;
    /**
     * 短促移动
     */
    private long goonTime = 200;
    /**
     * 短促移动距离
     */
    private int goonDistance = 100;
    /**
     * 画线画笔
     */
    private Paint linePaint;
    /**
     * 线的默认颜色
     */
    private int lineColor = 0xff000000;
    /**
     * 线的默认宽度
     */
    private float lineHeight = 2f;
    /**
     * 默认字体
     */
    private float normalFont = 14.0f;
    /**
     * 选中的时候字体
     */
    private float selectedFont = 22.0f;
    /**
     * 单元格高度
     */
    private int unitHeight = 50;
    /**
     * 显示多少个内容
     */
    private int itemNumber = 7;
    /**
     * 默认字体颜色
     */
    private int normalColor = 0xff000000;
    /**
     * 选中时候的字体颜色
     */
    private int selectedColor = 0xffff0000;
    /**
     * 蒙板高度
     */
    private float maskHeight = 48.0f;
    /**
     * 选择监听
     */
    private OnSelectListener onSelectListener;
    /**
     * 是否可用
     */
    private boolean isEnable = true;
    /**
     * 刷新界面
     */
    private static final int REFRESH_VIEW = 0x001;
    /**
     * 移动距离
     */
    private static final int MOVE_NUMBER = 5;
    /**
     * 是否允许选空
     */
    private boolean noEmpty = true;

    /**
     * 正在修改数据，避免ConcurrentModificationException异常
     */
    private boolean isClearing = false;

    public WheelView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context, attrs);
        initData();
    }

    public WheelView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context, attrs);
        initData();
    }

    public WheelView(Context context) {
        super(context);
        initData();
    }

    /**
     * 初始化，获取设置的属性
     *
     * @param context
     * @param attrs
     */
    private void init(Context context, AttributeSet attrs) {

        TypedArray attribute = context.obtainStyledAttributes(attrs, R.styleable.WheelView);
        unitHeight = (int) attribute.getDimension(R.styleable.WheelView_unitHeight, unitHeight);
        itemNumber = attribute.getInt(R.styleable.WheelView_itemNumber, itemNumber);

        normalFont = attribute.getDimension(R.styleable.WheelView_normalTextSize, normalFont);
        selectedFont = attribute.getDimension(R.styleable.WheelView_selectedTextSize, selectedFont);
        normalColor = attribute.getColor(R.styleable.WheelView_normalTextColor, normalColor);
        selectedColor = attribute.getColor(R.styleable.WheelView_selectedTextColor, selectedColor);

        lineColor = attribute.getColor(R.styleable.WheelView_lineColor, lineColor);
        lineHeight = attribute.getDimension(R.styleable.WheelView_lineHeight, lineHeight);

        maskHeight = attribute.getDimension(R.styleable.WheelView_maskHeight, maskHeight);
        noEmpty = attribute.getBoolean(R.styleable.WheelView_noEmpty, true);
        isEnable = attribute.getBoolean(R.styleable.WheelView_isEnable, true);

        attribute.recycle();

        controlHeight = itemNumber * unitHeight;
    }

    /**
     * 初始化数据
     */
    private void initData() {
        isClearing = true;
        itemList.clear();
        for (int i = 0; i < dataList.size(); i++) {
            ItemObject itemObject = new ItemObject();
            itemObject.id = i;
            itemObject.itemText = dataList.get(i);
            itemObject.x = 0;
            itemObject.y = i * unitHeight;
            itemList.add(itemObject);
        }
        isClearing = false;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        controlWidth = getMeasuredWidth();
        if (controlWidth != 0) {
            setMeasuredDimension(getMeasuredWidth(), itemNumber * unitHeight);
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        drawLine(canvas);
        drawList(canvas);
        drawMask(canvas);
    }

    /**
     * 绘制线条
     *
     * @param canvas
     */
    private void drawLine(Canvas canvas) {

        if (linePaint == null) {
            linePaint = new Paint();
            linePaint.setColor(lineColor);
            linePaint.setAntiAlias(true);
            linePaint.setStrokeWidth(lineHeight);
        }

        canvas.drawLine(0, controlHeight / 2 - unitHeight / 2 + lineHeight,
                controlWidth, controlHeight / 2 - unitHeight / 2 + lineHeight, linePaint);
        canvas.drawLine(0, controlHeight / 2 + unitHeight / 2 - lineHeight,
                controlWidth, controlHeight / 2 + unitHeight / 2 - lineHeight, linePaint);
    }

    private synchronized void drawList(Canvas canvas) {
        if (isClearing)
            return;
        try {
            for (ItemObject itemObject : itemList) {
                itemObject.drawSelf(canvas, getMeasuredWidth());
            }
        } catch (Exception e) {
        }
    }

    /**
     * 绘制遮盖板
     *
     * @param canvas
     */
    private void drawMask(Canvas canvas) {
        LinearGradient lg = new LinearGradient(0, 0, 0, maskHeight, 0x00f2f2f2,
                0x00f2f2f2, Shader.TileMode.MIRROR);
        Paint paint = new Paint();
        paint.setShader(lg);
        canvas.drawRect(0, 0, controlWidth, maskHeight, paint);

        LinearGradient lg2 = new LinearGradient(0, controlHeight - maskHeight,
                0, controlHeight, 0x00f2f2f2, 0x00f2f2f2, Shader.TileMode.MIRROR);
        Paint paint2 = new Paint();
        paint2.setShader(lg2);
        canvas.drawRect(0, controlHeight - maskHeight, controlWidth,
                controlHeight, paint2);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (!isEnable)
            return true;
        int y = (int) event.getY();
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                isScrolling = true;
                downY = (int) event.getY();
                downTime = System.currentTimeMillis();
                break;
            case MotionEvent.ACTION_MOVE:
                actionMove(y - downY);
                onSelectListener();
                break;
            case MotionEvent.ACTION_UP:
                int move = Math.abs(y - downY);
                // 判断这段时间移动的距离
                if (System.currentTimeMillis() - downTime < goonTime && move > goonDistance) {
                    goonMove(y - downY);
                } else {
                    actionUp(y - downY);
                    noEmpty();
                    isScrolling = false;
                }
                break;
            default:
                break;
        }
        return true;
    }

    /**
     * 继续移动一定距离
     */
    private synchronized void goonMove(final int move) {
        new Thread(new Runnable() {

            @Override
            public void run() {
                int distance = 0;
                while (distance < unitHeight * MOVE_NUMBER) {
                    try {
                        Thread.sleep(5);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    actionThreadMove(move > 0 ? distance : distance * (-1));
                    distance += 10;

                }
                actionUp(move > 0 ? distance - 10 : distance * (-1) + 10);
                noEmpty();
            }
        }).start();
    }

    /**
     * 不能为空，必须有选项
     */
    private void noEmpty() {
        if (!noEmpty)
            return;
        for (ItemObject item : itemList) {
            if (item.isSelected())
                return;
        }
        int move = (int) itemList.get(0).moveToSelected();
        if (move < 0) {
            defaultMove(move);
        } else {
            defaultMove((int) itemList.get(itemList.size() - 1)
                    .moveToSelected());
        }
        for (ItemObject item : itemList) {
            if (item.isSelected()) {
                if (onSelectListener != null)
                    onSelectListener.endSelect(WheelView.this, item.id, item.itemText);
                break;
            }
        }
    }

    /**
     * 移动的时候
     *
     * @param move
     */
    private void actionMove(int move) {
        for (ItemObject item : itemList) {
            item.move(move);
        }
        invalidate();
    }

    /**
     * 移动，线程中调用
     *
     * @param move
     */
    private void actionThreadMove(int move) {
        for (ItemObject item : itemList) {
            item.move(move);
        }
        Message rMessage = new Message();
        rMessage.what = REFRESH_VIEW;
        handler.sendMessage(rMessage);
    }

    /**
     * 松开的时候
     *
     * @param move
     */
    private void actionUp(int move) {
        int newMove = 0;
        if (move > 0) {
            for (int i = 0; i < itemList.size(); i++) {
                if (itemList.get(i).isSelected()) {
                    newMove = (int) itemList.get(i).moveToSelected();
                    if (onSelectListener != null)
                        onSelectListener.endSelect(WheelView.this, itemList.get(i).id,
                                itemList.get(i).itemText);
                    break;
                }
            }
        } else {
            for (int i = itemList.size() - 1; i >= 0; i--) {
                if (itemList.get(i).isSelected()) {
                    newMove = (int) itemList.get(i).moveToSelected();
                    if (onSelectListener != null)
                        onSelectListener.endSelect(WheelView.this, itemList.get(i).id,
                                itemList.get(i).itemText);
                    break;
                }
            }
        }
        for (ItemObject item : itemList) {
            item.newY(move + 0);
        }
        slowMove(newMove);
        Message rMessage = new Message();
        rMessage.what = REFRESH_VIEW;
        handler.sendMessage(rMessage);

    }

    /**
     * 缓慢移动
     *
     * @param move
     */
    private synchronized void slowMove(final int move) {
        new Thread(new Runnable() {

            @Override
            public void run() {
                // 判断正负
                int m = move > 0 ? move : move * (-1);
                int i = move > 0 ? 1 : (-1);
                // 移动速度
                int speed = 1;
                while (true) {
                    m = m - speed;
                    if (m <= 0) {
                        for (ItemObject item : itemList) {
                            item.newY(m * i);
                        }
                        Message rMessage = new Message();
                        rMessage.what = REFRESH_VIEW;
                        handler.sendMessage(rMessage);
                        try {
                            Thread.sleep(2);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                        break;
                    }
                    for (ItemObject item : itemList) {
                        item.newY(speed * i);
                    }
                    Message rMessage = new Message();
                    rMessage.what = REFRESH_VIEW;
                    handler.sendMessage(rMessage);
                    try {
                        Thread.sleep(2);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                for (ItemObject item : itemList) {
                    if (item.isSelected()) {
                        if (onSelectListener != null)
                            onSelectListener.endSelect(WheelView.this, item.id, item.itemText);
                        break;
                    }
                }

            }
        }).start();
    }

    /**
     * 移动到默认位置
     *
     * @param move
     */
    private void defaultMove(int move) {
        for (ItemObject item : itemList) {
            item.newY(move);
        }
        Message rMessage = new Message();
        rMessage.what = REFRESH_VIEW;
        handler.sendMessage(rMessage);
    }

    /**
     * 滑动监听
     */
    private void onSelectListener() {
        if (onSelectListener == null)
            return;
        for (ItemObject item : itemList) {
            if (item.isSelected()) {
                onSelectListener.selecting(item.id, item.itemText);
            }
        }
    }

    /**
     * 设置数据 （第一次）
     *
     * @param data
     */
    public void setData(ArrayList data) {
        this.dataList = data;
        initData();
    }

    /**
     * 重置数据
     *
     * @param data
     */
    public void refreshData(ArrayList data) {
        setData(data);
        invalidate();
    }

    /**
     * 获取返回项 id
     *
     * @return
     */
    public int getSelected() {
        for (ItemObject item : itemList) {
            if (item.isSelected())
                return item.id;
        }
        return -1;
    }

    /**
     * 获取返回的内容
     *
     * @return
     */
    public String getSelectedText() {
        for (ItemObject item : itemList) {
            if (item.isSelected())
                return item.itemText;
        }
        return "";
    }

    /**
     * 是否正在滑动
     *
     * @return
     */
    public boolean isScrolling() {
        return isScrolling;
    }

    /**
     * 是否可用
     *
     * @return
     */
    public boolean isEnable() {
        return isEnable;
    }

    /**
     * 设置是否可用
     *
     * @param isEnable
     */
    public void setEnable(boolean isEnable) {
        this.isEnable = isEnable;
    }

    /**
     * 设置默认选项
     *
     * @param index
     */
    public void setDefault(int index) {
        if (index > itemList.size() - 1)
            return;
        float move = itemList.get(index).moveToSelected();
        defaultMove((int) move);
    }

    /**
     * 获取列表大小
     *
     * @return
     */
    public int getListSize() {
        if (itemList == null)
            return 0;
        return itemList.size();
    }

    /**
     * 获取某项的内容
     *
     * @param index
     * @return
     */
    public String getItemText(int index) {
        if (itemList == null)
            return "";
        return itemList.get(index).itemText;
    }

    /**
     * 监听
     *
     * @param onSelectListener
     */
    public void setOnSelectListener(OnSelectListener onSelectListener) {
        this.onSelectListener = onSelectListener;
    }

    @SuppressLint("HandlerLeak")
    Handler handler = new Handler() {

        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what) {
                case REFRESH_VIEW:
                    invalidate();
                    break;
                default:
                    break;
            }
        }

    };

    /**
     * 单条内容
     *
     * @author JiangPing
     */
    private class ItemObject {
        /**
         * id
         */
        public int id = 0;
        /**
         * 内容
         */
        public String itemText = "";
        /**
         * x坐标
         */
        public int x = 0;
        /**
         * y坐标
         */
        public int y = 0;
        /**
         * 移动距离
         */
        public int move = 0;
        /**
         * 字体画笔
         */
        private TextPaint textPaint;
        /**
         * 字体范围矩形
         */
        private Rect textRect;

        public ItemObject() {
            super();
        }

        /**
         * 绘制自身
         *
         * @param canvas         画板
         * @param containerWidth 容器宽度
         */
        public void drawSelf(Canvas canvas, int containerWidth) {

            if (textPaint == null) {
                textPaint = new TextPaint();
                textPaint.setAntiAlias(true);
            }

            if (textRect == null)
                textRect = new Rect();

            // 判断是否被选择
            if (isSelected()) {
                textPaint.setColor(selectedColor);
                // 获取距离标准位置的距离
                float moveToSelect = moveToSelected();
                moveToSelect = moveToSelect > 0 ? moveToSelect : moveToSelect * (-1);
                // 计算当前字体大小
                float textSize = normalFont
                        + ((selectedFont - normalFont) * (1.0f - moveToSelect / (float) unitHeight));
                textPaint.setTextSize(textSize);
            } else {
                textPaint.setColor(normalColor);
                textPaint.setTextSize(normalFont);
            }

            // 返回包围整个字符串的最小的一个Rect区域
            itemText = (String) TextUtils.ellipsize(itemText, textPaint, containerWidth, TextUtils.TruncateAt.END);
            textPaint.getTextBounds(itemText, 0, itemText.length(), textRect);
            // 判断是否可视
            if (!isInView())
                return;

            // 绘制内容
            canvas.drawText(itemText, x + controlWidth / 2 - textRect.width() / 2,
                    y + move + unitHeight / 2 + textRect.height() / 2, textPaint);

        }

        /**
         * 是否在可视界面内
         *
         * @return
         */
        public boolean isInView() {
            if (y + move > controlHeight || (y + move + unitHeight / 2 + textRect.height() / 2) < 0)
                return false;
            return true;
        }

        /**
         * 移动距离
         *
         * @param _move
         */
        public void move(int _move) {
            this.move = _move;
        }

        /**
         * 设置新的坐标
         *
         * @param _move
         */
        public void newY(int _move) {
            this.move = 0;
            this.y = y + _move;
        }

        /**
         * 判断是否在选择区域内
         *
         * @return
         */
        public boolean isSelected() {
            if ((y + move) >= controlHeight / 2 - unitHeight / 2 + lineHeight
                    && (y + move) <= controlHeight / 2 + unitHeight / 2 - lineHeight) {
                return true;
            }
            if ((y + move + unitHeight) >= controlHeight / 2 - unitHeight / 2 + lineHeight
                    && (y + move + unitHeight) <= controlHeight / 2 + unitHeight / 2 - lineHeight) {
                return true;
            }
            if ((y + move) <= controlHeight / 2 - unitHeight / 2 + lineHeight
                    && (y + move + unitHeight) >= controlHeight / 2 + unitHeight / 2 - lineHeight) {
                return true;
            }
            return false;
        }

        /**
         * 获取移动到标准位置需要的距离
         */
        public float moveToSelected() {
            return (controlHeight / 2 - unitHeight / 2) - (y + move);
        }
    }

    /**
     * 选择监听
     *
     * @author JiangPing
     */
    public interface OnSelectListener {
        /**
         * 结束选择
         *
         * @param id
         * @param text
         */
        void endSelect(View view, int id, String text);

        /**
         * 选中的内容
         *
         * @param id
         * @param text
         */
        void selecting(int id, String text);

    }
}

日期选择器的效果如图所示：

public class DateSelectionDialog extends Dialog implements WheelView.OnSelectListener {
    @BindView(R.id.staff_birthday_selection_cancel)
    Button mStaffBirthdaySelectionCancel;
    @BindView(R.id.staff_birthday_selection_confrim)
    Button mStaffBirthdaySelectionConfrim;
    @BindView(R.id.year)
    WheelView mYear;
    @BindView(R.id.month)
    WheelView mMonth;
    @BindView(R.id.day)
    WheelView mDay;

    private OnClickListener positiveButtonClickListener;
    private OnClickListener negativeButtonClickListener;

    public void setNegativeButton(OnClickListener listener) {
        this.negativeButtonClickListener = listener;
    }

    public void setPositiveButton(OnClickListener listener) {
        this.positiveButtonClickListener = listener;
    }

    public DateSelectionDialog(@NonNull Context context) {
        super(context, R.style.select_dialog);
    }

    public DateSelectionDialog(@NonNull Context context, int themeResId) {
        super(context, themeResId);
    }

    protected DateSelectionDialog(@NonNull Context context, boolean cancelable, @Nullable OnCancelListener cancelListener) {
        super(context, cancelable, cancelListener);
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout_date_selection_dialog);
        ButterKnife.bind(this);

        // 格式化当前时间，并转换为年月日整型数据
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd", Locale.getDefault());
        String[] split = sdf.format(new Date()).split("-");
        int currentYear = Integer.parseInt(split[0]);
        int currentMonth = Integer.parseInt(split[1]);
        int currentDay = Integer.parseInt(split[2]);

        // 设置默认年月日为当前日期
        mYear.setData(getYearData());
        mYear.setDefault(currentYear - 1900);
        mMonth.setData(getMonthData());
        mMonth.setDefault(currentMonth - 1);
        mDay.setData(getDayData(getLastDay(currentYear, currentMonth)));
        mDay.setDefault(currentDay - 1);

        mYear.setOnSelectListener(this);
        mMonth.setOnSelectListener(this);
        mDay.setOnSelectListener(this);

    }

    @Override
    protected void onStart() {
        super.onStart();
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            Window window = this.getWindow();
            window.setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
            int uiOptions = View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                    | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
                    | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
                    | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                    | View.SYSTEM_UI_FLAG_FULLSCREEN
                    | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY;
            window.getDecorView().setSystemUiVisibility(uiOptions);
            getWindow().setStatusBarColor(Color.TRANSPARENT);
            getWindow().setNavigationBarColor(Color.TRANSPARENT);
        }
    }

    @OnClick({R.id.staff_birthday_selection_cancel, R.id.staff_birthday_selection_confrim})
    public void onViewClicked(View view) {
        switch (view.getId()) {
            case R.id.staff_birthday_selection_cancel:
                negativeButtonClickListener.onClick(this, DialogInterface.BUTTON_NEGATIVE);
                break;
            case R.id.staff_birthday_selection_confrim:
                positiveButtonClickListener.onClick(this, DialogInterface.BUTTON_POSITIVE);
                break;
        }
    }

    private ArrayList getYearData() {
        ArrayList list = new ArrayList<>();
        for (int i = 1900; i <= 2050; i++) {
            list.add(String.valueOf(i));
        }
        return list;
    }

    private ArrayList getMonthData() {
        ArrayList list = new ArrayList<>();
        for (int i = 1; i <= 12; i++) {
            list.add(String.valueOf(i));
        }
        return list;
    }

    private ArrayList getDayData(int lastDay) {
        //ignore condition
        ArrayList list = new ArrayList<>();
        for (int i = 1; i <= lastDay; i++) {
            list.add(String.valueOf(i));
        }
        return list;
    }

    public String getYear() {
        if (mDay == null) {
            return null;
        }
        return mYear.getSelectedText();
    }

    public String getMonth() {
        if (mMonth == null) {
            return null;
        }
        return mMonth.getSelectedText();
    }

    public String getDay() {
        if (mDay == null) {
            return null;
        }
        return mDay.getSelectedText();
    }

    public String getDate() {
        return getYear() + "." + getMonth() + "." + getDay();
    }

    /**
     * 判断是否闰年
     *
     * @param year
     * @return
     */
    private boolean isLeapYear(int year) {
        return (year % 100 == 0 && year % 400 == 0) || (year % 100 != 0 && year % 4 == 0);
    }

    /**
     * 获取特定年月对应的天数
     *
     * @param year
     * @param month
     * @return
     */
    private int getLastDay(int year, int month) {
        if (month == 2) {
            // 2月闰年的话返回29，防止28
            return isLeapYear(year) ? 29 : 28;
        }
        // 一三五七八十腊，三十一天永不差
        return month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12 ? 31 : 30;
    }

    @Override
    public void endSelect(View view, int id, String text) {
        // 滚轮滑动停止后调用
        switch (view.getId()) {
            case R.id.year:
            case R.id.month:
                // 记录当前选择的天数
                int selectDay = Integer.parseInt(getDay());
                // 根据当前选择的年月获取对应的天数
                int lastDay = getLastDay(Integer.parseInt(getYear()), Integer.parseInt(getMonth()));
                // 设置天数
                mDay.setData(getDayData(lastDay));
                // 如果选中的天数大于实际天数，那么将默认天数设为实际天数;否则还是设置默认天数为选中的天数
                if (selectDay > lastDay) {
                    mDay.setDefault(lastDay - 1);
                } else {
                    mDay.setDefault(selectDay - 1);
                }
                break;
        }
    }

    @Override
    public void selecting(int id, String text) {

    }
}