/** * 滾輪選擇器 * author LH * data 2016/8/20 17:26 */public class WheelView extends View {  public static final String TAG = "WheelView";  /** * 自動回滾到中間的速度 */ public static final float SPEED = 2;  /** * 除選中item外，上下各需要顯示的備選項數目 */ public static final int SHOW_SIZE = 1;  private Context context;  private List<String> itemList; private int itemCount;  /** * item高度 */ private int itemHeight = 50;  /** * 選中的位置，這個位置是mDataList的中心位置，一直不變 */ private int currentItem;  private Paint selectPaint; private Paint mPaint; // 畫背景圖中單獨的畫筆 private Paint centerLinePaint;  private float centerY; private float centerX;  private float mLastDownY; /** * 滑動的距離 */ 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 {  // 這里mMoveLen / Math.abs(mMoveLen)是為了保有mMoveLen的正負號，以實現上滾或下滾  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<String> 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; } /** * 選擇選中的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));  // 繪制背景 setBackground(null); }  @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); if (isInit) {  drawData(canvas); } }  private void drawData(Canvas canvas) { // 先繪制選中的text再往上往下繪制其余的text if (!itemList.isEmpty()) {  // 繪制中間data  drawCenterText(canvas);  // 繪制上方data  for (int i = 1; i < SHOW_SIZE + 1; i++) {  drawOtherText(canvas, i, -1);  }  // 繪制下方data  for (int i = 1; i < SHOW_SIZE + 1; i++) {  drawOtherText(canvas, i, 1);  } } }  private void drawCenterText(Canvas canvas) { // text居中繪制，注意baseline的計算才能達到居中，y值是text中心坐標 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); }  /** * 繪制文本 * author LH * data 2016/9/4 11:10 * @param canvas 畫布 * @param position 距離mCurrentSelected的差值 * @param type 1表示向下繪制，-1表示向上繪制 */ 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) {  // 往下滑超過離開距離  mMoveLen = mMoveLen - itemHeight;  currentItem--;  if (currentItem < 0) {  currentItem = itemCount - 1;  } } else if (mMoveLen < -itemHeight / 2) {  // 往上滑超過離開距離  mMoveLen = mMoveLen + itemHeight;  currentItem++;  if (currentItem >= itemCount) {  currentItem = 0;  } }  mLastDownY = event.getY(); invalidate(); }  private void doUp() { // 抬起手后mCurrentSelected的位置由當前位置move到中間選中位置 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); } }

/** * 時間選擇樣式 * 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<String> 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<String> createHourString() { List<String> wheelString = new ArrayList<>(); for (int i = 0; i < 24; i++) {  wheelString.add(String.format("%02d" + "時", i)); } return wheelString; }  private static List<String> createMinuteString() { List<String> wheelString = new ArrayList<>(); for (int i = 0; i < 60; i++) {  wheelString.add(String.format("%02d" + "分", i)); } return wheelString; }  private static List<String> createYearString() { List<String> wheelString = new ArrayList<>(); for (int i = minYear; i <= maxYear; i++) {  wheelString.add(Integer.toString(i)); } return wheelString; }  private static List<String> createMonthString() { List<String> wheelString = new ArrayList<>(); for (int i = 1; i <= 12; i++) {  wheelString.add(String.format("%02d" + "月", i)); } return wheelString; }  private static List<String> createDayString() { List<String> wheelString = new ArrayList<>(); for (int i = 1; i <= 31; i++) {  wheelString.add(String.format("%02d" + "日", i)); } return wheelString; }  private static List<String> createSimpleDayString() { List<String> wheelString = new ArrayList<>(); wheelString.add("一天后"); wheelString.add("兩天后"); wheelString.add("三天后"); return wheelString; }  private static List<String> createSetWarnTimeString() { List<String> wheelString = new ArrayList<>(); wheelString.add("30分鐘"); wheelString.add("60分鐘"); wheelString.add("90分鐘"); wheelString.add("120分鐘"); return wheelString; } /** * 計算閏月 * * @param month * @return */ private static boolean isLeapMonth(int month) { return month == 1 || month == 3 || month == 5 || month == 7  || month == 8 || month == 10 || month == 12; }  /** * 計算閏年 * * @param year * @return */ private static boolean isLeapYear(int year) { return (year % 4 == 0 && year % 100 != 0) || year % 400 == 0; }}

<com.example.view.timeview.WheelView  android:id="@+id/select_time_simple_wheel"  android:layout_width="match_parent"  android:layout_height="150dp"  android:layout_marginLeft="20dp"  android:layout_marginRight="20dp"  android:layout_weight="1" />