android仿iphone滚轮控件显示效果

android仿iphone滚轮控件显示效果，供大家参考，具体内容如下

在论坛里看到的，自己弄个效果：

这个滚动的WheelView

 /* 
 * Android Wheel Control. 
 * https://code.google.com/p/android-wheel/ 
 *  
 * Copyright 2010 Yuri Kanivets 
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); 
 * you may not use this file except in compliance with the License. 
 * You may obtain a copy of the License at 
 * 
 * http://www.apache.org/licenses/LICENSE-2.0 
 * 
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS, 
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 * See the License for the specific language governing permissions and 
 * limitations under the License. 
 */ 
 
package kankan.wheel.widget; 
 
import java.util.LinkedList; 
import java.util.List; 
 
import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Paint; 
import android.graphics.Rect; 
import android.graphics.drawable.Drawable; 
import android.graphics.drawable.GradientDrawable; 
import android.graphics.drawable.GradientDrawable.Orientation; 
import android.os.Handler; 
import android.os.Message; 
import android.text.Layout; 
import android.text.StaticLayout; 
import android.text.TextPaint; 
import android.util.AttributeSet; 
import android.util.FloatMath; 
import android.view.GestureDetector; 
import android.view.GestureDetector.SimpleOnGestureListener; 
import android.view.MotionEvent; 
import android.view.View; 
import android.view.animation.Interpolator; 
import android.widget.Scroller; 
 
import com.shao.pwd.R; 
 
/** 
 * Numeric wheel view. 
 * 
 * @author Yuri Kanivets 
 */ 
public class WheelView extends View { 
  /** Scrolling duration */ 
  private static final int SCROLLING_DURATION = 400; 
 
  /** Minimum delta for scrolling */ 
  private static final int MIN_DELTA_FOR_SCROLLING = 1; 
 
  /** Current value & label text color */ 
  private static final int VALUE_TEXT_COLOR = 0xF0000000; 
 
  /** Items text color */ 
  private static final int ITEMS_TEXT_COLOR = 0xFF000000; 
 
  /** Top and bottom shadows colors */ 
  private static final int[] SHADOWS_COLORS = new int[] { 0xFF111111, 
      0x00AAAAAA, 0x00AAAAAA }; 
 
  /** Additional items height (is added to standard text item height) */ 
  private static final int ADDITIONAL_ITEM_HEIGHT = 15; 
 
  /** Text size */ 
  private static final int TEXT_SIZE = 24; 
 
  /** Top and bottom items offset (to hide that) */ 
  private static final int ITEM_OFFSET = TEXT_SIZE / 5; 
 
  /** Additional width for items layout */ 
  private static final int ADDITIONAL_ITEMS_SPACE = 10; 
 
  /** Label offset */ 
  private static final int LABEL_OFFSET = 8; 
 
  /** Left and right padding value */ 
  private static final int PADDING = 10; 
 
  /** Default count of visible items */ 
  private static final int DEF_VISIBLE_ITEMS = 5; 
 
  // Wheel Values 
  private WheelAdapter adapter = null; 
  private int currentItem = 0; 
   
  // Widths 
  private int itemsWidth = 0; 
  private int labelWidth = 0; 
 
  // Count of visible items 
  private int visibleItems = DEF_VISIBLE_ITEMS; 
   
  // Item height 
  private int itemHeight = 0; 
 
  // Text paints 
  private TextPaint itemsPaint; 
  private TextPaint valuePaint; 
 
  // Layouts 
  private StaticLayout itemsLayout; 
  private StaticLayout labelLayout; 
  private StaticLayout valueLayout; 
 
  // Label & background 
  private String label; 
  private Drawable centerDrawable; 
 
  // Shadows drawables 
  private GradientDrawable topShadow; 
  private GradientDrawable bottomShadow; 
 
  // Scrolling 
  private boolean isScrollingPerformed;  
  private int scrollingOffset; 
 
  // Scrolling animation 
  private GestureDetector gestureDetector; 
  private Scroller scroller; 
  private int lastScrollY; 
 
  // Cyclic 
  boolean isCyclic = false; 
   
  // Listeners 
  private List<OnWheelChangedListener> changingListeners = new LinkedList<OnWheelChangedListener>(); 
  private List<OnWheelScrollListener> scrollingListeners = new LinkedList<OnWheelScrollListener>(); 
 
  /** 
   * Constructor 
   */ 
  public WheelView(Context context, AttributeSet attrs, int defStyle) { 
    super(context, attrs, defStyle); 
    initData(context); 
  } 
 
  /** 
   * Constructor 
   */ 
  public WheelView(Context context, AttributeSet attrs) { 
    super(context, attrs); 
    initData(context); 
  } 
 
  /** 
   * Constructor 
   */ 
  public WheelView(Context context) { 
    super(context); 
    initData(context); 
  } 
   
  /** 
   * Initializes class data 
   * @param context the context 
   */ 
  private void initData(Context context) { 
    gestureDetector = new GestureDetector(context, gestureListener); 
    gestureDetector.setIsLongpressEnabled(false); 
     
    scroller = new Scroller(context); 
  } 
   
  /** 
   * Gets wheel adapter 
   * @return the adapter 
   */ 
  public WheelAdapter getAdapter() { 
    return adapter; 
  } 
   
  /** 
   * Sets wheel adapter 
   * @param adapter the new wheel adapter 
   */ 
  public void setAdapter(WheelAdapter adapter) { 
    this.adapter = adapter; 
    invalidateLayouts(); 
    invalidate(); 
  } 
   
  /** 
   * Set the the specified scrolling interpolator 
   * @param interpolator the interpolator 
   */ 
  public void setInterpolator(Interpolator interpolator) { 
    scroller.forceFinished(true); 
    scroller = new Scroller(getContext(), interpolator); 
  } 
   
  /** 
   * Gets count of visible items 
   * 
   * @return the count of visible items 
   */ 
  public int getVisibleItems() { 
    return visibleItems; 
  } 
 
  /** 
   * Sets count of visible items 
   * 
   * @param count 
   *      the new count 
   */ 
  public void setVisibleItems(int count) { 
    visibleItems = count; 
    invalidate(); 
  } 
 
  /** 
   * Gets label 
   * 
   * @return the label 
   */ 
  public String getLabel() { 
    return label; 
  } 
 
  /** 
   * Sets label 
   * 
   * @param newLabel 
   *      the label to set 
   */ 
  public void setLabel(String newLabel) { 
    if (label == null || !label.equals(newLabel)) { 
      label = newLabel; 
      labelLayout = null; 
      invalidate(); 
    } 
  } 
   
  /** 
   * Adds wheel changing listener 
   * @param listener the listener 
   */ 
  public void addChangingListener(OnWheelChangedListener listener) { 
    changingListeners.add(listener); 
  } 
 
  /** 
   * Removes wheel changing listener 
   * @param listener the listener 
   */ 
  public void removeChangingListener(OnWheelChangedListener listener) { 
    changingListeners.remove(listener); 
  } 
   
  /** 
   * Notifies changing listeners 
   * @param oldValue the old wheel value 
   * @param newValue the new wheel value 
   */ 
  protected void notifyChangingListeners(int oldValue, int newValue) { 
    for (OnWheelChangedListener listener : changingListeners) { 
      listener.onChanged(this, oldValue, newValue); 
    } 
  } 
 
  /** 
   * Adds wheel scrolling listener 
   * @param listener the listener 
   */ 
  public void addScrollingListener(OnWheelScrollListener listener) { 
    scrollingListeners.add(listener); 
  } 
 
  /** 
   * Removes wheel scrolling listener 
   * @param listener the listener 
   */ 
  public void removeScrollingListener(OnWheelScrollListener listener) { 
    scrollingListeners.remove(listener); 
  } 
   
  /** 
   * Notifies listeners about starting scrolling 
   */ 
  protected void notifyScrollingListenersAboutStart() { 
    for (OnWheelScrollListener listener : scrollingListeners) { 
      listener.onScrollingStarted(this); 
    } 
  } 
 
  /** 
   * Notifies listeners about ending scrolling 
   */ 
  protected void notifyScrollingListenersAboutEnd() { 
    for (OnWheelScrollListener listener : scrollingListeners) { 
      listener.onScrollingFinished(this); 
    } 
  } 
 
  /** 
   * Gets current value 
   * 
   * @return the current value 
   */ 
  public int getCurrentItem() { 
    return currentItem; 
  } 
 
  /** 
   * Sets the current item. Does nothing when index is wrong. 
   * 
   * @param index the item index 
   * @param animated the animation flag 
   */ 
  public void setCurrentItem(int index, boolean animated) { 
    if (adapter == null || adapter.getItemsCount() == 0) { 
      return; // throw? 
    } 
    if (index < 0 || index >= adapter.getItemsCount()) { 
      if (isCyclic) { 
        while (index < 0) { 
          index += adapter.getItemsCount(); 
        } 
        index %= adapter.getItemsCount(); 
      } else{ 
        return; // throw? 
      } 
    } 
    if (index != currentItem) { 
      if (animated) { 
        scroll(index - currentItem, SCROLLING_DURATION); 
      } else { 
        invalidateLayouts(); 
       
        int old = currentItem; 
        currentItem = index; 
       
        notifyChangingListeners(old, currentItem); 
       
        invalidate(); 
      } 
    } 
  } 
 
  /** 
   * Sets the current item w/o animation. Does nothing when index is wrong. 
   * 
   * @param index the item index 
   */ 
  public void setCurrentItem(int index) { 
    setCurrentItem(index, false); 
  }   
   
  /** 
   * Tests if wheel is cyclic. That means before the 1st item there is shown the last one 
   * @return true if wheel is cyclic 
   */ 
  public boolean isCyclic() { 
    return isCyclic; 
  } 
 
  /** 
   * Set wheel cyclic flag 
   * @param isCyclic the flag to set 
   */ 
  public void setCyclic(boolean isCyclic) { 
    this.isCyclic = isCyclic; 
     
    invalidate(); 
    invalidateLayouts(); 
  } 
 
  /** 
   * Invalidates layouts 
   */ 
  private void invalidateLayouts() { 
    itemsLayout = null; 
    valueLayout = null; 
    scrollingOffset = 0; 
  } 
 
  /** 
   * Initializes resources 
   */ 
  private void initResourcesIfNecessary() { 
    if (itemsPaint == null) { 
      itemsPaint = new TextPaint(Paint.ANTI_ALIAS_FLAG 
          | Paint.FAKE_BOLD_TEXT_FLAG); 
      //itemsPaint.density = getResources().getDisplayMetrics().density; 
      itemsPaint.setTextSize(TEXT_SIZE); 
    } 
 
    if (valuePaint == null) { 
      valuePaint = new TextPaint(Paint.ANTI_ALIAS_FLAG 
          | Paint.FAKE_BOLD_TEXT_FLAG | Paint.DITHER_FLAG); 
      //valuePaint.density = getResources().getDisplayMetrics().density; 
      valuePaint.setTextSize(TEXT_SIZE); 
      valuePaint.setShadowLayer(0.1f, 0, 0.1f, 0xFFC0C0C0); 
    } 
 
    if (centerDrawable == null) { 
      centerDrawable = getContext().getResources().getDrawable(R.drawable.wheel_val); 
    } 
 
    if (topShadow == null) { 
      topShadow = new GradientDrawable(Orientation.TOP_BOTTOM, SHADOWS_COLORS); 
    } 
 
    if (bottomShadow == null) { 
      bottomShadow = new GradientDrawable(Orientation.BOTTOM_TOP, SHADOWS_COLORS); 
    } 
 
    setBackgroundResource(R.drawable.wheel_bg); 
  } 
 
  /** 
   * Calculates desired height for layout 
   * 
   * @param layout 
   *      the source layout 
   * @return the desired layout height 
   */ 
  private int getDesiredHeight(Layout layout) { 
    if (layout == null) { 
      return 0; 
    } 
 
    int desired = getItemHeight() * visibleItems - ITEM_OFFSET * 2 
        - ADDITIONAL_ITEM_HEIGHT; 
 
    // Check against our minimum height 
    desired = Math.max(desired, getSuggestedMinimumHeight()); 
 
    return desired; 
  } 
 
  /** 
   * Returns text item by index 
   * @param index the item index 
   * @return the item or null 
   */ 
  private String getTextItem(int index) { 
    if (adapter == null || adapter.getItemsCount() == 0) { 
      return null; 
    } 
    int count = adapter.getItemsCount(); 
    if ((index < 0 || index >= count) && !isCyclic) { 
      return null; 
    } else { 
      while (index < 0) { 
        index = count + index; 
      } 
    } 
     
    index %= count; 
    return adapter.getItem(index); 
  } 
   
  /** 
   * Builds text depending on current value 
   * 
   * @param useCurrentValue 
   * @return the text 
   */ 
  private String buildText(boolean useCurrentValue) { 
    StringBuilder itemsText = new StringBuilder(); 
    int addItems = visibleItems / 2 + 1; 
 
    for (int i = currentItem - addItems; i <= currentItem + addItems; i++) { 
      if (useCurrentValue || i != currentItem) { 
        String text = getTextItem(i); 
        if (text != null) { 
          itemsText.append(text); 
        } 
      } 
      if (i < currentItem + addItems) { 
        itemsText.append("\n"); 
      } 
    } 
     
    return itemsText.toString(); 
  } 
 
  /** 
   * Returns the max item length that can be present 
   * @return the max length 
   */ 
  private int getMaxTextLength() { 
    WheelAdapter adapter = getAdapter(); 
    if (adapter == null) { 
      return 0; 
    } 
     
    int adapterLength = adapter.getMaximumLength(); 
    if (adapterLength > 0) { 
      return adapterLength; 
    } 
 
    String maxText = null; 
    int addItems = visibleItems / 2; 
    for (int i = Math.max(currentItem - addItems, 0); 
        i < Math.min(currentItem + visibleItems, adapter.getItemsCount()); i++) { 
      String text = adapter.getItem(i); 
      if (text != null && (maxText == null || maxText.length() < text.length())) { 
        maxText = text; 
      } 
    } 
 
    return maxText != null ? maxText.length() : 0; 
  } 
 
  /** 
   * Returns height of wheel item 
   * @return the item height 
   */ 
  private int getItemHeight() { 
    if (itemHeight != 0) { 
      return itemHeight; 
    } else if (itemsLayout != null && itemsLayout.getLineCount() > 2) { 
      itemHeight = itemsLayout.getLineTop(2) - itemsLayout.getLineTop(1); 
      return itemHeight; 
    } 
     
    return getHeight() / visibleItems; 
  } 
 
  /** 
   * Calculates control width and creates text layouts 
   * @param widthSize the input layout width 
   * @param mode the layout mode 
   * @return the calculated control width 
   */ 
  private int calculateLayoutWidth(int widthSize, int mode) { 
    initResourcesIfNecessary(); 
 
    int width = widthSize; 
 
    int maxLength = getMaxTextLength(); 
    if (maxLength > 0) { 
      float textWidth = FloatMath.ceil(Layout.getDesiredWidth("0", itemsPaint)); 
      itemsWidth = (int) (maxLength * textWidth); 
    } else { 
      itemsWidth = 0; 
    } 
    itemsWidth += ADDITIONAL_ITEMS_SPACE; // make it some more 
 
    labelWidth = 0; 
    if (label != null && label.length() > 0) { 
      labelWidth = (int) FloatMath.ceil(Layout.getDesiredWidth(label, valuePaint)); 
    } 
 
    boolean recalculate = false; 
    if (mode == MeasureSpec.EXACTLY) { 
      width = widthSize; 
      recalculate = true; 
    } else { 
      width = itemsWidth + labelWidth + 2 * PADDING; 
      if (labelWidth > 0) { 
        width += LABEL_OFFSET; 
      } 
 
      // Check against our minimum width 
      width = Math.max(width, getSuggestedMinimumWidth()); 
 
      if (mode == MeasureSpec.AT_MOST && widthSize < width) { 
        width = widthSize; 
        recalculate = true; 
      } 
    } 
 
    if (recalculate) { 
      // recalculate width 
      int pureWidth = width - LABEL_OFFSET - 2 * PADDING; 
      if (pureWidth <= 0) { 
        itemsWidth = labelWidth = 0; 
      } 
      if (labelWidth > 0) { 
        double newWidthItems = (double) itemsWidth * pureWidth 
            / (itemsWidth + labelWidth); 
        itemsWidth = (int) newWidthItems; 
        labelWidth = pureWidth - itemsWidth; 
      } else { 
        itemsWidth = pureWidth + LABEL_OFFSET; // no label 
      } 
    } 
 
    if (itemsWidth > 0) { 
      createLayouts(itemsWidth, labelWidth); 
    } 
 
    return width; 
  } 
 
  /** 
   * Creates layouts 
   * @param widthItems width of items layout 
   * @param widthLabel width of label layout 
   */ 
  private void createLayouts(int widthItems, int widthLabel) { 
    if (itemsLayout == null || itemsLayout.getWidth() > widthItems) { 
      itemsLayout = new StaticLayout(buildText(isScrollingPerformed), itemsPaint, widthItems, 
          widthLabel > 0 ? Layout.Alignment.ALIGN_OPPOSITE : Layout.Alignment.ALIGN_CENTER, 
          1, ADDITIONAL_ITEM_HEIGHT, false); 
    } else { 
      itemsLayout.increaseWidthTo(widthItems); 
    } 
 
    if (!isScrollingPerformed && (valueLayout == null || valueLayout.getWidth() > widthItems)) { 
      String text = getAdapter() != null ? getAdapter().getItem(currentItem) : null; 
      valueLayout = new StaticLayout(text != null ? text : "", 
          valuePaint, widthItems, widthLabel > 0 ? 
              Layout.Alignment.ALIGN_OPPOSITE : Layout.Alignment.ALIGN_CENTER, 
              1, ADDITIONAL_ITEM_HEIGHT, false); 
    } else if (isScrollingPerformed) { 
      valueLayout = null; 
    } else { 
      valueLayout.increaseWidthTo(widthItems); 
    } 
 
    if (widthLabel > 0) { 
      if (labelLayout == null || labelLayout.getWidth() > widthLabel) { 
        labelLayout = new StaticLayout(label, valuePaint, 
            widthLabel, Layout.Alignment.ALIGN_NORMAL, 1, 
            ADDITIONAL_ITEM_HEIGHT, false); 
      } else { 
        labelLayout.increaseWidthTo(widthLabel); 
      } 
    } 
  } 
 
  @Override 
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 
    int widthMode = MeasureSpec.getMode(widthMeasureSpec); 
    int heightMode = MeasureSpec.getMode(heightMeasureSpec); 
    int widthSize = MeasureSpec.getSize(widthMeasureSpec); 
    int heightSize = MeasureSpec.getSize(heightMeasureSpec); 
 
    int width = calculateLayoutWidth(widthSize, widthMode); 
 
    int height; 
    if (heightMode == MeasureSpec.EXACTLY) { 
      height = heightSize; 
    } else { 
      height = getDesiredHeight(itemsLayout); 
 
      if (heightMode == MeasureSpec.AT_MOST) { 
        height = Math.min(height, heightSize); 
      } 
    } 
 
    setMeasuredDimension(width, height); 
  } 
 
  @Override 
  protected void onDraw(Canvas canvas) { 
    super.onDraw(canvas); 
     
    if (itemsLayout == null) { 
      if (itemsWidth == 0) { 
        calculateLayoutWidth(getWidth(), MeasureSpec.EXACTLY); 
      } else { 
        createLayouts(itemsWidth, labelWidth); 
      } 
    } 
 
    if (itemsWidth > 0) { 
      canvas.save(); 
      // Skip padding space and hide a part of top and bottom items 
      canvas.translate(PADDING, -ITEM_OFFSET); 
      drawItems(canvas); 
      drawValue(canvas); 
      canvas.restore(); 
    } 
 
    drawCenterRect(canvas); 
    drawShadows(canvas); 
  } 
 
  /** 
   * Draws shadows on top and bottom of control 
   * @param canvas the canvas for drawing 
   */ 
  private void drawShadows(Canvas canvas) { 
    topShadow.setBounds(0, 0, getWidth(), getHeight() / visibleItems); 
    topShadow.draw(canvas); 
 
    bottomShadow.setBounds(0, getHeight() - getHeight() / visibleItems, 
        getWidth(), getHeight()); 
    bottomShadow.draw(canvas); 
  } 
 
  /** 
   * Draws value and label layout 
   * @param canvas the canvas for drawing 
   */ 
  private void drawValue(Canvas canvas) { 
    valuePaint.setColor(VALUE_TEXT_COLOR); 
    valuePaint.drawableState = getDrawableState(); 
 
    Rect bounds = new Rect(); 
    itemsLayout.getLineBounds(visibleItems / 2, bounds); 
 
    // draw label 
    if (labelLayout != null) { 
      canvas.save(); 
      canvas.translate(itemsLayout.getWidth() + LABEL_OFFSET, bounds.top); 
      labelLayout.draw(canvas); 
      canvas.restore(); 
    } 
 
    // draw current value 
    if (valueLayout != null) { 
      canvas.save(); 
      canvas.translate(0, bounds.top + scrollingOffset); 
      valueLayout.draw(canvas); 
      canvas.restore(); 
    } 
  } 
 
  /** 
   * Draws items 
   * @param canvas the canvas for drawing 
   */ 
  private void drawItems(Canvas canvas) { 
    canvas.save(); 
     
    int top = itemsLayout.getLineTop(1); 
    canvas.translate(0, - top + scrollingOffset); 
     
    itemsPaint.setColor(ITEMS_TEXT_COLOR); 
    itemsPaint.drawableState = getDrawableState(); 
    itemsLayout.draw(canvas); 
     
    canvas.restore(); 
  } 
 
  /** 
   * Draws rect for current value 
   * @param canvas the canvas for drawing 
   */ 
  private void drawCenterRect(Canvas canvas) { 
    int center = getHeight() / 2; 
    int offset = getItemHeight() / 2; 
    centerDrawable.setBounds(0, center - offset, getWidth(), center + offset); 
    centerDrawable.draw(canvas); 
  } 
 
  @Override 
  public boolean onTouchEvent(MotionEvent event) { 
    WheelAdapter adapter = getAdapter(); 
    if (adapter == null) { 
      return true; 
    } 
     
      if (!gestureDetector.onTouchEvent(event) && event.getAction() == MotionEvent.ACTION_UP) { 
      justify(); 
    } 
    return true; 
  } 
   
  /** 
   * Scrolls the wheel 
   * @param delta the scrolling value 
   */ 
  private void doScroll(int delta) { 
    scrollingOffset += delta; 
     
    int count = scrollingOffset / getItemHeight(); 
    int pos = currentItem - count; 
    if (isCyclic && adapter.getItemsCount() > 0) { 
      // fix position by rotating 
      while (pos < 0) { 
        pos += adapter.getItemsCount(); 
      } 
      pos %= adapter.getItemsCount(); 
    } else if (isScrollingPerformed) { 
      //  
      if (pos < 0) { 
        count = currentItem; 
        pos = 0; 
      } else if (pos >= adapter.getItemsCount()) { 
        count = currentItem - adapter.getItemsCount() + 1; 
        pos = adapter.getItemsCount() - 1; 
      } 
    } else { 
      // fix position 
      pos = Math.max(pos, 0); 
      pos = Math.min(pos, adapter.getItemsCount() - 1); 
    } 
     
    int offset = scrollingOffset; 
    if (pos != currentItem) { 
      setCurrentItem(pos, false); 
    } else { 
      invalidate(); 
    } 
     
    // update offset 
    scrollingOffset = offset - count * getItemHeight(); 
    if (scrollingOffset > getHeight()) { 
      scrollingOffset = scrollingOffset % getHeight() + getHeight(); 
    } 
  } 
   
  // gesture listener 
  private SimpleOnGestureListener gestureListener = new SimpleOnGestureListener() { 
    public boolean onDown(MotionEvent e) { 
      if (isScrollingPerformed) { 
        scroller.forceFinished(true); 
        clearMessages(); 
        return true; 
      } 
      return false; 
    } 
     
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) { 
      startScrolling(); 
      doScroll((int)-distanceY); 
      return true; 
    } 
     
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { 
      lastScrollY = currentItem * getItemHeight() + scrollingOffset; 
      int maxY = isCyclic ? 0x7FFFFFFF : adapter.getItemsCount() * getItemHeight(); 
      int minY = isCyclic ? -maxY : 0; 
      scroller.fling(0, lastScrollY, 0, (int) -velocityY / 2, 0, 0, minY, maxY); 
      setNextMessage(MESSAGE_SCROLL); 
      return true; 
    } 
  }; 
 
  // Messages 
  private final int MESSAGE_SCROLL = 0; 
  private final int MESSAGE_JUSTIFY = 1; 
   
  /** 
   * Set next message to queue. Clears queue before. 
   * 
   * @param message the message to set 
   */ 
  private void setNextMessage(int message) { 
    clearMessages(); 
    animationHandler.sendEmptyMessage(message); 
  } 
 
  /** 
   * Clears messages from queue 
   */ 
  private void clearMessages() { 
    animationHandler.removeMessages(MESSAGE_SCROLL); 
    animationHandler.removeMessages(MESSAGE_JUSTIFY); 
  } 
   
  // animation handler 
  private Handler animationHandler = new Handler() { 
    public void handleMessage(Message msg) { 
      scroller.computeScrollOffset(); 
      int currY = scroller.getCurrY(); 
      int delta = lastScrollY - currY; 
      lastScrollY = currY; 
      if (delta != 0) { 
        doScroll(delta); 
      } 
       
      // scrolling is not finished when it comes to final Y 
      // so, finish it manually  
      if (Math.abs(currY - scroller.getFinalY()) < MIN_DELTA_FOR_SCROLLING) { 
        currY = scroller.getFinalY(); 
        scroller.forceFinished(true); 
      } 
      if (!scroller.isFinished()) { 
        animationHandler.sendEmptyMessage(msg.what); 
      } else if (msg.what == MESSAGE_SCROLL) { 
        justify(); 
      } else { 
        finishScrolling(); 
      } 
    } 
  }; 
   
  /** 
   * Justifies wheel 
   */ 
  private void justify() { 
    if (adapter == null) { 
      return; 
    } 
     
    lastScrollY = 0; 
    int offset = scrollingOffset; 
    int itemHeight = getItemHeight(); 
    boolean needToIncrease = offset > 0 ? currentItem < adapter.getItemsCount() : currentItem > 0;  
    if ((isCyclic || needToIncrease) && Math.abs((float) offset) > (float) itemHeight / 2) { 
      if (offset < 0) 
        offset += itemHeight + MIN_DELTA_FOR_SCROLLING; 
      else 
        offset -= itemHeight + MIN_DELTA_FOR_SCROLLING; 
    } 
    if (Math.abs(offset) > MIN_DELTA_FOR_SCROLLING) { 
      scroller.startScroll(0, 0, 0, offset, SCROLLING_DURATION); 
      setNextMessage(MESSAGE_JUSTIFY); 
    } else { 
      finishScrolling(); 
    } 
  } 
   
  /** 
   * Starts scrolling 
   */ 
  private void startScrolling() { 
    if (!isScrollingPerformed) { 
      isScrollingPerformed = true; 
      notifyScrollingListenersAboutStart(); 
    } 
  } 
 
  /** 
   * Finishes scrolling 
   */ 
  void finishScrolling() { 
    if (isScrollingPerformed) { 
      notifyScrollingListenersAboutEnd(); 
      isScrollingPerformed = false; 
    } 
    invalidateLayouts(); 
    invalidate(); 
  } 
   
   
  /** 
   * Scroll the wheel 
   * @param itemsToSkip items to scroll 
   * @param time scrolling duration 
   */ 
  public void scroll(int itemsToScroll, int time) { 
    scroller.forceFinished(true); 
 
    lastScrollY = scrollingOffset; 
    int offset = itemsToScroll * getItemHeight(); 
     
    scroller.startScroll(0, lastScrollY, 0, offset - lastScrollY, time); 
    setNextMessage(MESSAGE_SCROLL); 
     
    startScrolling(); 
  } 
 
} 

主布局文件

 <?xml version="1.0" encoding="utf-8"?> 
 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
  android:layout_height="wrap_content" 
  android:orientation="vertical" 
  android:background="@drawable/layout_bg" 
  android:layout_width="fill_parent"> 
   
  <TextView 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_marginTop="24dp" 
    android:layout_gravity="center_horizontal" 
    android:textSize="20sp" 
    android:textStyle="bold" 
    android:text="Please enter PIN"/> 
     
  <LinearLayout 
    android:layout_marginTop="24dp" 
    android:layout_gravity="center_horizontal" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content"> 
     
    <kankan.wheel.widget.WheelView android:id="@+id/passw_1" 
      android:layout_height="wrap_content" 
      android:layout_width="wrap_content"/> 
    <kankan.wheel.widget.WheelView android:id="@+id/passw_2" 
      android:layout_height="wrap_content" 
      android:layout_width="wrap_content"/> 
    <kankan.wheel.widget.WheelView android:id="@+id/passw_3" 
      android:layout_height="wrap_content" 
      android:layout_width="wrap_content"/> 
    <kankan.wheel.widget.WheelView android:id="@+id/passw_4" 
      android:layout_height="wrap_content" 
      android:layout_width="wrap_content"/> 
    <kankan.wheel.widget.WheelView android:id="@+id/passw_5" 
    android:layout_height="wrap_content" 
    android:layout_width="wrap_content"/> 
    <kankan.wheel.widget.WheelView android:id="@+id/passw_6" 
    android:layout_height="wrap_content" 
    android:layout_width="wrap_content"/> 
  </LinearLayout> 
   
  <TextView android:id="@+id/pwd_status" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_marginTop="24dp" 
    android:layout_gravity="center_horizontal" 
    android:textSize="18sp" 
    android:textColor="#FFF" 
    android:text="Wrong PIN"/> 
   
  <Button android:id="@+id/btn_mix" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_gravity="center_horizontal" 
    android:layout_marginTop="12dp" 
    android:textSize="18sp" 
    android:text="  Mix "/> 
 
</LinearLayout> 

适配器adapter 

/* 
 * Copyright 2010 Yuri Kanivets 
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); 
 * you may not use this file except in compliance with the License. 
 * You may obtain a copy of the License at 
 * 
 * http://www.apache.org/licenses/LICENSE-2.0 
 * 
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS, 
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 * See the License for the specific language governing permissions and 
 * limitations under the License. 
 */ 
 
package kankan.wheel.widget; 
 
public interface WheelAdapter { 
  /** 
   * Gets items count 
   * @return the count of wheel items 
   */ 
  public int getItemsCount(); 
   
  /** 
   * Gets a wheel item by index. 
   * 
   * @param index the item index 
   * @return the wheel item text or null 
   */ 
  public String getItem(int index); 
   
  /** 
   * Gets maximum item length. It is used to determine the wheel width. 
   * If -1 is returned there will be used the default wheel width. 
   * 
   * @return the maximum item length or -1 
   */ 
  public int getMaximumLength(); 
} 

/* 
 * Copyright 2010 Yuri Kanivets 
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); 
 * you may not use this file except in compliance with the License. 
 * You may obtain a copy of the License at 
 * 
 * http://www.apache.org/licenses/LICENSE-2.0 
 * 
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS, 
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 * See the License for the specific language governing permissions and 
 * limitations under the License. 
 */ 
 
package kankan.wheel.widget; 
 
 
/** 
 * Numeric Wheel adapter. 
 */ 
public class NumericWheelAdapter implements WheelAdapter { 
   
  /** The default min value */ 
  public static final int DEFAULT_MAX_VALUE = 9; 
 
  /** The default max value */ 
  private static final int DEFAULT_MIN_VALUE = 0; 
   
  // Values 
  private int minValue; 
  private int maxValue; 
   
  // format 
  private String format; 
   
  /** 
   * Default constructor 
   */ 
  public NumericWheelAdapter() { 
    this(DEFAULT_MIN_VALUE, DEFAULT_MAX_VALUE); 
  } 
 
  /** 
   * Constructor 
   * @param minValue the wheel min value 
   * @param maxValue the wheel max value 
   */ 
  public NumericWheelAdapter(int minValue, int maxValue) { 
    this(minValue, maxValue, null); 
  } 
 
  /** 
   * Constructor 
   * @param minValue the wheel min value 
   * @param maxValue the wheel max value 
   * @param format the format string 
   */ 
  public NumericWheelAdapter(int minValue, int maxValue, String format) { 
    this.minValue = minValue; 
    this.maxValue = maxValue; 
    this.format = format; 
  } 
 
  @Override 
  public String getItem(int index) { 
    if (index >= 0 && index < getItemsCount()) { 
      int value = minValue + index; 
      return format != null ? String.format(format, value) : Integer.toString(value); 
    } 
    return null; 
  } 
 
  @Override 
  public int getItemsCount() { 
    return maxValue - minValue + 1; 
  } 
   
  @Override 
  public int getMaximumLength() { 
    int max = Math.max(Math.abs(maxValue), Math.abs(minValue)); 
    int maxLen = Integer.toString(max).length(); 
    if (minValue < 0) { 
      maxLen++; 
    } 
    return maxLen; 
  } 
} 

监听器Listener文件：

/* 
 * Copyright 2010 Yuri Kanivets 
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); 
 * you may not use this file except in compliance with the License. 
 * You may obtain a copy of the License at 
 * 
 * http://www.apache.org/licenses/LICENSE-2.0 
 * 
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS, 
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 * See the License for the specific language governing permissions and 
 * limitations under the License. 
 */ 
 
package kankan.wheel.widget; 
 
/** 
 * Wheel scrolled listener interface. 
 */ 
public interface OnWheelScrollListener { 
  /** 
   * Callback method to be invoked when scrolling started. 
   * @param wheel the wheel view whose state has changed. 
   */ 
  void onScrollingStarted(WheelView wheel); 
   
  /** 
   * Callback method to be invoked when scrolling ended. 
   * @param wheel the wheel view whose state has changed. 
   */ 
  void onScrollingFinished(WheelView wheel); 
} 

/* 
 * Copyright 2010 Yuri Kanivets 
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); 
 * you may not use this file except in compliance with the License. 
 * You may obtain a copy of the License at 
 * 
 * http://www.apache.org/licenses/LICENSE-2.0 
 * 
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS, 
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 * See the License for the specific language governing permissions and 
 * limitations under the License. 
 */ 
 
package kankan.wheel.widget; 
 
/** 
 * Wheel changed listener interface. 
 * <p>The currentItemChanged() method is called whenever current wheel positions is changed: 
 * <li> New Wheel position is set 
 * <li> Wheel view is scrolled 
 */ 
public interface OnWheelChangedListener { 
 /** 
  * Callback method to be invoked when current item changed 
  * @param wheel the wheel view whose state has changed 
  * @param oldValue the old value of current item 
  * @param newValue the new value of current item 
  */ 
 void onChanged(WheelView wheel, int oldValue, int newValue); 
}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持鸟哥教程(niaoge.com)。

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