Android組件banner實現左右滑屏效果

什麼是banner組件？在許多Android應用上，比如愛奇藝客戶端、百度美拍、應用寶等上面，都有一個可以手動滑動的小廣告條，這就是banner，實際應用中的banner，其信息（圖片和點擊行為）是後台可配置的，是需要通過網絡從後台拉取的。網上有許多手動滑屏的例子，但是一般只是個demo，無法在實際中使用，因為其一般沒有考慮如下幾類問題：圖片緩存、OOM問題、是否可靈活配置、是否預留外部接口以及是否封裝良好。沒有良好的封裝，手動滑屏加在代碼中，會使得代碼變得很爛很脆弱。

1.原理
參見下圖。整個組件是一個FrameLayout，裡面有兩個view，第一個是LinearLayout，承載了4個（或多個）可以滑動的view，見圖中綠色背景的部分；第二個是一個RelativeLayout，在其底部放置了一個LinearLayout，在LinearLayout的內部放置了若干個小圓點，用來指示當前屏幕的索引。手勢檢測用了GestureDetector，並實現了OnGestureListener接口。為了能控制滑動速度，采用了Scroller彈性滑動對象。
為什麼組件繼承FrameLayout，是因為用於指示的小圓點是出現在view上面的，一個view疊在另一個view上面，這就是FrameLayout的特性

2.功能、效果
banner屬性可動態設置，默認數量為4，可以調整默認的數量
banner信息從後台獲取，banner的條數就是屏幕的數量
可自動滑動也能手動滑動
圖片下載為多線程，並采用常見的三級cache策略（內存、文件、網絡），節省流量，並處理了OOM異常
內部處理點擊事件，同時預留出了接口函數
banner封裝成一個ViewGroup類，使用起來簡單，最少只需要兩行代碼

3.代碼
代碼注釋寫的比較詳細，應該很好理解。分為2個文件，一個是banner的類，另一個是接口聲明。

ScrollBanner.java

/** 
 * ScrollBanner 支持滑屏效果的FrameLayout子類，可設置屏幕數量，尺寸。<br/> 
 * 典型的用法：<br/> 
 * ScrollBanner scrollBanner = new ScrollBanner(this, mScreenWidth, 100, this);<br/> 
 * linearLayout.addView(scrollBanner);<br/> 
 *注意事項：<br/> 
 *1.如果重新設置ScrollBanner的LayoutParams，則參數中的寬和高屬性將被忽略，仍然采用對象實例化的寬和高<br/> 
 *2.點擊事件的回調如果設為null，則采用默認的事件回調<br/> 
 *3.通過setOverScrollMode來設置 banner是否能夠滑出屏幕的邊界<br/> 
 *4通過xml方式加載banner，需要進行如下調用：<br/> 
 * setResolution(width, height);<br/> 
 setOnBannerClickListener(bannerClickListener);<br/> 
 showBanner()<br/> 
 * @author singwhatiwanna 
 * @version 2013.3.4 
 * 
 */ 
public class ScrollBanner extends FrameLayout implements 
ComponentCallBack.OnBannerClickListener, 
ResponseHandler.BannerInfoHandler 
{ 
 
 private static final String TAG = "ScrollBanner"; 
 
 private HorizontalScrollViewEx mHorizontalScrollViewEx; 
 
 //ScrollBanner的子view 
 private LinearLayout linearLayoutScrolLayout; 
 
 //linearLayoutScrolLayout的子view，用於放置若干個小圓點 
 private LinearLayout linearLayoutForDot; 
 
 private Scroller mScroller; 
 private Context mContext; 
 private OnBannerClickListener mBannerClickListener; 
 
 //屏幕及其bitmap 
 private List<View> mLinearLayoutScreens = new ArrayList<View>(); 
 private List<Bitmap> mBannerBitmaps = new ArrayList<Bitmap>(); 
 
 //banner信息 
 private List<BannerItem> mBannerItemsList = new ArrayList<BannerItem>(); 
 //小圓點 
 private List<ImageView> mImageViewList = new ArrayList<ImageView>(); 
 private Drawable mPageIndicator; 
 private Drawable mPageIndicatorFocused; 
 
 //banner默認圖片 
 private Bitmap mDefaultBitmap; 
 
 private int mScreenWidth; 
 private int mScreenHeight; 
 private int mScrollX; 
 
 //current screen index 
 private int mWhich = 0; 
 
 public static final int MESSAGE_AUTO_SCROLL = 1; 
 
 public static final int MESSAGE_FETCH_BANNER_SUCCESS = 2; 
 
 public static final int MARGIN_BOTTOM = 2; 
 
 //480*150 banner的圖片尺寸 150.0/480=0.3125f 
 public static final float ratio = 0.3125f; 
 
 //banner的位置 
 private int mLocation = -1; 
 
 //banner分為幾屏 
 private int PAGE_COUNT = 4; 
 
 //滑動方向 是否向右滑動 
 private boolean mScrollToRight = true; 
 
 //是否自動滑屏 
 private boolean mTimerResume = true; 
 
 //標志用戶是否手動滑動了屏幕 
 private boolean mByUserAction = false; 
 
 //標志banner是否可以滑出邊界 
 private boolean mOverScrollMode = false; 
 //標志banner可以滑出邊界多少像素 
 private int mOverScrollDistance = 0; 
 
 //定時器 用於banner的自動播放 
 final Timer timer = new Timer(); 
 
 //定時器的時間間隔 單位：ms 
 public static final int TIMER_DURATION = 5000; 
 
 private TimerTask mTimerTask = new TimerTask() 
 { 
 @Override 
 public void run() 
 { 
  if (mTimerResume && !mByUserAction) 
  { 
  mHandler.sendEmptyMessage(MESSAGE_AUTO_SCROLL); 
  } 
  mByUserAction = false; 
 } 
 }; 
 
 //ScrollBanner私有handler 用於處理內部邏輯 
 private Handler mHandler = new Handler() 
 { 
 public void handleMessage(Message msg) 
 { 
  //表示已經執行了onDetachedFromWindow，banner已經被銷毀了 
  if( mBannerBitmaps == null || mLinearLayoutScreens == null || 
   mImageViewList == null || mBannerItemsList == null || mContext == null ) 
  return; 
  
  switch (msg.what) 
  { 
  case MESSAGE_AUTO_SCROLL: 
  if (mWhich == PAGE_COUNT - 1) 
   mScrollToRight = false; 
  else if(mWhich == 0) 
  { 
   mScrollToRight = true; 
  } 
 
  if (mScrollToRight) 
   mWhich++; 
  else 
  { 
   mWhich--; 
  } 
 
  mHorizontalScrollViewEx.switchView(mWhich); 
  break; 
  case MESSAGE_FETCH_BANNER_SUCCESS: 
  int more = 0; 
  if(mBannerItemsList != null) 
   more = mBannerItemsList.size() - PAGE_COUNT; 
  if(mBannerItemsList.size() > 0) 
  { 
   //如果有banner 顯示它 
   ScrollBanner.this.show(true); 
  } 
  //如果後台返回的banneritem的數量大於預設值4 
  if(more > 0) 
  { 
   for (int i = 0; i < more; i++) 
   addBannerItem(); 
  } 
  fetchBannerImages(); 
  break; 
 
  default: 
  break; 
  } 
 }; 
 }; 
 
 //用於獲取bitmap 
 private Handler mBitmapHandler = new Handler() 
 { 
 
 public void handleMessage(Message msg) 
 { 
  //表示已經執行了onDetachedFromWindow，banner已經被銷毀了 
  if( mBannerBitmaps == null || mLinearLayoutScreens == null || 
   mImageViewList == null || mBannerItemsList == null || mContext == null ) 
  return; 
  
  Bitmap bitmap = (Bitmap)msg.obj; 
  String urlString = msg.getData().getString("url"); 
  Logger.d(TAG, "url=" + urlString); 
  if (urlString == null || bitmap == null || mBannerItemsList == null) 
  { 
  Logger.w(TAG, "bitmap=null imgurl=" + urlString); 
  return; 
  } 
 
  for( int i = 0; i < mBannerItemsList.size(); i++ ) 
  { 
  BannerItem item = mBannerItemsList.get(i); 
  if(item != null && urlString.equals(item.imgUrl) ) 
  { 
   Logger.d(TAG, "find " + i + urlString); 
   if( mBannerBitmaps != null ) 
   { 
   mBannerBitmaps.set( i, bitmap ); 
   setBannerImages(i); 
   } 
   break; 
  } 
  } 
  
 }; 
 
 }; 
 
 public ScrollBanner(Context context) 
 { 
 this(context, null); 
 } 
 
 public ScrollBanner(Context context, AttributeSet attrs) 
 { 
 super(context, attrs); 
 mContext = context; 
 } 
 
 public ScrollBanner(Context context, AttributeSet attrs, int defStyle) 
 { 
 super(context, attrs, defStyle); 
 mContext = context; 
 } 
 
 /** 
 * 
 * @param context activity實例 
 * @param width banner的寬度 單位px 
 * @param height banner的高度 單位dip,-1表示根據圖片比例自適應高度 
 * @param bannerClickListener 單擊banner的回調接口 
 */ 
 public ScrollBanner(Context context, final int width, final int height, OnBannerClickListener bannerClickListener) 
 { 
 this(context, null); 
 
 int activityId = ( (BaseActivity)context ).activityId(); 
 if(activityId == BaseActivity.ACCOUNT_ID)//位置3 
  mLocation = 3; 
 else if(activityId == BaseActivity.GAMEZONE_ID)//位置2 
 { 
  mLocation = 2; 
 } 
  
 //初始化時不顯示banner 
 this.show(false); 
 setResolution(width, height); 
 setOnBannerClickListener(bannerClickListener); 
 setDefaultBannerImages(); 
 fetchBannerInfo(); 
 } 
 
 /** 
 * 通過xml方式加載banner，必須調用此方法才能顯示 
 */ 
 public void showBanner() 
 { 
 int activityId = ( (BaseActivity)mContext ).activityId(); 
 if(activityId == BaseActivity.ACCOUNT_ID)//位置3 
  mLocation = 3; 
 else if(activityId == BaseActivity.GAMEZONE_ID)//位置2 
 { 
  mLocation = 2; 
 } 
  
 setDefaultBannerImages(); 
 fetchBannerInfo(); 
 } 
 
 /** 
 * 暫停滾動 
 */ 
 public void pauseScroll() 
 { 
 mTimerResume = false; 
 } 
 
 /** 
 * 恢復滾動 
 */ 
 public void resumeScroll() 
 { 
 mTimerResume = true; 
 } 
 
 /** 
 * 設置回調接口 
 * @param callBack 單擊banner的回調接口 
 */ 
 public void setOnBannerClickListener(OnBannerClickListener bannerClickListener) 
 { 
 mBannerClickListener = (bannerClickListener != null ? bannerClickListener : ScrollBanner.this); 
 } 
 
 /** 
 * 設置banner的解析度 
 * @param width banner的寬度 
 * @param height banner的高度 
 */ 
 public void setResolution(final int width, final int height) 
 { 
 int heightInPx = height; 
  
 if(height == -1) 
  heightInPx = (int)(ratio * width) ; 
 else 
 { 
  Resources resources = getResources(); 
  heightInPx = Math.round( TypedValue.applyDimension( 
   TypedValue.COMPLEX_UNIT_DIP, height, resources.getDisplayMetrics()) ); 
 } 
  
 mScreenWidth = width; 
 mScreenHeight = heightInPx; 
 setLayoutParams(new LayoutParams(width, heightInPx)); 
 
 initScrollView(); 
 } 
 
 /** 
 * 獲取banner的高度 
 * @return banner的高度 單位：px 
 */ 
 public int getHeightPixels() 
 { 
 return mScreenHeight; 
 } 
 
 /** 
 * 設置banner是否可以彈性滑出邊界 
 * @param canOverScroll true表示可以滑出邊界，false不能 
 */ 
 public void setOverScrollMode(boolean canOverScroll) 
 { 
 mOverScrollMode = canOverScroll; 
 if(canOverScroll == false) 
  mOverScrollDistance = 0; 
 } 
 
 /** 
 * 向後台獲取banner的各種信息 
 */ 
 private void fetchBannerInfo() 
 { 
 NetworkManager netManager = (NetworkManager) AppEngine.getInstance().getManager( 
  IManager.NETWORK_ID); 
 netManager.getBannerInfo( String.valueOf(mLocation), ScrollBanner.this ); 
 } 
 
 /** 
 * 獲取banner的滑屏圖像 
 */ 
 private void setDefaultBannerImages() 
 { 
 //為banner設置默認bitmap 
 BitmapFactory.Options bitmapFactoryOptions = new BitmapFactory.Options(); 
 bitmapFactoryOptions.inJustDecodeBounds = false; 
 bitmapFactoryOptions.inSampleSize = 2; 
 
 Resources res=mContext.getResources(); 
 mDefaultBitmap = BitmapFactory.decodeResource(res, R.drawable.banner_image_default, bitmapFactoryOptions); 
  
 for(int i = 0; i < PAGE_COUNT; i++) 
  mBannerBitmaps.add(i, mDefaultBitmap); 
 
 //初始化BannerItem對象 
 for (int i = 0; i < PAGE_COUNT; i++) 
  mBannerItemsList.add(i, null); 
 
 setBannerImages(-1); 
 } 
 
 private void fetchBannerImages() 
 { 
 //表示已經執行了onDetachedFromWindow，banner已經被銷毀了 
 if( mBannerItemsList == null ) 
  return; 
  
 //ImageManager 根據url向其獲取bitmap 
 ImageManager imageManager = (ImageManager)AppEngine.getInstance(). 
  getManager(IManager.IMAGE_ID); 
 
 BannerItem item = null; 
 for(int i = 0; i < PAGE_COUNT; i++) 
 { 
  try 
  { 
  item = mBannerItemsList.get(i); 
  } 
  catch (IndexOutOfBoundsException e) 
  { 
  Logger.e(TAG, "fetchBannerImages error: " + e); 
  } 
  catch (Exception e) 
  { 
  Logger.e(TAG, "fetchBannerImages error: " + e); 
  } 
  //ImageManager為多線程，采用常見的三級cache策略（內存、文件、網絡） 
  if( item != null && item.imgUrl != null ) 
  imageManager.loadBitmap( item.imgUrl, mBitmapHandler ); 
 } 
 } 
 
 /** 
 * 設置banner的滑屏圖像 
 * @param position 如果position=-1，則表示設置全部bitmap 
 */ 
 private void setBannerImages(final int position) 
 { 
 int size = mBannerBitmaps.size(); 
 if (size < PAGE_COUNT || mLinearLayoutScreens == null) 
 { 
  return; 
 } 
 if(position >=0 && position < PAGE_COUNT ) 
 { 
  Drawable drawable = mLinearLayoutScreens.get(position).getBackground(); 
  mLinearLayoutScreens.get(position).setBackgroundDrawable 
  (new BitmapDrawable( mBannerBitmaps.get(position) ) ); 
  drawable.setCallback(null); 
  drawable = null; 
  
  return; 
 } 
 
 for(int i = 0; i < PAGE_COUNT; i++) 
 { 
  mLinearLayoutScreens.get(i).setBackgroundDrawable(new BitmapDrawable(mBannerBitmaps.get(i))); 
 } 
 } 
 
 /** 
 * 是否顯示banner 
 * @param isShow true顯示 false不顯示 
 */ 
 public void show(boolean isShow) 
 { 
 if(isShow) 
 { 
  this.setVisibility(View.VISIBLE); 
  mTimerResume = true; 
 } 
 else 
 { 
  this.setVisibility(View.GONE); 
  mTimerResume = false; 
 } 
 } 
 
 /** 
 * 切換到指定屏幕 
 * @param which 屏幕索引 
 */ 
 public void switchToScreen(final int which) 
 { 
 mHorizontalScrollViewEx.switchView(which); 
 } 
 
 /** 
 * 設置屏幕的數量 （此函數暫不開放） 
 * @param count 屏幕數量 
 */ 
 protected void setScreenCount(final int count) 
 { 
 PAGE_COUNT = count; 
 } 
 
 /** 
 * 設置偏移的距離 如果mOverScrollMode為false，則此設置無效 （此函數暫不開放） 
 * @param distance 
 */ 
 protected void setOverScrollDistance(int distance) 
 { 
 if(distance < 0) 
  distance = 0; 
 
 mOverScrollDistance = mOverScrollMode ? distance : 0; 
 } 
 
 /** 
 * 切換小圓點 
 * @param position current screen index 
 */ 
 private void switchScreenPosition(final int position) 
 { 
 if( mPageIndicator == null || mPageIndicatorFocused == null ) 
  return; 
  
 int length = 0; 
 if(mImageViewList != null) 
  length = mImageViewList.size(); 
 if (position >= length || position < 0 || length <= 0) 
 { 
  return; 
 } 
 
 for(int i = 0; i < length; i++) 
 { 
  mImageViewList.get(i).setImageDrawable(mPageIndicator); 
 } 
  
 mImageViewList.get(position).setImageDrawable(mPageIndicatorFocused); 
 } 
 
 /** 
 * 初始化整個FrameLayout視圖組 
 */ 
 private void initScrollView() 
 { 
 setLayoutParams(new LayoutParams(mScreenWidth, mScreenHeight )); 
 
 linearLayoutScrolLayout = new LinearLayout(mContext); 
 linearLayoutScrolLayout.setBackgroundColor(Color.WHITE); 
 linearLayoutScrolLayout.setOrientation(LinearLayout.HORIZONTAL); 
  
 int mVersionCode = 8; 
 try 
 { 
  mVersionCode = Integer.valueOf(android.os.Build.VERSION.SDK); 
  Logger.d(TAG, "sdk version=" + mVersionCode); 
 } 
 catch (Exception e) 
 { 
  e.printStackTrace(); 
 } 
 //針對android1.6及以下的特殊處理 此為android的低版本bug 
 if(mVersionCode <= 5) 
 { 
  linearLayoutScrolLayout.setBaselineAligned(false); 
 } 
  
 //初始化四個滑動view 
 for(int i = 0; i < PAGE_COUNT; i++) 
 { 
  LinearLayout linearLayoutScreen = new LinearLayout(mContext); 
  linearLayoutScreen.setOrientation(LinearLayout.VERTICAL); 
  linearLayoutScrolLayout.addView(linearLayoutScreen, new LayoutParams( 
   mScreenWidth, 
   LayoutParams.FILL_PARENT)); 
 
  mLinearLayoutScreens.add(i, linearLayoutScreen); 
 } 
 
 //初始化小圓點視圖 
 RelativeLayout relativeLayout = new RelativeLayout(mContext); 
 relativeLayout.setLayoutParams(new LayoutParams( 
  LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT)); 
 
 //linearLayoutForDot為小圓點視圖 
 linearLayoutForDot =new LinearLayout(mContext); 
 android.widget.RelativeLayout.LayoutParams layoutParams = 
  new android.widget.RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, 
   LayoutParams.WRAP_CONTENT); 
 //小圓點距底部的距離 單位:px 
 layoutParams.bottomMargin = MARGIN_BOTTOM; 
 layoutParams.rightMargin = MARGIN_BOTTOM; 
 layoutParams.addRule(android.widget.RelativeLayout.ALIGN_PARENT_BOTTOM); 
 layoutParams.addRule(android.widget.RelativeLayout.CENTER_HORIZONTAL); 
 linearLayoutForDot.setLayoutParams(layoutParams); 
 linearLayoutForDot.setOrientation(LinearLayout.HORIZONTAL); 
 linearLayoutForDot.setHorizontalGravity(Gravity.CENTER); 
 linearLayoutForDot.setVerticalGravity(Gravity.CENTER); 
 //下面兩句實現圓角半透明效果 不采用 
 // linearLayoutForDot.setBackgroundResource(R.drawable.round_corner_bg); 
 // linearLayoutForDot.getBackground().setAlpha(100); 
 
 //初始化4個小圓點 
 mPageIndicator = getResources().getDrawable(R.drawable.page_indicator); 
 mPageIndicatorFocused = getResources().getDrawable(R.drawable.page_indicator_focused); 
 for(int i = 0; i < PAGE_COUNT; i++) 
 { 
  ImageView imageView = new ImageView(mContext); 
  imageView.setImageDrawable(mPageIndicator); 
  mImageViewList.add(i, imageView); 
  LinearLayout.LayoutParams layoutParamsForDot = 
   new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, 
    LayoutParams.WRAP_CONTENT); 
  layoutParamsForDot.rightMargin = 5; 
 
  linearLayoutForDot.addView(imageView, layoutParamsForDot); 
 } 
 mImageViewList.get(0).setImageDrawable(mPageIndicatorFocused); 
 relativeLayout.addView(linearLayoutForDot); 
 
 mHorizontalScrollViewEx = new HorizontalScrollViewEx(mContext, null, mBannerClickListener); 
 mHorizontalScrollViewEx.setLayoutParams(new LayoutParams( 
  mScreenWidth * PAGE_COUNT, 
  LayoutParams.FILL_PARENT)); 
 mHorizontalScrollViewEx.addView(linearLayoutScrolLayout, new LayoutParams( 
  LayoutParams.FILL_PARENT, 
  LayoutParams.FILL_PARENT)); 
 
 mHorizontalScrollViewEx.setHorizontalScrollBarEnabled(false); 
 mHorizontalScrollViewEx.setHorizontalFadingEdgeEnabled(false); 
 
 addView(mHorizontalScrollViewEx); 
 addView(relativeLayout); 
 
 //自動滑屏 5秒一次 
 timer.schedule(mTimerTask, 5000, TIMER_DURATION); 
 } 
 
 /** 
 * 加一個banner頁面 TODO此函數寫的不好 
 */ 
 private void addBannerItem() 
 { 
 //表示已經執行了onDetachedFromWindow，banner已經被銷毀了 
 if( mBannerBitmaps == null || mLinearLayoutScreens == null || 
  mImageViewList == null || mContext == null ) 
  return; 
  
 //調整屏幕數量和總寬度 
 PAGE_COUNT += 1; 
 mHorizontalScrollViewEx.getLayoutParams().width = mScreenWidth * PAGE_COUNT; 
   
 //加載默認圖片資源 
 if(mDefaultBitmap == null) 
 { 
  BitmapFactory.Options bitmapFactoryOptions = new BitmapFactory.Options(); 
  bitmapFactoryOptions.inJustDecodeBounds = false; 
  bitmapFactoryOptions.inSampleSize = 2; 
  Resources res=mContext.getResources(); 
  mDefaultBitmap = BitmapFactory.decodeResource(res, R.drawable.banner_image_default, bitmapFactoryOptions); 
 } 
 mBannerBitmaps.add(mDefaultBitmap); 
 mBannerItemsList.add(null); 
 //加一個屏幕 
 LinearLayout linearLayoutScreen = new LinearLayout(mContext); 
 linearLayoutScreen.setOrientation(LinearLayout.VERTICAL); 
 linearLayoutScreen.setBackgroundDrawable(new BitmapDrawable( mBannerBitmaps.get(PAGE_COUNT - 1) )); 
 linearLayoutScrolLayout.addView(linearLayoutScreen, new LayoutParams( 
  mScreenWidth, 
  LayoutParams.FILL_PARENT)); 
 mLinearLayoutScreens.add(linearLayoutScreen); 
  
 //加一個小圓點 
 ImageView imageView = new ImageView(mContext); 
 imageView.setImageDrawable(mPageIndicator); 
 mImageViewList.add(imageView); 
 LinearLayout.LayoutParams layoutParamsForDot = 
  new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, 
   LayoutParams.WRAP_CONTENT); 
 layoutParamsForDot.rightMargin = 5; 
 linearLayoutForDot.addView(imageView, layoutParamsForDot); 
 } 
 
 private class HorizontalScrollViewEx extends ViewGroup implements 
 OnGestureListener 
 { 
 
 private GestureDetector mGestureDetector; 
 private int mWhichScreen; 
 
 public HorizontalScrollViewEx(Context context, AttributeSet attrs, OnBannerClickListener bannerClickListener) 
 { 
  super(context, attrs); 
  
  mGestureDetector = new GestureDetector(this); 
  //解決長按屏幕後無法拖動的現象 
  mGestureDetector.setIsLongpressEnabled(false); 
 
  //構造彈性滑動對象 
  mScroller = new Scroller(context); 
 } 
 
 /** 
  * 切換到指定屏幕 
  * @param whichScreen 屏幕index 
  */ 
 public void switchView(int whichScreen) 
 { 
  if(mLinearLayoutScreens == null) 
  return; 
  
  // 防止非法參數 
  if (whichScreen < 0) 
  whichScreen = 0; 
  else if(whichScreen >= PAGE_COUNT) 
  whichScreen = PAGE_COUNT - 1; 
 
  Logger.i(TAG, "switch view to " + whichScreen); 
 
  int delta = whichScreen * mScreenWidth - HorizontalScrollViewEx.this.getScrollX(); 
 
  //緩慢滾動到指定位置 
  mScroller.startScroll(getScrollX(), 0, delta, 0, Math.abs(delta) * 3); 
 
  // refresh 
  invalidate(); 
 
  //delta>0 stands for user scroll view to right 
  if (delta > 0) 
  mScrollToRight = true; 
  else 
  { 
  mScrollToRight = false; 
  } 
 
  mWhichScreen = whichScreen; 
  mWhich = whichScreen; 
  //切換小圓點 
  switchScreenPosition(mWhichScreen); 
 } 
 
 /** 
  * 用戶輕觸觸摸屏，由1個MotionEvent ACTION_DOWN觸發 
  */ 
 @Override 
 public boolean onDown(MotionEvent e) 
 { 
  Logger.i("MyGesture", "onDown"); 
  
  mScrollX = HorizontalScrollViewEx.this.getScrollX(); 
 
  return true; 
 } 
 
 /** 
  * 用戶輕觸觸摸屏，尚未松開或拖動，由一個1個MotionEvent ACTION_DOWN觸發 
  * 注意和onDown()的區別，強調的是沒有松開或者拖動的狀態 
  */ 
 public void onShowPress(MotionEvent e) 
 { 
  Logger.i("MyGesture", "onShowPress"); 
 } 
 
 /** 
  * 用戶（輕觸觸摸屏後）松開，由一個1個MotionEvent ACTION_UP觸發 
  */ 
 public boolean onSingleTapUp(MotionEvent e) 
 { 
  Logger.i("MyGesture", "onSingleTapUp"); 
  if(mBannerItemsList == null || mBannerItemsList.size() <= mWhichScreen) 
  return false; 
  
  BannerItem bannerItem = mBannerItemsList.get(mWhichScreen); 
 
  if(bannerItem != null) 
  { 
  BannerMotionEvent bannerMotionEvent = 
   new BannerMotionEvent(mWhichScreen, bannerItem.action, bannerItem.url, 
    bannerItem.gameId, bannerItem.gameType, bannerItem.title); 
  mBannerClickListener.onBannerClick(bannerMotionEvent); 
  } 
 
  return false; 
 } 
 
 /** 用戶按下觸摸屏、快速移動後松開，由1個MotionEvent ACTION_DOWN, 多個ACTION_MOVE, 
  * 1個ACTION_UP觸發 
  */ 
 public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, 
  float velocityY) 
 { 
  Logger.i("MyGesture", "onFling velocityX=" + velocityX); 
 
  mWhichScreen = velocityX > 0 ? 
   mWhichScreen - 1 
   : mWhichScreen + 1; 
  switchView(mWhichScreen); 
 
  return true; 
 } 
 
 /** 
  * 用戶按下觸摸屏，並拖動，由1個MotionEvent ACTION_DOWN, 多個ACTION_MOVE觸發 
  */ 
 public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, 
  float distanceY) 
 { 
  Logger.i("MyGesture", "onScroll"); 
 
  //禁止彈性滾動 
  if (mOverScrollMode == false) 
  { 
  float x1 = e1.getX(); 
  float x2 = e2.getX(); 
  if(mWhichScreen == 0 && x1 < x2) 
   return false; 
  else if(mWhichScreen == PAGE_COUNT - 1 && x1 > x2) 
   return false; 
  } 
  
//  int distance = Math.abs(getScrollX() - mWhichScreen * mScreenWidth); 
//  if ((mWhichScreen ==0 || mWhichScreen == PAGE_COUNT -1) && distance > mOverScrollDistance) 
//  return false; 
  
  this.scrollBy((int)distanceX, 0); 
 
  return true; 
 } 
 
 /** 
  * 用戶長按觸摸屏，由多個MotionEvent ACTION_DOWN觸發 
  */ 
 public void onLongPress(MotionEvent e) 
 { 
  Logger.i("MyGesture", "onLongPress"); 
 } 
 
 @Override 
 public boolean onTouchEvent(MotionEvent event) 
 { 
  if(event.getAction() == MotionEvent.ACTION_DOWN) 
  { 
  mTimerResume = false; 
  if ( !mScroller.isFinished() ) 
   mScroller.abortAnimation(); 
  } 
  else if(event.getAction() == MotionEvent.ACTION_UP) 
  { 
  //開始自動滑屏 
  mTimerResume = true; 
  mByUserAction = true; 
  } 
 
  boolean consume = mGestureDetector.onTouchEvent(event); 
 
  if (consume == false && event.getAction() == MotionEvent.ACTION_UP) 
  { 
  int curScrollX = HorizontalScrollViewEx.this.getScrollX(); 
  int mWhichScreen = (curScrollX + mScreenWidth / 2) /mScreenWidth; 
 
  switchView(mWhichScreen); 
  } 
 
  return consume; 
 } 
 
 @Override 
 public void computeScroll() 
 { 
  if (mScroller.computeScrollOffset()) 
  { 
  scrollTo(mScroller.getCurrX(), mScroller.getCurrY()); 
  postInvalidate(); 
  } 
 } 
 
 @Override 
 protected void onLayout(boolean changed, int l, int t, int r, int b) 
 { 
  if (changed) 
  { 
  int childLeft = 0; 
  final int childCount = getChildCount(); 
 
  for (int i=0; i<childCount; i++) 
  { 
   final View childView = getChildAt(i); 
   if (childView.getVisibility() != View.GONE) 
   { 
   final int childWidth = childView.getMeasuredWidth(); 
   childView.layout(childLeft, 0, 
    childLeft+childWidth, childView.getMeasuredHeight()); 
   childLeft += childWidth; 
   } 
  } 
  } 
 } 
 
 @Override 
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) 
 { 
  super.onMeasure(widthMeasureSpec, heightMeasureSpec); 
 
  final int width = MeasureSpec.getSize(widthMeasureSpec); 
  final int count = getChildCount(); 
  
  for (int i = 0; i < count; i++) 
  { 
  getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec); 
  } 
  scrollTo(mWhich * mScreenWidth, 0); 
 } 
 
 } 
 
 /** 
 * override此函數，防止其修改構造方法所定義的寬和高<br/> 
 * 注意：在這裡，設置寬和高將不起作用 
 */ 
 @Override 
 public void setLayoutParams(android.view.ViewGroup.LayoutParams params) 
 { 
 params.width = mScreenWidth; 
 params.height = mScreenHeight; 
 
 super.setLayoutParams(params); 
 } 
 
 //標志view AttachedToWindow 
 @Override 
 protected void onAttachedToWindow() 
 { 
 super.onAttachedToWindow(); 
 mTimerResume = true; 
 } 
 
 //標志view已經脫離window，典型的情形是view被銷毀了，此時取消timer 
 @Override 
 protected void onDetachedFromWindow() 
 { 
 super.onDetachedFromWindow(); 
 Logger.d(TAG, "onDetachedFromWindow"); 
  
 mTimerResume = false; 
 int activityId = ( (BaseActivity)mContext ).activityId(); 
 //如果是賬號管理頁面 則釋放內存 
 if(activityId == BaseActivity.ACCOUNT_ID) 
 { 
  destroy(); 
 } 
 } 
 
 /** 
 * 銷毀banner 
 */ 
 public void destroy() 
 { 
 mTimerTask.cancel(); 
 timer.cancel(); 
 //去除各種bitmap對activity的引用關系 
 destoryBitmaps(); 
 System.gc(); 
 } 
 
 /** 
 * 去除各種bitmap對activity的引用關系 
 */ 
 private void destoryBitmaps() 
 {  
 for (View view : mLinearLayoutScreens) 
 { 
  Drawable drawable = view.getBackground(); 
  BitmapDrawable bitmapDrawable = null; 
  if(drawable instanceof BitmapDrawable) 
  bitmapDrawable = (BitmapDrawable)drawable; 
  
  if(bitmapDrawable != null) 
  { 
  //解除drawable對view的引用 
  bitmapDrawable.setCallback(null); 
  bitmapDrawable = null; 
  } 
 } 
  
 for (ImageView imageView : mImageViewList) 
 { 
  Drawable drawable = imageView.getDrawable(); 
  if(drawable != null) 
  { 
  drawable.setCallback(null); 
  drawable = null; 
  } 
 } 
  
 mPageIndicator.setCallback(null); 
 mPageIndicator = null; 
 mPageIndicatorFocused.setCallback(null); 
 mPageIndicatorFocused = null; 
  
 mLinearLayoutScreens.clear(); 
 mLinearLayoutScreens = null; 
  
 mBannerBitmaps.clear(); 
 mBannerBitmaps = null; 
  
 mImageViewList.clear(); 
 mImageViewList = null; 
  
 mBannerItemsList.clear(); 
 mBannerItemsList = null; 
 } 
 
 //單擊事件 
 @Override 
 public void onBannerClick( BannerMotionEvent bannerMotionEvent ) 
 { 
 final int position = bannerMotionEvent.index; 
 if(mContext == null) 
  return; 
  
 NotificationInfo notificationInfo = new NotificationInfo(); 
 notificationInfo.msgType = bannerMotionEvent.getAction(); 
 int action = bannerMotionEvent.getAction(); 
 if(action == NotificationInfo.NOTIFICATION_SINGLEGAME_MSG) //單個游戲消息，直接啟動該游戲 
 { 
  try 
  { 
  notificationInfo.gameId = Integer.parseInt( bannerMotionEvent.getGameId() ); 
  notificationInfo.gameType = Integer.parseInt( bannerMotionEvent.getGameType() ); 
  } 
  catch (NumberFormatException e) 
  { 
  Logger.e(TAG, e.toString()); 
  return; 
  } 
 } 
 else if(action == NotificationInfo.NOTIFICATION_GAMEPAGE_MSG) //游戲主頁消息，通過客戶端展示游戲主頁 
 { 
  try 
  { 
  notificationInfo.gameId = Integer.parseInt( bannerMotionEvent.getGameId() ); 
  } 
  catch (NumberFormatException e) 
  { 
  Logger.e(TAG, e.toString()); 
  return; 
  } 
  notificationInfo.issueTitle = bannerMotionEvent.getTitle(); 
 } 
 else if(action == NotificationInfo.NOTIFICATION_SHOW_WEBVIEW_MSG) //交叉推廣消息，通過一個webview展示 
 { 
  notificationInfo.issueTitle = bannerMotionEvent.getTitle(); 
  notificationInfo.openUrl = bannerMotionEvent.getResponseUrl(); 
 } 
 else //reserved 
 { 
  return; 
 } 
  
 Intent intent = notificationInfo.generateIntent(mContext); 
 if(intent != null) 
  mContext.startActivity(intent); 
 } 
 
 /** 
 * ScrollBanner所關聯的banner項 可以為多個 一個為一屏 
 */ 
 public static class BannerItem extends Object 
 { 
 public static final String ACTION = "action"; 
 public static final String URL = "url"; 
 public static final String IMGURL = "imgurl"; 
 public static final String GAMEID = "gameid"; 
 public static final String GAMETYPE = "gametype"; 
 public static final String TITLE = "title"; 
 
 public int index = -1; 
 public int action = -1; 
 public String url = ""; 
 public String imgUrl = ""; 
 public String gameId = ""; 
 public String gameType = ""; 
 public String title = ""; 
 
 public BannerItem(){} 
 } 
 
 /** 
 * BannerMotionEvent：單擊banner所產生的事件對象<br/> 
 *getAction()來獲取動作類別<br/> 
 *getResponseUrl()來獲取響應url<br/> 
 *... 
 */ 
 public static class BannerMotionEvent extends Object 
 { 
 /** 
  * ACTION_PLAY_FLASH： 播放游戲 
  */ 
 public static final int ACTION_PLAY = 2; 
 /** 
  * ACTION_HOMEPAGE：打開官網 
  */ 
 public static final int ACTION_HOMEPAGE = 3; 
 /** 
  * ACTION_OPEN_URL：打開指定url 
  */ 
 public static final int ACTION_OPEN_URL = 4; 
 
 //banner中屏幕的index 
 private int index = -1; 
 //響應url 
 private String responseUrl = ""; 
 //動作種類 
 private int action = -1; 
 //gameid 
 private String gameId = ""; 
 //gametype flash游戲(0) or h5游戲(1) 
 private String gameType = ""; 
 //webview的標題 
 private String title = ""; 
  
 public BannerMotionEvent(int index, int action, String responseUrl, 
  String gameId, String gameType, String title) 
 { 
  BannerMotionEvent.this.index = index; 
  BannerMotionEvent.this.action = action; 
  BannerMotionEvent.this.responseUrl = responseUrl; 
  BannerMotionEvent.this.gameId = gameId; 
  BannerMotionEvent.this.gameType = gameType; 
  BannerMotionEvent.this.title = title; 
 } 
 
 /** 
  * 獲取當前BannerMotionEvent事件對象的動作種類 
  * @return 動作種類：ACTION_PLAY等 
  */ 
 public int getAction() 
 { 
  return action; 
 } 
 
 /** 
  * 獲取當前BannerMotionEvent事件對象的title 
  * @return title webview的標題 
  */ 
 public String getTitle() 
 { 
  return title; 
 } 
  
 /** 
  * 獲取當前BannerMotionEvent事件對象的gameId 
  * @return gameId 
  */ 
 public String getGameId() 
 { 
  return gameId; 
 } 
  
 /** 
  * 獲取當前BannerMotionEvent事件對象的gameType 
  * @return gameType 0 or 1 
  */ 
 public String getGameType() 
 { 
  return gameType; 
 } 
  
 /** 
  * 獲取當前BannerMotionEvent事件對象的響應url 
  * @return 響應url 
  */ 
 public String getResponseUrl() 
 { 
  return responseUrl; 
 } 
 
 @SuppressLint("DefaultLocale") 
 @Override 
 public String toString() 
 { 
  return String.format("BannerMotionEvent { index=%d, action=%d, responseUrl=%s, gameId=%s, gameType=%s, title=%s }", 
   index, action, responseUrl, gameId, gameType, title); 
 } 
 } 
 
 @Override 
 public void onBannerInfoSuccess(List<BannerItem> items) 
 { 
 Logger.d(TAG, "onBannerInfoSuccess"); 
 mBannerItemsList = items; 
 mHandler.sendEmptyMessage(MESSAGE_FETCH_BANNER_SUCCESS); 
 } 
 
 @Override 
 public void onBannerInfoFailed() 
 { 
 Logger.e(TAG, "onBannerInfoFailed"); 
 } 
 
} 

ComponentCallBack.java

public interface ComponentCallBack 
{ 
 
 public static interface OnBannerClickListener 
 { 
 /** 
  * banner單擊事件 
  * @param bannerMotionEvent 單擊事件對象，包含所需的響應信息 
  * 參見 {@link BannerMotionEvent} 
  */ 
 public abstract void onBannerClick( BannerMotionEvent bannerMotionEvent ); 
 } 
 
} 

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