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Android组件banner实现左右滑屏效果

什么是banner组件？在许多Android应用上，比如爱奇艺客户端、百度美拍、应用宝等上面，都有一个可以手动滑动的小广告条，这就是banner，实际应用中的banner，其信息（图片和点击行为）是后台可配置的，是需要通过网络从后台拉取的。网上有许多手动滑屏的例子，但是一般只是个demo，无法在实际中使用，因为其一般没有考虑如下几类问题：图片缓存、OOM问题、是否可灵活配置、是否预留外部接口以及是否封装良好。没有良好的封装，手动滑屏加在代码中，会使得代码变得很烂很脆弱。

1.原理
参见下图。整个组件是一个FrameLayout，里面有两个view，第一个是LinearLayout，承载了4个（或多个）可以滑动的view，见图中绿色背景的部分；第二个是一个RelativeLayout，在其底部放置了一个LinearLayout，在LinearLayout的内部放置了若干个小圆点，用来指示当前屏幕的索引。手势检测用了GestureDetector，并实现了OnGestureListener接口。为了能控制滑动速度，采用了Scroller弹性滑动对象。
为什么组件继承FrameLayout，是因为用于指示的小圆点是出现在view上面的，一个view叠在另一个view上面，这就是FrameLayout的特性

2.功能、效果
banner属性可动态设置，默认数量为4，可以调整默认的数量
banner信息从后台获取，banner的条数就是屏幕的数量
可自动滑动也能手动滑动
图片下载为多线程，并采用常见的三级cache策略（内存、文件、网络），节省流量，并处理了OOM异常
内部处理点击事件，同时预留出了接口函数
banner封装成一个ViewGroup类，使用起来简单，最少只需要两行代码

3.代码
代码注释写的比较详细，应该很好理解。分为2个文件，一个是banner的类，另一个是接口声明。

ScrollBanner.java

/** 
 * ScrollBanner 支持滑屏效果的FrameLayout子类，可设置屏幕数量，尺寸。<br/> 
 * 典型的用法：<br/> 
 * ScrollBanner scrollBanner = new ScrollBanner(this, mScreenWidth, 100, this);<br/> 
 * linearLayout.addView(scrollBanner);<br/> 
 *注意事项：<br/> 
 *1.如果重新设置ScrollBanner的LayoutParams，则参数中的宽和高属性将被忽略，仍然采用对象实例化的宽和高<br/> 
 *2.点击事件的回调如果设为null，则采用默认的事件回调<br/> 
 *3.通过setOverScrollMode来设置 banner是否能够滑出屏幕的边界<br/> 
 *4通过xml方式加载banner，需要进行如下调用：<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，用于放置若干个小圆点 
 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>(); 
 //小圆点 
 private List<ImageView> mImageViewList = new ArrayList<ImageView>(); 
 private Drawable mPageIndicator; 
 private Drawable mPageIndicatorFocused; 
 
 //banner默认图片 
 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的图片尺寸 150.0/480=0.3125f 
 public static final float ratio = 0.3125f; 
 
 //banner的位置 
 private int mLocation = -1; 
 
 //banner分为几屏 
 private int PAGE_COUNT = 4; 
 
 //滑动方向 是否向右滑动 
 private boolean mScrollToRight = true; 
 
 //是否自动滑屏 
 private boolean mTimerResume = true; 
 
 //标志用户是否手动滑动了屏幕 
 private boolean mByUserAction = false; 
 
 //标志banner是否可以滑出边界 
 private boolean mOverScrollMode = false; 
 //标志banner可以滑出边界多少像素 
 private int mOverScrollDistance = 0; 
 
 //定时器 用于banner的自动播放 
 final Timer timer = new Timer(); 
 
 //定时器的时间间隔 单位：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 用于处理内部逻辑 
 private Handler mHandler = new Handler() 
 { 
 public void handleMessage(Message msg) 
 { 
  //表示已经执行了onDetachedFromWindow，banner已经被销毁了 
  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 显示它 
   ScrollBanner.this.show(true); 
  } 
  //如果后台返回的banneritem的数量大于预设值4 
  if(more > 0) 
  { 
   for (int i = 0; i < more; i++) 
   addBannerItem(); 
  } 
  fetchBannerImages(); 
  break; 
 
  default: 
  break; 
  } 
 }; 
 }; 
 
 //用于获取bitmap 
 private Handler mBitmapHandler = new Handler() 
 { 
 
 public void handleMessage(Message msg) 
 { 
  //表示已经执行了onDetachedFromWindow，banner已经被销毁了 
  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实例 
 * @param width banner的宽度 单位px 
 * @param height banner的高度 单位dip,-1表示根据图片比例自适应高度 
 * @param bannerClickListener 单击banner的回调接口 
 */ 
 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; 
 } 
  
 //初始化时不显示banner 
 this.show(false); 
 setResolution(width, height); 
 setOnBannerClickListener(bannerClickListener); 
 setDefaultBannerImages(); 
 fetchBannerInfo(); 
 } 
 
 /** 
 * 通过xml方式加载banner，必须调用此方法才能显示 
 */ 
 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(); 
 } 
 
 /** 
 * 暂停滚动 
 */ 
 public void pauseScroll() 
 { 
 mTimerResume = false; 
 } 
 
 /** 
 * 恢复滚动 
 */ 
 public void resumeScroll() 
 { 
 mTimerResume = true; 
 } 
 
 /** 
 * 设置回调接口 
 * @param callBack 单击banner的回调接口 
 */ 
 public void setOnBannerClickListener(OnBannerClickListener bannerClickListener) 
 { 
 mBannerClickListener = (bannerClickListener != null ? bannerClickListener : ScrollBanner.this); 
 } 
 
 /** 
 * 设置banner的解析度 
 * @param width banner的宽度 
 * @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(); 
 } 
 
 /** 
 * 获取banner的高度 
 * @return banner的高度 单位：px 
 */ 
 public int getHeightPixels() 
 { 
 return mScreenHeight; 
 } 
 
 /** 
 * 设置banner是否可以弹性滑出边界 
 * @param canOverScroll true表示可以滑出边界，false不能 
 */ 
 public void setOverScrollMode(boolean canOverScroll) 
 { 
 mOverScrollMode = canOverScroll; 
 if(canOverScroll == false) 
  mOverScrollDistance = 0; 
 } 
 
 /** 
 * 向后台获取banner的各种信息 
 */ 
 private void fetchBannerInfo() 
 { 
 NetworkManager netManager = (NetworkManager) AppEngine.getInstance().getManager( 
  IManager.NETWORK_ID); 
 netManager.getBannerInfo( String.valueOf(mLocation), ScrollBanner.this ); 
 } 
 
 /** 
 * 获取banner的滑屏图像 
 */ 
 private void setDefaultBannerImages() 
 { 
 //为banner设置默认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对象 
 for (int i = 0; i < PAGE_COUNT; i++) 
  mBannerItemsList.add(i, null); 
 
 setBannerImages(-1); 
 } 
 
 private void fetchBannerImages() 
 { 
 //表示已经执行了onDetachedFromWindow，banner已经被销毁了 
 if( mBannerItemsList == null ) 
  return; 
  
 //ImageManager 根据url向其获取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为多线程，采用常见的三级cache策略（内存、文件、网络） 
  if( item != null && item.imgUrl != null ) 
  imageManager.loadBitmap( item.imgUrl, mBitmapHandler ); 
 } 
 } 
 
 /** 
 * 设置banner的滑屏图像 
 * @param position 如果position=-1，则表示设置全部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))); 
 } 
 } 
 
 /** 
 * 是否显示banner 
 * @param isShow true显示 false不显示 
 */ 
 public void show(boolean isShow) 
 { 
 if(isShow) 
 { 
  this.setVisibility(View.VISIBLE); 
  mTimerResume = true; 
 } 
 else 
 { 
  this.setVisibility(View.GONE); 
  mTimerResume = false; 
 } 
 } 
 
 /** 
 * 切换到指定屏幕 
 * @param which 屏幕索引 
 */ 
 public void switchToScreen(final int which) 
 { 
 mHorizontalScrollViewEx.switchView(which); 
 } 
 
 /** 
 * 设置屏幕的数量 （此函数暂不开放） 
 * @param count 屏幕数量 
 */ 
 protected void setScreenCount(final int count) 
 { 
 PAGE_COUNT = count; 
 } 
 
 /** 
 * 设置偏移的距离 如果mOverScrollMode为false，则此设置无效 （此函数暂不开放） 
 * @param distance 
 */ 
 protected void setOverScrollDistance(int distance) 
 { 
 if(distance < 0) 
  distance = 0; 
 
 mOverScrollDistance = mOverScrollMode ? distance : 0; 
 } 
 
 /** 
 * 切换小圆点 
 * @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); 
 } 
 
 /** 
 * 初始化整个FrameLayout视图组 
 */ 
 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(); 
 } 
 //针对android1.6及以下的特殊处理 此为android的低版本bug 
 if(mVersionCode <= 5) 
 { 
  linearLayoutScrolLayout.setBaselineAligned(false); 
 } 
  
 //初始化四个滑动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); 
 } 
 
 //初始化小圆点视图 
 RelativeLayout relativeLayout = new RelativeLayout(mContext); 
 relativeLayout.setLayoutParams(new LayoutParams( 
  LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT)); 
 
 //linearLayoutForDot为小圆点视图 
 linearLayoutForDot =new LinearLayout(mContext); 
 android.widget.RelativeLayout.LayoutParams layoutParams = 
  new android.widget.RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, 
   LayoutParams.WRAP_CONTENT); 
 //小圆点距底部的距离 单位: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); 
 //下面两句实现圆角半透明效果 不采用 
 // linearLayoutForDot.setBackgroundResource(R.drawable.round_corner_bg); 
 // linearLayoutForDot.getBackground().setAlpha(100); 
 
 //初始化4个小圆点 
 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); 
 
 //自动滑屏 5秒一次 
 timer.schedule(mTimerTask, 5000, TIMER_DURATION); 
 } 
 
 /** 
 * 加一个banner页面 TODO此函数写的不好 
 */ 
 private void addBannerItem() 
 { 
 //表示已经执行了onDetachedFromWindow，banner已经被销毁了 
 if( mBannerBitmaps == null || mLinearLayoutScreens == null || 
  mImageViewList == null || mContext == null ) 
  return; 
  
 //调整屏幕数量和总宽度 
 PAGE_COUNT += 1; 
 mHorizontalScrollViewEx.getLayoutParams().width = mScreenWidth * PAGE_COUNT; 
   
 //加载默认图片资源 
 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); 
 //加一个屏幕 
 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); 
  
 //加一个小圆点 
 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); 
  //解决长按屏幕后无法拖动的现象 
  mGestureDetector.setIsLongpressEnabled(false); 
 
  //构造弹性滑动对象 
  mScroller = new Scroller(context); 
 } 
 
 /** 
  * 切换到指定屏幕 
  * @param whichScreen 屏幕index 
  */ 
 public void switchView(int whichScreen) 
 { 
  if(mLinearLayoutScreens == null) 
  return; 
  
  // 防止非法参数 
  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(); 
 
  //缓慢滚动到指定位置 
  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; 
  //切换小圆点 
  switchScreenPosition(mWhichScreen); 
 } 
 
 /** 
  * 用户轻触触摸屏，由1个MotionEvent ACTION_DOWN触发 
  */ 
 @Override 
 public boolean onDown(MotionEvent e) 
 { 
  Logger.i("MyGesture", "onDown"); 
  
  mScrollX = HorizontalScrollViewEx.this.getScrollX(); 
 
  return true; 
 } 
 
 /** 
  * 用户轻触触摸屏，尚未松开或拖动，由一个1个MotionEvent ACTION_DOWN触发 
  * 注意和onDown()的区别，强调的是没有松开或者拖动的状态 
  */ 
 public void onShowPress(MotionEvent e) 
 { 
  Logger.i("MyGesture", "onShowPress"); 
 } 
 
 /** 
  * 用户（轻触触摸屏后）松开，由一个1个MotionEvent ACTION_UP触发 
  */ 
 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; 
 } 
 
 /** 用户按下触摸屏、快速移动后松开，由1个MotionEvent ACTION_DOWN, 多个ACTION_MOVE, 
  * 1个ACTION_UP触发 
  */ 
 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; 
 } 
 
 /** 
  * 用户按下触摸屏，并拖动，由1个MotionEvent ACTION_DOWN, 多个ACTION_MOVE触发 
  */ 
 public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, 
  float distanceY) 
 { 
  Logger.i("MyGesture", "onScroll"); 
 
  //禁止弹性滚动 
  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; 
 } 
 
 /** 
  * 用户长按触摸屏，由多个MotionEvent ACTION_DOWN触发 
  */ 
 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) 
  { 
  //开始自动滑屏 
  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此函数，防止其修改构造方法所定义的宽和高<br/> 
 * 注意：在这里，设置宽和高将不起作用 
 */ 
 @Override 
 public void setLayoutParams(android.view.ViewGroup.LayoutParams params) 
 { 
 params.width = mScreenWidth; 
 params.height = mScreenHeight; 
 
 super.setLayoutParams(params); 
 } 
 
 //标志view AttachedToWindow 
 @Override 
 protected void onAttachedToWindow() 
 { 
 super.onAttachedToWindow(); 
 mTimerResume = true; 
 } 
 
 //标志view已经脱离window，典型的情形是view被销毁了，此时取消timer 
 @Override 
 protected void onDetachedFromWindow() 
 { 
 super.onDetachedFromWindow(); 
 Logger.d(TAG, "onDetachedFromWindow"); 
  
 mTimerResume = false; 
 int activityId = ( (BaseActivity)mContext ).activityId(); 
 //如果是账号管理页面 则释放内存 
 if(activityId == BaseActivity.ACCOUNT_ID) 
 { 
  destroy(); 
 } 
 } 
 
 /** 
 * 销毁banner 
 */ 
 public void destroy() 
 { 
 mTimerTask.cancel(); 
 timer.cancel(); 
 //去除各种bitmap对activity的引用关系 
 destoryBitmaps(); 
 System.gc(); 
 } 
 
 /** 
 * 去除各种bitmap对activity的引用关系 
 */ 
 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对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; 
 } 
 
 //单击事件 
 @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) //单个游戏消息，直接启动该游戏 
 { 
  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) //游戏主页消息，通过客户端展示游戏主页 
 { 
  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) //交叉推广消息，通过一个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所关联的banner项 可以为多个 一个为一屏 
 */ 
 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：单击banner所产生的事件对象<br/> 
 *getAction()来获取动作类别<br/> 
 *getResponseUrl()来获取响应url<br/> 
 *... 
 */ 
 public static class BannerMotionEvent extends Object 
 { 
 /** 
  * ACTION_PLAY_FLASH： 播放游戏 
  */ 
 public static final int ACTION_PLAY = 2; 
 /** 
  * ACTION_HOMEPAGE：打开官网 
  */ 
 public static final int ACTION_HOMEPAGE = 3; 
 /** 
  * ACTION_OPEN_URL：打开指定url 
  */ 
 public static final int ACTION_OPEN_URL = 4; 
 
 //banner中屏幕的index 
 private int index = -1; 
 //响应url 
 private String responseUrl = ""; 
 //动作种类 
 private int action = -1; 
 //gameid 
 private String gameId = ""; 
 //gametype flash游戏(0) or h5游戏(1) 
 private String gameType = ""; 
 //webview的标题 
 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; 
 } 
 
 /** 
  * 获取当前BannerMotionEvent事件对象的动作种类 
  * @return 动作种类：ACTION_PLAY等 
  */ 
 public int getAction() 
 { 
  return action; 
 } 
 
 /** 
  * 获取当前BannerMotionEvent事件对象的title 
  * @return title webview的标题 
  */ 
 public String getTitle() 
 { 
  return title; 
 } 
  
 /** 
  * 获取当前BannerMotionEvent事件对象的gameId 
  * @return gameId 
  */ 
 public String getGameId() 
 { 
  return gameId; 
 } 
  
 /** 
  * 获取当前BannerMotionEvent事件对象的gameType 
  * @return gameType 0 or 1 
  */ 
 public String getGameType() 
 { 
  return gameType; 
 } 
  
 /** 
  * 获取当前BannerMotionEvent事件对象的响应url 
  * @return 响应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单击事件 
  * @param bannerMotionEvent 单击事件对象，包含所需的响应信息 
  * 参见 {@link BannerMotionEvent} 
  */ 
 public abstract void onBannerClick( BannerMotionEvent bannerMotionEvent ); 
 } 
 
}

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呐喊教程。

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