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 * 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 * 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 );
}

}