android应用app离不开服务器端的数据，我们装在手机上的app应用都是通过http相关协议及方法从对应的服务器上取下来的。几乎所有的app 都少不了从网络加载图片并展示在手机上，今天我写的就是把网络图片加载到本地并用ViewPager展示出来，可以实现图片自动滚动播放，当然可以手动翻 页。借助了网络图片开源框架ImageLoader，其在github开源地址是：https://github.com/nostra13/Android-Universal-Image-Loader，如果想知道这开源框架的具体使用方法可以参考http://blog.csdn.net/wwj_748/article/details/10079311这篇博客。

   下面直接贴代码：

<?xml version="1.0" encoding="utf-8"?>  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"      android:layout_width="match_parent"      android:layout_height="match_parent"      android:background="#fff0f0ed"      android:orientation="vertical" >            <android.support.v4.view.AutoScrollViewPager              android:id="@+id/advertisementVp"              android:layout_width="match_parent"              android:layout_height="wrap_content"              android:background="#ffa1a1a1" />          <LinearLayout              android:id="@+id/advertisement_dotLl"              android:layout_width="match_parent"              android:layout_height="wrap_content"              android:layout_alignParentBottom="true"              android:gravity="center"              android:orientation="horizontal"              android:paddingBottom="4.5dp"              android:paddingTop="4.5dp" >          </LinearLayout>  </RelativeLayout><!--实际项目布局不是这样，这只是个举例-->

下面这个类是我们在实际项目中把V4包中的AutoScrollViewPager做了修改：

public class AutoScrollViewPager<T extends PagerData> extends ViewPager {  public interface OnPageItemClickListener<T extends PagerData> {  void onPageItemClickListener(T pd);  }  private int mScrollTime = 0;  private int oldIndex = 0;  private int curIndex = 0;  private List<T> mPagerData = new ArrayList<T>();  private PagerAdapter pagerAdapter;  private LinearLayout indicatorView;  private int focusedDrawable, normalDrawable;  private LayoutInflater inflater;  private OnPageItemClickListener<T> pageItemClickListener;  private boolean isFakeCycle = false;// 是否是假的循环  private boolean isStartScroll;  public AutoScrollViewPager(Context context, AttributeSet attrs) {  super(context, attrs);  inflater = LayoutInflater.from(context);  focusedDrawable = R.drawable.common_dot_selected;  normalDrawable = R.drawable.common_dot_normal;  setInternalPageChangeListener(new OnPageChangeListener() {  public void onPageSelected(int i) {  if (mPagerData.isEmpty() || indicatorView == null || indicatorView.getChildCount() == 0)  return;  curIndex = i % mPagerData.size();  // 取消圆点选中  indicatorView.getChildAt(oldIndex).setBackgroundResource(normalDrawable);  // 圆点选中  indicatorView.getChildAt(curIndex).setBackgroundResource(focusedDrawable);  oldIndex = curIndex;  }    public void onPageScrolled(int arg0, float arg1, int arg2) {}  public void onPageScrollStateChanged(int arg0) {}    });    // 设置滑动动画时间 ,如果用默认动画时间可不用 ,反射技术实现  new FixedSpeedScroller(getContext()).setDuration(this, 700);  pagerAdapter = new MyPagerAdapter();  setAdapter(pagerAdapter);  setOffscreenPageLimit(2);  requestDisallowInterceptTouchEvent(true);  options = new DisplayImageOptions.Builder()                                    .showImageOnLoading(R.drawable.index_advert_default) //加载中显示的默认图片  .showImageForEmptyUri(R.drawable.index_advert_default) //加载错误默认图片  .showImageOnFail(R.drawable.index_advert_default)//加载错误时的默认图片  .cacheInMemory(true)// 开启内存缓存  .cacheOnDisk(true) // 开启硬盘缓存  .resetViewBeforeLoading(false).build());  }  @Override  protected void onAttachedToWindow() {  super.onAttachedToWindow();  if (isStartScroll) {  start(mScrollTime);  }  }  @Override  protected void onDetachedFromWindow() {  super.onDetachedFromWindow();  if (isStartScroll)  handler.removeCallbacksAndMessages(null);  }  /** 构建内部索引父view */  private void initInnerIndicator() {  indicatorView = new IndicatorView(getContext());  indicatorView.setGravity(Gravity.CENTER);  indicatorView.setBackgroundColor(0x0fFF00FF);  indicatorView.setOrientation(LinearLayout.HORIZONTAL);  LayoutParams params = new LayoutParams();  params.width = ViewGroup.LayoutParams.MATCH_PARENT;  params.height = 40;  params.gravity = Gravity.BOTTOM;  addView(indicatorView, params);  }  public void setDatas(List<T> imgUrls, LinearLayout outIndicator, boolean needInnerIndicator, boolean isFakeCycle) {  this.isFakeCycle = isFakeCycle;  setDatas(imgUrls, outIndicator, needInnerIndicator);  }  /**重复调用可能会anr*/  public void setDatas(List<T> imgUrls, LinearLayout outIndicator, boolean needInnerIndicator) {  if (outIndicator != null) {  indicatorView = outIndicator;  } else if (needInnerIndicator) {  initInnerIndicator();  }  mPagerData.clear();  mPagerData.addAll(imgUrls);  pagerAdapter.notifyDataSetChanged();  }  /**重新加载图片数据，刷新vp内容*/  public void refreshDatas(List<T> imgUrls, LinearLayout outIndicator, boolean needInnerIndicator, boolean isFakeCycle) {  this.isFakeCycle = isFakeCycle;  if (outIndicator != null) {  indicatorView = outIndicator;  } else if (needInnerIndicator) {  initInnerIndicator();  }  mPagerData.clear();  mPagerData.addAll(imgUrls);  pagerAdapter = new MyPagerAdapter();  setAdapter(pagerAdapter);  pagerAdapter.notifyDataSetChanged();  }  @Override  void dataSetChanged() {  super.dataSetChanged();  setUpIndicator();  }    // 设置圆点  private void setUpIndicator() {  if (indicatorView != null) {  indicatorView.removeAllViews();  if (mPagerData.isEmpty()) {  indicatorView.setVisibility(View.GONE);  return;  } else {  indicatorView.setVisibility(View.VISIBLE);  }  for (int i = 0; i < mPagerData.size(); i++) {  View v = inflater.inflate(R.layout.auto_scrollpage_dot, indicatorView, false);  v.setBackgroundResource(normalDrawable);  indicatorView.addView(v);  }  indicatorView.getChildAt(0).setBackgroundResource(focusedDrawable);  }  curIndex = oldIndex = 0;  if (mPagerData.size() > 1 && isFakeCycle) {  setCurrentItem(15 - 15 % mPagerData.size());// 设置选中为中间/图片为和第0张一样  } else {  setCurrentItem(0);  }  }  /** 获取真实的当前位置 */  public int getCurrentPosition() {  return curIndex;  }    /** 获取真实的当前位置的数据 */  public T getCurrentData() throws IndexOutOfBoundsException {  return mPagerData.get(curIndex);  }    @Override  public boolean onInterceptTouchEvent(MotionEvent ev) {  if (ev.getAction() == MotionEvent.ACTION_UP || ev.getAction() == MotionEvent.ACTION_CANCEL) {  start();  } else {  handler.removeCallbacksAndMessages(null);  }  return super.onInterceptTouchEvent(ev);  }    @Override  public boolean onTouchEvent(MotionEvent ev) {  if (ev.getAction() == MotionEvent.ACTION_UP || ev.getAction() == MotionEvent.ACTION_CANCEL) {  start();  } else {  handler.removeCallbacksAndMessages(null);  }  return super.onTouchEvent(ev);  }    /** 开始广告滚动 */  private void start() {  start(mScrollTime);  }  public void start(int scrollTime) {  // handler.removeCallbacksAndMessages(null);  mScrollTime = scrollTime;  isStartScroll = false;  if (mScrollTime > 0 && !mPagerData.isEmpty()) {  isStartScroll = true;  handler.sendMessageDelayed(handler.obtainMessage(), mScrollTime);  }  }  private Handler handler = new Handler() {  public void handleMessage(android.os.Message msg) {  handler.removeCallbacksAndMessages(null);  if (isFakeCycle) {  setCurrentItem(getCurrentItem() + 1);  } else {  if (getCurrentItem() == mPagerData.size() - 1) {  setCurrentItem(0, true);  } else {  setCurrentItem(getCurrentItem() + 1);  }  }  handler.sendMessageDelayed(handler.obtainMessage(), mScrollTime);  };  };  private DisplayImageOptions options;  public void setImageOptions(DisplayImageOptions options) {  this.options = options;  }  // 适配器 //循环设置  private class MyPagerAdapter extends PagerAdapter {    @Override  public int getCount() {  if (mPagerData.size() == 1) {  return 1;  } else if (mPagerData.size() > 1) { return isFakeCycle ? Integer.MAX_VALUE : mPagerData.size(); }  return 0;  }    @Override  public Object instantiateItem(ViewGroup container, int position) {  final int realP = position % mPagerData.size();  final ImageView netImgView = (ImageView) inflater.inflate(R.layout.auto_scrollpage_img, container, false);  ImageLoader.getInstance().displayImage(mPagerData.get(realP).getImageUrl(), netImgView, options);  netImgView.setOnClickListener(new View.OnClickListener() {  @Override  public void onClick(View v) {  if (pageItemClickListener != null) {  pageItemClickListener.onPageItemClickListener(mPagerData.get(realP));  }  }  });  container.addView(netImgView);  return netImgView;  }  @Override  public void destroyItem(ViewGroup container, int position, Object object) {  if (object instanceof View) {  container.removeView((View) object);  }  }  @Override  public boolean isViewFromObject(View view, Object object) {  return view == object;  }  }  /** 设置显示条目的点击事件 */  public void setOnPageItemClickListener(OnPageItemClickListener<T> pageItemClickListener) {  this.pageItemClickListener = pageItemClickListener;  }  }

是个接口，主要实现取得图片的url:

public interface PagerData{  public String getImageUrl();//用于显示网络图片  public void setImageUrl(String imgUrl);  }

有了以上的准备，只需要在Activity中取得图片的url地址，调用refreshDatas()方法把参数传入就可以了，activity中关键代码：

viewPager = (AutoScrollViewPager<AdvertisementInfo>) headerView.findViewById(R.id.viewPager );//获取ViewPager对象，                    advertisementVp.refreshDatas();//传入对应参数          advertisementVp.start(3000);

ok啦，时间原因，没有贴出所有代码，仅供参考。