android Universal-Image-Loader架構學習（下）

標籤：android

一.GridView顯示圖片加進度框：

    在Universal-Image-Loader架構可以讓載入圖片變的簡單，下面我們看一下如何在GridView中使用附加上進度條。

：

主介面：

<span style="font-size:18px;">public class GridActivity extends Activity{private GridView grid;public static final String[] IMAGES = new String[] {"http://img.dapixie.com/uploads/allimg/111105/1-111105145231.jpg","http://img3.3lian.com/2014/c2/61/d/1.jpg","http://img3.3lian.com/2014/c2/61/d/2.jpg","http://img3.3lian.com/2014/c2/61/d/3.jpg","http://img3.3lian.com/2014/c2/61/d/4.jpg","http://img3.3lian.com/2014/c2/61/d/5.jpg","http://img3.3lian.com/2014/c2/61/d/6.jpg","http://img3.3lian.com/2014/c2/61/d/7.jpg","http://img3.3lian.com/2014/c2/61/d/8.jpg","http://img3.3lian.com/2014/c2/61/d/9.jpg","http://img3.3lian.com/2014/c2/61/d/10.jpg","http://img3.3lian.com/2014/c2/61/d/11.jpg","http://img3.3lian.com/2014/c2/61/d/12.jpg" };@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.grid_activity);grid = (GridView)findViewById(R.id.grid);grid.setAdapter(new ImageAdapter(this));}@Overrideprotected void onDestroy() {super.onDestroy();ImageLoader.getInstance().clearMemoryCache();// 清空緩衝ImageLoader.getInstance().clearDiskCache();//清空緩衝ImageLoader.getInstance().stop();// 停止}private static class ImageAdapter extends BaseAdapter {private static final String[] IMAGE_URLS = GridActivity.IMAGES;private LayoutInflater inflater;private DisplayImageOptions options;ImageAdapter(Context context) {inflater = LayoutInflater.from(context);options = new DisplayImageOptions.Builder().showImageOnLoading(R.drawable.ic_stub).showImageForEmptyUri(R.drawable.ic_empty).showImageOnFail(R.drawable.ic_error).cacheInMemory(true).cacheOnDisk(true).considerExifParams(true).bitmapConfig(Bitmap.Config.RGB_565).build();}@Overridepublic int getCount() {return IMAGE_URLS.length;}@Overridepublic Object getItem(int position) {return null;}@Overridepublic long getItemId(int position) {return position;}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {final ViewHolder holder;View view = convertView;if (view == null) {view = inflater.inflate(R.layout.grid_listview_item, parent, false);holder = new ViewHolder();assert view != null;holder.imageView = (ImageView) view.findViewById(R.id.image);holder.progressBar = (ProgressBar) view.findViewById(R.id.progress);view.setTag(holder);} else {holder = (ViewHolder) view.getTag();}ImageLoader.getInstance().displayImage(IMAGE_URLS[position], holder.imageView, options, new SimpleImageLoadingListener() {@Overridepublic void onLoadingStarted(String imageUri, View view) {//設定進度條為0holder.progressBar.setProgress(0);//開始下載時顯示holder.progressBar.setVisibility(View.VISIBLE);}@Overridepublic void onLoadingFailed(String imageUri, View view, FailReason failReason) {//下載失敗隱藏holder.progressBar.setVisibility(View.GONE);}@Overridepublic void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {//下載失敗隱藏holder.progressBar.setVisibility(View.GONE);}}, new ImageLoadingProgressListener() {@Overridepublic void onProgressUpdate(String imageUri, View view, int current, int total) {//current當前進度，total總進度holder.progressBar.setProgress(Math.round(100.0f * current / total));}});return view;}}static class ViewHolder {ImageView imageView;ProgressBar progressBar;}}</span>

主介面布局：

<span style="font-size:18px;"><?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:orientation="vertical" >        <GridViewandroid:id="@+id/grid"android:layout_width="match_parent"android:layout_height="match_parent"android:gravity="center"android:horizontalSpacing="4dip"android:numColumns="3"android:stretchMode="columnWidth"android:verticalSpacing="4dip"android:padding="4dip" /></LinearLayout></span>

grid_item布局：

<span style="font-size:18px;"><?xml version="1.0" encoding="utf-8"?><FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="120dip"><ImageViewandroid:id="@+id/image"android:layout_width="match_parent"android:layout_height="120dip"android:adjustViewBounds="true"android:contentDescription="@string/descr_image"android:scaleType="centerCrop" /><ProgressBarandroid:id="@+id/progress"android:layout_width="match_parent"android:layout_height="wrap_content"android:indeterminate="false"android:max="100"android:layout_gravity="bottom"style="@style/ProgressBarStyle" /></FrameLayout></span>

進度條樣式：

<span style="font-size:18px;"><style name="ProgressBarStyle" parent="@android:style/Widget.Holo.ProgressBar.Horizontal"/></span>

ImageLoader配置：

<span style="font-size:18px;">public class MyApp extends Application {@Overridepublic void onCreate() {super.onCreate();initImageLoader1(getApplicationContext());}/* * 自訂配置 */public static void initImageLoader(Context context) {ImageLoaderConfiguration.Builder config = new ImageLoaderConfiguration.Builder(context);config.threadPoolSize(3);//線程池內載入的數量 config.threadPriority(Thread.NORM_PRIORITY - 2);config.denyCacheImageMultipleSizesInMemory();// 不緩衝圖片的多種尺寸在記憶體中config.diskCacheFileNameGenerator(new Md5FileNameGenerator());// 將儲存的時候的URI名稱用MD5config.diskCacheSize(50 * 1024 * 1024); // 50 MiBconfig.tasksProcessingOrder(QueueProcessingType.LIFO);config.writeDebugLogs();// Remove for release app// 初始化ImageLoader使用ImageLoader.getInstance().init(config.build());}/* * 預設的配置，一般沒有特殊的要求的時候就使用預設就好了。 */public static void initImageLoader1(Context context) {// 建立預設的ImageLoader配置參數ImageLoaderConfiguration configuration = ImageLoaderConfiguration.createDefault(context);// 初始化ImageLoader使用ImageLoader.getInstance().init(configuration);}}</span>

這個例子是從上篇文章繼續寫的，也是在它項目裡繼續寫的。

如果你想在滑動中停止載入，而在停止滑動後再繼續載入圖片，Universal-Image-Loader也提供了這樣的功能，PauseOnScrollListener這個類就是監聽。

listView.setOnScrollListener(new PauseOnScrollListener(ImageLoader.getInstance(), pauseOnScroll, pauseOnFling));

PauseOnScrollListener的第一個參數是圖片載入對象ImageLoader，第二個是控制是否在滑動過程中暫停載入圖片，如果需要暫停傳true就行了，第三個參數控制猛的滑動介面的時候圖片是否載入。

android Universal-Image-Loader架構學習（下）