Androidの开源框架ImageLoader的完美使用

最新推荐文章于 2024-05-03 02:00:38 发布

SteamPY

最新推荐文章于 2024-05-03 02:00:38 发布

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分类专栏：【android】文章标签： Android ImageLoader 加载图片

本文链接：https://blog.youkuaiyun.com/xiabing082/article/details/44962915

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本文详细介绍了一个Android开源框架ImageLoader的使用方法，包括初始化配置、ListView图片加载等，并提供了一个完善的示例项目，涵盖ListView、GridView等多种场景的图片加载。

Androidの开源框架ImageLoader的完美使用

1. 很多人都在讨论如何让图片能在异步加载更加流畅，可以显示大量图片，在拖动ListView的时候不会出现卡的现象。

关于ImageLoader这个开源框架的使用有很多网友都介绍过，不过还不够清楚，这里有一个关于这个开源项目的完美例子，ListView的图片加载、GridView的图片加载、ViewPager的图片加载、Gallery画廊的图片加载、Widget的使用。很完善的一个例子，在这里我把所有界面效果做出博客分享出来，需要源码的朋友到我的资源页下载

2. 实现ListView 图片加载

首先加载一个application 类，主要加载ImageLoader

public class UILApplication extends Application {
	@TargetApi(Build.VERSION_CODES.GINGERBREAD)
	@SuppressWarnings("unused")
	@Override
	public void onCreate() {
		if (Constants.Config.DEVELOPER_MODE && Build.VERSION.SDK_INT >= Build.VERSION_CODES.GINGERBREAD) {
			StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder().detectAll().penaltyDialog().build());
			StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder().detectAll().penaltyDeath().build());
		}
		super.onCreate();
		initImageLoader(getApplicationContext());
	}

	public static void initImageLoader(Context context) {
		ImageLoaderConfiguration.Builder config = new ImageLoaderConfiguration.Builder(context);
		config.threadPriority(Thread.NORM_PRIORITY - 2);
		config.denyCacheImageMultipleSizesInMemory();
		config.diskCacheFileNameGenerator(new Md5FileNameGenerator());
		config.diskCacheSize(50 * 1024 * 1024); // 50 MiB
		config.tasksProcessingOrder(QueueProcessingType.LIFO);
		config.writeDebugLogs(); // Remove for release app
		// Initialize ImageLoader with configuration.
		ImageLoader.getInstance().init(config.build());
	}
}

然后在listview中主类加载图片，如下

public class MainActivity extends Activity {

	String[] imageUrls = new String[] { };

	DisplayImageOptions options;
	private ListView listView;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	
		//imageLoader.init(ImageLoaderConfiguration.createDefault(MainActivity.this));
		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)
				.displayer(new RoundedBitmapDisplayer(20)).build();

		listView = (ListView) findViewById(R.id.list);
		listView.setAdapter(new ImageAdapter());
		listView.setOnItemClickListener(new OnItemClickListener() {
			@Override
			public void onItemClick(AdapterView<?> parent, View view,
					int position, long id) {
				// startImagePagerActivity(position);
			}
		});
	}

	private static class ViewHolder {
		TextView text;
		ImageView image;
	}

	class ImageAdapter extends BaseAdapter {
		private LayoutInflater inflater;
		private ImageLoadingListener animateFirstListener = new AnimateFirstDisplayListener();

		ImageAdapter() {
			inflater = LayoutInflater.from(MainActivity.this);
		}

		@Override
		public int getCount() {
			return imageUrls.length;
		}

		@Override
		public Object getItem(int position) {
			return position;
		}

		@Override
		public long getItemId(int position) {
			return position;
		}

		@Override
		public View getView(final int position, View convertView,
				ViewGroup parent) {
			View view = convertView;
			final ViewHolder holder;
			if (convertView == null) {
				view = inflater
						.inflate(R.layout.item_list_image, parent, false);
				holder = new ViewHolder();
				holder.text = (TextView) view.findViewById(R.id.text);
				holder.image = (ImageView) view.findViewById(R.id.image);
				view.setTag(holder);
			} else {
				holder = (ViewHolder) view.getTag();
			}
			holder.text.setText("Item " + (position + 1));
			ImageLoader.getInstance().displayImage(imageUrls[position],
					holder.image, options, animateFirstListener);
			return view;
		}
	}

	private static class AnimateFirstDisplayListener extends
			SimpleImageLoadingListener {

		static final List<String> displayedImages = Collections
				.synchronizedList(new LinkedList<String>());

		@Override
		public void onLoadingComplete(String imageUri, View view,
				Bitmap loadedImage) {
			if (loadedImage != null) {
				ImageView imageView = (ImageView) view;
				boolean firstDisplay = !displayedImages.contains(imageUri);
				if (firstDisplay) {
					FadeInBitmapDisplayer.animate(imageView, 500);
					displayedImages.add(imageUri);
				}
			}
		}
	}

}

2. 源码下载

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