java – 正确使用Universal Image Loader

好的,我一直在尝试优化我的照片库几天(这是我的第一个Android项目).所有照片都是通过网页加载的.我已经开始使用Universal Image Loader,但我仍然不满意结果.

这是我的班级：

public class Galerija extends Activity {

ArrayList<RSSItem> lista = new ArrayList<RSSItem>();
ArrayList<String> lst_slika = new ArrayList<String>();
RSSItem tempItem = new RSSItem();
ImageAdapter adapter;
ImageLoader imageLoader;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_galerija);

    try 
    {
        SAXParserFactory spf = SAXParserFactory.newInstance();
        SAXParser sp = spf.newSAXParser();
        XMLReader myReader = sp.getXMLReader();

        URL url = new URL("http://erdut.gausstesting.info/generateXML/galerija.php");

        XMLHandler myXMLHandler = new XMLHandler();
        myReader.setContentHandler(myXMLHandler);
        myReader.parse(new InputSource(url.openStream()));
        lista = myXMLHandler.getRss_lista();
        lst_slika = lista.get(0).getImages();

    } catch (Exception e) {
        System.out.println(e);
    }

    adapter = new ImageAdapter(this, lst_slika);
    GridView gridview = (GridView) findViewById(R.id.gridview);
    gridview.setAdapter(adapter);

    gridview.setOnItemClickListener(new OnItemClickListener() {

        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                long arg3) {
            // TODO Auto-generated method stub

        }
    });

} 

public class ImageAdapter extends BaseAdapter {
    private Context mContext;
    private ArrayList<String> lista;   
    /*
    final ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(this.mContext)
    .enableLogging()
    .memoryCacheSize(41943040)
    .discCacheSize(104857600)
    .threadPoolSize(10)
    .build();
    */
    final DisplayImageOptions options = new DisplayImageOptions.Builder()
    .showStubImage(R.drawable.ic_stub)
    .showImageForEmptyUri(R.drawable.ic_empty)
    .showImageOnFail(R.drawable.ic_error)
    .cacheInMemory()
    .cacheOnDisc()
    .build();

    public ImageAdapter(Context c, ArrayList<String> lista) {
        this.mContext = c;
        this.lista = lista;
        imageLoader = ImageLoader.getInstance();
        //imageLoader.init(config);
        imageLoader.init(ImageLoaderConfiguration.createDefault(c));
    }

    public int getCount() {
        return lista.size();
    }

    public Object getItem(int position) {
        return null;
    }

    public long getItemId(int position) {
        return 0;
    }

    // create a new ImageView for each item referenced by the Adapter
    public View getView(int position, View convertView, ViewGroup parent) {
        ImageView imageView;

        if (convertView == null) {  // if it's not recycled, initialize some attributes
            imageView = new ImageView(mContext);
            //ova 3 polja označavaju veličinu, cropanje i padding prikazanih slika
            imageView.setLayoutParams(new GridView.LayoutParams(150, 150));
            imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
            imageView.setPadding(0, 0, 0, 0);
        } else {
            imageView = (ImageView) convertView;
        }

        imageLoader.displayImage(lista.get(position), imageView, options);
        //new ImageDownloadTask(imageView).execute(lista.get(position));

        return imageView;
    }
}

}

与我以前的解决方案相比,它确实加快了速度,但我并不满足.首先,我甚至无法在我的HTC Incredible S上启动它 – 只需启动黑屏活动,无需加载.这是为什么？

它仅适用于模拟器,但在滚动时会重新加载所有图像.因此,一旦您向下滚动然后再向上,所有图像似乎都会重新加载.它是如何工作的？还有什么方法可以改善这个吗？

提前致谢！

解决方法:

您应该考虑使用asynctask从服务器获取URL.

你应该使用视图持有人来平滑滚动和表现.
http://www.youtube.com/watch?v=wDBM6wVEO70.谈话是关于观看者和列表视图的表现.

http://developer.android.com/training/improving-layouts/smooth-scrolling.html

https://github.com/nostra13/Android-Universal-Image-Loader.检查“配置和显示选项”下的主题.

您应该将图像缓存在手机记忆库或SD卡中,而不是再次下载.

它使用url作为密钥,在sdcard中缓存图像(如果已正确配置).如果存在显示从缓存否则下载,缓存和显示图像.

在自定义适配器构造函数中

 File cacheDir = StorageUtils.getOwnCacheDirectory(activity context, "your folder");//for caching

 // Get singletone instance of ImageLoader
 imageLoader = ImageLoader.getInstance();
 // Create configuration for ImageLoader (all options are optional)
 ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(a)
 // You can pass your own memory cache implementation
.discCache(new UnlimitedDiscCache(cacheDir)) // You can pass your own disc cache implementation
.discCacheFileNameGenerator(new HashCodeFileNameGenerator())
.enableLogging()
.build();
// Initialize ImageLoader with created configuration. Do it once.
imageLoader.init(config);
options = new DisplayImageOptions.Builder()
.cacheInMemory(true)
.cacheOnDisk(true)
.showImageOnLoading(R.drawable.default_pic)//display stub image until image is loaded
.displayer(new RoundedBitmapDisplayer(20))
.build();

在你的getView()中

viewholder.image=(ImageView)vi.findViewById(R.id.imageview); 
imageLoader.displayImage(imageurl, viewholder.image,options);//provide imageurl, imageview and options.

标签：android,java,photo-gallery,universal-image-loader
来源： https://codeday.me/bug/20190723/1510075.html