将图像从四方形加载到图库适配器

Question

您正在创建一个应用程序，它从Foursquare中提取资源并将其显示在Android手机上，并且在加载图像时遇到问题。该应用程序运行，但由于某种原因，它没有加载到手机上它只显示我定义的加载程序图像

我的代码如下：

public class PicAdapter extends BaseAdapter {

    //use the default gallery background image
    int defaultItemBackground;

    //gallery context
    private Context galleryContext;

    //array to store bitmaps to display
    private Bitmap[] imageBitmaps;
    //placeholder bitmap for empty spaces in gallery
    Bitmap placeholder;

    //constructor
    public PicAdapter(Context c) {

        //instantiate context
        galleryContext = c;

        //create bitmap array
        //imageBitmaps  = new Bitmap[10];
        //decode the placeholder image
        //placeholder = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);

    }

    //BaseAdapter methods

    //return number of data items i.e. bitmap images
    public int getCount() {
        return PicturesURLlist.size();
    }

    //return item at specified position
    public Object getItem(int position) {
        return position;
    }

    //return item ID at specified position
    public long getItemId(int position) {
        return position;
    }

    //get view specifies layout and display options for each thumbnail in the gallery
    public View getView(int position, View convertView, ViewGroup parent) {

        //create the view
        ImageView imageView = new ImageView(galleryContext);
        //specify the bitmap at this position in the array
        //imageView.setImageBitmap(imageBitmaps[position]);
        ImageLoader imgloader = new ImageLoader(getApplicationContext());

        int loader = R.drawable.ic_launcher;

        HashMap<String, String> song = new HashMap<String, String>();

        song = PicturesURLlist.get(position);
        //Log.d("Links", song.get(picurl));

        imgloader.DisplayImage(song.get(picurl), loader, imageView );
        //imageView.setImageBitmap((imgloader.DisplayImage(song.get(picurl), loader, imageView)));
        //set layout options
        imageView.setLayoutParams(new Gallery.LayoutParams(400, 600));
        //scale type within view area
        imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
        //set default gallery item background
        imageView.setBackgroundResource(defaultItemBackground);
        //return the view
        return imageView;
    }

    //custom methods for this app

    //helper method to add a bitmap to the gallery when the user chooses one

}

我的想象器类

public class ImageLoader {

MemoryCache memoryCache=new MemoryCache();
FileCache fileCache;
private Map<ImageView, String> imageViews=Collections.synchronizedMap(new WeakHashMap<ImageView, String>());
ExecutorService executorService; 

public ImageLoader(Context context){
    fileCache=new FileCache(context);
    executorService=Executors.newFixedThreadPool(5);
}

int stub_id = R.drawable.ic_launcher;
public String DisplayImage(String url, int loader, ImageView imageView)
{
    stub_id = loader;
    imageViews.put(imageView, url);
    Bitmap bitmap=memoryCache.get(url);
    Log.d("Image loader succes", url);
    if(bitmap!=null){
        imageView.setImageBitmap(bitmap);
        Log.d("Image loader succes", "true");
    }
    else
    {
        queuePhoto(url, imageView);
        imageView.setImageResource(loader);
        Log.d("Image loader succes", "false");
    }
    return null;
}

private void queuePhoto(String url, ImageView imageView)
{
    PhotoToLoad p=new PhotoToLoad(url, imageView);
    executorService.submit(new PhotosLoader(p));
}

private Bitmap getBitmap(String url)
{
    File f=fileCache.getFile(url);

    //from SD cache
    Bitmap b = decodeFile(f);
    if(b!=null)
        return b;

    //from web
    try {
        Bitmap bitmap=null;
        URL imageUrl = new URL(url);
        HttpURLConnection conn = (HttpURLConnection)imageUrl.openConnection();
        conn.setConnectTimeout(30000);
        conn.setReadTimeout(30000);
        conn.setInstanceFollowRedirects(true);
        InputStream is=conn.getInputStream();
        OutputStream os = new FileOutputStream(f);
        Utils.CopyStream(is, os);
        os.close();
        bitmap = decodeFile(f);
        return bitmap;
    } catch (Exception ex){
       ex.printStackTrace();
       return null;
    }
}

//decodes image and scales it to reduce memory consumption
private Bitmap decodeFile(File f){
    try {
        //decode image size
        BitmapFactory.Options o = new BitmapFactory.Options();
        o.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(new FileInputStream(f),null,o);

        //Find the correct scale value. It should be the power of 2.
        final int REQUIRED_SIZE=70;
        int width_tmp=o.outWidth, height_tmp=o.outHeight;
        int scale=1;
        while(true){
            if(width_tmp/2<REQUIRED_SIZE || height_tmp/2<REQUIRED_SIZE)
                break;
            width_tmp/=2;
            height_tmp/=2;
            scale*=2;
        }

        //decode with inSampleSize
        BitmapFactory.Options o2 = new BitmapFactory.Options();
        o2.inSampleSize=scale;
        return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
    } catch (FileNotFoundException e) {}
    return null;
}

//Task for the queue
private class PhotoToLoad
{
    public String url;
    public ImageView imageView;
    public PhotoToLoad(String u, ImageView i){
        url=u;
        imageView=i;
    }
}

class PhotosLoader implements Runnable {
    PhotoToLoad photoToLoad;
    PhotosLoader(PhotoToLoad photoToLoad){
        this.photoToLoad=photoToLoad;
    }

    public void run() {
        if(imageViewReused(photoToLoad))
            return;
        Bitmap bmp=getBitmap(photoToLoad.url);
        memoryCache.put(photoToLoad.url, bmp);
        if(imageViewReused(photoToLoad))
            return;
        BitmapDisplayer bd=new BitmapDisplayer(bmp, photoToLoad);
        Activity a=(Activity)photoToLoad.imageView.getContext();
        a.runOnUiThread(bd);
    }
}

boolean imageViewReused(PhotoToLoad photoToLoad){
    String tag=imageViews.get(photoToLoad.imageView);
    if(tag==null || !tag.equals(photoToLoad.url))
        return true;
    return false;
}

//Used to display bitmap in the UI thread
class BitmapDisplayer implements Runnable
{
    Bitmap bitmap;
    PhotoToLoad photoToLoad;
    public BitmapDisplayer(Bitmap b, PhotoToLoad p){bitmap=b;photoToLoad=p;}
    public void run()
    {
        if(imageViewReused(photoToLoad))
            return;
        if(bitmap!=null)
            photoToLoad.imageView.setImageBitmap(bitmap);
        else
            photoToLoad.imageView.setImageResource(stub_id);
    }
}

public void clearCache() {
    memoryCache.clear();
    fileCache.clear();
}

}