来自用于社交网络应用程序的服务器的Android图库图像

Question

嗨，大家好，我在寻找如何有效地将图像从服务器加载到我的画廊中。 现在我正在使用延迟加载技术在此URL中进行解释

但是当图库图像的数量增加时，它的速度仍然会变慢。 任何人都可以找到或使用其他任何技术吗？ 我也不了解某些社交网络应用程序（例如POF和match.com等）如何实现它们，其中图像最初显示为模糊并达到良好的质量。 希望大家能理解我的问题。希望能有更好的答复。 提前致谢。

编辑＃1：

抱歉，我刚刚在上面粘贴了其他网址... 这是我在实现过程中遵循的网址

还浏览了第一个网址，发现他们也使用了相同的逻辑...

编辑＃2：

gallery.setAdapter(new LazyGalleryBaseAdapter(this, mStrings)); 
imageLoader.DisplayImage(data[position], activity, image);// called from the getview method of LazyGalleryBaseAdapter class 

并且ImageLoader类如下：

package com.sdi.lazyimageloader;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Collections;
import java.util.Map;
import java.util.Stack;
import java.util.WeakHashMap;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.widget.ImageView;

import com.sdi.videodate.R;

public class ImageLoader {

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

public ImageLoader(Context context) {
    // Make the background thead low priority. This way it will not affect
    // the UI performance
    photoLoaderThread.setPriority(Thread.NORM_PRIORITY - 1);
    ctx = context;
    fileCache = new FileCache(context);
}

final int stub_id = R.drawable.stub;

public void DisplayImage(String url, Activity activity, ImageView imageView) {
    imageViews.put(imageView, url);
    Bitmap bitmap = memoryCache.get(url);
    System.err.println("bitmap ??????"+bitmap);
    System.out.println("imageView ===> "+imageView);
    if (bitmap != null) {
        // call the below line to get the rounded corner image
//          Bitmap bitmap1 = LazyAdapter.getRoundedCornerBitmap(ctx, bitmap,
//                  7f, 7f, 7f, 7f, 85, 85);            

        imageView.setImageBitmap(bitmap);
    } else {
        queuePhoto(url, activity, imageView);
        imageView.setImageResource(stub_id);
        System.err.println("bitmap stub_id??????"+stub_id);
    }
}

private void queuePhoto(String url, Activity activity, ImageView imageView) {
    // This ImageView may be used for other images before. So there may be
    // some old tasks in the queue. We need to discard them.
    photosQueue.Clean(imageView);
    PhotoToLoad p = new PhotoToLoad(url, imageView);
    synchronized (photosQueue.photosToLoad) {
        photosQueue.photosToLoad.push(p);
        photosQueue.photosToLoad.notifyAll();
    }

    // start thread if it's not started yet
    if (photoLoaderThread.getState() == Thread.State.NEW)
        photoLoaderThread.start();
}

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);
        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;
    }
}

private static Bitmap decodeFiles(File f) {
    Bitmap b = null;
    try {
        // Decode image size
        int IMAGE_MAX_SIZE = 80;
        BitmapFactory.Options o = new BitmapFactory.Options();
        o.inJustDecodeBounds = true;

        FileInputStream fis = new FileInputStream(f);
        BitmapFactory.decodeStream(fis, null, o);
        try {
            fis.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        int scale = 1;
        if (o.outHeight <= 1300 && o.outWidth <= 1000) {
            scale = 1;
        } else if (o.outHeight >= 1280 && o.outWidth >= 960) {
            scale = 6;
        } else if (o.outHeight > IMAGE_MAX_SIZE
                || o.outWidth > IMAGE_MAX_SIZE) {

            // scale = (int) Math.pow(2,(int)
            // Math.round(Math.log(IMAGE_MAX_SIZE / (double)
            // Math.max(o.outHeight, o.outWidth))/ Math.log(0.5)));
            scale = 5;
        }
        /*
         * else if (o.outHeight > IMAGE_MAX_SIZE || o.outWidth >
         * IMAGE_MAX_SIZE) { // scale = (int) Math.pow( 2,(int) //
         * Math.round(Math.log(IMAGE_MAX_SIZE / (double) //
         * Math.max(o.outHeight, o.outWidth))/ Math.log(0.5))); scale = 8; }
         */

        System.err.println(scale
                + "---Scale Value (((((((((((((((((((((((((((((("
                + o.outHeight + "---" + o.outWidth);

        // Decode with inSampleSize
        BitmapFactory.Options o2 = new BitmapFactory.Options();
        o2.inSampleSize = scale;
        fis = new FileInputStream(f);
        try{
        b = BitmapFactory.decodeStream(fis, null, o2);
        }
        catch (OutOfMemoryError e) {
            // TODO: handle exception
        }
        try {
            fis.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }

    return b;
}

// decodes image and scales it to reduce memory consumption
/*
 * rename by dinash from decodeFile to decodeFiles
 */
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;
        try{
        return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
        }
        catch (OutOfMemoryError e) {
            // TODO: handle exception
        }
    } 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;
    }
}

PhotosQueue photosQueue = new PhotosQueue();

public void stopThread() {
    photoLoaderThread.interrupt();
}

// stores list of photos to download
class PhotosQueue {
    private Stack<PhotoToLoad> photosToLoad = new Stack<PhotoToLoad>();

    // removes all instances of this ImageView
    public void Clean(ImageView image) {
        for (int j = 0; j < photosToLoad.size();) {
            if (photosToLoad.get(j).imageView == image)
                photosToLoad.remove(j);
            else
                ++j;
        }
    }
}

class PhotosLoader extends Thread {
    public void run() {
        try {
            while (true) {
                // thread waits until there are any images to load in the
                // queue
                if (photosQueue.photosToLoad.size() == 0)
                    synchronized (photosQueue.photosToLoad) {
                        photosQueue.photosToLoad.wait();
                    }
                if (photosQueue.photosToLoad.size() != 0) {
                    PhotoToLoad photoToLoad;
                    synchronized (photosQueue.photosToLoad) {
                        photoToLoad = photosQueue.photosToLoad.pop();
                    }
                    Bitmap bmp = getBitmap(photoToLoad.url);
                    memoryCache.put(photoToLoad.url, bmp);
                    String tag = imageViews.get(photoToLoad.imageView);
                    if (tag != null && tag.equals(photoToLoad.url)) {
                        BitmapDisplayer bd = new BitmapDisplayer(bmp,
                                photoToLoad.imageView);
                        Activity a = (Activity) photoToLoad.imageView
                                .getContext();
                        a.runOnUiThread(bd);
                    }
                }
                if (Thread.interrupted())
                    break;
            }
        } catch (InterruptedException e) {
            // allow thread to exit
        }
    }
}

PhotosLoader photoLoaderThread = new PhotosLoader();

// Used to display bitmap in the UI thread
class BitmapDisplayer implements Runnable {
    Bitmap bitmap;
    ImageView imageView;

    public BitmapDisplayer(Bitmap b, ImageView i) {
        bitmap = b;
        imageView = i;
    }

    public void run() {
        System.out.println("imageView ===> "+imageView);
        if (bitmap != null)
            imageView.setImageBitmap(bitmap);
        else
            imageView.setImageResource(stub_id);
    }
}

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

}

Answer 1

据我了解，您正在使用我的实现https://github.com/thest1/LazyList 。 如果您获得最新的代码，则可以看到我已对其进行了修改以使用线程池。 因此，现在它可以同时下载多个图像。 尝试演示，它现在真的很快。

您还说过模糊的图像。 当您有缩略图可用时，通常会发生这种情况，并且在下载全尺寸图像时可以将其模糊显示。 如果没有缩略图，则不会模糊。