Android Open Source - lastfm-android-music-discovery Image Loader

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Back to project page lastfm-android-music-discovery.

License

The source code is released under:

Apache License

Java Source Code

package com.mikeladze.musicdiscovery.view.gridview.loader;
//from  w w w. j av a  2  s.c  o m
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.WeakHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.widget.ImageView;

/**
 * Using LazyList via
 * https://github.com/thest1/LazyList/tree/master/src/com/fedorvlasov/lazylist
 */
public class ImageLoader {
  
  MemoryCache memoryCache = new MemoryCache();
  FileCache fileCache;
  private Map<ImageView, String> imageViews = Collections.synchronizedMap(new WeakHashMap<ImageView, String>());
  ExecutorService executorService;
  Handler handler = new Handler();//handler to display images in UI thread
  
  public ImageLoader(Context context) {
    fileCache = new FileCache(context);
    executorService = Executors.newFixedThreadPool(5);
  }
  
  //    final int stub_id= android.R.drawable.alert_dark_frame;
  
  public void displayImage(String url, ImageView imageView) {
    imageViews.put(imageView, url);
    Bitmap bitmap = memoryCache.get(url);
    if (bitmap != null) {
      imageView.setImageBitmap(bitmap);
    } else {
      queuePhoto(url, imageView);
      imageView.setImageDrawable(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 (Throwable ex) {
      ex.printStackTrace();
      if (ex instanceof OutOfMemoryError) {
        memoryCache.clear();
      }
      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;
      FileInputStream stream1 = new FileInputStream(f);
      BitmapFactory.decodeStream(stream1, null, o);
      stream1.close();
      
      //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;
      }
      
      if (scale >= 2) {
        scale /= 2;
      }
      
      //decode with inSampleSize
      BitmapFactory.Options o2 = new BitmapFactory.Options();
      o2.inSampleSize = scale;
      FileInputStream stream2 = new FileInputStream(f);
      Bitmap bitmap = BitmapFactory.decodeStream(stream2, null, o2);
      stream2.close();
      return bitmap;
    } catch (FileNotFoundException e) {
    } catch (IOException e) {
      e.printStackTrace();
    }
    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;
    }
    
    @Override
    public void run() {
      try {
        if (imageViewReused(photoToLoad)) {
          return;
        }
        Bitmap bmp = getBitmap(photoToLoad.url);
        memoryCache.put(photoToLoad.url, bmp);
        if (imageViewReused(photoToLoad)) {
          return;
        }
        BitmapDisplayer bd = new BitmapDisplayer(bmp, photoToLoad);
        handler.post(bd);
      } catch (Throwable th) {
        th.printStackTrace();
      }
    }
  }
  
  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;
    }
    
    @Override
    public void run() {
      if (imageViewReused(photoToLoad)) {
        return;
      }
      if (bitmap != null) {
        photoToLoad.imageView.setImageBitmap(bitmap);
      } else {
        photoToLoad.imageView.setImageDrawable(null);
      }
    }
  }
  
  public void clearCache() {
    memoryCache.clear();
    fileCache.clear();
  }
  
}

Java Source Code List

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