Android Open Source - Findbooks Bitmap Cache

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License

The source code is released under:

Copyright (c) 2010, Shaka Huang All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: Re...

Java Source Code

package com.corner23.android.findbooks;
/* w w  w . j  av  a2s  .  c  o  m*/
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.ref.SoftReference;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.net.URL;
import java.net.Proxy;
import java.net.URLConnection;
import java.net.UnknownHostException;
import java.util.concurrent.ConcurrentHashMap;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;

public class BitmapCache {
  
  private static BitmapCache instance = null;

  private ConcurrentHashMap<URL, SoftReference<Bitmap>> cache = new ConcurrentHashMap<URL, SoftReference<Bitmap>>();
    private static final int DEFAULT_READ_TIMEOUT = 10000;
    private static final int DEFAULT_CONN_TIMEOUT = 10000;
    private static final int IO_BUFFER_SIZE = 4 * 1024;
    private static final int MAX_PICTURE_SIZE = 70000;  // 70K
    
    private Proxy httpProxy = null;
    private String httpProxyHost = null;
    private Integer httpProxyPort;
    
  public BitmapCache(boolean bHasProxy) {
    if (bHasProxy) {
      this.configureHttpProxy();
    }
  }

  public static BitmapCache getInstance(boolean bHasProxy) {
    if (instance == null) {
      instance = new BitmapCache(bHasProxy);
    }
    return instance;
  }

  public boolean containsURL(URL url) {
    if (url == null)
      return false;

    return cache.containsKey(url);
  }
  
  private Bitmap get(URL url) {
    if (url == null)
      return null;

    Bitmap bitmap = null;
    SoftReference<Bitmap> reference = cache.get(url);
    if (reference != null) {
      bitmap = reference.get();
    }
    
    return bitmap;
  }
    
  public Bitmap load(URL url) {
    if (url == null)
      return null;

    if (containsURL(url)) { 
      Bitmap bitmap = get(url); 
      if (bitmap != null) {
        return bitmap;
      }
    }
    
    return fetch(url);
  }
  
    private void configureHttpProxy() {
        this.httpProxyHost = android.net.Proxy.getDefaultHost();
        this.httpProxyPort = android.net.Proxy.getDefaultPort();
        if (this.httpProxyHost != null && this.httpProxyPort != null) {
          SocketAddress proxyAddress = new InetSocketAddress( this.httpProxyHost, this.httpProxyPort);
          this.httpProxy = new Proxy(Proxy.Type.HTTP, proxyAddress);
        } else {
          this.httpProxy = Proxy.NO_PROXY;
        }
    }
    
    /**
     * Copy the content of the input stream into the output stream, using a temporary
     * byte array buffer whose size is defined by {@link #IO_BUFFER_SIZE}.
     *
     * @param in The input stream to copy from.
     * @param out The output stream to copy to.
     *
     * @throws IOException If any error occurs during the copy.
     */
    private static int copy(InputStream in, OutputStream out) throws IOException {
        byte[] b = new byte[IO_BUFFER_SIZE];
        int read, size = 0;
        
      while ((read = in.read(b)) != -1) {
          out.write(b, 0, read);
          size += read;
      }
        return size;
    }

    /**
     * Closes the specified stream.
     *
     * @param stream The stream to close.
     */
    private static void closeStream(Closeable stream) {
        if (stream != null) {
            try {
                stream.close();
            } catch (IOException e) {
              e.printStackTrace();
            }
        }
    }

    private synchronized Bitmap fetch(URL url) {
    if (url == null)
      return null;
    
    // Double confirm if last thread has fetched the bitmap.
    if (containsURL(url)) { 
      Bitmap bitmap = get(url); 
      if (bitmap != null) {
        return bitmap;
      }
    }

    Bitmap bitmap = null;
        InputStream in = null;
        OutputStream out = null;
        URLConnection urlc = null;
        
    try {
      // If proxy has been set, check if it changed
      if (this.httpProxyHost != null) {
        String proxy = android.net.Proxy.getDefaultHost();
        if (proxy != null && !proxy.equals(this.httpProxyHost) || 
          android.net.Proxy.getDefaultPort() != this.httpProxyPort) {
          this.configureHttpProxy();
        }
      }
      
      if (this.httpProxy != null) {
        urlc = url.openConnection(this.httpProxy);
      } else {
        urlc = url.openConnection();
      }
      urlc.setRequestProperty("User-Agent", "Mozilla/5.0");
      urlc.setReadTimeout(DEFAULT_READ_TIMEOUT);
      urlc.setConnectTimeout(DEFAULT_CONN_TIMEOUT);
      String url_orig = urlc.getURL().toString();
      in = new BufferedInputStream(urlc.getInputStream(), IO_BUFFER_SIZE);
      String url_after = urlc.getURL().toString();
      if (!url_after.equals(url_orig)) {
        Log.d("BitmapCache", "redirected..");
        return null;
      }

            ByteArrayOutputStream dataStream = new ByteArrayOutputStream();
            out = new BufferedOutputStream(dataStream, IO_BUFFER_SIZE);
            int size = copy(in, out);
            out.flush();

        BitmapFactory.Options options = new BitmapFactory.Options();
        if (size > MAX_PICTURE_SIZE) {
        // set sample size to 5 avoiding memory exception
        options.inSampleSize = 5;
        }

        byte[] data = dataStream.toByteArray();
        bitmap = BitmapFactory.decodeByteArray(data, 0, data.length, options);
        
      cache.put(url, new SoftReference<Bitmap>(bitmap));
    } catch (UnknownHostException e) {
      // e.printStackTrace();
      closeStream(in);
      closeStream(out);
      return null;
    } catch (IOException e) {
      // e.printStackTrace();
      closeStream(in);
      closeStream(out);
      return null;
    } catch (Exception e) {
      // e.printStackTrace();
      closeStream(in);
      closeStream(out);
      return null;
    } finally {
      closeStream(in);
      closeStream(out);
    }
    
    return bitmap;      
  }
}

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