WebImageCache.java

/*
	Copyright (c) 2011 Rapture In Venice

	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this software and associated documentation files (the "Software"), to deal
	in the Software without restriction, including without limitation the rights
	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	copies of the Software, and to permit persons to whom the Software is
	furnished to do so, subject to the following conditions:

	The above copyright notice and this permission notice shall be included in
	all copies or substantial portions of the Software.

	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	THE SOFTWARE.
*/

package com.insthub.BeeFramework.view;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.ref.SoftReference;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

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

public class WebImageCache {
	private final static String TAG = WebImageCache.class.getSimpleName();

	// cache rules
	private static boolean mIsMemoryCachingEnabled = true;
	private static boolean mIsDiskCachingEnabled = true;
	private static int mDefaultDiskCacheTimeoutInSeconds = 60 * 60 * 24; // one day default 
		
	private Map<String, SoftReference<Bitmap>> mMemCache;
	
	public WebImageCache() {
		mMemCache = new HashMap<String, SoftReference<Bitmap>>();
	}

	public static void setMemoryCachingEnabled(boolean enabled) {
		mIsMemoryCachingEnabled = enabled;
		Log.v(TAG, "Memory cache " + (enabled ? "enabled" : "disabled") + ".");
	}

	public static void setDiskCachingEnabled(boolean enabled) {
		mIsDiskCachingEnabled = enabled;
		Log.v(TAG, "Disk cache " + (enabled ? "enabled" : "disabled") + ".");
	}

	public static void setDiskCachingDefaultCacheTimeout(int seconds) {
		mDefaultDiskCacheTimeoutInSeconds = seconds;
		Log.v(TAG, "Disk cache timeout set to " + seconds + " seconds.");
	}
	
	public Bitmap getBitmapFromMemCache(String urlString) {
		if (mIsMemoryCachingEnabled) {
			synchronized (mMemCache) {
				SoftReference<Bitmap> bitmapRef = mMemCache.get(urlString);
				
				if (bitmapRef != null) {
					Bitmap bitmap = bitmapRef.get();
					
					if (bitmap == null) {
						mMemCache.remove(urlString);
				        Log.v(TAG, "Expiring memory cache for URL " + urlString + ".");
					} else {
				        Log.v(TAG, "Retrieved " + urlString + " from memory cache.");
						return bitmap; 
					}
				}				
			}
		}
		
		return null;
	}

	public Bitmap getBitmapFromDiskCache(Context context, String urlString, int diskCacheTimeoutInSeconds) {
		if (mIsDiskCachingEnabled) {
			Bitmap bitmap = null;
			File path = context.getCacheDir();
	        InputStream is = null;
	        String hashedURLString = hashURLString(urlString);
	        
	        // correct timeout
	        if (diskCacheTimeoutInSeconds < 0) {
	        	diskCacheTimeoutInSeconds = mDefaultDiskCacheTimeoutInSeconds;
	        }
	        
	        File file = new File(path, hashedURLString);
	
	        if (file.exists() && file.canRead()) {
	        	// check for timeout
	        	if ((file.lastModified() + (diskCacheTimeoutInSeconds * 1000L)) < new Date().getTime()) {
	        		Log.v(TAG, "Expiring disk cache (TO: " + diskCacheTimeoutInSeconds + "s) for URL " + urlString);
	        		
	        		// expire
	        		file.delete();
	        	} else {
			        try {
			        	is = new FileInputStream(file);
				
			        	bitmap = BitmapFactory.decodeStream(is);
				        Log.v(TAG, "Retrieved " + urlString + " from disk cache (TO: " + diskCacheTimeoutInSeconds + "s).");
			        } catch (Exception ex) {
			        	Log.e(TAG, "Could not retrieve " + urlString + " from disk cache: " + ex.toString());
			        } finally {
			        	try {
			        		is.close();
			        	} catch (Exception ex) {}
			        }
	        	}
	        }			
			
			return bitmap;
		}
		
		return null;
	}


	public void addBitmapToMemCache(String urlString, Bitmap bitmap) {
		if (mIsMemoryCachingEnabled) {
			synchronized (mMemCache) {
				mMemCache.put(urlString, new SoftReference<Bitmap>(bitmap));
			}
		}
	}
	
	public void addBitmapToCache(Context context, String urlString, Bitmap bitmap) {
		// mem cache
		addBitmapToMemCache(urlString, bitmap);

		// disk cache
		// TODO: manual cache cleanup
		if (mIsDiskCachingEnabled) {
			File path =  context.getCacheDir();
	        OutputStream os = null;
	        String hashedURLString = hashURLString(urlString);
	        
	        try {
		        // NOWORKY File tmpFile = File.createTempFile("wic.", null);
		        File file = new File(path, hashedURLString);
		        os = new FileOutputStream(file.getAbsolutePath());
		
		        bitmap.compress(Bitmap.CompressFormat.PNG, 100, os);
		        os.flush();
		        os.close();
		        
		        // NOWORKY tmpFile.renameTo(file);
	        } catch (Exception ex) {
	        	Log.e(TAG, "Could not store " + urlString + " to disk cache: " + ex.toString());
	        } finally {
	        	try {
	        		os.close();
	        	} catch (Exception ex) {}
	        }
		}
	}
	
	private String hashURLString(String urlString) {
	    try {
	        // Create MD5 Hash
	        MessageDigest digest = java.security.MessageDigest.getInstance("MD5");
	        digest.update(urlString.getBytes());
	        byte messageDigest[] = digest.digest();
	        
	        // Create Hex String
	        StringBuffer hexString = new StringBuffer();
	        for (int i=0; i<messageDigest.length; i++)
	            hexString.append(Integer.toHexString(0xFF & messageDigest[i]));
	        return hexString.toString();
	        
	    } catch (NoSuchAlgorithmException e) {
	        e.printStackTrace();
	    }
	    
	    //fall back to old method
	    return urlString.replaceAll("[^A-Za-z0-9]", "#");
	}
}