Android Open Source - Android-Universal-Image-Loader Memory Cache Utils

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Apache License
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Java Source Code

/*******************************************************************************
 * Copyright 2011-2014 Sergey Tarasevich
 */*from w w w  .j  av  a 2  s  .  c  o  m*/
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *******************************************************************************/
package com.nostra13.universalimageloader.utils;

import android.graphics.Bitmap;

import com.nostra13.universalimageloader.cache.memory.MemoryCache;
import com.nostra13.universalimageloader.core.ImageLoaderConfiguration;
import com.nostra13.universalimageloader.core.assist.ImageSize;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;

/**
 * Utility for generating of keys for memory cache, key comparing and other work with memory cache
 *
 * @author Sergey Tarasevich (nostra13[at]gmail[dot]com)
 * @since 1.6.3
 */
public final class MemoryCacheUtils {

  private static final String URI_AND_SIZE_SEPARATOR = "_";
  private static final String WIDTH_AND_HEIGHT_SEPARATOR = "x";

  private MemoryCacheUtils() {
  }

  /**
   * Generates key for memory cache for incoming image (URI + size).<br />
   * Pattern for cache key - <b>[imageUri]_[width]x[height]</b>.
   */
  public static String generateKey(String imageUri, ImageSize targetSize) {
    return new StringBuilder(imageUri).append(URI_AND_SIZE_SEPARATOR).append(targetSize.getWidth()).append(WIDTH_AND_HEIGHT_SEPARATOR).append(targetSize.getHeight()).toString();
  }

  public static Comparator<String> createFuzzyKeyComparator() {
    return new Comparator<String>() {
      @Override
      public int compare(String key1, String key2) {
        String imageUri1 = key1.substring(0, key1.lastIndexOf(URI_AND_SIZE_SEPARATOR));
        String imageUri2 = key2.substring(0, key2.lastIndexOf(URI_AND_SIZE_SEPARATOR));
        return imageUri1.compareTo(imageUri2);
      }
    };
  }

  /**
   * Searches all bitmaps in memory cache which are corresponded to incoming URI.<br />
   * <b>Note:</b> Memory cache can contain multiple sizes of the same image if only you didn't set
   * {@link ImageLoaderConfiguration.Builder#denyCacheImageMultipleSizesInMemory()
   * denyCacheImageMultipleSizesInMemory()} option in {@linkplain ImageLoaderConfiguration configuration}
   */
  public static List<Bitmap> findCachedBitmapsForImageUri(String imageUri, MemoryCache memoryCache) {
    List<Bitmap> values = new ArrayList<Bitmap>();
    for (String key : memoryCache.keys()) {
      if (key.startsWith(imageUri)) {
        values.add(memoryCache.get(key));
      }
    }
    return values;
  }

  /**
   * Searches all keys in memory cache which are corresponded to incoming URI.<br />
   * <b>Note:</b> Memory cache can contain multiple sizes of the same image if only you didn't set
   * {@link ImageLoaderConfiguration.Builder#denyCacheImageMultipleSizesInMemory()
   * denyCacheImageMultipleSizesInMemory()} option in {@linkplain ImageLoaderConfiguration configuration}
   */
  public static List<String> findCacheKeysForImageUri(String imageUri, MemoryCache memoryCache) {
    List<String> values = new ArrayList<String>();
    for (String key : memoryCache.keys()) {
      if (key.startsWith(imageUri)) {
        values.add(key);
      }
    }
    return values;
  }

  /**
   * Removes from memory cache all images for incoming URI.<br />
   * <b>Note:</b> Memory cache can contain multiple sizes of the same image if only you didn't set
   * {@link ImageLoaderConfiguration.Builder#denyCacheImageMultipleSizesInMemory()
   * denyCacheImageMultipleSizesInMemory()} option in {@linkplain ImageLoaderConfiguration configuration}
   */
  public static void removeFromCache(String imageUri, MemoryCache memoryCache) {
    List<String> keysToRemove = new ArrayList<String>();
    for (String key : memoryCache.keys()) {
      if (key.startsWith(imageUri)) {
        keysToRemove.add(key);
      }
    }
    for (String keyToRemove : keysToRemove) {
      memoryCache.remove(keyToRemove);
    }
  }
}
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