Android Open Source - WebImageView Lmt Space File Cache

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License

The source code is released under:

MIT License

Java Source Code

package com.rsv.cache;
/*  w w  w .  j  av  a2s.co m*/
import java.io.File;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import com.rsv.utils.LogUtils;
import com.rsv.utils.StorageUtils;

/**
 * A space size limited file cache implementation
 * 
 */
public class LmtSpaceFileCache extends BaseFileCache {

  private int cachedSpace = 0;

  private int spaceLimit;

  private final Map<String, Long> lastUsageDates = Collections
      .synchronizedMap(new HashMap<String, Long>());

  public LmtSpaceFileCache(File cacheDir, int spaceLimit) {
    super(cacheDir);

    setSpaceLimit((int) Math.min(spaceLimit,
        StorageUtils.getFreeSpace(cacheDir.getAbsolutePath())));

    LogUtils.d(this, "size limit: " + this.spaceLimit);

    scanCacheDirAndFillStat();
  }

  public void setSpaceLimit(int spaceLimit) {
    this.spaceLimit = spaceLimit;
  }

  public int getCachedSize() {
    return this.cachedSpace;
  }

  private void scanCacheDirAndFillStat() {
    int size = 0;
    File[] cachedFiles = getCacheDir().listFiles();

    for (File cachedFile : cachedFiles) {
      size += getSize(cachedFile);

      lastUsageDates.put(cachedFile.getAbsolutePath(), cachedFile.lastModified());
    }
    cachedSpace = size;

    LogUtils.i(this, "cached size " + cachedSpace);

    if (cachedSpace > spaceLimit) {
      freeCache(0);
    }
  }

  @Override
  public File put(String key, File file) {
    file = super.put(key, file);

    int valueSize = getSize(file);

    if (cachedSpace + valueSize > spaceLimit) {
      freeCache(valueSize);
    }

    cachedSpace += valueSize;

    Long currentTime = System.currentTimeMillis();
    // file.setLastModified(currentTime);
    lastUsageDates.put(file.getAbsolutePath(), currentTime);

    return file;
  }

  private synchronized void freeCache(int reqiredExtraSize) {
    int tSize = (int) Math.max(Math.ceil(spaceLimit * 0.8), spaceLimit - 1024 * 1024);

    while (cachedSpace + reqiredExtraSize > tSize) {
      int freedSize = removeNext();

      if (freedSize == 0)
        break; // cache is empty (have nothing to delete)

      cachedSpace -= freedSize;
    }

    LogUtils.i(this, "free to " + cachedSpace);
  }

  @Override
  public File get(String key) {
    File file = super.get(key);

    if (file != null) {
      Long currentTime = System.currentTimeMillis();
      // file.setLastModified(currentTime);
      lastUsageDates.put(file.getAbsolutePath(), currentTime);
    }

    return file;
  }

  @Override
  public void remove(String key) {

    File file = this.get(key);

    if (file != null) {
      cachedSpace -= this.getSize(file);
      lastUsageDates.remove(file);
    }

    super.remove(key);
  }

  @Override
  public void clear() {

    lastUsageDates.clear();
    cachedSpace = 0;

    super.clear();
  }

  private int removeNext() {
    if (lastUsageDates.isEmpty()) {
      return 0;
    }

    Long oldestUsage = null;

    String mostLongUsedFilePath = null;

    Set<Entry<String, Long>> entries = lastUsageDates.entrySet();

    for (Entry<String, Long> entry : entries) {

      if (mostLongUsedFilePath == null) {

        mostLongUsedFilePath = entry.getKey();
        oldestUsage = entry.getValue();

      } else {

        Long lastValueUsage = entry.getValue();

        if (lastValueUsage < oldestUsage) {
          oldestUsage = lastValueUsage;
          mostLongUsedFilePath = entry.getKey();
        }
      }
    }

    if (mostLongUsedFilePath != null) {

      lastUsageDates.remove(mostLongUsedFilePath);

      File mostLongUsedFile = new File(mostLongUsedFilePath);

      if (!mostLongUsedFile.exists()) {
        return 1;
      }

      int fileSize = getSize(mostLongUsedFile);

      if (mostLongUsedFile.delete()) {
        LogUtils.i(this, "remove " + mostLongUsedFile.getName());
      }

      return fileSize;
    }

    return 1;
  }

  protected int getSize(File file) {
    return (int) file.length();
  }

}

Java Source Code List

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