DiskLruImageCache.java

package de.hdodenhof.holoreader.misc;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.CompressFormat;
import android.graphics.BitmapFactory;
import android.os.Build;
import android.os.Environment;

import com.jakewharton.DiskLruCache;

/*
 * Based on http://stackoverflow.com/a/10235381
 */
public class DiskLruImageCache {

    private static final int APP_VERSION = 1;
    private static final int VALUE_COUNT = 1;

    private DiskLruCache mDiskCache;
    private CompressFormat mCompressFormat = CompressFormat.JPEG;
    private int mCompressQuality = 70;

    public DiskLruImageCache(Context context, String uniqueName, int diskCacheSize) {
        try {
            final File diskCacheDir = getDiskCacheDir(context, uniqueName);
            mDiskCache = DiskLruCache.open(diskCacheDir, APP_VERSION, VALUE_COUNT, diskCacheSize);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private boolean writeBitmapToFile(Bitmap bitmap, DiskLruCache.Editor editor) throws IOException, FileNotFoundException {
        OutputStream out = null;
        try {
            out = new BufferedOutputStream(editor.newOutputStream(0));
            return bitmap.compress(mCompressFormat, mCompressQuality, out);
        } finally {
            if (out != null) {
                out.close();
            }
        }
    }

    private File getDiskCacheDir(Context context, String uniqueName) {
        File cacheDir;

        if (Environment.getExternalStorageState() == Environment.MEDIA_MOUNTED || !isExternalStorageRemovable()) {
            if (context.getExternalCacheDir() != null) {
                cacheDir = context.getExternalCacheDir();
            } else {
                cacheDir = context.getCacheDir();
            }
        } else {
            cacheDir = context.getCacheDir();
        }

        return new File(cacheDir.getPath() + File.separator + uniqueName);
    }

    public void put(String key, Bitmap data) {

        DiskLruCache.Editor editor = null;
        try {
            editor = mDiskCache.edit(key);
            if (editor == null) {
                return;
            }

            if (writeBitmapToFile(data, editor)) {
                mDiskCache.flush();
                editor.commit();
            } else {
                editor.abort();
            }
        } catch (IOException e) {
            try {
                if (editor != null) {
                    editor.abort();
                }
            } catch (IOException ignored) {
            }
        }

    }

    public Bitmap getBitmap(String key) {

        Bitmap bitmap = null;
        DiskLruCache.Snapshot snapshot = null;
        try {

            snapshot = mDiskCache.get(key);
            if (snapshot == null) {
                return null;
            }
            final InputStream in = snapshot.getInputStream(0);
            if (in != null) {
                final BufferedInputStream buffIn = new BufferedInputStream(in);
                bitmap = BitmapFactory.decodeStream(buffIn);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (snapshot != null) {
                snapshot.close();
            }
        }
        return bitmap;

    }

    public boolean containsKey(String key) {

        boolean contained = false;
        DiskLruCache.Snapshot snapshot = null;
        try {
            snapshot = mDiskCache.get(key);
            contained = snapshot != null;
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (snapshot != null) {
                snapshot.close();
            }
        }

        return contained;

    }

    public void clearCache() {
        try {
            mDiskCache.delete();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public File getCacheFolder() {
        return mDiskCache.getDirectory();
    }

    @SuppressLint("NewApi")
    private static boolean isExternalStorageRemovable() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.GINGERBREAD) {
            return Environment.isExternalStorageRemovable();
        } else {
            return true;
        }
    }

}