MemoryCache.java

/*
 * Copyright 2014 Jeremie Long
 *
 * 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.lithidsw.wallbox.loader;

import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;

import android.graphics.Bitmap;

public class MemoryCache {

    private Map<String, Bitmap> cache = Collections
            .synchronizedMap(new LinkedHashMap<String, Bitmap>(10, 1.5f, true));
    private long size = 0;
    private long limit = 100000;

    public MemoryCache() {
        setLimit(Runtime.getRuntime().maxMemory() / 4);
    }

    public void setLimit(long new_limit) {
        limit = new_limit;
    }

    public Bitmap get(String id) {
        try {
            if (!cache.containsKey(id)) {
                return null;
            }
            // NullPointerException sometimes happen here
            // http://code.google.com/p/osmdroid/issues/detail?id=78
            return cache.get(id);
        } catch (NullPointerException ex) {
            ex.printStackTrace();
            return null;
        }
    }

    public void put(String id, Bitmap bitmap) {
        try {
            if (cache.containsKey(id)) {
                size -= getSizeInBytes(cache.get(id));
            }
            cache.put(id, bitmap);
            size += getSizeInBytes(bitmap);
            checkSize();
        } catch (Throwable th) {
            th.printStackTrace();
        }
    }

    private void checkSize() {
        if (size > limit) {
            Iterator<Entry<String, Bitmap>> iter = cache.entrySet().iterator();
            while (iter.hasNext()) {
                Entry<String, Bitmap> entry = iter.next();
                size -= getSizeInBytes(entry.getValue());
                iter.remove();
                if (size <= limit)
                    break;
            }
        }
    }

    public void clear() {
        try {
            // NullPointerException sometimes happen here
            // http://code.google.com/p/osmdroid/issues/detail?id=78
            cache.clear();
            size = 0;
        } catch (NullPointerException ex) {
            ex.printStackTrace();
        }
    }

    long getSizeInBytes(Bitmap bitmap) {
        if (bitmap == null) {
            return 0;
        }
        return bitmap.getRowBytes() * bitmap.getHeight();
    }
}