MemoryCache.java

package com.rubika.aotalk.util;

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 static final String APP_TAG = "--> The Leet :: MemoryCache";
    
    private Map<String, Bitmap> cache = Collections.synchronizedMap(new LinkedHashMap<String, Bitmap>(10,1.5f,true)); //Last argument true for LRU ordering
    private long size = 0; //current allocated size
    private long limit = 1000000; //max memory in bytes

    public MemoryCache(){
        //use 25% of available heap size
        setLimit(Runtime.getRuntime().maxMemory() / 4);
    }
    
    public void setLimit(long new_limit){
        limit = new_limit;
        Logging.log(APP_TAG, "MemoryCache will use up to " + limit/1024./1024. + "MB");
    }

    public Bitmap get(String id){
        try{
            if (!cache.containsKey(id)) {
                return null;
            }
            
            return cache.get(id);
        } catch(NullPointerException ex) {
            Logging.log(APP_TAG, ex.getMessage());
            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) {
            Logging.log(APP_TAG, th.getMessage());
        }
    }
    
    private void checkSize() {
        Logging.log(APP_TAG, "cache size=" + size + " length=" + cache.size());
        
        if (size>limit) {
            Iterator<Entry<String, Bitmap>> iter = cache.entrySet().iterator(); //least recently accessed item will be the first one iterated  
            
            while (iter.hasNext()) {
                Entry<String, Bitmap> entry = iter.next();
                size -= getSizeInBytes(entry.getValue());
                iter.remove();
                
                if (size <= limit) {
                    break;
                }
            }
            
            Logging.log(APP_TAG, "Clean cache. New size "+cache.size());
        }
    }

    public void clear() {
        try{
            cache.clear();
            size = 0;
        } catch (NullPointerException ex) {
            Logging.log(APP_TAG, ex.getMessage());
        }
    }

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