MyVolley.java

package com.shizhefei.utils;

import android.app.ActivityManager;
import android.content.Context;
import android.graphics.Bitmap;
import android.support.v4.util.LruCache;

import com.android.volley.RequestQueue;
import com.android.volley.toolbox.ImageLoader;
import com.android.volley.toolbox.ImageLoader.ImageCache;
import com.android.volley.toolbox.Volley;

/**
 * Helper class that is used to provide references to initialized
 * RequestQueue(s) and ImageLoader(s)
 * 
 * @author Ognyan Bankov
 * 
 */
public class MyVolley {
	private volatile static RequestQueue mRequestQueue;
	private volatile static ImageLoader mImageLoader;

	private MyVolley() {
		// no instances
	}

	public static void init(Context context) {
		mRequestQueue = Volley.newRequestQueue(context);

		int memClass = ((ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE)).getMemoryClass();
		// Use 1/8th of the available memory for this memory cache.
		int cacheSize = 1024 * 1024 * memClass / 8;
		mImageLoader = new ImageLoader(mRequestQueue, new BitmapLruCache(cacheSize));
	}

	public static RequestQueue getRequestQueue() {
		if (mRequestQueue != null) {
			return mRequestQueue;
		} else {
			throw new IllegalStateException("RequestQueue not initialized");
		}
	}

	/**
	 * Returns instance of ImageLoader initialized with {@see FakeImageCache}
	 * which effectively means that no memory caching is used. This is useful
	 * for images that you know that will be show only once.
	 * 
	 * @return
	 */
	public static ImageLoader getImageLoader() {
		if (mImageLoader != null) {
			return mImageLoader;
		} else {
			throw new IllegalStateException("ImageLoader not initialized");
		}
	}

	public static class BitmapLruCache extends LruCache<String, Bitmap> implements ImageCache {
		public BitmapLruCache(int maxSize) {
			super(maxSize);
		}

		@Override
		protected int sizeOf(String key, Bitmap value) {
			return value.getRowBytes() * value.getHeight();
		}

		@Override
		public Bitmap getBitmap(String url) {
			return get(url);
		}

		@Override
		public void putBitmap(String url, Bitmap bitmap) {
			put(url, bitmap);
		}
	}
}