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ÏÈ¿´Ò»¸öVolleyʹÓõÄÀý×Ó<†·Ÿ"http://www.bkjia.com/kf/ware/vc/" target="_blank" class="keylink">vcD4KPHA+PC9wPgo8cHJlIGNsYXNzPQ=="brush:java;">final TextView mTextView = (TextView) findViewById(R.id.text);...// Instantiate the RequestQueue.RequestQueue queue = Volley.newRequestQueue(this);String url ="http://www.google.com";// Request a string response from the provided URL.StringRequest stringRequest = new StringRequest(Request.Method.GET, url, new Response.Listener() { @Override public void onResponse(String response) { // Display the first 500 characters of the response string. mTextView.setText("Response is: "+ response.substring(0,500)); }}, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError error) { mTextView.setText("That didn't work!"); }});// Add the request to the RequestQueue.queue.add(stringRequest);
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1¡¢Volley.newRequestQueue();

2¡¢new Request();

3¡¢queue.add(request);

ÔÚnewRequestQueueµÄʱºò»á³õʼ»¯»ù±¾µÄ×é¼þ

    public static RequestQueue newRequestQueue(Context context, HttpStack stack) {        File cacheDir = new File(context.getCacheDir(), DEFAULT_CACHE_DIR);        String userAgent = "volley/0";        try {            String packageName = context.getPackageName();            PackageInfo info = context.getPackageManager().getPackageInfo(packageName, 0);            userAgent = packageName + "/" + info.versionCode;        } catch (NameNotFoundException e) {        }        if (stack == null) {            if (Build.VERSION.SDK_INT >= 9) {                stack = new HurlStack();            } else {                // Prior to Gingerbread, HttpUrlConnection was unreliable.                // See: http://android-developers.blogspot.com/2011/09/androids-http-clients.html                stack = new HttpClientStack(AndroidHttpClient.newInstance(userAgent));            }        }        Network network = new BasicNetwork(stack);        RequestQueue queue = new RequestQueue(new DiskBasedCache(cacheDir), network);        queue.start();        return queue;    }

1¡¢BasicNetwork

BasicNetworkÊǶÔNetwork½Ó¿ÚµÄʵÏÖ£¬Í¬Ê±»¹½«ÁªÍø²Ù×÷²¿·ÖÌáÈ¡³öÀ´ÐγÉHttpStack£¬ÔÒòÊÇAndroid 2.3ÖÇ°ÍøÂç²Ù×÷ÍƼöʹÓÃHttpClient£¬2.3ÖºóAndroid×öÁËÓÅ»¯ÍƼöʹÓÃHttpUrlConnection¡£

2¡¢DiskBasedCache

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get¡ª¡ªkeyµ½entryµÄÓ³Éä

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3¡¢ImageLoader

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        mImageLoader = new ImageLoader(mRequestQueue,                new ImageLoader.ImageCache() {            private final LruCache                    cache = new LruCache(20);            @Override            public Bitmap getBitmap(String url) {                return cache.get(url);            }            @Override            public void putBitmap(String url, Bitmap bitmap) {                cache.put(url, bitmap);            }

mImageLoader.get(IMAGE_URL, ImageLoader.getImageListener(mImageView,         R.drawable.def_image, R.drawable.err_image));

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Äڴ滺´æÍƼöʹÓÃLruCache£¬ÐèҪʵÏÖImageLoader.ImageCache½Ó¿Ú¡£Í¼Æ¬µÄ¼ÓÔØͨ¹ýimageLoader.get()·½·¨ÊµÏÖ£¬

    public ImageContainer get(String requestUrl, ImageListener imageListener,            int maxWidth, int maxHeight) {        // only fulfill requests that were initiated from the main thread.        throwIfNotOnMainThread();        final String cacheKey = getCacheKey(requestUrl, maxWidth, maxHeight);        // Try to look up the request in the cache of remote images.        Bitmap cachedBitmap = mCache.getBitmap(cacheKey);        if (cachedBitmap != null) {            // Return the cached bitmap.            ImageContainer container = new ImageContainer(cachedBitmap, requestUrl, null, null);            imageListener.onResponse(container, true);            return container;        }        // The bitmap did not exist in the cache, fetch it!        ImageContainer imageContainer =                new ImageContainer(null, requestUrl, cacheKey, imageListener);        // Update the caller to let them know that they should use the default bitmap.        imageListener.onResponse(imageContainer, true);        // Check to see if a request is already in-flight.        BatchedImageRequest request = mInFlightRequests.get(cacheKey);        if (request != null) {            // If it is, add this request to the list of listeners.            request.addContainer(imageContainer);            return imageContainer;        }        // The request is not already in flight. Send the new request to the network and        // track it.        Request newRequest =            new ImageRequest(requestUrl, new Listener() {                @Override                public void onResponse(Bitmap response) {                    onGetImageSuccess(cacheKey, response);                }            }, maxWidth, maxHeight,            Config.RGB_565, new ErrorListener() {                @Override                public void onErrorResponse(VolleyError error) {                    onGetImageError(cacheKey, error);                }            });        mRequestQueue.add(newRequest);        mInFlightRequests.put(cacheKey,                new BatchedImageRequest(newRequest, imageContainer));        return imageContainer;    }

Ê×Ïȵõ½Ò»¸öcacheKey£¬Õâ¸öÊÇͳһµÄ¹æÔò

    private static String getCacheKey(String url, int maxWidth, int maxHeight) {        return new StringBuilder(url.length() + 12).append("#W").append(maxWidth)                .append("#H").append(maxHeight).append(url).toString();    }

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