Android Volley specifically explains Google's published set of tools for network communications

: Git clone Https://android.googlesource.com/platform/frameworks/volley

Or: Https://github.com/mcxiaoke/android-volley

what can volley do?

A network communication library published at the Google I/O conference.

Handle some network requests, such as data parsing, downloading display pictures.

• Data processing : The processing of data obtained by a network request.

· Image loading: Download and display of Web images.

Use stepsUse Permissions

<uses-permissionandroid:name=" Android.permission.INTERNET "/>

< uses-permission android:name="Android.permission.WRITE_EXTERNAL_STORAGE"/>

initializing the request queue

Requestqueue Mrequestqueue = volley.newrequestqueue (context context);

Network request data processing

The default provides two types of data requests, one for Stringrequest and one for Jsonrequest

The jsonrequest is also divided into:

· jsonarrayrequest

Jsonarrayrequest request = new jsonarrayrequest ("url", new response.listener<jsonarray> () {@Overridepublic void Onresponse (Jsonarray response) {//Request response returned Jsonarray}}, New Response.errorlistener () {@Overridepublic void Onerrorresponse (Volleyerror error) {}}); Mrequestqueue.add (request);

· jsonobjectrequest

Jsonobjectrequest request = new Jsonobjectrequest (method.get, weather_json_address, NULL, new response.listener< Jsonobject> () {@Overridepublic void Onresponse (jsonobject response) {//The JSONObjectSystem.out.println returned by the request response ( Response);}},new Response.errorlistener () {@Overridepublic void Onerrorresponse (volleyerror error) { System.out.println ("Test4jsonobjectrequest-error");}); Mrequestqueue.add (Request);

Mrequestqueue.add (Request); Increase the queue for the request. Able to have very many add queued operations. Then start
Mrequestqueue.start (); Start request
Mrequestqueue.stop (); Stop Request

Picture Loading Request· Imagerequest Loading Pictures

Used in the same way as above jsonrequest

private void Requestbyimagerequest (final ImageView ImageView, String url) {imagerequest imgrequest = new Imagerequest (URL , new response.listener<bitmap> () {@Overridepublic void Onresponse (Bitmap Bitmap) {// After successful download imageview.setimagebitmap (bitmap),}, Imageview.getwidth (), Imageview.getheight (), config.rgb_565, new Errorlistener () {@Overridepublic void Onerrorresponse (volleyerror error) {//Download Error}}); Mrequestqueue.add (imgrequest); Mrequestqueue.start ();}

· Imageloader Loading Pictures

private void Requestbyimageloader (ImageView ImageView, String url) {int maxmemory = (int) runtime.getruntime (). maxmemory  ();//app maximum memory bytes int mcachesize = MAXMEMORY/8; Use 1/8 as the cache final lrucache<string, bitmap> mlruimagecache = new lrucache<string, bitmap> (mcachesize) {@ overrideprotected int sizeOf (String key, Bitmap value) {//Calculate memory for a picture Sizeif (Android.os.Build.VERSION.SDK_INT >= 12) { return Value.getbytecount (); Requires API >=12, total bytes} else {return value.getrowbytes () * value.getheight ();//per line byte multiplied by high (row) Api1}}};imagecache Imagecach E = new Imagecache () {@Overridepublic void Putbitmap (String key, Bitmap value) {mlruimagecache.put (key, value);} @Overridepublic Bitmap Getbitmap (String key) {return mlruimagecache.get (key);}};i Mageloader Mimageloader = new Imageloader (Mrequestqueue, Imagecache);// The second parameter of Imageloader.getimagelistener is the default picture resource ID, the requested picture is empty when set///The third parameter is the resource ID when the request fails, can be specified as 0ImageListener listener = Imageloader.getimagelistener (ImageView, Android. R.drawable.ic_menu_rOtate,android. R.drawable.ic_delete); Mimageloader.get (URL, listener); The Get method has started to run loaded url-bitmap//imagecontainer Imagecontainer = mimageloader.get (URL, listener); The Get method has started to run loaded url-bitmap//bitmap bitmap = Imagecontainer.getbitmap ();//string Requesturl = Imagecontainer.getrequesturl ();}

Imageloader need to be constructed in conjunction with Imagecache.

Imagecache is a interface

Imagecache's method of Put/get bitmap. It is recommended to use LRUCache to implement.

Imagelistener is a interface, available in two ways: Onresponse (), Onresponseerror ()

Imageloader Picture loading process:imageloader.get (URL, listener), inferred if it exists in the cache. Suppose there is. is removed directly and displayed in the listener. If not, then a new imagerequest is added to the requestqueue. The corresponding method in listener is called in the Response.listener in Imagerequest.

· networkimageview loading Pictures

private void Requestbynetworkimg (Networkimageview imageView, String URL) {Final lrucache<string, bitmap> Mimagecache = new lrucache<string, bitmap> (8*1024*1024) {@Overrideprotected int sizeOf (String key, Bitmap value) {/ /Calculate the memory of a picture Sizereturn value.getrowbytes () * Value.getheight (); Bytes per row multiplied by high (OK)   api1}};imagecache imagecache = new Imagecache () {@Overridepublic void Putbitmap (String key, Bitmap Value) {Mimagecache.put (key, value);} @Overridepublic Bitmap Getbitmap (String key) {return mimagecache.get (key);}};i Mageloader Mimageloader = new Imageloader (Mrequestqueue, Imagecache);/* * SetUrl. The implementation of the inside is: With the Imageloader, you can run the operation loaded into the Url-bitmap */imageview.setdefaultimageresid (0); Default Figure Imageview.seterrorimageresid (0); Error figure Imageview.setimageurl (URL, mimageloader); }

This is a self-defining component that inherits from ImageView.

Imageview.setdefaultimageresid (0); Default diagram
Imageview.seterrorimageresid (0); Error map
Imageview.setimageurl (URL, mimageloader);

Combining Imageloader, the internal call Imageloader.get () to implement the image loading.

The item in the ListView uses Networkimageview:

Just need a new Imageloader object. Different Item,set different URLs are available.

The download is run in Imageloader with new Imagerequest added to Requestqueue.

define the request yourself

/** * Volley adapter for JSON requests that'll be parsed into Java objects by Gson.    */public class Gsonobjectrequest<t> extends request<t> {protected final Gson Gson = new Gson ();    Protected final class<t> Clazz;    Protected final map<string, string> headers;    Protected final listener<t> Listener;     /** * Make a GET request and return a parsed an object from JSON.  * * @param URL of the URL of the request to make * @param clazz relevant class object, for Gson ' s reflection * @param Headers Map of Request headers */public gsonobjectrequest (int method, String URL, class<t> clazz, map<st Ring, string> headers, listener<t> Listener, Errorlistener Errorlistener) {Super (method, URL,        Errorlistener);        This.clazz = Clazz;        This.headers = headers;    This.listener = listener; } public gsonobjectrequest (String URL, class<t> clazz, map<string, string> headers, ListEner<t> Listener, Errorlistener Errorlistener) {This (Method.get, URL, clazz, headers, listener, errorlistener);  } @Override public map<string, String> getheaders () throws Authfailureerror {return headers! = NULL ?
Headers:super.getHeaders ();    } @Override protected void Deliverresponse (T response) {listener.onresponse (response); }//Convert the requested JSON into the corresponding object with Gson @Override protected response<t> parsenetworkresponse (Networkresponse R Esponse) {try {string json = new String (Response.data, Httpheaderparser.parsechars            ET (response.headers));        Return response.success (Gson.fromjson (JSON, Clazz), Httpheaderparser.parsecacheheaders (Response));        } catch (Unsupportedencodingexception e) {return response.error (new ParseError (e));        } catch (Jsonsyntaxexception e) {return response.error (new ParseError (e)); }    }}

Define the request yourself. At least rewrite parsenetworkresponse () ,deliverresponse ()

Other Instructions

The disk cache folder is defined in the volley class.

Request. Cancel (), the ability to cancel a demand.

Request. Settag (String tag). Set a tag

Requestqueue. Cancelall (String tag), cancels the request for the same tag identity

Requestqueue. Cancelall (New Requestfilter () {}); Use Requestfilter to filter the request that needs to be canceled

Demo sample : http://download.csdn.net/detail/jjwwmlp456/8176595

Android Volley specifically explains Google's published set of tools for network communications