Volley - Android HTTP client
Part 2 - Application Model
Do I need to instantiate request queue in each Service or Activity?
No
Should I create singleton wrapper?
Yes
Why ?
- Request Queue creation is quite expensive
- You will be able to access and cancel all your requests
- You will be able to access and clear your cache
Let's create two class.
Request Proxy
- wrapper for request queue
- holds list of all application requests
Request Manager
- singleton which hold Request Proxy
Put those two classes in the same package.
public class RequestProxy {
private RequestQueue mRequestQueue;
// package access constructor
RequestProxy(Context context) {
mRequestQueue = Volley.newRequestQueue(context.getApplicationContext());
}
public void login() {
// login request
}
public void weather() {
// weather request
}
}
public class RequestManager {
private static RequestManager instance;
private RequestProxy mRequestProxy;
private RequestManager(Context context) {
mRequestProxy = new RequestProxy(context);
}
public RequestProxy doRequest() {
return mRequestProxy;
}
// This method should be called first to do singleton initialization
public static synchronized RequestManager getInstance(Context context) {
if (instance == null) {
instance = new RequestManager(context);
}
return instance;
}
public static synchronized RequestManager getInstance() {
if (instance == null) {
throw new IllegalStateException(RequestManager.class.getSimpleName() +
" is not initialized, call getInstance(..) method first.");
}
return instance;
}
}
Usage
Initialize RequestManager in application class
public class MyApplication extends Application {
@Override
public void onCreate() {
super.onCreate();
// RequestManager initialization
RequestManager.getInstance(getApplicationContext());
}
}
Now you can start your request as following.
RequestManager.getInstance().doRequest().login(..); RequestManager.getInstance().doRequest().weather(..);