There is no any simple way to set priority for ImageRequest about volley HOT 3 CLOSED

I'm not quite sure I see what's difficult here. You can extend ImageRequest and override getPriority to set a request. You can also extend ImageLoader and override makeImageRequest to return your custom ImageRequest which overrides getPriority. None of this should require too much duplicated/custom code.

What APIs are you proposing to add?

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I was thinking on extending:
public ImageContainer get(String requestUrl, ImageListener imageListener, int maxWidth, int maxHeight, ScaleType scaleType)

to

public ImageContainer get(String requestUrl, ImageListener imageListener, int maxWidth, int maxHeight, ScaleType scaleType, Priority priority) {

And then add appropriate convenience methods with smaller number of parameters in the same time supporting API backward compatibility, passing Priority.LOW when priority not passed.

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I think that approach might run into issues with makeImageRequest(), which is protected and thus can't have its signature changed. Open to ideas on how to resolve that, but I'm not seeing a simple one at a glance. It's not as simple as adding an overloaded copy like you propose for get(), because get() needs to know which version of makeImageRequest to call, and it can't know whether there's an overridden version of makeImageRequest. But you presumably need some way to propagate the priority down to it.

Also, for what it's worth, I think the semantics are a bit hard to define when it comes to the request batching that ImageLoader does. If a request is in the queue for an image at one priority, and a new one comes in with a higher priority, what should happen? We don't really have a way to promote the priority of an in-flight request. That makes me a bit hesitant to explicitly add this as an API, because you might call get with a high priority and not realize that it would have no impact if a low priority request is already in flight.

I don't know how an app might decide to prioritize requests, but it still seems to me like subclassing ImageLoader would be the way to go here if you accept the above caveat and still want custom priorities, maybe because you can guarantee in your application that there's a unique URL -> priority mapping. But in that case, it should be possible to just override makeImageRequest and apply that mapping on the given requestUrl and return an ImageRequest with the given priority.

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