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Volley or Service with cursor loader

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天命终不由人
天命终不由人 2021-02-01 09:49

I almost always use a Service when I download data from a web service. I store the result in a database and displays the result in my view using a cursor loader. But after Googl

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  • 陌清茗
    陌清茗 (楼主)
    2021-02-01 09:52

    I encountered the same issue, and I didn't like to have separated processes for local and network request. I extended the Volley library to include the process of having a local database request (for offline content) and a network request.

    Basically I have a CompleteRequest that will return:

    • an intermediate response, which can be either from http cache or from local database (run in parallel, the fastest that finishes return a result, the second one is ignored)
    • a final response, which will be from the network (or an error)

    The request looks like:

    public class SampleRequest extends CompleteRequest {

    public SampleRequest(int method, String url, ResponseListener responseListener, Response.ErrorListener errorListener) {
        super(method, url, responseListener, errorListener);
    }

    @Override
    protected Object getLocalResponse() {
        // query your local database for example
        // return the result or null if there is no result from database
        return new Object();
    }

    @Override
    public void saveNetworkResponseToLocal(Object response) {
        // save the network response to the local database
        // next time the request is performed the local response will return the result faster than the network request
    }

    @Override
    protected BallResponse parseBallNetworkResponse(NetworkResponse response) {
        // parse the result from the network request, in the same way than with volley
        return Response.success(new Object());
    }
}



    And you perform the request like that, with the response listener that includes the intermediate and the final response:
    


    mRequestQue.add(new SampleRequest(Request.Method.GET, "http://some.url", new ResponseListener() {
    @Override
    public void onIntermediateResponse(Object response, BallResponse.ResponseSource responseSource) {
        // intermediate response, such as from local database or soft cached network response
    }

    @Override
    public void onFinalResponse(Object response, BallResponse.ResponseSource responseSource) {
        // final response, which is the network response
    }

    @Override
    public void onFinalResponseIdenticalToIntermediate(BallResponse.ResponseSource responseSource) {
        // final response is identical to intermediate one
        // happens when intermediate is from soft cache and network response is identical (not modified)
    }

}, new Response.ErrorListener() {
    @Override
    public void onErrorResponse(VolleyError error) {
        // network response is an error, in the same way than with volley
    }
}
));



    It's still in an early stage of development, but I'm using it in several apps and it works nice. I wrote a quick readme with examples and there is sample project that can help.
    


    You can check it out at https://github.com/lukaspili/Volley-Ball
    
    
    
             
    
                                                        
    
            
            
    
              
                
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