2

My case is that I need to get two sets of data from sever with two HTTP get request, then process them together.

I'm using loopj's http library to do the task.

The problem is that since loopj's http is Async, which means I can't determine when they will be complete and which will complete first.They all have their own onSuccess function. I tried to put a boolean flag into each of them, and make the calling activity check the change of AND operation of these two boolean, but seems if I make the main thread wait, the onSuccess Function will also wait...

Is there a way I could determine when the two request are both completed, and then I could proceed with next step?

Code is like:

In Calling Activity:

boolean A;
boolean B;

HttpRequestA();
HttpRequestB();

while (!(A&&B)) {
  Thread.sleep(100);
}

HttpRequestA is:

public void HttpRequestA() {
  A = false;
  HTTPService.get(url, new TextHttpResponseHandler() {
  @Override
  public void onFailure(int statusCode, Header[] header, String responseString, Throwable throwable) {
}

  @Override
  public void onSuccess(int statusCode, Header[] header, String responseString) {
    A = true;
  }
});
}
Arthur Wang
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  • pretty much what you've got: your A,B vars. each success function sets the appropriate boolean to TRUE, and then calls can_i_proceed(), which does `if (a && b) { proceed(); }`. first call comes back, sets its var, and can't proceed because a && b is false. second call comes back, sets its var, and now a && b is true and processing continues. – Marc B Dec 16 '14 at 20:19
  • Thanks for the reply. The problem is that it seems not working that way. So if the onSuccess method is also running on Main thread, so we have a 'wait' function on main thread, it will block the running of onSuccess! So we don't have a chance to change the checker. – Arthur Wang Dec 16 '14 at 20:25

1 Answers1

2

you could use 

SyncHttpClient

instead of 

AsyncHttpClient

Then you execute each SyncHttpClient in two different threads and pass the same callback for each SyncHttpClient. Continue with your code when the callback has been executed for the second time. The callback method should be defined with the synchronized keyword to avoid that the function is accessed/invoked by two different threads at the same time.

Edit:

so something like this

class Example implements AsyncHttpResponseHandler{

    int executedTasks = 2;

    void executeHttpRequests(){
        new HttpExecutor(this).start();
        new HttpExecutor(this).start();
    }

    @Override
    public synchronized void onStart() {
        // called before request is started
    }

    @Override
    public synchronized void onSuccess(int statusCode, Header[] headers, byte[] response) {
        executedTasks--;
        if (executedTasks == 0){
            // continue, otherwise wait for other callback
        }
    }

    @Override
    public synchronized void onFailure(int statusCode, Header[] headers, byte[] errorResponse, Throwable e) {
        // called when response HTTP status is "4XX" (eg. 401, 403, 404)
    }

    @Override
    public synchronized void onRetry(int retryNo) {
        // called when request is retried
    }

}

class HttpExecutor extends Thread{

    AsyncHttpResponseHandler callback;

    public HttpExecutor(AsyncHttpResponseHandler callback){
        this.callback = callback;
    }

    @Override
    public void run(){

        SyncHttpClient client = new SyncHttpClient();
        client.get("http://www.google.com", callback);

    }

}
aschattney
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