Package org.asynchttpclient

Interface AsyncHttpClient

  • All Superinterfaces:
    AutoCloseable, Closeable
    All Known Implementing Classes:
    DefaultAsyncHttpClient
    public interface AsyncHttpClient
extends Closeable
    This class support asynchronous and synchronous HTTP requests.
    To execute a synchronous HTTP request, you just need to do 
        AsyncHttpClient c = new AsyncHttpClient();
    Future<Response> f = c.prepareGet(TARGET_URL).execute();

    The code above will block until the response is fully received. To execute an asynchronous HTTP request, you create an AsyncHandler or its abstract implementation, AsyncCompletionHandler 
           AsyncHttpClient c = new AsyncHttpClient();
       Future<Response> f = c.prepareGet(TARGET_URL).execute(new AsyncCompletionHandler<Response>() {

          @Override
          public Response onCompleted(Response response) throws IOException {
               // Do something
              return response;
          }

          @Override
          public void onThrowable(Throwable t) {
          }
      });
      Response response = f.get();

      // We are just interested in retrieving the status code.
     Future<Integer> f = c.prepareGet(TARGET_URL).execute(new AsyncCompletionHandler<Integer>() {

          @Override
          public Integer onCompleted(Response response) throws IOException {
               // Do something
              return response.getStatusCode();
          }

          @Override
          public void onThrowable(Throwable t) {
          }
      });
      Integer statusCode = f.get();
    The AsyncCompletionHandler.onCompleted(Response) method will be invoked once the http response has been fully read. The Response object includes the http headers and the response body. Note that the entire response will be buffered in memory.
    You can also have more control about how the response is asynchronously processed by using an AsyncHandler 
          AsyncHttpClient c = new AsyncHttpClient();
      Future<String> f = c.prepareGet(TARGET_URL).execute(new AsyncHandler<String>() {
          private StringBuilder builder = new StringBuilder();

          @Override
          public STATE onStatusReceived(HttpResponseStatus s) throws Exception {
               // return STATE.CONTINUE or STATE.ABORT
               return STATE.CONTINUE
          }

          @Override
          public STATE onHeadersReceived(HttpResponseHeaders bodyPart) throws Exception {
               // return STATE.CONTINUE or STATE.ABORT
               return STATE.CONTINUE

          }
          @Override

          public STATE onBodyPartReceived(HttpResponseBodyPart bodyPart) throws Exception {
               builder.append(new String(bodyPart));
               // return STATE.CONTINUE or STATE.ABORT
               return STATE.CONTINUE
          }

          @Override
          public String onCompleted() throws Exception {
               // Will be invoked once the response has been fully read or a ResponseComplete exception
               // has been thrown.
               return builder.toString();
          }

          @Override
          public void onThrowable(Throwable t) {
          }
      });

      String bodyResponse = f.get();
    You can asynchronously process the response status, headers and body and decide when to stop processing the response by returning a new AsyncHandler.State.ABORT at any moment.

    This class can also be used without the need of AsyncHandler. 

          AsyncHttpClient c = new AsyncHttpClient();
      Future<Response> f = c.prepareGet(TARGET_URL).execute();
      Response r = f.get();

    Finally, you can configure the AsyncHttpClient using an DefaultAsyncHttpClientConfig instance. 

          AsyncHttpClient c = new AsyncHttpClient(new DefaultAsyncHttpClientConfig.Builder().setRequestTimeout(...).build());
      Future<Response> f = c.prepareGet(TARGET_URL).execute();
      Response r = f.get();

    An instance of this class will cache every HTTP 1.1 connection and close them when the DefaultAsyncHttpClientConfig.getReadTimeout() expires. This object can hold many persistent connections to different hosts.