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An Asynchronous HTTP Library for Android
/*
Android Asynchronous Http Client
Copyright (c) 2011 James Smith
https://loopj.com
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
https://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package com.loopj.android.http;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.UnknownHostException;
import java.util.concurrent.atomic.AtomicBoolean;
import cz.msebera.android.httpclient.HttpResponse;
import cz.msebera.android.httpclient.client.HttpRequestRetryHandler;
import cz.msebera.android.httpclient.client.methods.HttpUriRequest;
import cz.msebera.android.httpclient.impl.client.AbstractHttpClient;
import cz.msebera.android.httpclient.protocol.HttpContext;
/**
* Internal class, representing the HttpRequest, done in asynchronous manner
*/
public class AsyncHttpRequest implements Runnable {
private final AbstractHttpClient client;
private final HttpContext context;
private final HttpUriRequest request;
private final ResponseHandlerInterface responseHandler;
private final AtomicBoolean isCancelled = new AtomicBoolean();
private int executionCount;
private boolean cancelIsNotified;
private volatile boolean isFinished;
private boolean isRequestPreProcessed;
public AsyncHttpRequest(AbstractHttpClient client, HttpContext context, HttpUriRequest request, ResponseHandlerInterface responseHandler) {
this.client = Utils.notNull(client, "client");
this.context = Utils.notNull(context, "context");
this.request = Utils.notNull(request, "request");
this.responseHandler = Utils.notNull(responseHandler, "responseHandler");
}
/**
* This method is called once by the system when the request is about to be
* processed by the system. The library makes sure that a single request
* is pre-processed only once.
*
* Please note: pre-processing does NOT run on the main thread, and thus
* any UI activities that you must perform should be properly dispatched to
* the app's UI thread.
*
* @param request The request to pre-process
*/
public void onPreProcessRequest(AsyncHttpRequest request) {
// default action is to do nothing...
}
/**
* This method is called once by the system when the request has been fully
* sent, handled and finished. The library makes sure that a single request
* is post-processed only once.
*
* Please note: post-processing does NOT run on the main thread, and thus
* any UI activities that you must perform should be properly dispatched to
* the app's UI thread.
*
* @param request The request to post-process
*/
public void onPostProcessRequest(AsyncHttpRequest request) {
// default action is to do nothing...
}
@Override
public void run() {
if (isCancelled()) {
return;
}
// Carry out pre-processing for this request only once.
if (!isRequestPreProcessed) {
isRequestPreProcessed = true;
onPreProcessRequest(this);
}
if (isCancelled()) {
return;
}
responseHandler.sendStartMessage();
if (isCancelled()) {
return;
}
try {
makeRequestWithRetries();
} catch (IOException e) {
if (!isCancelled()) {
responseHandler.sendFailureMessage(0, null, null, e);
} else {
AsyncHttpClient.log.e("AsyncHttpRequest", "makeRequestWithRetries returned error", e);
}
}
if (isCancelled()) {
return;
}
responseHandler.sendFinishMessage();
if (isCancelled()) {
return;
}
// Carry out post-processing for this request.
onPostProcessRequest(this);
isFinished = true;
}
private void makeRequest() throws IOException {
if (isCancelled()) {
return;
}
// Fixes #115
if (request.getURI().getScheme() == null) {
// subclass of IOException so processed in the caller
throw new MalformedURLException("No valid URI scheme was provided");
}
if (responseHandler instanceof RangeFileAsyncHttpResponseHandler) {
((RangeFileAsyncHttpResponseHandler) responseHandler).updateRequestHeaders(request);
}
HttpResponse response = client.execute(request, context);
if (isCancelled()) {
return;
}
// Carry out pre-processing for this response.
responseHandler.onPreProcessResponse(responseHandler, response);
if (isCancelled()) {
return;
}
// The response is ready, handle it.
responseHandler.sendResponseMessage(response);
if (isCancelled()) {
return;
}
// Carry out post-processing for this response.
responseHandler.onPostProcessResponse(responseHandler, response);
}
private void makeRequestWithRetries() throws IOException {
boolean retry = true;
IOException cause = null;
HttpRequestRetryHandler retryHandler = client.getHttpRequestRetryHandler();
try {
while (retry) {
try {
makeRequest();
return;
} catch (UnknownHostException e) {
// switching between WI-FI and mobile data networks can cause a retry which then results in an UnknownHostException
// while the WI-FI is initialising. The retry logic will be invoked here, if this is NOT the first retry
// (to assist in genuine cases of unknown host) which seems better than outright failure
cause = new IOException("UnknownHostException exception: " + e.getMessage());
retry = (executionCount > 0) && retryHandler.retryRequest(e, ++executionCount, context);
} catch (NullPointerException e) {
// there's a bug in HttpClient 4.0.x that on some occasions causes
// DefaultRequestExecutor to throw an NPE, see
// https://code.google.com/p/android/issues/detail?id=5255
cause = new IOException("NPE in HttpClient: " + e.getMessage());
retry = retryHandler.retryRequest(cause, ++executionCount, context);
} catch (IOException e) {
if (isCancelled()) {
// Eating exception, as the request was cancelled
return;
}
cause = e;
retry = retryHandler.retryRequest(cause, ++executionCount, context);
}
if (retry) {
responseHandler.sendRetryMessage(executionCount);
}
}
} catch (Exception e) {
// catch anything else to ensure failure message is propagated
AsyncHttpClient.log.e("AsyncHttpRequest", "Unhandled exception origin cause", e);
cause = new IOException("Unhandled exception: " + e.getMessage());
}
// cleaned up to throw IOException
throw (cause);
}
public boolean isCancelled() {
boolean cancelled = isCancelled.get();
if (cancelled) {
sendCancelNotification();
}
return cancelled;
}
private synchronized void sendCancelNotification() {
if (!isFinished && isCancelled.get() && !cancelIsNotified) {
cancelIsNotified = true;
responseHandler.sendCancelMessage();
}
}
public boolean isDone() {
return isCancelled() || isFinished;
}
public boolean cancel(boolean mayInterruptIfRunning) {
isCancelled.set(true);
request.abort();
return isCancelled();
}
/**
* Will set Object as TAG to this request, wrapped by WeakReference
*
* @param TAG Object used as TAG to this RequestHandle
* @return this AsyncHttpRequest to allow fluid syntax
*/
public AsyncHttpRequest setRequestTag(Object TAG) {
this.responseHandler.setTag(TAG);
return this;
}
/**
* Will return TAG of this AsyncHttpRequest
*
* @return Object TAG, can be null, if it's been already garbage collected
*/
public Object getTag() {
return this.responseHandler.getTag();
}
}