com.ayuget.redface.network.HTTPRedirection.java Source code

Introduction

Here is the source code for com.ayuget.redface.network.HTTPRedirection.java

Source

/*
 * Copyright 2015 Ayuget
 *
 * 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
 *
 *     http://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.ayuget.redface.network;

import com.squareup.okhttp.OkHttpClient;
import com.squareup.okhttp.Request;
import com.squareup.okhttp.Response;

import java.io.IOException;
import java.net.URL;

import rx.Observable;
import rx.Subscriber;
import timber.log.Timber;

/**
 * Resolves an URL which is causing a redirection (HTTP code {@code 301}) to its destination URL
 */
public class HTTPRedirection {
    /**
     * HTTP status code for "redirected"
     */
    private static final int REDIRECTED_STATUS_CODE = 301;

    /**
     * HTTP location header indicating the target URL when redirected
     */
    private static final String LOCATION_HEADER = "Location";

    private HTTPRedirection() {
        // Utility class, prevent instantiation
    }

    /**
     * Resolves a redirected URL {@code originalUrl} to its final location.
     *
     * If the URL is not really redirected, the original URL is returned.
     */
    public static Observable<String> resolve(final String originalUrl) {
        return Observable.create(new Observable.OnSubscribe<String>() {
            @Override
            public void call(Subscriber<? super String> subscriber) {
                OkHttpClient httpClient = new OkHttpClient();
                httpClient.setFollowRedirects(false);

                Request request = new Request.Builder().url(originalUrl).build();

                try {
                    Response response = httpClient.newCall(request).execute();

                    if (response.code() == REDIRECTED_STATUS_CODE) {
                        String locationHeader = response.header(LOCATION_HEADER);
                        String targetUrl = locationHeader == null ? originalUrl
                                : "http://" + new URL(originalUrl).getHost() + locationHeader;
                        Timber.d("URL '%s' is redirected to '%s'", originalUrl, targetUrl);
                        subscriber.onNext(targetUrl);
                    } else {
                        Timber.w("URL '%s' is not redirected", originalUrl);
                        subscriber.onNext(originalUrl);
                    }
                } catch (IOException e) {
                    subscriber.onError(e);
                }
            }
        });
    }
}