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OptaPlanner solves planning problems. This lightweight, embeddable planning engine implements powerful and scalable algorithms to optimize business resource scheduling and planning. This module contains the examples which demonstrate how to use it in a normal Java application.

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/*
 * Copyright 2018 Red Hat, Inc. and/or its affiliates.
 *
 * 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.
 */

// credits for https://www.cs.mun.ca/java-api-1.5/guide/deployment/deployment-guide/upgrade-guide/article-17.html

package org.optaplanner.examples.conferencescheduling.persistence;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;

public class ConnectionFollowRedirects {

    private URLConnection connection;
    private boolean isRedirect;
    private int redirects = 0;

    public ConnectionFollowRedirects(String url) throws IOException {
        this.connection = new URL(url).openConnection();
    }

    public URLConnection getConnection() {
        return connection;
    }

    public int getRedirects() {
        return redirects;
    }

    public InputStream getInputStream() throws IOException {
        InputStream in = null;
        do {
            if (connection instanceof HttpURLConnection) {
                ((HttpURLConnection) connection).setInstanceFollowRedirects(false);
            }
            // We want to open the input stream before getting headers
            // because getHeaderField() et al swallow IOExceptions.
            in = connection.getInputStream();
            followRedirects();
        } while (isRedirect);
        return in;
    }

    private void followRedirects() throws IOException {
        isRedirect = false;
        if (connection instanceof HttpURLConnection) {
            HttpURLConnection http = (HttpURLConnection) connection;
            int stat = http.getResponseCode();
            if (stat >= 300 && stat <= 307 && stat != 306 &&
                    stat != HttpURLConnection.HTTP_NOT_MODIFIED) {
                redirectConnection(http);
            }
        }
    }

    private void redirectConnection(HttpURLConnection http) throws IOException {
        URL base = http.getURL();
        String location = http.getHeaderField("Location");
        URL target = null;
        if (location != null) {
            target = new URL(base, location);
        }
        http.disconnect();
        // Redirection should be allowed only for HTTP and HTTPS
        // and should be limited to 5 redirections at most.
        if (target == null || !(target.getProtocol().equals("http")
                || target.getProtocol().equals("https"))
                || redirects >= 5) {
            throw new SecurityException("illegal URL redirect");
        }
        isRedirect = true;
        connection = target.openConnection();
        redirects++;
    }
}