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Java example source code file (BasicRouteDirector.java)

This example source code file (BasicRouteDirector.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java tags/keywords

basicroutedirector, complete, connect_proxy, connect_target, httproutedirector, illegalargumentexception, immutable, layer_protocol, planned, routeinfo, tunnel_proxy, tunnel_target, unreachable

The BasicRouteDirector.java example source code

/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.conn.routing;

import org.apache.http.annotation.Immutable;

/**
 * Basic implementation of an {@link HttpRouteDirector HttpRouteDirector}.
 * This implementation is stateless and therefore thread-safe.
 *
 * @since 4.0
 */
@Immutable
public class BasicRouteDirector implements HttpRouteDirector {

    /**
     * Provides the next step.
     *
     * @param plan      the planned route
     * @param fact      the currently established route, or
     *                  <code>null if nothing is established
     *
     * @return  one of the constants defined in this class, indicating
     *          either the next step to perform, or success, or failure.
     *          0 is for success, a negative value for failure.
     */
    public int nextStep(RouteInfo plan, RouteInfo fact) {
        if (plan == null) {
            throw new IllegalArgumentException
                ("Planned route may not be null.");
        }

        int step = UNREACHABLE;

        if ((fact == null) || (fact.getHopCount() < 1))
            step = firstStep(plan);
        else if (plan.getHopCount() > 1)
            step = proxiedStep(plan, fact);
        else
            step = directStep(plan, fact);

        return step;

    } // nextStep


    /**
     * Determines the first step to establish a route.
     *
     * @param plan      the planned route
     *
     * @return  the first step
     */
    protected int firstStep(RouteInfo plan) {

        return (plan.getHopCount() > 1) ?
            CONNECT_PROXY : CONNECT_TARGET;
    }


    /**
     * Determines the next step to establish a direct connection.
     *
     * @param plan      the planned route
     * @param fact      the currently established route
     *
     * @return  one of the constants defined in this class, indicating
     *          either the next step to perform, or success, or failure
     */
    protected int directStep(RouteInfo plan, RouteInfo fact) {

        if (fact.getHopCount() > 1)
            return UNREACHABLE;
        if (!plan.getTargetHost().equals(fact.getTargetHost()))
            return UNREACHABLE;
        // If the security is too low, we could now suggest to layer
        // a secure protocol on the direct connection. Layering on direct
        // connections has not been supported in HttpClient 3.x, we don't
        // consider it here until there is a real-life use case for it.

        // Should we tolerate if security is better than planned?
        // (plan.isSecure() && !fact.isSecure())
        if (plan.isSecure() != fact.isSecure())
            return UNREACHABLE;

        // Local address has to match only if the plan specifies one.
        if ((plan.getLocalAddress() != null) &&
            !plan.getLocalAddress().equals(fact.getLocalAddress())
            )
            return UNREACHABLE;

        return COMPLETE;
    }


    /**
     * Determines the next step to establish a connection via proxy.
     *
     * @param plan      the planned route
     * @param fact      the currently established route
     *
     * @return  one of the constants defined in this class, indicating
     *          either the next step to perform, or success, or failure
     */
    protected int proxiedStep(RouteInfo plan, RouteInfo fact) {

        if (fact.getHopCount() <= 1)
            return UNREACHABLE;
        if (!plan.getTargetHost().equals(fact.getTargetHost()))
            return UNREACHABLE;
        final int phc = plan.getHopCount();
        final int fhc = fact.getHopCount();
        if (phc < fhc)
            return UNREACHABLE;

        for (int i=0; i<fhc-1; i++) {
            if (!plan.getHopTarget(i).equals(fact.getHopTarget(i)))
                return UNREACHABLE;
        }
        // now we know that the target matches and proxies so far are the same
        if (phc > fhc)
            return TUNNEL_PROXY; // need to extend the proxy chain
            
        // proxy chain and target are the same, check tunnelling and layering
        if ((fact.isTunnelled() && !plan.isTunnelled()) ||
            (fact.isLayered()   && !plan.isLayered()))
            return UNREACHABLE;

        if (plan.isTunnelled() && !fact.isTunnelled())
            return TUNNEL_TARGET;
        if (plan.isLayered() && !fact.isLayered())
            return LAYER_PROTOCOL;

        // tunnel and layering are the same, remains to check the security
        // Should we tolerate if security is better than planned?
        // (plan.isSecure() && !fact.isSecure())
        if (plan.isSecure() != fact.isSecure())
            return UNREACHABLE;

        return COMPLETE;
    }

}

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