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Java example source code file (Scheme.java)

This example source code file (Scheme.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

illegalargumentexception, immutable, layeredsocketfactory, override, port, scheme, socketfactory, string, stringbuilder, util

The Scheme.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.scheme;

import java.util.Locale;

import org.apache.http.annotation.Immutable;

import org.apache.http.util.LangUtils;

/**
 * Encapsulates specifics of a protocol scheme such as "http" or "https".
 * Schemes are identified by lowercase names.
 * Supported schemes are typically collected in a
 * {@link SchemeRegistry SchemeRegistry}.
 *
 * <p>
 * For example, to configure support for "https://" URLs,
 * you could write code like the following:
 * </p>
 * <pre>
 * Scheme https = new Scheme("https", new MySecureSocketFactory(), 443);
 * SchemeRegistry.DEFAULT.register(https);
 * </pre>
 *
 *
 * @since 4.0
 */
@Immutable
public final class Scheme {

    /** The name of this scheme, in lowercase. (e.g. http, https) */
    private final String name;
    
    /** The socket factory for this scheme */
    private final SocketFactory socketFactory;
    
    /** The default port for this scheme */
    private final int defaultPort;
    
    /** Indicates whether this scheme allows for layered connections */
    private final boolean layered;


    /** A string representation, for {@link #toString toString}. */
    private String stringRep;
    /*
     *  This is used to cache the result of the toString() method
     *  Since the method always generates the same value, there's no
     *  need to synchronize, and it does not affect immutability.
    */


    /**
     * Creates a new scheme.
     * Whether the created scheme allows for layered connections
     * depends on the class of <code>factory.
     *
     * @param name      the scheme name, for example "http".
     *                  The name will be converted to lowercase.
     * @param factory   the factory for creating sockets for communication
     *                  with this scheme
     * @param port      the default port for this scheme
     */
    public Scheme(final String name,
                  final SocketFactory factory,
                  final int port) {

        if (name == null) {
            throw new IllegalArgumentException
                ("Scheme name may not be null");
        }
        if (factory == null) {
            throw new IllegalArgumentException
                ("Socket factory may not be null");
        }
        if ((port <= 0) || (port > 0xffff)) {
            throw new IllegalArgumentException
                ("Port is invalid: " + port);
        }

        this.name = name.toLowerCase(Locale.ENGLISH);
        this.socketFactory = factory;
        this.defaultPort = port;
        this.layered = (factory instanceof LayeredSocketFactory);
    }


    /**
     * Obtains the default port.
     *
     * @return  the default port for this scheme
     */
    public final int getDefaultPort() {
        return defaultPort;
    }


    /**
     * Obtains the socket factory.
     * If this scheme is {@link #isLayered layered}, the factory implements
     * {@link LayeredSocketFactory LayeredSocketFactory}.
     *
     * @return  the socket factory for this scheme
     */
    public final SocketFactory getSocketFactory() {
        return socketFactory;
    }


    /**
     * Obtains the scheme name.
     *
     * @return  the name of this scheme, in lowercase
     */
    public final String getName() {
        return name;
    }


    /**
     * Indicates whether this scheme allows for layered connections.
     *
     * @return <code>true if layered connections are possible,
     *         <code>false otherwise
     */
    public final boolean isLayered() {
        return layered;
    }


    /**
     * Resolves the correct port for this scheme.
     * Returns the given port if it is valid, the default port otherwise.
     * 
     * @param port      the port to be resolved,
     *                  a negative number to obtain the default port
     * 
     * @return the given port or the defaultPort
     */
    public final int resolvePort(int port) {
        return port <= 0 ? defaultPort : port;
    }


    /**
     * Return a string representation of this object.
     *
     * @return  a human-readable string description of this scheme
     */
    @Override
    public final String toString() {
        if (stringRep == null) {
            StringBuilder buffer = new StringBuilder();
            buffer.append(this.name);
            buffer.append(':');
            buffer.append(Integer.toString(this.defaultPort));
            stringRep = buffer.toString();
        }
        return stringRep;
    }


    /**
     * Compares this scheme to an object.
     *
     * @param obj       the object to compare with
     *
     * @return  <code>true iff the argument is equal to this scheme
     */
    @Override
    public final boolean equals(Object obj) {
        if (obj == null) return false;
        if (this == obj) return true;
        if (!(obj instanceof Scheme)) return false;

        Scheme s = (Scheme) obj;
        return (name.equals(s.name) &&
                defaultPort == s.defaultPort &&
                layered == s.layered &&
                socketFactory.equals(s.socketFactory)
                );
    } // equals


    /**
     * Obtains a hash code for this scheme.
     *
     * @return  the hash code
     */
    @Override
    public int hashCode() {
        int hash = LangUtils.HASH_SEED;
        hash = LangUtils.hashCode(hash, this.defaultPort);
        hash = LangUtils.hashCode(hash, this.name);
        hash = LangUtils.hashCode(hash, this.layered);
        hash = LangUtils.hashCode(hash, this.socketFactory);
        return hash;
    }

} // class Scheme

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