linux-x86/sample/nio/chatserver/NameReader.java

/*
 * Copyright (c) 2011 Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * This source code is provided to illustrate the usage of a given feature
 * or technique and has been deliberately simplified. Additional steps
 * required for a production-quality application, such as security checks,
 * input validation and proper error handling, might not be present in
 * this sample code.
 */


import java.nio.ByteBuffer;

/**
 * The first state a newly connected {@code Client} is in, this
 * handles writing out the welcoming message and reads the response
 * up to a newline. When a newline character have been received
 * it changes the handler from NameReader to MessageReader on the
 * client.
 */
class NameReader implements DataReader {
    private final StringBuilder buffer = new StringBuilder();
    private final ChatServer chatServer;
    private boolean once = true;
    private static final String NEWLINE = "\n";

    public NameReader(ChatServer chatServer) {
        this.chatServer = chatServer;
    }

    /**
     * Writes the welcoming message to the client the first time this method
     * is called.
     *
     * @param client the client to receive the message
     */
    @Override
    public void beforeRead(Client client) {
        // if it is a long name that takes more than one read we only want to display Name: once.
        if (once) {
            client.writeStringMessage("Name: ");
            once = false;
        }
    }

    public boolean acceptsMessages() {
        return false;
    }

    /**
     * Receives incoming data from the socket, searches for a newline
     * and tries to set the username if one is found
     */
    @Override
    public void onData(Client client, ByteBuffer buffer, int bytes) {
        buffer.flip();
        String name;
        name = this.buffer.append(new String(buffer.array(), 0, bytes)).toString();
        if (name.contains(NEWLINE)) {
            onUserNameRead(client, name);
        }
    }

    /**
     * Splits the name on the newlines, takes the first as the username
     * and appends everything else to the clients message buffer.
     * Sets the clients handler to MessageReader.
     *
     * @param client the client to set the username for
     * @param name the string containing the buffered input
     */
    private void onUserNameRead(Client client, String name) {
        String[] strings = name.split(NEWLINE, 2);
        client.setUserName(strings[0].trim());
        sendRemainingParts(client, strings);
        client.setReader(new ClientReader(chatServer, new MessageReader(chatServer)));
        client.writeStringMessage("Welcome " + client.getUserName() + "\n");
    }

    /**
     * Appends the remaining parts to the clients message buffer
     *
     * @param client the client
     * @param strings the messages to append to the buffer
     */
    private void sendRemainingParts(Client client, String[] strings) {
        for (int i = 1; i < strings.length; ++i) {
            client.appendMessage(strings[i]);
        }
    }
}