001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.net.daytime;
019
020import java.io.BufferedReader;
021import java.io.IOException;
022import java.io.InputStreamReader;
023
024import org.apache.commons.net.SocketClient;
025
026/**
027 * The DaytimeTCPClient class is a TCP implementation of a client for the Daytime protocol described in RFC 867. To use the class, merely establish a connection
028 * with {@link org.apache.commons.net.SocketClient#connect connect } and call {@link #getTime getTime() } to retrieve the daytime string, then call
029 * {@link org.apache.commons.net.SocketClient#disconnect disconnect } to close the connection properly.
030 *
031 * @see DaytimeUDPClient
032 */
033public final class DaytimeTCPClient extends SocketClient {
034    /** The default daytime port. It is set to 13 according to RFC 867. */
035    public static final int DEFAULT_PORT = 13;
036
037    // Received dates will likely be less than 64 characters.
038    // This is a temporary buffer used while receiving data.
039    private final char[] buffer = new char[64];
040
041    /**
042     * The default DaytimeTCPClient constructor. It merely sets the default port to <code>DEFAULT_PORT</code>.
043     */
044    public DaytimeTCPClient() {
045        setDefaultPort(DEFAULT_PORT);
046    }
047
048    /**
049     * Retrieves the time string from the server and returns it. The server will have closed the connection at this point, so you should call
050     * {@link org.apache.commons.net.SocketClient#disconnect disconnect } after calling this method. To retrieve another time, you must initiate another
051     * connection with {@link org.apache.commons.net.SocketClient#connect connect } before calling <code>getTime()</code> again.
052     *
053     * @return The time string retrieved from the server.
054     * @throws IOException If an error occurs while fetching the time string.
055     */
056    public String getTime() throws IOException {
057        int read;
058        final StringBuilder result = new StringBuilder(buffer.length);
059        final BufferedReader reader;
060
061        reader = new BufferedReader(new InputStreamReader(_input_, getCharset()));
062
063        while (true) {
064            read = reader.read(buffer, 0, buffer.length);
065            if (read <= 0) {
066                break;
067            }
068            result.append(buffer, 0, read);
069        }
070
071        return result.toString();
072    }
073
074}