1/*
2 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25package sun.management.jdp;
26
27import java.io.ByteArrayOutputStream;
28import java.io.DataOutputStream;
29import java.io.IOException;
30
31/**
32 * JdpPacketWriter responsible for writing a packet
33 * <p>This class assembles a set of key/value pairs to valid JDP packet,
34 * ready to be sent across a Net</p>
35 */
36public final class JdpPacketWriter {
37
38    private final ByteArrayOutputStream baos;
39    private final DataOutputStream pkt;
40
41    /**
42     * Create a JDP packet, add mandatory magic and version headers
43     *
44     * @throws IOException
45     */
46    public JdpPacketWriter()
47            throws IOException {
48        baos = new ByteArrayOutputStream();
49        pkt = new DataOutputStream(baos);
50
51        pkt.writeInt(JdpGenericPacket.getMagic());
52        pkt.writeShort(JdpGenericPacket.getVersion());
53    }
54
55    /**
56     * Put string entry to packet
57     *
58     * @param entry - string to put (utf-8 encoded)
59     * @throws IOException
60     */
61    public void addEntry(String entry)
62            throws IOException {
63        /* DataOutputStream.writeUTF() do essentially
64         *  the same as:
65         *    pkt.writeShort(entry.getBytes("UTF-8").length);
66         *    pkt.write(entry.getBytes("UTF-8"));
67         */
68        pkt.writeUTF(entry);
69    }
70
71    /**
72     * Put key/value pair to packet
73     *
74     * @param key - key to put (utf-8 encoded)
75     * @param val - value to put (utf-8 encoded)
76     * @throws IOException
77     */
78    public void addEntry(String key, String val)
79            throws IOException {
80        /* Silently skip key if value is null.
81         * We don't need to distinguish between key missing
82         * and key has no value cases
83         */
84        if (val != null) {
85            addEntry(key);
86            addEntry(val);
87        }
88    }
89
90    /**
91     * Return assembled packet as a byte array
92     *
93     * @return packet bytes
94     */
95    public byte[] getPacketBytes() {
96        return baos.toByteArray();
97    }
98}
99