1 /***
2 *
3 * Copyright 2004 Protique Ltd
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 **/
18 package org.codehaus.activemq.message;
19
20 import java.io.ByteArrayOutputStream;
21 import java.io.DataOutput;
22 import java.io.DataOutputStream;
23 import java.io.IOException;
24 import java.io.ObjectOutputStream;
25
26 /***
27 * Allows instances implementing Packet interface to be serailized/deserailized
28 */
29 public abstract class AbstractPacketWriter implements PacketWriter {
30 /***
31 * simple helper method to ensure null strings are catered for
32 *
33 * @param str
34 * @param dataOut
35 * @throws IOException
36 */
37 protected void writeUTF(String str, DataOutput dataOut) throws IOException {
38 if (str == null) {
39 str = "";
40 }
41 dataOut.writeUTF(str);
42 }
43
44 /***
45 * @param packet
46 * @return true if this PacketWriter can write this type of Packet
47 */
48 public boolean canWrite(Packet packet) {
49 return packet.getPacketType() == this.getPacketType();
50 }
51
52 /***
53 * Simple (but inefficent) utility method to write an object on to a stream
54 *
55 * @param object
56 * @param dataOut
57 * @throws IOException
58 */
59 protected void writeObject(Object object, DataOutput dataOut) throws IOException {
60 if (object != null) {
61 ByteArrayOutputStream bytesOut = new ByteArrayOutputStream();
62 ObjectOutputStream objOut = new ObjectOutputStream(bytesOut);
63 objOut.writeObject(object);
64 objOut.flush();
65 byte[] data = bytesOut.toByteArray();
66 dataOut.writeInt(data.length);
67 dataOut.write(data);
68 }
69 else {
70 dataOut.writeInt(0);
71 }
72 }
73
74 /***
75 * Serializes a Packet int a byte array
76 *
77 * @param packet
78 * @return the byte[]
79 * @throws IOException
80 */
81 public byte[] writePacketToByteArray(Packet packet) throws IOException {
82 ByteArrayOutputStream bytesOut = new ByteArrayOutputStream();
83 DataOutputStream dataOut = new DataOutputStream(bytesOut);
84 writePacket(packet, dataOut);
85 dataOut.flush();
86 return bytesOut.toByteArray();
87 }
88
89 /***
90 * Write a Packet instance to data output stream
91 *
92 * @param packet the instance to be seralized
93 * @param dataOut the output stream
94 * @throws IOException thrown if an error occurs
95 */
96 public void writePacket(Packet packet, DataOutput dataOut) throws IOException {
97 writeUTF(packet.getId(), dataOut);
98 dataOut.writeBoolean(packet.isReceiptRequired());
99 }
100 }