1 /*
2 * Copyright 2012 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License,
5 * version 2.0 (the "License"); you may not use this file except in compliance
6 * with the License. You may obtain a copy of the License at:
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations
14 * under the License.
15 */
16 package io.netty.handler.codec.serialization;
17
18 import io.netty.buffer.ByteBuf;
19 import io.netty.buffer.ByteBufInputStream;
20 import io.netty.channel.ChannelHandlerContext;
21 import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
22
23 import java.io.ObjectInputStream;
24 import java.io.ObjectOutputStream;
25 import java.io.StreamCorruptedException;
26
27 /**
28 * A decoder which deserializes the received {@link ByteBuf}s into Java
29 * objects.
30 * <p>
31 * Please note that the serialized form this decoder expects is not
32 * compatible with the standard {@link ObjectOutputStream}. Please use
33 * {@link ObjectEncoder} or {@link ObjectEncoderOutputStream} to ensure the
34 * interoperability with this decoder.
35 */
36 public class ObjectDecoder extends LengthFieldBasedFrameDecoder {
37
38 private final ClassResolver classResolver;
39
40 /**
41 * Creates a new decoder whose maximum object size is {@code 1048576}
42 * bytes. If the size of the received object is greater than
43 * {@code 1048576} bytes, a {@link StreamCorruptedException} will be
44 * raised.
45 *
46 * @param classResolver the {@link ClassResolver} to use for this decoder
47 */
48 public ObjectDecoder(ClassResolver classResolver) {
49 this(1048576, classResolver);
50 }
51
52 /**
53 * Creates a new decoder with the specified maximum object size.
54 *
55 * @param maxObjectSize the maximum byte length of the serialized object.
56 * if the length of the received object is greater
57 * than this value, {@link StreamCorruptedException}
58 * will be raised.
59 * @param classResolver the {@link ClassResolver} which will load the class
60 * of the serialized object
61 */
62 public ObjectDecoder(int maxObjectSize, ClassResolver classResolver) {
63 super(maxObjectSize, 0, 4, 0, 4);
64 this.classResolver = classResolver;
65 }
66
67 @Override
68 protected Object decode(ChannelHandlerContext ctx, ByteBuf in) throws Exception {
69 ByteBuf frame = (ByteBuf) super.decode(ctx, in);
70 if (frame == null) {
71 return null;
72 }
73
74 ObjectInputStream ois = new CompactObjectInputStream(new ByteBufInputStream(frame, true), classResolver);
75 try {
76 return ois.readObject();
77 } finally {
78 ois.close();
79 }
80 }
81 }