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Java > Open Source Codes > org > apache > coyote > http11 > filters > GzipOutputFilter


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. 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.apache.coyote.http11.filters;
19
20 import java.io.IOException JavaDoc;
21 import java.io.OutputStream JavaDoc;
22 import java.util.zip.GZIPOutputStream JavaDoc;
23
24 import org.apache.tomcat.util.buf.ByteChunk;
25
26 import org.apache.coyote.OutputBuffer;
27 import org.apache.coyote.Response;
28 import org.apache.coyote.http11.OutputFilter;
29
30 /**
31  * Gzip output filter.
32  *
33  * @author Remy Maucherat
34  */
35 public class GzipOutputFilter implements OutputFilter {
36
37
38     // -------------------------------------------------------------- Constants
39
40
41     protected static final String JavaDoc ENCODING_NAME = "gzip";
42     protected static final ByteChunk ENCODING = new ByteChunk();
43
44
45     // ----------------------------------------------------- Static Initializer
46
47
48     static {
49         ENCODING.setBytes(ENCODING_NAME.getBytes(), 0, ENCODING_NAME.length());
50     }
51
52
53     // ----------------------------------------------------- Instance Variables
54
55
56     /**
57      * Next buffer in the pipeline.
58      */
59     protected OutputBuffer buffer;
60
61
62     /**
63      * Compression output stream.
64      */
65     protected GZIPOutputStream JavaDoc compressionStream = null;
66
67
68     /**
69      * Fake internal output stream.
70      */
71     protected OutputStream JavaDoc fakeOutputStream = new FakeOutputStream();
72
73
74     // --------------------------------------------------- OutputBuffer Methods
75
76
77     /**
78      * Write some bytes.
79      *
80      * @return number of bytes written by the filter
81      */
82     public int doWrite(ByteChunk chunk, Response res)
83         throws IOException JavaDoc {
84         if (compressionStream == null) {
85             compressionStream = new GZIPOutputStream JavaDoc(fakeOutputStream);
86         }
87         compressionStream.write(chunk.getBytes(), chunk.getStart(),
88                                 chunk.getLength());
89         return chunk.getLength();
90     }
91
92
93     // --------------------------------------------------- OutputFilter Methods
94
95
96     /**
97      * Some filters need additional parameters from the response. All the
98      * necessary reading can occur in that method, as this method is called
99      * after the response header processing is complete.
100      */
101     public void setResponse(Response response) {
102     }
103
104
105     /**
106      * Set the next buffer in the filter pipeline.
107      */
108     public void setBuffer(OutputBuffer buffer) {
109         this.buffer = buffer;
110     }
111
112
113     /**
114      * End the current request. It is acceptable to write extra bytes using
115      * buffer.doWrite during the execution of this method.
116      */
117     public long end()
118         throws IOException JavaDoc {
119         if (compressionStream == null) {
120             compressionStream = new GZIPOutputStream JavaDoc(fakeOutputStream);
121         }
122         compressionStream.finish();
123         compressionStream.close();
124         return ((OutputFilter) buffer).end();
125     }
126
127
128     /**
129      * Make the filter ready to process the next request.
130      */
131     public void recycle() {
132         // Set compression stream to null
133 compressionStream = null;
134     }
135
136
137     /**
138      * Return the name of the associated encoding; Here, the value is
139      * "identity".
140      */
141     public ByteChunk getEncodingName() {
142         return ENCODING;
143     }
144
145
146     // ------------------------------------------- FakeOutputStream Inner Class
147
148
149     protected class FakeOutputStream
150         extends OutputStream JavaDoc {
151         protected ByteChunk outputChunk = new ByteChunk();
152         protected byte[] singleByteBuffer = new byte[1];
153         public void write(int b)
154             throws IOException JavaDoc {
155             // Shouldn't get used for good performance, but is needed for
156 // compatibility with Sun JDK 1.4.0
157 singleByteBuffer[0] = (byte) (b & 0xff);
158             outputChunk.setBytes(singleByteBuffer, 0, 1);
159             buffer.doWrite(outputChunk, null);
160         }
161         public void write(byte[] b, int off, int len)
162             throws IOException JavaDoc {
163             outputChunk.setBytes(b, off, len);
164             buffer.doWrite(outputChunk, null);
165         }
166         public void flush() throws IOException JavaDoc {}
167         public void close() throws IOException JavaDoc {}
168     }
169
170
171 }
172
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