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Java > Open Source Codes > org > apache > cocoon > components > source > impl > JPEGSourceInspector


1 /*
2  * Copyright 1999-2004 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * 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,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.apache.cocoon.components.source.impl;
17
18 import java.io.BufferedInputStream JavaDoc;
19 import java.io.IOException JavaDoc;
20
21 import org.apache.avalon.framework.thread.ThreadSafe;
22 import org.apache.excalibur.source.Source;
23 import org.apache.excalibur.source.SourceException;
24
25 /**
26  * This source inspector adds extra attributes for image files.
27  *
28  * @author <a HREF="mailto:stephan@apache.org">Stephan Michels</a>
29  * @author <a HREF="mailto:balld@webslingerZ.com">Donald A. Ball Jr.</a>
30  * @version CVS $Id: JPEGSourceInspector.java 30932 2004-07-29 17:35:38Z vgritsenko $
31  */
32 public class JPEGSourceInspector extends AbstractImageSourceInspector implements ThreadSafe {
33
34
35     public JPEGSourceInspector() {
36     }
37     
38     /**
39      * Checks the source uri for the .jp(e)g extension.
40      */
41     protected final boolean isImageMimeType(Source source) {
42         final String JavaDoc uri = source.getURI();
43         final int index = uri.lastIndexOf('.');
44         if (index != -1) {
45             String JavaDoc extension = uri.substring(index);
46             return extension.equalsIgnoreCase(".jpg") || extension.equalsIgnoreCase(".JPEG");
47         }
48         return false;
49     }
50     
51     /**
52      * Checks that this is in fact a jpeg file.
53      */
54     protected final boolean isImageFileType(Source source) throws SourceException {
55         BufferedInputStream JavaDoc in = null;
56         try {
57             in = new BufferedInputStream JavaDoc(source.getInputStream());
58             byte[] buf = new byte[2];
59             int count = in.read(buf, 0, 2);
60             if (count < 2)
61                 return false;
62
63             if ((buf[0] == (byte)0xFF) &&
64                 (buf[1] == (byte)0xD8))
65                 return true;
66         } catch (IOException JavaDoc ioe) {
67             throw new SourceException("Could not read source", ioe);
68         } finally {
69             if (in != null)
70                 try {
71                     in.close();
72                 } catch(Exception JavaDoc e) {}
73         }
74         return false;
75     }
76     
77     /**
78      * returns width as first element, height as second
79      */
80     protected final int[] getImageSize(Source source) throws SourceException {
81         BufferedInputStream JavaDoc in = null;
82         try {
83             in = new BufferedInputStream JavaDoc(source.getInputStream());
84             // check for "magic" header
85 byte[] buf = new byte[2];
86             int count = in.read(buf, 0, 2);
87             if (count < 2) throw new SourceException("Not a valid Jpeg file!");
88             if((buf[0]) != (byte)0xFF
89             || (buf[1]) != (byte)0xD8 )
90             throw new SourceException("Not a valid Jpeg file!");
91
92             int width = 0;
93             int height = 0;
94
95             boolean done = false;
96             int ch = 0;
97
98             try {
99                 while(ch != 0xDA && !done) {
100                     /* Find next marker (JPEG markers begin with 0xFF) */
101                     while (ch != 0xFF) { ch = in.read(); }
102                     /* JPEG markers can be padded with unlimited 0xFF's */
103                     while (ch == 0xFF) { ch = in.read(); }
104                     /* Now, ch contains the value of the marker. */
105                     if(ch >= 0xC0 && ch <= 0xC3) {
106                         // skip 3 bytes
107 in.read();
108                         in.read();
109                         in.read();
110                         height = 256 * in.read();
111                         height += in.read();
112                         width = 256 * in.read();
113                         width += in.read();
114                         done = true;
115                     } else {
116                         /* We MUST skip variables, since FF's within variable names
117                            are NOT valid JPEG markers */
118                         int length = 256 * in.read();
119                         length += in.read();
120                         if(length < 2) throw new RuntimeException JavaDoc("Erroneous JPEG marker length");
121                         for(int foo = 0; foo<length-2; foo++)
122                             in.read();
123                     }
124                 }
125             } catch (Exception JavaDoc e) {
126                 throw new SourceException("Not a valid Jpeg file!", e);
127             }
128
129             int[] dim = { width, height };
130             return dim;
131
132         } catch (IOException JavaDoc ioe) {
133             throw new SourceException("Could not read source", ioe);
134         } finally {
135             if (in != null)
136                 try {
137                     in.close();
138                 } catch (Exception JavaDoc e) {}
139         }
140     }
141
142 }
143
144
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