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Java > Open Source Codes > com > opensymphony > module > sitemesh > filter > TextEncoder


1 /* This software is published under the terms of the OpenSymphony Software
2  * License version 1.1, of which a copy has been included with this
3  * distribution in the LICENSE.txt file. */
4 package com.opensymphony.module.sitemesh.filter;
5
6 import java.io.ByteArrayInputStream JavaDoc;
7 import java.io.CharArrayWriter JavaDoc;
8 import java.io.IOException JavaDoc;
9 import java.io.InputStreamReader JavaDoc;
10 import java.nio.ByteBuffer JavaDoc;
11 import java.nio.CharBuffer JavaDoc;
12 import java.nio.charset.Charset JavaDoc;
13 import java.nio.charset.CharsetDecoder JavaDoc;
14 import java.nio.charset.CoderResult JavaDoc;
15 import java.nio.charset.CodingErrorAction JavaDoc;
16
17 /**
18  * Converts text stored in byte[] to char[] using specified encoding.
19  *
20  * @author <a HREF="mailto:scott@atlassian.com">Scott Farquhar</a>
21  * @author <a HREF="mailto:hani@formicary.net">Hani Suleiman</a>
22  * @author Joe Walnes
23  * @version $Revision: 1.1 $
24 */
25 public class TextEncoder {
26
27     private static final String JavaDoc DEFAULT_ENCODING = System.getProperty("file.encoding");
28     private static final boolean JDK14 =
29             System.getProperty("java.version").startsWith("1.4")
30             || System.getProperty("java.version").startsWith("1.5");
31
32     public char[] encode(byte[] data, String JavaDoc encoding) throws IOException JavaDoc {
33         if (encoding == null) {
34             encoding = DEFAULT_ENCODING;
35         }
36         if (JDK14) {
37             return get14Buffer(data, encoding);
38         } else {
39             return get13Buffer(data, encoding);
40         }
41     }
42
43     private char[] get13Buffer(byte[] data, String JavaDoc encoding) throws IOException JavaDoc {
44         CharArrayWriter JavaDoc out = null;
45         // Why all this indirection? Because we are being given bytes, and we have to then write
46 // them to characters. We need to know the encoding of the characterset that we are creating.
47 // The test that verifies this is InlineDecoratorTest (inline/page6.jsp).
48 InputStreamReader JavaDoc reader;
49         out = new CharArrayWriter JavaDoc();
50         if (encoding != null) {
51             reader = new InputStreamReader JavaDoc(new ByteArrayInputStream JavaDoc(data), encoding);
52         } else {
53             reader = new InputStreamReader JavaDoc(new ByteArrayInputStream JavaDoc(data));
54         }
55
56         int i;
57         while ((i = reader.read()) != -1) {
58             out.write(i);
59         }
60         return out.toCharArray();
61     }
62
63     private char[] get14Buffer(byte[] data, String JavaDoc encoding) throws IOException JavaDoc {
64         if (!Charset.isSupported(encoding)) throw new IOException JavaDoc("Unsupported encoding " + encoding);
65         Charset JavaDoc charset = Charset.forName(encoding);
66         CharsetDecoder JavaDoc cd = charset.newDecoder().onMalformedInput(CodingErrorAction.REPLACE).onUnmappableCharacter(CodingErrorAction.REPLACE);
67         int en = (int) (cd.maxCharsPerByte() * data.length);
68         char[] ca = new char[en];
69         ByteBuffer JavaDoc bb = ByteBuffer.wrap(data);
70         CharBuffer JavaDoc cb = CharBuffer.wrap(ca);
71         CoderResult JavaDoc cr = cd.decode(bb, cb, true);
72         if (!cr.isUnderflow()) {
73             cr.throwException();
74         }
75         cr = cd.flush(cb);
76         if (!cr.isUnderflow()) {
77             cr.throwException();
78         }
79         return trim(ca, cb.position());
80     }
81
82     private char[] trim(char[] ca, int len) {
83         if (len == ca.length) {
84             return ca;
85         }
86         char[] tca = new char[len];
87         System.arraycopy(ca, 0, tca, 0, len);
88         return tca;
89     }
90
91 }
92
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