1/*
2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23package util;
24
25import java.io.BufferedInputStream;
26import java.io.ByteArrayInputStream;
27import java.io.IOException;
28import java.io.InputStream;
29import java.io.InputStreamReader;
30import java.io.UnsupportedEncodingException;
31import java.util.HashMap;
32import java.util.Map;
33
34public class BOMInputStream {
35        public static InputStream createStream(String charset, InputStream input) {
36
37                        try {
38                                byte[] content = read(input).getBytes(charset);
39                                byte[] head = bom.get(charset);
40                                if (head == null)
41                                        return null;
42                                byte[] result = new byte[head.length + content.length];
43                                System.arraycopy(head, 0, result, 0, head.length);
44                                System.arraycopy(content, 0, result, head.length, content.length);
45                                return new ByteArrayInputStream(result);
46                        } catch (UnsupportedEncodingException e) {
47                                return null;
48                        }
49        }
50
51        private static String read(InputStream input)
52        {
53                try {
54                        StringBuffer sb = new StringBuffer();
55                        InputStreamReader r = new InputStreamReader(new BufferedInputStream(input));
56                        int c = 0;
57                        while ((c = r.read()) != -1)
58                                sb.append((char)c);
59                        return sb.toString();
60                } catch (IOException e) {
61                        return "";
62                } finally {
63                        try {
64                                input.close();
65                        } catch (IOException e)
66                        {}
67                }
68        }
69
70
71        private final static Map<String, byte[]> bom = new HashMap();
72        private final static byte[][] bomBytes = {{(byte)0xEF, (byte)0xBB, (byte)0xBF},
73                                        {(byte)0xFE, (byte)0xFF}};
74
75        static {
76                bom.put("UTF-8", bomBytes[0]);
77                bom.put("UTF-16BE", bomBytes[1]);
78        }
79
80}
81