1 /*
2 * Copyright (c) 2012, 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package jdk.internal.util.xml.impl;
27
28 import java.io.Reader;
29 import java.io.InputStream;
30 import java.io.IOException;
31 import java.io.UnsupportedEncodingException;
32
33 /**
34 * UTF-8 transformed UCS-2 character stream reader.
35 *
36 * This reader converts UTF-8 transformed UCS-2 characters to Java characters.
37 * The UCS-2 subset of UTF-8 transformation is described in RFC-2279 #2
38 * "UTF-8 definition":
39 * 0000 0000-0000 007F 0xxxxxxx
40 * 0000 0080-0000 07FF 110xxxxx 10xxxxxx
41 * 0000 0800-0000 FFFF 1110xxxx 10xxxxxx 10xxxxxx
42 *
43 * This reader will return incorrect last character on broken UTF-8 stream.
44 */
45 public class ReaderUTF8
46 extends Reader
47 {
48 private InputStream is;
49
50 /**
51 * Constructor.
52 *
53 * @param is A byte input stream.
54 */
55 public ReaderUTF8(InputStream is)
56 {
57 this.is = is;
58 }
59
60 /**
61 * Reads characters into a portion of an array.
62 *
63 * @param cbuf Destination buffer.
64 * @param off Offset at which to start storing characters.
65 * @param len Maximum number of characters to read.
66 * @exception IOException If any IO errors occur.
67 * @exception UnsupportedEncodingException If UCS-4 character occur in the stream.
68 */
69 public int read(char[] cbuf, int off, int len)
70 throws IOException
71 {
72 int num = 0;
73 int val;
74 while (num < len) {
75 if ((val = is.read()) < 0)
76 return (num != 0)? num: -1;
77 switch (val & 0xf0) {
78 case 0xc0:
79 case 0xd0:
80 cbuf[off++] = (char)(((val & 0x1f) << 6) | (is.read() & 0x3f));
81 break;
82
83 case 0xe0:
84 cbuf[off++] = (char)(((val & 0x0f) << 12) |
85 ((is.read() & 0x3f) << 6) | (is.read() & 0x3f));
86 break;
87
88 case 0xf0: // UCS-4 character
89 throw new UnsupportedEncodingException("UTF-32 (or UCS-4) encoding not supported.");
90
91 default:
92 cbuf[off++] = (char)val;
93 break;
94 }
95 num++;
96 }
97 return num;
98 }
99
100 /**
101 * Reads a single character.
102 *
103 * @return The character read, as an integer in the range 0 to 65535
104 * (0x00-0xffff), or -1 if the end of the stream has been reached.
105 * @exception IOException If any IO errors occur.
106 * @exception UnsupportedEncodingException If UCS-4 character occur in the stream.
107 */
108 public int read()
109 throws IOException
110 {
111 int val;
112 if ((val = is.read()) < 0)
113 return -1;
114 switch (val & 0xf0) {
115 case 0xc0:
116 case 0xd0:
117 val = ((val & 0x1f) << 6) | (is.read() & 0x3f);
118 break;
119
120 case 0xe0:
121 val = ((val & 0x0f) << 12) |
122 ((is.read() & 0x3f) << 6) | (is.read() & 0x3f);
123 break;
124
125 case 0xf0: // UCS-4 character
126 throw new UnsupportedEncodingException();
127
128 default:
129 break;
130 }
131 return val;
132 }
133
134 /**
135 * Closes the stream.
136 *
137 * @exception IOException If any IO errors occur.
138 */
139 public void close()
140 throws IOException
141 {
142 is.close();
143 }
144 }