1 // ========================================================================
2 // Copyright (c) 2006-2009 Mort Bay Consulting Pty. Ltd.
3 // ------------------------------------------------------------------------
4 // All rights reserved. This program and the accompanying materials
5 // are made available under the terms of the Eclipse Public License v1.0
6 // and Apache License v2.0 which accompanies this distribution.
7 // The Eclipse Public License is available at
8 // http://www.eclipse.org/legal/epl-v10.html
9 // The Apache License v2.0 is available at
10 // http://www.opensource.org/licenses/apache2.0.php
11 // You may elect to redistribute this code under either of these licenses.
12 // ========================================================================
13
14 package org.eclipse.jetty.util;
15
16 /* ------------------------------------------------------------ */
17 /** UTF-8 StringBuffer.
18 *
19 * This class wraps a standard {@link java.lang.StringBuffer} and provides methods to append
20 * UTF-8 encoded bytes, that are converted into characters.
21 *
22 * This class is stateful and up to 6 calls to {@link #append(byte)} may be needed before
23 * state a character is appended to the string buffer.
24 *
25 * The UTF-8 decoding is done by this class and no additional buffers or Readers are used.
26 * The UTF-8 code was inspired by http://javolution.org
27 *
28 * This class is not synchronised and should probably be called Utf8StringBuilder
29 */
30 public class Utf8StringBuffer
31 {
32 StringBuffer _buffer;
33 int _more;
34 int _bits;
35
36 public Utf8StringBuffer()
37 {
38 _buffer=new StringBuffer();
39 }
40
41 public Utf8StringBuffer(int capacity)
42 {
43 _buffer=new StringBuffer(capacity);
44 }
45
46 public void append(byte[] b,int offset, int length)
47 {
48 int end=offset+length;
49 for (int i=offset; i<end;i++)
50 append(b[i]);
51 }
52
53 public void append(byte b)
54 {
55 if (b>=0)
56 {
57 if (_more>0)
58 {
59 _buffer.append('?');
60 _more=0;
61 _bits=0;
62 }
63 else
64 _buffer.append((char)(0x7f&b));
65 }
66 else if (_more==0)
67 {
68 if ((b&0xc0)!=0xc0)
69 {
70 // 10xxxxxx
71 _buffer.append('?');
72 _more=0;
73 _bits=0;
74 }
75 else
76
77 {
78 if ((b & 0xe0) == 0xc0)
79 {
80 //110xxxxx
81 _more=1;
82 _bits=b&0x1f;
83 }
84 else if ((b & 0xf0) == 0xe0)
85 {
86 //1110xxxx
87 _more=2;
88 _bits=b&0x0f;
89 }
90 else if ((b & 0xf8) == 0xf0)
91 {
92 //11110xxx
93 _more=3;
94 _bits=b&0x07;
95 }
96 else if ((b & 0xfc) == 0xf8)
97 {
98 //111110xx
99 _more=4;
100 _bits=b&0x03;
101 }
102 else if ((b & 0xfe) == 0xfc)
103 {
104 //1111110x
105 _more=5;
106 _bits=b&0x01;
107 }
108 else
109 {
110 throw new IllegalArgumentException("!utf8");
111 }
112
113 }
114 }
115 else
116 {
117 if ((b&0xc0)==0xc0)
118 { // 11??????
119 _buffer.append('?');
120 _more=0;
121 _bits=0;
122 throw new IllegalArgumentException("!utf8");
123 }
124 else
125 {
126 // 10xxxxxx
127 _bits=(_bits<<6)|(b&0x3f);
128 if (--_more==0)
129 _buffer.append((char)_bits);
130 }
131 }
132 }
133
134 public int length()
135 {
136 return _buffer.length();
137 }
138
139 public void reset()
140 {
141 _buffer.setLength(0);
142 _more=0;
143 _bits=0;
144 }
145
146 public StringBuffer getStringBuffer()
147 {
148 if (_more!=0)
149 throw new IllegalStateException("!utf8");
150 return _buffer;
151 }
152
153 @Override
154 public String toString()
155 {
156 if (_more!=0)
157 throw new IllegalStateException("!utf8");
158 return _buffer.toString();
159 }
160 }