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 26package jdk.internal.util.xml.impl; 27 28import java.io.Reader; 29import java.io.InputStream; 30import java.io.IOException; 31import 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 */ 45public class ReaderUTF8 extends Reader { 46 47 private InputStream is; 48 49 /** 50 * Constructor. 51 * 52 * @param is A byte input stream. 53 */ 54 public ReaderUTF8(InputStream is) { 55 this.is = is; 56 } 57 58 /** 59 * Reads characters into a portion of an array. 60 * 61 * @param cbuf Destination buffer. 62 * @param off Offset at which to start storing characters. 63 * @param len Maximum number of characters to read. 64 * @exception IOException If any IO errors occur. 65 * @exception UnsupportedEncodingException If UCS-4 character occur in the stream. 66 */ 67 public int read(char[] cbuf, int off, int len) throws IOException { 68 int num = 0; 69 int val; 70 while (num < len) { 71 if ((val = is.read()) < 0) { 72 return (num != 0) ? num : -1; 73 } 74 switch (val & 0xf0) { 75 case 0xc0: 76 case 0xd0: 77 cbuf[off++] = (char) (((val & 0x1f) << 6) | (is.read() & 0x3f)); 78 break; 79 80 case 0xe0: 81 cbuf[off++] = (char) (((val & 0x0f) << 12) 82 | ((is.read() & 0x3f) << 6) | (is.read() & 0x3f)); 83 break; 84 85 case 0xf0: // UCS-4 character 86 throw new UnsupportedEncodingException("UTF-32 (or UCS-4) encoding not supported."); 87 88 default: 89 cbuf[off++] = (char) val; 90 break; 91 } 92 num++; 93 } 94 return num; 95 } 96 97 /** 98 * Reads a single character. 99 * 100 * @return The character read, as an integer in the range 0 to 65535 101 * (0x00-0xffff), or -1 if the end of the stream has been reached. 102 * @exception IOException If any IO errors occur. 103 * @exception UnsupportedEncodingException If UCS-4 character occur in the stream. 104 */ 105 public int read() throws IOException { 106 int val; 107 if ((val = is.read()) < 0) { 108 return -1; 109 } 110 switch (val & 0xf0) { 111 case 0xc0: 112 case 0xd0: 113 val = ((val & 0x1f) << 6) | (is.read() & 0x3f); 114 break; 115 116 case 0xe0: 117 val = ((val & 0x0f) << 12) 118 | ((is.read() & 0x3f) << 6) | (is.read() & 0x3f); 119 break; 120 121 case 0xf0: // UCS-4 character 122 throw new UnsupportedEncodingException(); 123 124 default: 125 break; 126 } 127 return val; 128 } 129 130 /** 131 * Closes the stream. 132 * 133 * @exception IOException If any IO errors occur. 134 */ 135 public void close() throws IOException { 136 is.close(); 137 } 138} 139