1 | /**************************************************************** |
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2 | * Licensed to the Apache Software Foundation (ASF) under one * |
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3 | * or more contributor license agreements. See the NOTICE file * |
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4 | * distributed with this work for additional information * |
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5 | * regarding copyright ownership. The ASF licenses this file * |
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6 | * to you under the Apache License, Version 2.0 (the * |
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7 | * "License"); you may not use this file except in compliance * |
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8 | * with the License. You may obtain a copy of the License at * |
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9 | * * |
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10 | * http://www.apache.org/licenses/LICENSE-2.0 * |
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11 | * * |
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12 | * Unless required by applicable law or agreed to in writing, * |
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13 | * software distributed under the License is distributed on an * |
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14 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * |
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15 | * KIND, either express or implied. See the License for the * |
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16 | * specific language governing permissions and limitations * |
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17 | * under the License. * |
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18 | ****************************************************************/ |
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19 | |
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20 | package org.apache.james.mime4j.util; |
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21 | |
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22 | import java.nio.charset.Charset; |
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23 | import java.nio.charset.IllegalCharsetNameException; |
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24 | import java.nio.charset.UnsupportedCharsetException; |
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25 | |
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26 | /** |
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27 | * Utility class for working with character sets. |
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28 | */ |
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29 | public class CharsetUtil { |
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30 | |
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31 | /** carriage return - line feed sequence */ |
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32 | public static final String CRLF = "\r\n"; |
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33 | |
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34 | /** US-ASCII CR, carriage return (13) */ |
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35 | public static final int CR = '\r'; |
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36 | |
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37 | /** US-ASCII LF, line feed (10) */ |
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38 | public static final int LF = '\n'; |
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39 | |
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40 | /** US-ASCII SP, space (32) */ |
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41 | public static final int SP = ' '; |
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42 | |
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43 | /** US-ASCII HT, horizontal-tab (9) */ |
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44 | public static final int HT = '\t'; |
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45 | |
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46 | public static final Charset US_ASCII = Charset.forName("US-ASCII"); |
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47 | |
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48 | public static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1"); |
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49 | |
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50 | public static final Charset UTF_8 = Charset.forName("UTF-8"); |
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51 | |
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52 | public static final Charset DEFAULT_CHARSET = US_ASCII; |
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53 | |
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54 | /** |
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55 | * Returns <code>true</code> if the specified character falls into the US |
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56 | * ASCII character set (Unicode range 0000 to 007f). |
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57 | * |
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58 | * @param ch |
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59 | * character to test. |
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60 | * @return <code>true</code> if the specified character falls into the US |
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61 | * ASCII character set, <code>false</code> otherwise. |
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62 | */ |
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63 | public static boolean isASCII(char ch) { |
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64 | return (0xFF80 & ch) == 0; |
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65 | } |
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66 | |
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67 | /** |
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68 | * Returns <code>true</code> if the specified string consists entirely of |
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69 | * US ASCII characters. |
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70 | * |
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71 | * @param s |
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72 | * string to test. |
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73 | * @return <code>true</code> if the specified string consists entirely of |
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74 | * US ASCII characters, <code>false</code> otherwise. |
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75 | */ |
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76 | public static boolean isASCII(final String s) { |
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77 | if (s == null) { |
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78 | throw new IllegalArgumentException("String may not be null"); |
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79 | } |
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80 | final int len = s.length(); |
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81 | for (int i = 0; i < len; i++) { |
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82 | if (!isASCII(s.charAt(i))) { |
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83 | return false; |
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84 | } |
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85 | } |
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86 | return true; |
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87 | } |
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88 | |
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89 | /** |
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90 | * Returns <code>true</code> if the specified character is a whitespace |
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91 | * character (CR, LF, SP or HT). |
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92 | * |
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93 | * @param ch |
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94 | * character to test. |
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95 | * @return <code>true</code> if the specified character is a whitespace |
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96 | * character, <code>false</code> otherwise. |
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97 | */ |
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98 | public static boolean isWhitespace(char ch) { |
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99 | return ch == SP || ch == HT || ch == CR || ch == LF; |
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100 | } |
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101 | |
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102 | /** |
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103 | * Returns <code>true</code> if the specified string consists entirely of |
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104 | * whitespace characters. |
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105 | * |
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106 | * @param s |
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107 | * string to test. |
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108 | * @return <code>true</code> if the specified string consists entirely of |
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109 | * whitespace characters, <code>false</code> otherwise. |
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110 | */ |
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111 | public static boolean isWhitespace(final String s) { |
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112 | if (s == null) { |
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113 | throw new IllegalArgumentException("String may not be null"); |
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114 | } |
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115 | final int len = s.length(); |
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116 | for (int i = 0; i < len; i++) { |
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117 | if (!isWhitespace(s.charAt(i))) { |
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118 | return false; |
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119 | } |
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120 | } |
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121 | return true; |
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122 | } |
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123 | |
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124 | /** |
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125 | * Returns a {@link Charset} instance if character set with the given name |
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126 | * is recognized and supported by Java runtime. Returns <code>null</code> |
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127 | * otherwise. |
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128 | * <p/> |
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129 | * This method is a wrapper around {@link Charset#forName(String)} method |
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130 | * that catches {@link IllegalCharsetNameException} and |
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131 | * {@link UnsupportedCharsetException} and returns <code>null</code>. |
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132 | */ |
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133 | public static Charset lookup(final String name) { |
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134 | if (name == null) { |
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135 | return null; |
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136 | } |
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137 | try { |
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138 | return Charset.forName(name); |
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139 | } catch (IllegalCharsetNameException ex) { |
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140 | return null; |
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141 | } catch (UnsupportedCharsetException ex) { |
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142 | return null; |
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143 | } |
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144 | } |
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145 | |
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146 | } |
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