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1 /* |
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2 * ==================================================================== |
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3 * Licensed to the Apache Software Foundation (ASF) under one |
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4 * or more contributor license agreements. See the NOTICE file |
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5 * distributed with this work for additional information |
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6 * regarding copyright ownership. The ASF licenses this file |
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7 * to you under the Apache License, Version 2.0 (the |
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8 * "License"); you may not use this file except in compliance |
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9 * with the License. You may obtain a copy of the License at |
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10 * |
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11 * http://www.apache.org/licenses/LICENSE-2.0 |
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12 * |
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13 * Unless required by applicable law or agreed to in writing, |
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14 * software distributed under the License is distributed on an |
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15 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
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16 * KIND, either express or implied. See the License for the |
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17 * specific language governing permissions and limitations |
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18 * under the License. |
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19 * ==================================================================== |
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20 * |
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21 * This software consists of voluntary contributions made by many |
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22 * individuals on behalf of the Apache Software Foundation. For more |
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23 * information on the Apache Software Foundation, please see |
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24 * <http://www.apache.org/>. |
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25 * |
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26 */ |
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27 |
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28 package ch.boye.httpclientandroidlib.message; |
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29 |
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30 import java.util.NoSuchElementException; |
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31 |
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32 import ch.boye.httpclientandroidlib.Header; |
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33 import ch.boye.httpclientandroidlib.HeaderIterator; |
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34 |
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35 /** |
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36 * Basic implementation of a {@link HeaderIterator}. |
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37 * |
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38 * @since 4.0 |
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39 */ |
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40 public class BasicHeaderIterator implements HeaderIterator { |
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41 |
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42 /** |
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43 * An array of headers to iterate over. |
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44 * Not all elements of this array are necessarily part of the iteration. |
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45 * This array will never be modified by the iterator. |
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46 * Derived implementations are expected to adhere to this restriction. |
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47 */ |
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48 protected final Header[] allHeaders; |
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49 |
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50 |
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51 /** |
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52 * The position of the next header in {@link #allHeaders allHeaders}. |
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53 * Negative if the iteration is over. |
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54 */ |
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55 protected int currentIndex; |
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56 |
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57 |
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58 /** |
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59 * The header name to filter by. |
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60 * <code>null</code> to iterate over all headers in the array. |
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61 */ |
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62 protected String headerName; |
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63 |
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64 |
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65 |
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66 /** |
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67 * Creates a new header iterator. |
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68 * |
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69 * @param headers an array of headers over which to iterate |
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70 * @param name the name of the headers over which to iterate, or |
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71 * <code>null</code> for any |
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72 */ |
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73 public BasicHeaderIterator(Header[] headers, String name) { |
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74 if (headers == null) { |
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75 throw new IllegalArgumentException |
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76 ("Header array must not be null."); |
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77 } |
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78 |
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79 this.allHeaders = headers; |
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80 this.headerName = name; |
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81 this.currentIndex = findNext(-1); |
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82 } |
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83 |
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84 |
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85 /** |
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86 * Determines the index of the next header. |
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87 * |
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88 * @param from one less than the index to consider first, |
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89 * -1 to search for the first header |
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90 * |
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91 * @return the index of the next header that matches the filter name, |
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92 * or negative if there are no more headers |
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93 */ |
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94 protected int findNext(int from) { |
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95 if (from < -1) |
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96 return -1; |
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97 |
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98 final int to = this.allHeaders.length-1; |
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99 boolean found = false; |
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100 while (!found && (from < to)) { |
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101 from++; |
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102 found = filterHeader(from); |
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103 } |
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104 return found ? from : -1; |
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105 } |
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106 |
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107 |
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108 /** |
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109 * Checks whether a header is part of the iteration. |
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110 * |
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111 * @param index the index of the header to check |
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112 * |
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113 * @return <code>true</code> if the header should be part of the |
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114 * iteration, <code>false</code> to skip |
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115 */ |
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116 protected boolean filterHeader(int index) { |
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117 return (this.headerName == null) || |
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118 this.headerName.equalsIgnoreCase(this.allHeaders[index].getName()); |
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119 } |
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120 |
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121 |
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122 // non-javadoc, see interface HeaderIterator |
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123 public boolean hasNext() { |
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124 return (this.currentIndex >= 0); |
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125 } |
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126 |
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127 |
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128 /** |
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129 * Obtains the next header from this iteration. |
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130 * |
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131 * @return the next header in this iteration |
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132 * |
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133 * @throws NoSuchElementException if there are no more headers |
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134 */ |
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135 public Header nextHeader() |
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136 throws NoSuchElementException { |
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137 |
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138 final int current = this.currentIndex; |
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139 if (current < 0) { |
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140 throw new NoSuchElementException("Iteration already finished."); |
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141 } |
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142 |
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143 this.currentIndex = findNext(current); |
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144 |
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145 return this.allHeaders[current]; |
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146 } |
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147 |
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148 |
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149 /** |
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150 * Returns the next header. |
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151 * Same as {@link #nextHeader nextHeader}, but not type-safe. |
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152 * |
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153 * @return the next header in this iteration |
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154 * |
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155 * @throws NoSuchElementException if there are no more headers |
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156 */ |
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157 public final Object next() |
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158 throws NoSuchElementException { |
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159 return nextHeader(); |
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160 } |
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161 |
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162 |
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163 /** |
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164 * Removing headers is not supported. |
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165 * |
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166 * @throws UnsupportedOperationException always |
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167 */ |
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168 public void remove() |
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169 throws UnsupportedOperationException { |
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170 |
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171 throw new UnsupportedOperationException |
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172 ("Removing headers is not supported."); |
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173 } |
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174 } |