1 | /*
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2 | * Copyright 2003-2004 The Apache Software Foundation
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3 | *
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4 | * Licensed under the Apache License, Version 2.0 (the "License");
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5 | * you may not use this file except in compliance with the License.
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6 | * You may obtain a copy of the License at
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7 | *
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8 | * http://www.apache.org/licenses/LICENSE-2.0
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9 | *
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10 | * Unless required by applicable law or agreed to in writing, software
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11 | * distributed under the License is distributed on an "AS IS" BASIS,
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12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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13 | * See the License for the specific language governing permissions and
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14 | * limitations under the License.
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15 | *
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16 | */
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17 |
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18 | package org.apache.tools.ant.types.selectors.modifiedselector;
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19 |
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20 |
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21 | import java.io.File;
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22 | import java.io.FileInputStream;
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23 | import java.io.FileOutputStream;
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24 | import java.security.DigestInputStream;
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25 | import java.security.MessageDigest;
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26 | import java.security.NoSuchAlgorithmException;
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27 | import java.security.NoSuchProviderException;
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28 | import org.apache.tools.ant.BuildException;
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29 |
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30 |
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31 | /**
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32 | * Computes a 'hashvalue' for the content of file using
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33 | * java.security.MessageDigest.
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34 | * Use of this algorithm doesn't require any additional nested <param>s.
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35 | * Supported <param>s are:
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36 | * <table>
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37 | * <tr>
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38 | * <th>name</th><th>values</th><th>description</th><th>required</th>
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39 | * </tr>
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40 | * <tr>
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41 | * <td> algorithm.algorithm </td>
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42 | * <td> MD5 | SHA (default provider) </td>
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43 | * <td> name of the algorithm the provider should use </td>
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44 | * <td> no, defaults to MD5 </td>
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45 | * </tr>
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46 | * <tr>
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47 | * <td> algorithm.provider </td>
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48 | * <td> </td>
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49 | * <td> name of the provider to use </td>
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50 | * <td> no, defaults to <i>null</i> </td>
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51 | * </tr>
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52 | * </table>
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53 | *
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54 | * @version 2003-09-13
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55 | * @since Ant 1.6
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56 | */
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57 | public class DigestAlgorithm implements Algorithm {
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58 |
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59 |
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60 | // ----- member variables -----
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61 |
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62 |
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63 | /**
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64 | * MessageDigest algorithm to be used.
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65 | */
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66 | private String algorithm = "MD5";
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67 |
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68 | /**
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69 | * MessageDigest Algorithm provider
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70 | */
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71 | private String provider = null;
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72 |
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73 | /**
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74 | * Message Digest instance
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75 | */
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76 | private MessageDigest messageDigest = null;
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77 |
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78 | /**
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79 | * Size of the read buffer to use.
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80 | */
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81 | private int readBufferSize = 8 * 1024;
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82 |
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83 |
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84 | // ----- Algorithm-Configuration -----
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85 |
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86 |
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87 | /**
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88 | * Specifies the algorithm to be used to compute the checksum.
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89 | * Defaults to "MD5". Other popular algorithms like "SHA" may be used as well.
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90 | * @param algorithm the digest algorithm to use
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91 | */
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92 | public void setAlgorithm(String algorithm) {
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93 | this.algorithm = algorithm;
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94 | }
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95 |
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96 |
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97 | /**
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98 | * Sets the MessageDigest algorithm provider to be used
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99 | * to calculate the checksum.
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100 | * @param provider provider to use
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101 | */
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102 | public void setProvider(String provider) {
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103 | this.provider = provider;
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104 | }
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105 |
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106 |
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107 | /** Initialize the security message digest. */
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108 | public void initMessageDigest() {
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109 | if (messageDigest != null) {
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110 | return;
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111 | }
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112 |
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113 | if ((provider != null) && !"".equals(provider) && !"null".equals(provider)) {
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114 | try {
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115 | messageDigest = MessageDigest.getInstance(algorithm, provider);
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116 | } catch (NoSuchAlgorithmException noalgo) {
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117 | throw new BuildException(noalgo);
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118 | } catch (NoSuchProviderException noprovider) {
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119 | throw new BuildException(noprovider);
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120 | }
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121 | } else {
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122 | try {
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123 | messageDigest = MessageDigest.getInstance(algorithm);
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124 | } catch (NoSuchAlgorithmException noalgo) {
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125 | throw new BuildException(noalgo);
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126 | }
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127 | }
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128 | }
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129 |
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130 |
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131 | // ----- Logic -----
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132 |
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133 |
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134 | /**
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135 | * This algorithm doesn't need any configuration.
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136 | * Therefore it's always valid.
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137 | * @return <i>true</i> if all is ok, otherwise <i>false</i>.
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138 | */
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139 | public boolean isValid() {
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140 | return true;
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141 | }
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142 |
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143 |
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144 | /**
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145 | * Computes a value for a file content with the specified digest algorithm.
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146 | * @param file File object for which the value should be evaluated.
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147 | * @return The value for that file
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148 | */
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149 | // implementation adapted from ...taskdefs.Checksum, thanks to Magesh for hint
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150 | public String getValue(File file) {
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151 | initMessageDigest();
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152 | String checksum = null;
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153 | try {
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154 | if (!file.canRead()) {
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155 | return null;
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156 | }
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157 | FileInputStream fis = null;
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158 | FileOutputStream fos = null;
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159 | byte[] buf = new byte[readBufferSize];
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160 | try {
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161 | messageDigest.reset();
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162 | fis = new FileInputStream(file);
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163 | DigestInputStream dis = new DigestInputStream(fis,
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164 | messageDigest);
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165 | while (dis.read(buf, 0, readBufferSize) != -1) {
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166 | // do nothing
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167 | }
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168 | dis.close();
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169 | fis.close();
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170 | fis = null;
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171 | byte[] fileDigest = messageDigest.digest();
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172 | StringBuffer checksumSb = new StringBuffer();
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173 | for (int i = 0; i < fileDigest.length; i++) {
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174 | String hexStr = Integer.toHexString(0x00ff & fileDigest[i]);
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175 | if (hexStr.length() < 2) {
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176 | checksumSb.append("0");
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177 | }
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178 | checksumSb.append(hexStr);
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179 | }
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180 | checksum = checksumSb.toString();
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181 | } catch (Exception e) {
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182 | return null;
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183 | }
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184 | } catch (Exception e) {
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185 | return null;
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186 | }
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187 | return checksum;
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188 | }
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189 |
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190 |
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191 | /**
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192 | * Override Object.toString().
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193 | * @return some information about this algorithm.
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194 | */
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195 | public String toString() {
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196 | StringBuffer buf = new StringBuffer();
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197 | buf.append("<DigestAlgorithm:");
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198 | buf.append("algorithm=").append(algorithm);
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199 | buf.append(";provider=").append(provider);
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200 | buf.append(">");
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201 | return buf.toString();
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202 | }
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203 | }
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