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From j..@apache.org
Subject cvs commit: ant/src/main/org/apache/tools/ant/types/selectors/modifiedselector ChecksumAlgorithm.java
Date Sat, 10 Jul 2004 17:22:21 GMT
jhm         2004/07/10 10:22:21

  Added:       src/main/org/apache/tools/ant/types/selectors/modifiedselector
                        ChecksumAlgorithm.java
  Log:
  Forgot to add the Checksum
  
  Revision  Changes    Path
  1.1                  ant/src/main/org/apache/tools/ant/types/selectors/modifiedselector/ChecksumAlgorithm.java
  
  Index: ChecksumAlgorithm.java
  ===================================================================
  /*
   * Copyright  2003-2004 The Apache Software Foundation
   *
   *  Licensed under the Apache License, Version 2.0 (the "License");
   *  you may not use this file except in compliance with the License.
   *  You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS,
   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   *
   */
  
  package org.apache.tools.ant.types.selectors.modifiedselector;
  
  
  import java.util.zip.Checksum;
  import java.util.zip.CRC32;
  import java.util.zip.Adler32;
  import java.util.zip.CheckedInputStream;
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.BufferedInputStream;
  import java.security.NoSuchAlgorithmException;
  import org.apache.tools.ant.BuildException;
  
  
  /**
   * Computes a 'checksum' for the content of file using
   * java.util.zip.CRC32 and java.util.zip.Adler32.
   * Use of this algorithm doesn't require any additional nested <param>s.
   * Supported <param>s are:
   * <table>
   * <tr>
   *   <th>name</th><th>values</th><th>description</th><th>required</th>
   * </tr>
   * <tr>
   *   <td> algorithm.algorithm </td>
   *   <td> ADLER | CRC ( default ) </td>
   *   <td> name of the algorithm the checksum should use </td>
   *   <td> no, defaults to CRC </td>
   * </tr>
   * </table>
   *
   * @version 2004-06-17
   * @since  Ant 1.7
   */
  public class ChecksumAlgorithm implements Algorithm {
  
  
      // -----  member variables  -----
  
  
      /**
       * Checksum algorithm to be used.
       */
      private String algorithm = "CRC";
  
      /**
       * Checksum interface instance
       */
      private Checksum checksum = null;
  
  
      // -----  Algorithm-Configuration  -----
  
  
      /**
       * Specifies the algorithm to be used to compute the checksum.
       * Defaults to "CRC". Other popular algorithms like "ADLER" may be used as well.
       * @param algorithm the digest algorithm to use
       */
      public void setAlgorithm(String algorithm) {
          this.algorithm = algorithm;
      }
  
  
      /** Initialize the checksum interface. */
      public void initChecksum() {
          if (checksum != null) {
              return;
          }
          if ("CRC".equalsIgnoreCase(algorithm)) {
              checksum = new CRC32();
          } else if ("ADLER".equalsIgnoreCase(algorithm)) {
              checksum = new Adler32();
          } else {
              throw new BuildException(new NoSuchAlgorithmException());
          }
      }
  
  
      // -----  Logic  -----
  
  
      /**
       * This algorithm supports only CRC and Adler.
       * @return <i>true</i> if all is ok, otherwise <i>false</i>.
       */
      public boolean isValid() {
          return "CRC".equalsIgnoreCase(algorithm) || "ADLER".equalsIgnoreCase(algorithm);
      }
  
  
      /**
       * Computes a value for a file content with the specified checksum algorithm.
       * @param file    File object for which the value should be evaluated.
       * @return        The value for that file
       */
      public String getValue(File file) {
          initChecksum();
          String rval = null;
  
          try {
              if (file.canRead()) {
                   checksum.reset();
                   FileInputStream fis = new FileInputStream(file);
                   CheckedInputStream check = new CheckedInputStream(fis, checksum);
                   BufferedInputStream in = new BufferedInputStream(check);
                   while (in.read() != -1) {
                       // Read the file
                   }
                   rval = Long.toString(check.getChecksum().getValue());
                   in.close();
              }
          } catch (Exception e) {
              rval = null;
          }
          return rval;
      }
  
  
      /**
       * Override Object.toString().
       * @return some information about this algorithm.
       */
      public String toString() {
          StringBuffer buf = new StringBuffer();
          buf.append("<ChecksumAlgorithm:");
          buf.append("algorithm=").append(algorithm);
          buf.append(">");
          return buf.toString();
      }
  }
  
  

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