content: /*******************************************************************************
   * Copyright 2011-2013 Sergey Tarasevich
   *
   * 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 com.nostra13.universalimageloader.cache.disc.naming;
  
  import com.nostra13.universalimageloader.utils.L;
  
  import java.math.BigInteger;
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  
  /**
   * Names image file as MD5 hash of image URI
   *
   * @author Sergey Tarasevich (nostra13[at]gmail[dot]com)
   * @since 1.4.0
   */
  public class Md5FileNameGenerator implements FileNameGenerator {
  
  	private static final String HASH_ALGORITHM = "MD5";
  	private static final int RADIX = 10 + 26; // 10 digits + 26 letters
  
  	@Override
  	public String generate(String imageUri) {
  		byte[] md5 = getMD5(imageUri.getBytes());
  		BigInteger bi = new BigInteger(md5).abs();
  		return bi.toString(RADIX);
  	}
  
  	private byte[] getMD5(byte[] data) {
  		byte[] hash = null;
  		try {
  			MessageDigest digest = MessageDigest.getInstance(HASH_ALGORITHM);
  			digest.update(data);
  			hash = digest.digest();
  		} catch (NoSuchAlgorithmException e) {
  			L.e(e);
  		}
  		return hash;
  	}
  }
  