content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * 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.alibaba.nacos.common.utils;
  
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  
  /**
   * MD5 util.
   *
   * @author nacos
   */
  @SuppressWarnings("PMD.ClassNamingShouldBeCamelRule")
  public class MD5Utils {
  
      private MD5Utils() {
      }
      
      private static final char[] DIGITS_LOWER = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
              'e', 'f'};
      
      private static final ThreadLocal<MessageDigest> MESSAGE_DIGEST_LOCAL = ThreadLocal.withInitial(() -> {
          try {
              return MessageDigest.getInstance("MD5");
          } catch (NoSuchAlgorithmException e) {
              return null;
          }
      });
      
      /**
       * Calculate MD5 hex string.
       *
       * @param bytes byte arrays
       * @return MD5 hex string of input
       * @throws NoSuchAlgorithmException if can't load md5 digest spi.
       */
      public static String md5Hex(byte[] bytes) throws NoSuchAlgorithmException {
          try {
              MessageDigest messageDigest = MESSAGE_DIGEST_LOCAL.get();
              if (messageDigest != null) {
                  return encodeHexString(messageDigest.digest(bytes));
              }
              throw new NoSuchAlgorithmException("MessageDigest get MD5 instance error");
          } finally {
              MESSAGE_DIGEST_LOCAL.remove();
          }
      }
      
      /**
       * Calculate MD5 hex string with encode charset.
       *
       * @param value  value
       * @param encode encode charset of input
       * @return MD5 hex string of input
       */
      public static String md5Hex(String value, String encode) {
          try {
              return md5Hex(value.getBytes(encode));
          } catch (Exception e) {
              throw new RuntimeException(e);
          }
      }
      
      /**
       * Convert a byte array into a visible string.
       */
      public static String encodeHexString(byte[] bytes) {
          int l = bytes.length;
          
          char[] out = new char[l << 1];
          
          for (int i = 0, j = 0; i < l; i++) {
              out[j++] = DIGITS_LOWER[(0xF0 & bytes[i]) >>> 4];
              out[j++] = DIGITS_LOWER[0x0F & bytes[i]];
          }
          
          return new String(out);
      }
      
  }
  