content: /*
   * 微信公众平台(JAVA) SDK
   *
   * Copyright (c) 2014, Ansitech Network Technology Co.,Ltd All rights reserved.
   * 
   * http://www.weixin4j.org/
   *
   * 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.weixin4j.util;
  
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  
  /**
   * SHA1算法
   *
   * @author yangqisheng
   * @since 0.0.1
   */
  public final class SHA1 {
  
      private static final char[] HEX_DIGITS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
  
      /**
       * Takes the raw bytes from the digest and formats them correct.
       *
       * @param bytes the raw bytes from the digest.
       * @return the formatted bytes.
       */
      private static String getFormattedText(byte[] bytes) {
          int len = bytes.length;
          StringBuilder buf = new StringBuilder(len * 2);
          // 把密文转换成十六进制的字符串形式
          for (int j = 0; j < len; j++) {
              buf.append(HEX_DIGITS[(bytes[j] >> 4) & 0x0f]);
              buf.append(HEX_DIGITS[bytes[j] & 0x0f]);
          }
          return buf.toString();
      }
  
      public static String encode(String str) {
          if (str == null) {
              return null;
          }
          try {
              MessageDigest messageDigest = MessageDigest.getInstance("SHA1");
              messageDigest.update(str.getBytes());
              return getFormattedText(messageDigest.digest());
          } catch (NoSuchAlgorithmException e) {
              throw new RuntimeException(e);
          }
      }
  }
  