content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.aliyun.oss.utils;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.UnsupportedEncodingException;
  import java.security.DigestInputStream;
  import java.security.MessageDigest;
  
  public class StreamUtils {
      
      public static String readContent(InputStream contentStream, String charset)
              throws UnsupportedEncodingException{
  
          InputStreamReader reader =
                  new InputStreamReader(contentStream, charset);
          BufferedReader br = new BufferedReader(reader);
          StringBuilder sb = new StringBuilder();
          String line = null;
          try {
              while((line = br.readLine()) != null){
                  sb.append(line);
              }
              return sb.toString();
          } catch (IOException e) {
              return null;
          }
          finally{
              try {
                  br.close();
                  reader.close();
              } catch (IOException e) {
              }
          }
      }
  
      public static String calculateMD5(InputStream in) throws Exception {
  
          DigestInputStream ds = new DigestInputStream(in, MessageDigest.getInstance("MD5"));
          while (ds.read() != -1) {
          }
  
          byte[] md5bytes = ds.getMessageDigest().digest();
  
          StringBuilder sb = new StringBuilder();
          for (byte md5byte : md5bytes) {
              String hexBiChars = String.format("%02x", md5byte);
              sb.append(hexBiChars);
          }
  
          return sb.toString();
      }
  }
  