code: public static String getContentTypeAttribute(String input, String name) {
          int begin;
          int end;
          int index = input.toUpperCase().indexOf(name.toUpperCase());
          if (index == -1) {
              return null;
          }
          index = index + name.length(); // positioned after the attribute name
          index = input.indexOf('=', index); // positioned at the '='
          if (index == -1) {
              return null;
          }
          index += 1; // positioned after the '='
          input = input.substring(index).trim();
  
          if (input.charAt(0) == '"') {
              // attribute value is a quoted string
              begin = 1;
              end = input.indexOf('"', begin);
              if (end == -1) {
                  return null;
              }
          } else {
              begin = 0;
              end = input.indexOf(';');
              if (end == -1) {
                  end = input.indexOf(' ');
              }
              if (end == -1) {
                  end = input.length();
              }
          }
          return input.substring(begin, end).trim();
      }
docs: Get the value associated with a content-type attribute.
  Syntax defined in RFC 2045, section 5.1.