code: @Override
      public String getUserAgent(){
          String[] uas = new String[]{"Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.157 Safari/537.36",
                  "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:42.0) Gecko/20100101 Firefox/42.0",
                  "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:42.0) Gecko/20100101 Firefox/38.0"
          };
          return uas[RandomUtils.nextInt(0,uas.length)]+" "+ RandomStringUtils.randomAlphanumeric(8);
      }
docs: UA库可以自行查找整理，这里仅为样例
  @return