code: public static String lowerWord(CharSequence cs, char c) {
          StringBuilder sb = new StringBuilder();
          int len = cs.length();
          for (int i = 0; i < len; i++) {
              char ch = cs.charAt(i);
              if (Character.isUpperCase(ch)) {
                  if (i > 0)
                      sb.append(c);
                  sb.append(Character.toLowerCase(ch));
              } else {
                  sb.append(ch);
              }
          }
          return sb.toString();
      }
docs: 将一个字符串由驼峰式命名变成分割符分隔单词
  <p>
  
  <pre>
  lowerWord("helloWorld", '-') => "hello-world"
  </pre>
  
  @param cs
  字符串
  @param c
  分隔符
  @return 转换后字符串