code: private String generateXml(String encrypt, String signature, String timestamp, String nonce) {
      String format =
          "<xml>\n"
              + "<Encrypt><![CDATA[%1$s]]></Encrypt>\n"
              + "<MsgSignature><![CDATA[%2$s]]></MsgSignature>\n"
              + "<TimeStamp>%3$s</TimeStamp>\n"
              + "<Nonce><![CDATA[%4$s]]></Nonce>\n"
              + "</xml>";
      return String.format(format, encrypt, signature, timestamp, nonce);
    }
docs: 生成xml消息
  
  @param encrypt   加密后的消息密文
  @param signature 安全签名
  @param timestamp 时间戳
  @param nonce     随机字符串
  @return 生成的xml字符串