import org.apache.commons.codec.digest.DigestUtils;

//导入org.apache.commons.codec.digest.DigestUtils;

String timeStamp = "${__time(/1000,)}";

//定义时间timeStamp=服务器时间;

String randomStr = "${__Random(11111111,99999999)}";

//定义时间随机数=8位1-9的随机数;

String tmp = timeStamp + randomStr + "xxxxx";

//定义tmp=时间timeStamp，8位随机数和密码xxxxx;

log.info("timeStamp:" + timeStamp);

//打印timeStamp;

log.info("randomStr:" + randomStr);

//打印randomStr;

log.info("tmp:" + tmp);

//打印tmp;

//String un = DigestUtils.sha1Hex(tmp);

//定义un=哈希sha1加密的tmp;

//log.info("un:" + un);

//打印un;

String signature = DigestUtils.md5Hex (DigestUtils.sha1Hex(tmp)).toUpperCase();

//定义signature==哈希sha1加密的tmp然后再进行md5加密后进行大写;

log.info("signature:" + signature);

//打印signature;

vars.put("signature", signature);

//打印signature;

vars.put("timeStamp", timeStamp);

//打印timeStamp;

vars.put("randomStr", randomStr);

//打印randomStr;

注意固定密码需要引号引起来

至于这个是放在请求头还是，参数，还是body就看具体的接口定义了。