java如何计算响应时长rt

import com.google.common.base.Stopwatch;

开始计时

Stopwatch stopwatch = Stopwatch.createStarted();

停止计时

stopwatch.stop();

计算出来的rt就是 

stopwatch.elapsed(TimeUnit.MILLISECONDS)

日志输出样例

schedulingLogger.info("refresh[{}], gray:[{}], resultMap.size:[{}], elapsed(ms):[{}]",
    dbEventMessage.getDbEnum().getTableName(), gray, positionTagAndTerminalMap.size(), 
    stopwatch.elapsed(TimeUnit.MILLISECONDS));