java 计算代码耗时

 

使用System.currentTimeMillis()函数

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long startMs = System.currentTimeMillis(); TimeUnit.SECONDS.sleep(2); System.out.println("timeCost: " + (System.currentTimeMillis() - startMs));//2001

　　

使用System.nanoTime()函数

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long start = System.nanoTime(); TimeUnit.SECONDS.sleep(2); long finish = System.nanoTime(); long timeElapsed = finish - start; System.out.println("timeElapsed: " + timeElapsed);//2000132106

　　

在java8中使用Instant.now()函数

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Instant start = Instant.now(); TimeUnit.SECONDS.sleep(2); Instant finish = Instant.now(); long timeElapsed = Duration.between(start, finish).toMillis(); System.out.println("timeElapsed: " + timeElapsed);//2001

　　

使用apache.commons提供的StopWatch

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import org.apache.commons.lang3.time.StopWatch; import java.util.concurrent.TimeUnit; public class StopWatchTest {     public static void main(String[] args) throws InterruptedException {         StopWatch started = StopWatch.createStarted();         TimeUnit.SECONDS.sleep(2);         started.stop();         long time = started.getTime();         long nanoTime = started.getNanoTime();         long startTime = started.getStartTime();         System.out.println(time);         System.out.println(nanoTime);         System.out.println(startTime);     } }

　　

使用Spring 框架提供的StopWatch

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import com.alibaba.fastjson.JSON; import org.springframework.util.StopWatch; import java.util.concurrent.TimeUnit; public class StopWatchTest {     public static void main(String[] args) throws InterruptedException {         StopWatch stopWatch = new StopWatch();           stopWatch.start("function1");         TimeUnit.SECONDS.sleep(1); // 模拟业务代码         stopWatch.stop();           stopWatch.start("function2");         TimeUnit.SECONDS.sleep(1); // 模拟业务代码         stopWatch.stop();           System.out.println(JSON.toJSONString(stopWatch.getTaskInfo()));         System.out.println(stopWatch.prettyPrint());     } }