Java计时新姿势StopWatch详解

public static void main(String[] args) {
  Long startTime = System.currentTimeMillis();
  doSomeThing();
  Long endTime = System.currentTimeMillis();
  Long elapsedTime = (endTime - startTime) / 1000;
  System.out.println("总共耗时：" + elapsedTime + "s");
}
// 用于模拟一些操作
private static void doSomeThing() {
  try {
    Thread.sleep(1000);
  } catch (InterruptedException e) {
    e.printStackTrace();
  }
}

<!-- spring核心包 -->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-core</artifactId>
  <version>${spring.version}</version>
</dependency>

public static void main(String[] args) {
  StopWatch clock = new StopWatch();

  clock.start("开始任务一");
  doSomeThing();
  clock.stop();

  clock.start("开始任务二");
  doSomeThing();
  clock.stop();

  System.out.println(clock.prettyPrint());
}

// 用于模拟一些操作
private static void doSomeThing() {
  try {
    Thread.sleep(1000);
  } catch (InterruptedException e) {
    e.printStackTrace();
  }
}

StopWatch '': running time (millis) = 2009
-----------------------------------------
ms   %   Task name
-----------------------------------------
01005 050% 开始任务一
01004 050% 开始任务二

  public void start(String taskName) throws IllegalStateException {
    if (this.currentTaskName != null) {
      throw new IllegalStateException("Can't start StopWatch: it's already running");
    } else {
      this.currentTaskName = taskName;
      this.startTimeMillis = System.currentTimeMillis();
    }
  }

  public void stop() throws IllegalStateException {
    if (this.currentTaskName == null) {
      throw new IllegalStateException("Can't stop StopWatch: it's not running");
    } else {
      long lastTime = System.currentTimeMillis() - this.startTimeMillis;
      this.totalTimeMillis += lastTime;
      this.lastTaskInfo = new StopWatch.TaskInfo(this.currentTaskName, lastTime);
      if (this.keepTaskList) {
        this.taskList.add(this.lastTaskInfo);
      }

      ++this.taskCount;
      this.currentTaskName = null;
    }
  }

  public String shortSummary() {
    return "StopWatch '" + this.getId() + "': running time (millis) = " + this.getTotalTimeMillis();
  }

  public String prettyPrint() {
    StringBuilder sb = new StringBuilder(this.shortSummary());
    sb.append('\n');
    if (!this.keepTaskList) {
      sb.append("No task info kept");
    } else {
      sb.append("-----------------------------------------\n");
      sb.append("ms   %   Task name\n");
      sb.append("-----------------------------------------\n");
      NumberFormat nf = NumberFormat.getNumberInstance();
      nf.setMinimumIntegerDigits(5);
      nf.setGroupingUsed(false);
      NumberFormat pf = NumberFormat.getPercentInstance();
      pf.setMinimumIntegerDigits(3);
      pf.setGroupingUsed(false);
      StopWatch.TaskInfo[] var4 = this.getTaskInfo();
      int var5 = var4.length;

      for(int var6 = 0; var6 < var5; ++var6) {
        StopWatch.TaskInfo task = var4[var6];
        sb.append(nf.format(task.getTimeMillis())).append(" ");
        sb.append(pf.format(task.getTimeSeconds() / this.getTotalTimeSeconds())).append(" ");
        sb.append(task.getTaskName()).append("\n");
      }
    }

    return sb.toString();
  }