合肥网站制作前3名的,宁波网站优化公司推荐,功能型类的网站,北京住房和建设部网站首页StopWatch的使用 【一】简介【1】不使用StopWatch的案例【2】使用StopWatch的案例 【二】源码分析【1】查看源码【2】StopWatch优缺点#xff1a; 【一】简介
stopWatch是org.springframework.util包下的一个工具类#xff0c;使用它可直观的输出代码执行耗时#xff0c;以… StopWatch的使用 【一】简介【1】不使用StopWatch的案例【2】使用StopWatch的案例 【二】源码分析【1】查看源码【2】StopWatch优缺点 【一】简介
stopWatch是org.springframework.util包下的一个工具类使用它可直观的输出代码执行耗时以及执行时间百分比
【1】不使用StopWatch的案例
在未使用这个工具类之前如果我们需要统计某段代码的耗时我们会这样写
public static void main(String[] args) throws InterruptedException {test0();
}public static void test0() throws InterruptedException {long start System.currentTimeMillis();// do somethingThread.sleep(100);long end System.currentTimeMillis();long start2 System.currentTimeMillis();// do somethingThread.sleep(200);long end2 System.currentTimeMillis();System.out.println(某某1执行耗时: (end - start));System.out.println(某某2执行耗时: (end2 - start2));
}执行结果如下
某某1执行耗时:100
某某2执行耗时:200【2】使用StopWatch的案例
public class StopWatchDemo {public static void main(String[] args) throws InterruptedException {test1();}public static void test1() throws InterruptedException {StopWatch sw new StopWatch(test);sw.start(task1);// do somethingThread.sleep(100);sw.stop();sw.start(task2);// do somethingThread.sleep(200);sw.stop();System.out.println(sw.prettyPrint()~~~~~~~~~~~~~~~~~);System.out.println(sw.prettyPrint());}}运行结果如下
sw.prettyPrint()~~~~~~~~~~~~~~~~~
StopWatch test: running time (millis) 310
-----------------------------------------
ms % Task name
-----------------------------------------
00110 035% task1
00200 065% task2除此之外还有以下两个方法shortSummary,getTotalTimeMillis查看程序执行时间。
System.out.println(sw.shortSummary()~~~~~~~~~~~~~~~~~);
System.out.println(sw.shortSummary());
System.out.println(sw.getTotalTimeMillis()~~~~~~~~~~~~~~~~~);
System.out.println(sw.getTotalTimeMillis());
运行结果
sw.shortSummary()~~~~~~~~~~~~~~~~~
StopWatch test: running time (millis) 308
sw.getTotalTimeMillis()~~~~~~~~~~~~~~~~~
308【二】源码分析
【1】查看源码
其实以上内容在该工具类中实现也极其简单通过start与stop方法分别记录开始时间与结束时间其中在记录结束时间时会维护一个链表类型的tasklist属性从而使该类可记录多个任务最后的输出也仅仅是对之前记录的信息做了一个统一的归纳输出从而使结果更加直观的展示出来。 我们来看下源码
import java.text.NumberFormat;
import java.util.LinkedList;
import java.util.List;public class StopWatch {private final String id;private boolean keepTaskList true;private final ListTaskInfo taskList new LinkedList();private long startTimeMillis;private boolean running;private String currentTaskName;private StopWatch.TaskInfo lastTaskInfo;private int taskCount;private long totalTimeMillis;public StopWatch() {this.id ;}public StopWatch(String id) {this.id id;}public void setKeepTaskList(boolean keepTaskList) {this.keepTaskList keepTaskList;}public void start() throws IllegalStateException {this.start();}public void start(String taskName) throws IllegalStateException {if (this.running) {throw new IllegalStateException(Cant start StopWatch: its already running);} else {this.startTimeMillis System.currentTimeMillis();this.running true;this.currentTaskName taskName;}}public void stop() throws IllegalStateException {if (!this.running) {throw new IllegalStateException(Cant stop StopWatch: its 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.running false;this.currentTaskName null;}}public boolean isRunning() {return this.running;}public long getLastTaskTimeMillis() throws IllegalStateException {if (this.lastTaskInfo null) {throw new IllegalStateException(No tasks run: cant get last task interval);} else {return this.lastTaskInfo.getTimeMillis();}}public String getLastTaskName() throws IllegalStateException {if (this.lastTaskInfo null) {throw new IllegalStateException(No tasks run: cant get last task name);} else {return this.lastTaskInfo.getTaskName();}}public StopWatch.TaskInfo getLastTaskInfo() throws IllegalStateException {if (this.lastTaskInfo null) {throw new IllegalStateException(No tasks run: cant get last task info);} else {return this.lastTaskInfo;}}public long getTotalTimeMillis() {return this.totalTimeMillis;}public double getTotalTimeSeconds() {return (double) this.totalTimeMillis / 1000.0D;}public int getTaskCount() {return this.taskCount;}public StopWatch.TaskInfo[] getTaskInfo() {if (!this.keepTaskList) {throw new UnsupportedOperationException(Task info is not being kept!);} else {return (StopWatch.TaskInfo[]) this.taskList.toArray(new StopWatch.TaskInfo[this.taskList.size()]);}}public String shortSummary() {return StopWatch this.id : 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[] var7;int var6 (var7 this.getTaskInfo()).length;for (int var5 0; var5 var6; var5) {StopWatch.TaskInfo task var7[var5];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();}Overridepublic String toString() {StringBuilder sb new StringBuilder(this.shortSummary());if (this.keepTaskList) {StopWatch.TaskInfo[] var5;int var4 (var5 this.getTaskInfo()).length;for (int var3 0; var3 var4; var3) {StopWatch.TaskInfo task var5[var3];sb.append(; [).append(task.getTaskName()).append(] took ).append(task.getTimeMillis());long percent Math.round(100.0D * task.getTimeSeconds() / this.getTotalTimeSeconds());sb.append( ).append(percent).append(%);}} else {sb.append(; no task info kept);}return sb.toString();}public static final class TaskInfo {private final String taskName;private final long timeMillis;TaskInfo(String taskName, long timeMillis) {this.taskName taskName;this.timeMillis timeMillis;}public String getTaskName() {return this.taskName;}public long getTimeMillis() {return this.timeMillis;}public double getTimeSeconds() {return (double) this.timeMillis / 1000.0D;}}}【2】StopWatch优缺点
优点 1.spring自带工具类可直接使用 2.代码实现简单使用更简单 3.统一归纳展示每项任务耗时与占用总时间的百分比展示结果直观性能消耗相对较小并且最大程度的保证了start与stop之间的时间记录的准确性 4.可在start时直接指定任务名字从而更加直观的显示记录结果。
缺点 1.一个StopWatch实例一次只能开启一个task不能同时start多个task并且在该task未stop之前不能,start一个新的task必须在该task stop之后才能开启新的task若要一次开启多个需要new不同的StopWatch实例 3.代码侵入式使用需要改动多处代码。
