Java中StopWatch的使用示例詳解
stopWatch 是org.springframework.util 包下的一個(gè)工具類,使用它可直觀的輸出代碼執(zhí)行耗時(shí),以及執(zhí)行時(shí)間百分比。
在未使用這個(gè)工具類之前,如果我們需要統(tǒng)計(jì)某段代碼的耗時(shí),我們會(huì)這樣寫:
public static void main(String[] args) throws InterruptedException {
test0();
}
public static void test0() throws InterruptedException {
long start = System.currentTimeMills();
// do something
Thread.sleep(100);
long end = System.currentTimeMills();
long start2 = System.currentTimeMills();
// do somethind
long end2 = System.currentTimeMills();
System.out.println("某某1執(zhí)行耗時(shí):" + (end -start));
System.out.println("某某2執(zhí)行耗時(shí):" + (end2 -start2));
}如果改用stopWatch 實(shí)現(xiàn)的一個(gè)示例
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 something
Thread.sleep(100);
sw.stop();
sw.start("task2");
// do someting
Thread.sleep(200);
sw.stop();
System.out.println("sw.prettyPrint()-------");
System.out.println(sw.prettyPrint());
}
}運(yùn)行結(jié)果如下:
sw.prettyPrint()------
StopWatch 'test': running time (millis) = 310
-----------------------------------------
ms % Task name
-----------------------------------------
00110 035% task1
00200 065% task2
通過start 與stop 方法分別記錄開始時(shí)間與結(jié)束時(shí)間,其中在記錄結(jié)束時(shí)間的時(shí)候,會(huì)維護(hù)一個(gè)鏈表類型的taskList 屬性,從而時(shí)該類可記錄多個(gè)任務(wù),最后的輸出頁僅僅是對(duì)之前的記錄信息做了一個(gè)統(tǒng)一的歸納輸出。
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 List<TaskInfo> 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("Can't start StopWatch: it's already running");
} else {
this.startTimeMillis = System.currentTimeMillis();
this.running = true;
this.currentTaskName = taskName;
}
}
public void stop() throws IllegalStateException {
if (!this.running) {
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.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: can't get last task interval");
} else {
return this.lastTaskInfo.getTimeMillis();
}
}
public String getLastTaskName() throws IllegalStateException {
if (this.lastTaskInfo == null) {
throw new IllegalStateException("No tasks run: can't 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: can't 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();
}
@Override
public 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;
}
}
}從代碼上可以看出, 其原理為使用LinkList 來承接歷史任務(wù),使用自身屬性來承接當(dāng)前的狀態(tài),調(diào)用start 的時(shí)候初始化自身狀態(tài),使用stop 的時(shí)候來結(jié)束當(dāng)前的狀態(tài)然后加入到LinkList中
到此這篇關(guān)于Java中StopWatch的使用詳解的文章就介紹到這了,更多相關(guān)Java StopWatch使用內(nèi)容請(qǐng)搜索腳本之家以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持腳本之家!
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