5、线程状态
1.线程五大状态:
2.线程方法
2.1停止线程
案例
package com.xing.demo03;
/**
* 测试stop
* 1.建议线程正常停止-->利用次数,不建议死循环
* 2.建议使用标志位-->设置一个标志位
* 3.不要使用stop或者destroy等过时或者JDK不建议使用的方法
*/
public class TestStop implements Runnable {
// 1. 设置一个标志位
private boolean flag = true;
@Override
public void run() {
int i = 0;
while (flag) {
System.out.println("run...Thread" + i++);
}
}
// 2. 设置一个公开的方法停止线程,转换标志位
public void stop() {
this.flag = false;
}
public static void main(String[] args) {
TestStop testStop = new TestStop();
new Thread(testStop).start();
for (int i = 0; i < 1000; i++) {
System.out.println("main..." + i);
if (i == 900) {
//调用stop()切换标志位,让线程终止
testStop.stop();
System.out.println("该线程停止了");
}
}
}
}
2.2线程休眠（阻塞）
案例
package com.xing.demo03;
/**
* 模拟网络延迟:放大问题的发生性
*/
public class TestSleep implements Runnable {
//票数
private int ticketNums = 10;
@Override
public void run() {
while (true) {
if (ticketNums <= 0) {
break;
}
//捕获异常
try {
Thread.sleep(200);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName() + "--->拿到了第" + ticketNums-- + "张票");
}
}
public static void main(String[] args) {
TestSleep ticket = new TestSleep();
new Thread(ticket, "小红").start();
new Thread(ticket, "老师").start();
new Thread(ticket, "黄牛1").start();
}
}
案例2
package com.xing.demo03;
/**
* 模拟倒计时
*/
public class TestSleep2 {
public static void main(String[] args) {
try {
tenDown();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
//模拟倒计时
public static void tenDown() throws InterruptedException {
int num = 10; //10秒
while (true) {
Thread.sleep(1000); //每一秒钟跑一次
System.out.println(num--);
if (num <= 0) {
break;
}
}
}
}
案例3
package com.xing.demo03;
import java.text.SimpleDateFormat;
import java.util.Date;
/**
* 每一秒获取当前时间
*/
public class TestSleep3 {
public static void main(String[] args) {
//获取系统当前时间
Date startTime = new Date(System.currentTimeMillis());
while (true) {
try {
Thread.sleep(1000);
System.out.println(new SimpleDateFormat("HH:mm:ss").format(startTime));
//更新系统时间
startTime = new Date(System.currentTimeMillis());
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
2.3线程礼让
案例
package com.xing.demo03;
/**
* 测试礼让线程
* 礼让不一定成功,看cpu心情
*/
public class TestYield {
public static void main(String[] args) {
MyYeild myYeild = new MyYeild();
new Thread(myYeild, "a").start();
new Thread(myYeild, "b").start();
}
}
class MyYeild implements Runnable {
@Override
public void run() {
System.out.println(Thread.currentThread().getName() + "线程开始执行");
Thread.yield();//礼让
System.out.println(Thread.currentThread().getName() + "线程停止执行");
}
}
礼让成功，否则a线程执行完才执行b线程
礼让失败
2.4线程插队
案例
package com.xing.demo03;
/**
* 测试join
* 插队
*/
public class TestJoin implements Runnable {
@Override
public void run() {
for (int i = 0; i < 3; i++) {
System.out.println("线程vip" + i);
}
}
public static void main(String[] args) throws InterruptedException {
//启动我们的线程
TestJoin testJoin = new TestJoin();
Thread thread = new Thread(testJoin);
thread.start();
//主线程
for (int i = 0; i < 500; i++) {
if (i == 200) {
thread.join();//插队
}
System.out.println("main" + i);
}
}
}
3.线程状态观测
实现
package com.xing.demo03;
/**
* 观察测试线程状态
*/
public class TestState {
public static void main(String[] args) throws InterruptedException {
Thread thread = new Thread(() -> {
for (int i = 0; i < 5; i++) {
try {
Thread.sleep(1000); //这时是阻塞状态
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("//");
});
//观察状态
Thread.State state = thread.getState();
System.out.println(state);
//观察启动后
thread.start();// 启动线程
state = thread.getState();
System.out.println(state);//Run
while (state != Thread.State.TERMINATED) {//只要现成不终止,就一直输出状态
Thread.sleep(100);
state = thread.getState();//更新线程状态
System.out.println(state);
}
//死亡后的线程不能再启动了,启动会报异常
//thread.start();
}
}
4.线程优先级
-
Java提供一个线程调度器来监控程序中启动后进入就绪状态的所有线程，线程调度器按照优先级决定应该调度哪个线程来执行。
-
线程的优先级用数字表示，范围从1~10.
-
Thread.MIN_PRIORITY = 1;
-
Thread.MAX_PRIORITY = 10;
-
Thread.NORM_PRIORITY = 5;
-
-
使用以下方式改变或获取优先级
-
getPriority()
-
setPriority(int xxx)
-
-
优先级的设定建议在start()调度前
-
优先级低只是意味着获得调度的概率低，并不是优先级低就不会被调用了，这都是看CPU的调度
数字越大优先级越高，但是优先级高的不一定先执行，只是先执行的概率大
实现
package com.xing.demo03;
/**
* 线程优先级
*/
public class TestPriority{
public static void main(String[] args) {
//主线程默认优先级
System.out.println(Thread.currentThread().getName()+"-->"+Thread.currentThread().getPriority());
MyPriority myPriority = new MyPriority();
Thread thread1 = new Thread(myPriority);
Thread thread2 = new Thread(myPriority);
Thread thread3 = new Thread(myPriority);
Thread thread4 = new Thread(myPriority);
Thread thread5 = new Thread(myPriority);
//先设置优先级,再启动
thread1.start();//没有设置
//设置优先级
thread2.setPriority(1);
thread2.start();
//设置优先级
thread3.setPriority(4);
thread3.start();
//设置优先级
thread4.setPriority(Thread.MAX_PRIORITY);//MAX_PRIORITY=10
thread4.start();
//设置优先级
thread5.setPriority(8);
thread5.start();
}
}
class MyPriority implements Runnable{
@Override
public void run() {
//打印线程优先级
System.out.println(Thread.currentThread().getName()+"-->"+Thread.currentThread().getPriority());
}
}
5.守护(daemon)线程
-
线程分为用户线程和守护线程
-
虚拟机必须确保用户线程执行完毕
-
虚拟机不用等待守护线程执行完毕
-
守护线程如,后台记录操作日志,监控内存,垃圾回收等待..
实现
package com.xing.demo03;
/**
* 测试守护线程
* 上帝守护你
*/
public class TestDaemon {
//主线程
public static void main(String[] args) {
God god = new God();
You you = new You();
Thread thread = new Thread(god);
//默认false表示是用户线程,正常的线程都是用户线程...
thread.setDaemon(true);//true 变为守护线程
//上帝守护线程启动
thread.start();//虚拟机不用等待守护线程执行完毕
//你 用户线程启动
new Thread(you).start();//虚拟机必须确保用户线程执行完毕
}
}
//上帝
class God implements Runnable{
@Override
public void run() {
while (true){
System.out.println("上帝保佑着你");
}
}
}
//你
class You implements Runnable{
@Override
public void run() {
for (int i = 0; i < 36500; i++) {
System.out.println("你一生都开心的活着");
}
System.out.println("====goodbye!world====");
}
}
