线程的五大状态及常用方法
线程的五大状态
- 创建--new Thread()
- 就绪--调用start()
- 阻塞--sleep()、wait()
- 运行--CPU调度
- 死亡--线程中断或结束，一旦进入死亡状态，就不能再次启动
线程的基本方法
线程stop方法
package com.edgar.lesson03;
//测试stop方法
//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destory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方法切换标志位，让线程停止
testStop.stop();
System.out.println("线程该停止了");
}
}
}
}
线程休眠sleep()
package com.edgar.lesson03;
import java.text.SimpleDateFormat;
import java.util.Date;
//线程休眠
//模拟倒计时
public class TestSleep {
public static void main(String[] args) {
//打印当前系统时间
Date date = new Date(System.currentTimeMillis());
while(true){
try {
Thread.sleep(1000);
System.out.println(new SimpleDateFormat("HH:mm:ss").format(date));
date = new Date(System.currentTimeMillis());//更新当前时间
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public static void tendown() throws InterruptedException {
int num=10;
while(true){
Thread.sleep(1000);
System.out.println(num--);
if(num<=0){
break;
}
}
}
}
线程礼让yeild()
package com.edgar.lesson03;
//线程礼让
//礼让不一定成功，看CPU心情
public class TestYield {
public static void main(String[] args) {
MyYield myYield = new MyYield();
new Thread(myYield,"a").start();
new Thread(myYield,"b").start();
}
}
class MyYield implements Runnable{
@Override
public void run() {
System.out.println(Thread.currentThread().getName()+"线程开始");
Thread.yield();
System.out.println(Thread.currentThread().getName()+"线程结束");
}
}
线程强行执行jion()
package com.edgar.lesson03;
//线程强行执行
public class TestJoin implements Runnable{
@Override
public void run() {
for (int i = 0; i < 1000; i++) {
System.out.println("线程"+i);
}
}
public static void main(String[] args) throws InterruptedException {
TestJoin testJoin = new TestJoin();
Thread thread = new Thread(testJoin);
thread.start();
for (int i = 0; i < 1000; i++) {
if(i==200){
thread.join();
}
System.out.println("主线程"+i);
}
}
}
线程优先级setPriority()
package com.edgar.lesson03;
//线程的优先级
//优先级高不一定先执行，看CPU心情
public class TestPriority {
public static void main(String[] args) {
System.out.println(Thread.currentThread().getName()+"--->"+Thread.currentThread().getPriority());
MyPriority myPriority = new MyPriority();
Thread t1 = new Thread(myPriority);
Thread t2 = new Thread(myPriority);
Thread t3 = new Thread(myPriority);
Thread t4 = new Thread(myPriority);
t1.start();
t2.setPriority(3);
t2.start();
t3.setPriority(7);
t3.start();
t4.setPriority(Thread.MAX_PRIORITY);
t4.start();
}
}
class MyPriority implements Runnable{
@Override
public void run() {
System.out.println(Thread.currentThread().getName()+"--->"+Thread.currentThread().getPriority());
}
}
测试线程的状态getState()
package com.edgar.lesson03;
//观察测试线程的状态
public class TestState {
public static void main(String[] args) throws InterruptedException {
Thread thread = new Thread(() -> {
for (int i = 0; i < 10; i++) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("///////////");
});
Thread.State state = thread.getState();
System.out.println(state);//NEW
thread.start();//启动线程
state = thread.getState();
System.out.println(state);//RUNNABLE
while(state!=Thread.State.TERMINATED){
Thread.sleep(100);
state = thread.getState();//更新状态
System.out.println(state);
}
}
}
守护线程setDaemon（）
package com.edgar.lesson03;
//守护线程：gc()、main()
public class TestDaemon {
public static void main(String[] args) {
God god = new God();
You you = new You();
Thread thread = new Thread(god);
Thread thread2 = new Thread(you);//用户线程
thread.setDaemon(true);//设置守护线程
thread.start();
thread2.start();
}
}
class God implements Runnable{
@Override
public void run() {
while (true){
System.out.println("上帝保佑着你");
}
}
}
class You implements Runnable{
@Override
public void run() {
for (int i = 0; i < 36500; i++) {
System.out.println("永远开心的活着");
}
System.out.println("你结束了生命！！");
}
}
高并发场景
多个线程对同一个资源进行操作会出现高并发场景
