创立线程的办法
- 继承Thread类
- 继承Thread类，重写run办法，通过线程类实例.start()办法开启线程。
public class TestThread1 extends Thread{
@override
public void run(){
System.out.println("线程run办法！");
}
public static void main(String){
new TestThread1().start();
}
}
-
实现Runnable接口
- 实现Runnable接口，重写run办法，通过new Thread(线程类实例).start()开启线程
- 举荐应用该形式，防止java的单继承局限性
public class TestThread2 implements Runnable{
@Override
public void run() {
System.out.println("线程run办法！");
}
public static void main(String[] args) {
new Thread(new TestThread2()).start();
}
}
- 实现Callable接口
-
实现Callable接口，重写call办法，call办法有返回值
-
启动形式：
- 创立执行服务
- 提交执行
- 获取后果
- 敞开服务
-
public class TestThread2 implements Callable{
@Override
public Boolean call() {
System.out.println("线程call办法！");
return true;
}
public static void main(String[] args) throws InterruptedException, ExecutionException {
TestThread2 t1 = new TestThread2();
TestThread2 t2 = new TestThread2();
TestThread2 t3 = new TestThread2();
//创立执行服务
ExecutorService ser = Executors.newFixedThreadPool(3);
//提交执行
Future<Boolean> r1 = ser.submit(t1);
Future<Boolean> r2 = ser.submit(t2);
Future<Boolean> r3 = ser.submit(t3);
//获取后果
boolean rs1 = r1.get();
boolean rs2 = r2.get();
boolean rs3 = r3.get();
//敞开服务
ser.shutdownNow();
}
线程同步
- 多个线程同时操作同一资源，线程不平安，变量值错乱
- 加锁
- 队列+锁(synchronized)
- synchronized默认锁this，能够显示指定锁的对象来批改
1. synchronized润饰办法，线程平安办法
public class TestThreadSafe {
public static void main(String[] args) {
BuyTicket bt1 = new BuyTicket();
Thread thread1 = new Thread(bt1,"张三");
Thread thread2 = new Thread(bt1,"李四");
Thread thread3 = new Thread(bt1,"黄牛");
thread1.start();
thread2.start();
thread3.start();
}
}
class BuyTicket implements Runnable{
private int ticketNumber = 10;
private boolean flag = true;
@Override
public void run() {
while(flag) {
try {
buy();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public synchronized void buy() throws InterruptedException {
//买票
if(ticketNumber <= 0){
System.out.println("票卖完了！");
flag = false;
return;
}
Thread.sleep(100);
//Thread.yield();
System.out.println(Thread.currentThread().getName() + "买到了一张票，还剩下"+(--ticketNumber) + "张票！");
}
}
2. synchronized润饰代码块，线程平安代码块
public class TestThreadSafe {
public static void main(String[] args) {
BuyTicket bt1 = new BuyTicket();
Thread thread1 = new Thread(bt1,"张三");
Thread thread2 = new Thread(bt1,"李四");
Thread thread3 = new Thread(bt1,"黄牛");
thread1.start();
thread2.start();
thread3.start();
}
}
class BuyTicket implements Runnable{
private int ticketNumber = 10;
private boolean flag = true;
@Override
public void run() {
while(flag) {
System.out.println(Thread.currentThread().getName() + "筹备买票" + flag);
try {
buy();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public void buy() throws InterruptedException {
synchronized(this){
//买票
if(ticketNumber <= 0){
flag = false;
System.out.println("票卖完了！");
return;
}
Thread.sleep(100);
//Thread.yield();
System.out.println(Thread.currentThread().getName() + "买到了一张票，还剩下"+(--ticketNumber) + "张票！");
}
}
}
3. 应用可反复锁ReentrantLock
import java.util.concurrent.locks.ReentrantLock;
public class TestLock {
public static void main(String[] args) {
BuyTicket bt1 = new BuyTicket();
Thread thread1 = new Thread(bt1,"张三");
Thread thread2 = new Thread(bt1,"李四");
Thread thread3 = new Thread(bt1,"黄牛");
thread1.start();
thread2.start();
thread3.start();
}
}
class BuyTicket implements Runnable{
private int ticketNumber = 1000;
private boolean flag = true;
//定义可反复锁
private final ReentrantLock lock = new ReentrantLock();
@Override
public void run() {
while(flag) {
try {
buy();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public void buy() throws InterruptedException {
lock.lock();
//买票
if(ticketNumber <= 0){
System.out.println("票卖完了！");
flag = false;
}else {
Thread.sleep(100);
//Thread.yield();
System.out.println(Thread.currentThread().getName() + "买到了一张票，还剩下"+(--ticketNumber) + "张票！");
}
lock.unlock();
}
}
-
死锁
- 两个以上的对象锁，每个线程相互占有对方须要的资源。造成死锁。
线程状态
- 新生状态（new）
- 就绪状态（start）
- 阻塞状态（sleep、wait、同步锁定）
- 运行状态
- 死亡状态 线程对象进入死亡状态后，将不能再次调用start()办法再次启动
线程（Thread类）办法
- setPriority(int newPriority) 更改线程优先级 newPriority从1到10
- static void sleep(long millis) 使以后正在执行的线程休眠指定毫秒，不会开释线程锁对象
- void join() 线程合并，期待该线程终止
- static void yield() 暂停以后正在执行的线程，执行其它线程
- void interrupt() 中断线程
- boolean isAlive() 该线程是否沉闷
守护线程
- setDaemon(true) : 设置为守护线程
- 线程分为用户线程和守护线程
- JVM虚拟机确保用户线程执行结束
- JVM虚拟机不必期待守护线程执行结束
eg：后盾记录操作日志，监控内存，垃圾回收期待
最初
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