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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