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（JAVA）线程

news 2025/8/9 1:25:19

线程的创建

方式一：Thread

public class dome {public static void main(String[] args) {MyThread myThread = new MyThread();myThread.start();for(int i=1;i<=5;i++){System.out.println("主线程"+i);}}
}

public class MyThread extends Thread{@Overridepublic void run() {for(int i=0;i<5;i++){System.out.println("MyThread线程"+i);}}
}

方式二：Runnable

public class dome {public static void main(String[] args) {Runnable r = new MyRunnable();new Thread(r).start();for(int i=1;i<=5;i++){System.out.println("主线程"+i);}}
}

public class MyRunnable implements Runnable{@Overridepublic void run() {for(int i=1;i<=5;i++){System.out.println("MyRunnable"+i);}}
}

方式三：Callable

public class dome {public static void main(String[] args) throws ExecutionException, InterruptedException {//3.创建一个Callable对象Callable c = new MaCallable(100);//4.把Callable对象封装成一个FutureTask对象（任务对象）FutureTask<String> f = new FutureTask<>(c);//作用//1.是一个任务对象，实现了Ruuable类//2.可以用get()方法获取任务执行完后的结果new Thread(f).start();//获取执行完之后的结果//如果此时还未执行完，则在此等待String s = f.get();System.out.println(s);}
}

//1.实现Callable接口
public class MaCallable implements Callable<String> {private int n;public MaCallable(int n){this.n=n;}//2.重写call方法@Overridepublic String call() throws Exception {int sum=0;for(int i=1;i<=n;i++){sum+=i;}return "1-"+n+"的和为："+sum;}
}

Thread常用方法

public class dome {public static void main(String[] args) throws ExecutionException, InterruptedException {Thread t1 = new MyThread("1号");
//        t1.setName("1号");//设置线程名称t1.start();Thread t2 = new MyThread("2号");
//        t1.setName("2号");t2.start();Thread t = Thread.currentThread();for(int i=1;i<=5;i++){System.out.println(t.getName()+"线程"+i);}}
}

public class MyThread extends Thread{public MyThread(String name){super(name);}@Overridepublic void run() {Thread t = Thread.currentThread();//用来获取线程名称for(int i=0;i<5;i++){System.out.println(t.getName()+"线程"+i);}}
}

public class dome {public static void main(String[] args) throws ExecutionException, InterruptedException {for(int i=1;i<=5;i++){if(i==3){//休眠5秒Thread.sleep(5000);}System.out.println(i);}//join：让当前线程先跑完Thread t1 = new MyThread("1号");t1.start();t1.join();Thread t2 = new MyThread("2号");t2.start();Thread t3 = new MyThread("3号");t3.start();t2.join();}
}

线程同步

线程安全

线程同步的几种方式

1.同步代码块（比2好）

    public void dr(int n) {String name = Thread.currentThread().getName();synchronized (this) {//实力方法建议用this,静态方法建议用。classif(n<=num){System.out.println(name+"取钱"+n);num-=n;System.out.println(name+"剩"+num);}else {System.out.println(name+"不足");}}}

2.同步方法（可读性好）

 public synchronized void dr(int n) {String name = Thread.currentThread().getName();if(n<=num){System.out.println(name+"取钱"+n);num-=n;System.out.println(name+"剩"+num);}else {System.out.println(name+"不足");}}

3.Lock锁

    private final Lock l = new ReentrantLock();public synchronized void dr(int n) {String name = Thread.currentThread().getName();//加锁try {l.lock();if(n<=num){System.out.println(name+"取钱"+n);num-=n;System.out.println(name+"剩"+num);}else {System.out.println(name+"不足");}} catch (Exception e) {throw new RuntimeException(e);} finally {//防止程序出错时不能解锁//解锁l.unlock();}}

线程池

ThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory, RejectedExecutionHandler handler)

1.corePoolSize:线程池的核心线程数量

2.maximumPoolSize：线程池的最大线程数量（多出的为临时线程）

3.keepAliveTime：临时线程的存活时间

4.unit：临时线程存活时间的单位

5.workQueue:线程池的任务队列

6.threadFactory:指定线程池的线程池的线程工厂

7.handler：线程池的拒绝策略

`处理Runnable`

public class dome {public static void main(String[] args) throws ExecutionException, InterruptedException {/* public ThreadPoolExecutor(int corePoolSize,int maximumPoolSize,long keepAliveTime,TimeUnit unit,BlockingQueue<Runnable> workQueue,ThreadFactory threadFactory,RejectedExecutionHandler handler)*/ExecutorService e = new ThreadPoolExecutor(3, 5, 3, TimeUnit.SECONDS,new ArrayBlockingQueue<>(4), Executors.defaultThreadFactory(), new ThreadPoolExecutor.AbortPolicy());//LinkedBlockingQueue<>(),链表，无限大小MyThread myThread = new MyThread();e.execute(myThread);e.execute(myThread);e.execute(myThread);e.execute(myThread);e.execute(myThread);e.execute(myThread);e.execute(myThread);//添加临时线程e.execute(myThread);e.execute(myThread);//达到最大值e.execute(myThread);
//        e.shutdown();//等线程执行完后，关闭线程
//        e.shutdownNow();//直接关闭线程}
}

处理Callable

public class dome {public static void main(String[] args)  {/* public ThreadPoolExecutor(int corePoolSize,int maximumPoolSize,long keepAliveTime,TimeUnit unit,BlockingQueue<Runnable> workQueue,ThreadFactory threadFactory,RejectedExecutionHandler handler)*/ExecutorService e = new ThreadPoolExecutor(3, 5, 3, TimeUnit.SECONDS,new ArrayBlockingQueue<>(4), Executors.defaultThreadFactory(), new ThreadPoolExecutor.AbortPolicy());//LinkedBlockingQueue<>(),链表，无限大小Future<String> f1 = e.submit(new MaCallable(100));Future<String> f2 = e.submit(new MaCallable(200));Future<String> f3 = e.submit(new MaCallable(300));Future<String> f4 = e.submit(new MaCallable(400));try {System.out.println(f1.get());System.out.println(f2.get());System.out.println(f3.get());System.out.println(f4.get());} catch (InterruptedException ex) {System.out.println(ex.getLocalizedMessage());} catch (ExecutionException ex) {System.out.println(ex.getLocalizedMessage());}}
}

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