Java 多线程--ThreadLocal Timer ExecutorService

ThreadLocal

/**
 * ThreadLocal:每个线程自身的存储本地、局部区域
 * @author xzlf
 *
 */
public class ThreadLocalTest01 {
//	private static ThreadLocal<Integer> threadLocal = new ThreadLocal<Integer>();
	// 更改初始化值
	/*private static ThreadLocal<Integer> threadLocal = new ThreadLocal<Integer>() {
		protected Integer initialValue() {
			return 100;};
	};*/
	
	private static ThreadLocal<Integer> threadLocal = new ThreadLocal<Integer>().withInitial(()->50);
	public static void main(String[] args) {
		// 获取
		System.out.println(Thread.currentThread().getName() +"-->" + threadLocal.get());
		// 设置
		threadLocal.set(200);
		System.out.println(Thread.currentThread().getName() +"-->" + threadLocal.get());
	}
}

**
 * ThreadLocal:每个线程自身的数据，更改不会影响其他线程
 * @author xzlf
 *
 */
public class TheadLocalTest02 {
	private static ThreadLocal<Integer> threadLocal = new ThreadLocal<Integer>().withInitial(()->1);
	public static void main(String[] args) {
		for(int i=0; i<5; i++) {
			new Thread(new MyRun()).start();
		}
	}
	
	public static class MyRun implements Runnable{
		@Override
		public void run() {
			int left = threadLocal.get();
			System.out.println(Thread.currentThread().getName() + "得到了-->" + left);
			threadLocal.set(left - 1);
			System.out.println(Thread.currentThread().getName() + "还剩下-->" + threadLocal.get());
			
		}
	}
}

/**
 * ThreadLocal:分析上下文 环境  起点
 * 1、构造器: 哪里调用 就属于哪里 找线程体
 * 2、run方法:本线程自身的
 * @author xzlf
 *
 */
public class TheadLocalTest03 {
	private static ThreadLocal<Integer> threadLocal = new ThreadLocal<Integer>() {
		protected Integer initialValue() {
			return 100;
		};
	};
	
	public static void main(String[] args) {
		new Thread(new MyRun()).start();
		new Thread(new MyRun()).start();
	}
	
	static class MyRun implements Runnable{
		public MyRun() {
			threadLocal.set(200);
			System.out.println(Thread.currentThread().getName() + "-->" + threadLocal.get());
		}
		@Override
		public void run() {
			System.out.println(Thread.currentThread().getName() + "-->" + threadLocal.get());
			
		}
	}
	
}

运行：

/**
 * InheritableThreadLocal:继承环境上下文的数据，拷贝一份给子线程
 * 
 * @author xzlf
 *
 */
public class TheadLocalTest04 {
	private static ThreadLocal<Integer> threadLocal = new InheritableThreadLocal<Integer>();
	public static void main(String[] args) {
		threadLocal.set(2);
		System.out.println(Thread.currentThread().getName()+"-->"+threadLocal.get());
		new Thread(()-> {
			System.out.println(Thread.currentThread().getName() + "-->" + threadLocal.get());
			threadLocal.set(100);
			System.out.println(Thread.currentThread().getName() + "-->" + threadLocal.get());
		}).start();
	}
	
}

运行：

ExcutorService

线程池

public class TestFutrueTask {
	public static void main(String[] args) throws InterruptedException, ExecutionException {
		// 创建任务
		MyCall call = new MyCall();
		// 交给任务管理器
		FutureTask<String> task = new FutureTask<String>(call);
		// 创建代理类并启动线程
		new Thread(task).start();
		System.out.println("获取结果-->" + task.get());
		System.out.println("任务是否执行完成-->" + task.isDone());
	}
}

线程池执行带返回值的callable时需要加入到集合中，避免get() 等待结果是阻塞

package com.xzlf.testThread;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;

public class TestPool2 {
	public static void main(String[] args) throws Exception, Exception {
		// 创建一个线程池，线程池中只有一个线程对象
//		ExecutorService pool = Executors.newSingleThreadExecutor();
		// 创建一个线程池，线程池中数量固定
		ExecutorService pool = Executors.newFixedThreadPool(10);
		// 创建一个线程池，线程池中数量可以动态改变
//		ExecutorService pool = Executors.newCachedThreadPool();
		
		List<Future<Integer>> list = new ArrayList<Future<Integer>>();
		/**使用线程池执行大量的Callable任务*/
		for (int i = 0; i < 20; i++) {
			Callable<Integer> command = new Callable<Integer>() {

				@Override
				public Integer call() throws Exception {
					Thread.sleep(2000);
					return (int) (Math.random()*10);
				}
				
			};
			// 将任务交给线程池
			FutureTask<Integer> task =(FutureTask<Integer>) pool.submit(command);
			list.add(task);
//			pool.execute(task);
//			System.out.println(task.get());
			
		}
		System.out.println("ok?");
		for (Future<Integer> f : list) {
			System.out.println(f.get());
		}
		System.out.println("ok!");
		pool.shutdown();
	}
}

运行：

Timer

package com.xzlf.testThread;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;

public class TestTimer {
	public static void main(String[] args) throws InterruptedException {
		// 创建Timer对象
		Timer timer = new Timer();
		// 创建任务对象
		TimerTask task = new Clock();
		// 调用schedule()方法执行任务
		timer.schedule(task, new Date(System.currentTimeMillis() + 2000), 1000);
		Thread.sleep(5000);
		timer.cancel();
		
	}
}

/**
 * 任务
 * @author xzlf
 *
 */
class Clock extends TimerTask{
	DateFormat df = new SimpleDateFormat("yyyy-MM-DD HH:mm:ss");
	@Override
	public void run() {
		Date date = new Date();
		String dateStr = df.format(date);
		System.out.println(dateStr);
	}
}

运行：