线程 相关

守护线程：垃圾回收（GC）线程

线程最大优先级10，最小优先级1，默认优先级5

线程的执行状态：新建、就绪、运行、阻塞、结束

start() 分配资源

run() 执行具体的用户线程代码；不是由用户程序来调用的，当调用start()方法启动一个线程之后，只要线程获得了CPU执行时间，便进入run()方法体执行具体的用户线程

run()为同步执行，失去了线程的意义

线程创建的方法：

一、继承Thread

package com.crazymakercircle.multithread.basic.create;
import personal.nien.javabook.util.Print;
public class CreateDemo {
public static final int MAX_TURN = 5;
public static String getCurThreadName() {
return Thread.currentThread().getName();
}
//线程的编号
static int threadNo = 1;
static class DemoThread extends Thread { //①
public DemoThread() {
super("DemoThread-" + threadNo++); //②
}
public void run() { //③
for (int i = 1; i < MAX_TURN; i++) {
Print.cfo(getName() + ", 轮次：" + i);
}
Print.cfo(getName() + " 运行结束.");
}
}
public static void main(String args[]) throws InterruptedException {
Thread thread = null;
//方法一：使用Thread子类创建和启动线程
for (int i = 0; i < 2; i++) {
thread = new DemoThread();
thread.start();
}
Print.cfo(getCurThreadName() + " 运行结束.");
}
}

二、实现Runnable 

Runnable逻辑和数据更好的分离，面向对象,避免单继承带来的局限性

package com.crazymakercircle.multithread.basic.create;
// 省略import
public class SalesDemo
{
public static final int MAX_AMOUNT = 5; //商品数量
//商店商品类（销售线程类），一个商品一个销售线程，每个线程异步销售4次
static class StoreGoods extends Thread
{
StoreGoods(String name)
{
super(name);
}
private int goodsAmount = MAX_AMOUNT;
public void run()
{
for (int i = 0; i <= MAX_AMOUNT; i++)
{
if (this.goodsAmount > 0)
{
Print.cfo(getCurThreadName() + " 卖出一件，还剩："
+ (--goodsAmount));
sleepMilliSeconds(10);
}
}
Print.cfo(getCurThreadName() + " 运行结束.");
}
}
//商场商品类（target销售线程的目标类），一个商品最多销售4次，可以多人销售
static class MallGoods implements Runnable
{
//多人销售可能导致数据出错，使用原子数据类型保障数据安全
private AtomicInteger goodsAmount = new AtomicInteger(MAX_AMOUNT);
public void run()
{
for (int i = 0; i <= MAX_AMOUNT; i++)
{
if (this.goodsAmount.get() > 0)
{
Print.cfo(getCurThreadName() + " 卖出一件，还剩："
+ (goodsAmount.decrementAndGet()));
sleepMilliSeconds(10);
}
}
Print.cfo(getCurThreadName() + " 运行结束.");
}
}
public static void main(String args[]) throws InterruptedException
{
Print.hint("商店版本的销售");
for (int i = 1; i <= 2; i++)
{
Thread thread = null;
thread = new StoreGoods("店员-" + i);
thread.start();
}
Thread.sleep(1000);
Print.hint("商场版本的销售");
MallGoods mallGoods = new MallGoods();
for (int i = 1; i <= 2; i++)
{
Thread thread = null;
thread = new Thread(mallGoods, "商场销售员-" + i);
thread.start();
}
Print.cfo(getCurThreadName() + " 运行结束.");
}
}

三、实现Callable

Callable有返回值

/**
 * Copyright (c) 2022,TravelSky.
 * All Rights Reserved.
 * TravelSky CONFIDENTIAL
 * 
 * Project Name:ldpCoreCompApp
 * Package Name:PACKAGE_NAME
 * File Name:Test.java
 * Date:2022年08月2022/8/2日 10:01:14
 */
 
import java.util.concurrent.*;
 
/**
 * ClassName: Test 
 * Description: TODO 
 * Date: 2022年08月2022/8/2日 10:01:14 
 * 
 *
 * @author lixin(邮箱)
 *
 * 修改记录
 * @version 产品版本信息 yyyy-mm-dd 姓名(邮箱) 修改信息
 *
 */
public class Test {
    /**
     * 继承Thread
     */
    static class TestThread extends Thread{
 
        @Override
        public void run() {
            System.out.println("TestThread");
        }
    }
 
    /**
     * 实现Runnable
     */
    static class TestRunnable implements Runnable{
 
        @Override
        public void run() {
            System.out.println("TestRunnable");
        }
    }
 
    /**
     * 实现Callable
     */
    static class TestCallable implements Callable {
 
        @Override
        public String call() throws Exception {
            return "TestCallable";
        }
    }
 
    /**
     * 线程池创建
     */
    private static ExecutorService executorService = Executors.newFixedThreadPool(3);
    static class TestExecutor implements Callable {
 
        @Override
        public Long call() throws Exception {
            long startTime = System.currentTimeMillis();
            for (int i = 0; i < 5; i++){
                System.out.println(Thread.currentThread().getName()+" : "+i);
                Thread.sleep(100);
            }
            long used = System.currentTimeMillis() - startTime;
            return used;
        }
    }
 
    public static void main(String[] args) throws ExecutionException, InterruptedException {
 
        Thread thread = new TestThread();
        thread.start();
 
        Runnable runnable = new TestRunnable();
        Thread thread1 = new Thread(runnable);
        thread1.start();
 
        TestCallable testCallable = new TestCallable();
        FutureTask futureTask = new FutureTask(testCallable);
        Thread thread2 = new Thread(futureTask);
        thread2.start();
        System.out.println(futureTask.get());
 
        Future future = executorService.submit(new TestExecutor());
        System.out.println(future.get());
    }
}

四、线程池Executor

submit() 接收有返回值和无返回值的入参，有返回值

execute() 只接收无返回值的入参，无返回值