Java 多线程学习

}

}

Runnable：实现 Runnable 接口

• 定义 MyRunnable 类实现 Runnable 接口

• 实现 run()方法，编写线程执行体

• 创建线程对象，调用 start()方法启动线程

不建议使用 Thread，避免 OOP 单继承局限性，推荐使用 Runnable，方便同一个对象被多个线程使用。

package com.thread.lesson01;

//实现 runnable 接口，重写 run 方法，执行线程需要丢入 runable 接口实现类,调用 start 方法

public class TestThread03 implements Runnable{

@Override

public void run() {

for (int i = 0; i < 100; i++) {

System.out.println("我在读书！"+i);

}

}

public static void main(String[] args) {

//创建 runable 接口实现类对象

TestThread03 t3 = new TestThread03();

//创建线程对象 i

//Thread thread = new Thread(t3);

//thread.start();

new Thread(t3).start();

for (int i = 0; i < 100; i++) {

System.out.println("我在学多线程！"+i);

}

}

}

下载图片

package com.thread.lesson01;

import org.apache.commons.io.FileUtils;

import java.io.File;

import java.io.IOException;

import java.net.URL;

//练习 Runnable 实现多线程下载图片

public class TestThread04 implements Runnable{

private String url;

private String name;

public TestThread04(String url,String name){

this.url = url;//图片地址

this.name = name;//文件名

}

//下载图片线程执行体

@Override

public void run() {

WebDownLoaders webDownLoader = new WebDownLoaders();

webDownLoader.downloader(url,name);

System.out.println("下载了文件名为："+name);

}

public static void main(String[] args) {

TestThread04 t1 = new TestThread04("https://www.baidu.com/img/PCtm_d9c8750bed0b3c7d089fa7d55720d6cf.png","1.jpg");

TestThread04 t2 = new TestThread04("https://www.baidu.com/img/PCtm_d9c8750bed0b3c7d089fa7d55720d6cf.png","2.jpg");

TestThread04 t3 = new TestThread04("https://www.baidu.com/img/PCtm_d9c8750bed0b3c7d089fa7d55720d6cf.png","3.jpg");

new Thread(t1).start();

new Thread(t2).start();

new Thread(t3).start();

}

}

//下载器

class WebDownLoaders{

//下载方法

public void downloader(String url,String name) {

try {

FileUtils.copyURLToFile(new URL(url),new File(name));

} catch (IO 《一线大厂 Java 面试题解析+后端开发学习笔记+最新架构讲解视频+实战项目源码讲义》无偿开源 威信搜索公众号【编程进阶路】 Exception e) {

e.printStackTrace();

}

}

}

模拟抢票

package com.thread.lesson01;

//多个线程同时操作同一个对象(买火车票)

//发现问题，多个进程操作同一个资源的情况下，线程不安全，数据紊乱

public class TestThread05 implements Runnable{

//票数

private int tickeNums = 10;

@Override

public void run() {

while (true){

if (tickeNums<=0){

break;

}

//模拟延时

try {

Thread.sleep(200);

} catch (InterruptedException e) {

e.printStackTrace();

}

System.out.println(Thread.currentThread().getName()+"拿到了第"+tickeNums--+"张票");

}

}

public static void main(String[] args) {

TestThread05 t5 = new TestThread05();

new Thread(t5,"小周").start();

new Thread(t5,"小秦").start();

new Thread(t5,"小王").start();

}

}

模拟龟兔赛跑

package com.thread.lesson01;

//模拟龟兔赛跑

public class Race implements Runnable{

//胜利者

private static String winner;

@Override

public void run() {

for (int i = 0; i <= 100; i++) {

//模拟兔子休息

if (Thread.currentThread().getName().equals("兔子")&&i%20==0){

try {

Thread.sleep(50);

} catch (InterruptedException e) {

e.printStackTrace();

}

}

//判断比赛是否结束

boolean flag = gameOver(i);

//如果比赛结束 停止程序

if (flag){

break;

}

System.out.println(Thread.currentThread().getName()+"跑了"+i+"步");

}

}

//判断是否完成比赛

private boolean gameOver(int steps){

//判断是否有胜利者

if (winner!=null){//已经存在胜利者了

return true;

}{

if (steps>=100){

winner = Thread.currentThread().getName();

System.out.println("winner is"+winner);

return false;

}

}

return false;

}

public static void main(String[] args) {

Race race = new Race();

new Thread(race,"兔子").start();

new Thread(race,"乌龟").start();

}

}

Callable：实现 Callable 接口

了解即可

• 实现 Callable 接口，需要返回值类型

• 重写 call 方法，需要抛出异常

• 创建目标对象

• 创建执行服务：ExecutorService ser = Executors.newFixedThreadPool()

• 提交执行：Future?result1 = ser.submit()

• 获取结果：boolean r1 = result1.get()

• 关闭服务：ser.shutdownNow()

package com.thread.lesson01;

import org.apache.commons.io.FileUtils;

import java.io.File;

import java.io.IOException;

import java.net.URL;

import java.util.concurrent.*;

//实现 Callable 接口

//有返回值 抛出了异常

public class TestThread06 implements Callable<Boolean> {

private String url;

private String name;

public TestThread06(String url,String name){

this.url = url;//图片地址

this.name = name;//文件名

}

//下载图片线程执行体

@Override

public Boolean call() {

WebDownLoader3 webDownLoader = new WebDownLoader3();

webDownLoader.downloader(url,name);

System.out.println("下载了文件名为："+name);

return true;

}

public static void main(String[] args) throws ExecutionException, InterruptedException {