[Java]多线程基础操作/创建线程/下载图片

创建线程的三种方式

• 继承Thread类（重点）
• 实现Runnable接口（重点）推荐使用
• 实现Callable接口（了解）

继承Thread类

package Thread;

/**
 * 创建线程方式一：继承Thread
 *
 * @author ZhaoLu cang on 2021/4/10 0010
 */
//注意，线程开启不一定立即执行，由cpu调度执行
public class Thread01 extends Thread{
    //重写run方法
    @Override
    public void run() {
        //run方法线程体
        for(int i=0;i<20;i++){
            System.out.println("学习多线程中......");

        }
    }

    public static void main(String[] args) throws InterruptedException {
        //创建一个线程对象
        Thread01 thread=new Thread01();
        //调用start方法
        thread.start();
        //main主线程
        for(int i=0;i<20;i++){
            System.out.println("正在学习代码......");

        }
    }
}

多线程下载图片

package Thread;

import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.IOException;
import java.net.URL;

/**
 * 练习Thread，多线程下载图片
 *
 * @author ZhaoLu cang on 2021/4/10 0010
 */
public class Thread02 extends Thread{

    private String name;//文件名
    private String url;//地址

    public Thread02(String url,String name){
        this.url=url;
        this.name=name;
    }

    //执行体
    @Override
    public void run() {
        WebDownloader webDownloader=new WebDownloader();
        webDownloader.downloader(url,name);
        System.out.println("下载的文件名为"+name);
    }

    public static void main(String[] args) {
        Thread02 t1=new Thread02("https://pic.cnblogs.com/avatar/1280312/20190419133542.png","我的头像.jpg");
        Thread02 t2=new Thread02("https://5b0988e595225.cdn.sohucs.com/images/20190108/c060afad8f594428a584e5efd8b64f23.jpeg","apache图标.jpg");
        Thread02 t3=new Thread02("https://avatar.csdnimg.cn/1/7/D/1_weixin_43847567_1584060639.jpg","CSDN头像.jpg");

        t1.start();
        t2.start();
        t3.start();

    }
}

class WebDownloader{
    //下载方法
    public void downloader(String url,String name){
        try {
            //爬取从地址到文件
            FileUtils.copyURLToFile(new URL(url),new File(name));
        }catch (IOException e){
            System.out.println("IO异常，downloader方法"+e);
        }
        }

}

实现Runnable接口

package Thread;

/**
 * 创建线程方式二：Runnable方法
 *
 * @author ZhaoLu cang on 2021/4/10 0010
 */
public class Thread03 implements Runnable {
    //重写run方法
    @Override
    public void run() {
        //run方法线程体
        for(int i=0;i<20;i++){
            System.out.println("学习多线程中......");

        }
    }

    public static void main(String[] args) throws InterruptedException {
        //创建Runnable接口的实现类对象
        Thread01 thread01=new Thread01();
        //创建线程对象，通过线程对象来开启我们的线程
        Thread thread=new Thread(thread01);

        new Thread(thread01).start();

        //main主线程
        for(int i=0;i<20;i++){
            System.out.println("正在学习代码......");

        }
    }
}

多线程下载图片

package Thread;

import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.IOException;
import java.net.URL;

/**
 * 练习Thread，多线程下载图片
 *
 * @author ZhaoLu cang on 2021/4/10 0010
 */
public class Thread04 implements Runnable{

    private String name;//文件名
    private String url;//地址

    public Thread04(String url,String name){
        this.url=url;
        this.name=name;
    }

    //执行体
    @Override
    public void run() {
        WebDownloader02 webDownloader=new WebDownloader02();
        webDownloader.downloader(url,name);
        System.out.println("下载的文件名为"+name);
    }

    public static void main(String[] args) {
        Thread04 t1=new Thread04("https://pic.cnblogs.com/avatar/1280312/20190419133542.png","我的头像.jpg");
        Thread04 t2=new Thread04("https://5b0988e595225.cdn.sohucs.com/images/20190108/c060afad8f594428a584e5efd8b64f23.jpeg","apache图标.jpg");
        Thread04 t3=new Thread04("https://avatar.csdnimg.cn/1/7/D/1_weixin_43847567_1584060639.jpg","CSDN头像.jpg");

        new Thread(t1).start();
        new Thread(t2).start();
        new Thread(t3).start();

    }
}

class WebDownloader02{
    //下载方法
    public void downloader(String url,String name){
        try {
            //爬取从地址到文件
            FileUtils.copyURLToFile(new URL(url),new File(name));
        }catch (IOException e){
            System.out.println("IO异常，downloader方法"+e);
        }
        }

}

实现Callable接口

多线程下载图片

package Thread;

import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.concurrent.*;

/**
 * 线程创建方式三：Callable
 *
 * @author ZhaoLu cang on 2021/4/10 0010
 */
public class ThreadCallable implements  Callable<Boolean>{
    private String name;//文件名
    private String url;//地址

    public ThreadCallable(String url,String name){
        this.url=url;
        this.name=name;
    }

    //执行体
    @Override
    public Boolean call() {
        WebDownloader01 webDownloader=new WebDownloader01();
        webDownloader.downloader(url,name);
        System.out.println("下载的文件名为"+name);
        return true;
    }

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ThreadCallable t1=new ThreadCallable("https://pic.cnblogs.com/avatar/1280312/20190419133542.png","我的头像.jpg");
        ThreadCallable t2=new ThreadCallable("https://5b0988e595225.cdn.sohucs.com/images/20190108/c060afad8f594428a584e5efd8b64f23.jpeg","apache图标.jpg");
        ThreadCallable t3=new ThreadCallable("https://avatar.csdnimg.cn/1/7/D/1_weixin_43847567_1584060639.jpg","CSDN头像.jpg");
        //创建执行服务
        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);

        //获取结果
        boolean rs1=r1.get();
        boolean rs2=r2.get();
        boolean rs3=r3.get();

        //关闭服务
        ser.shutdown();
    }
}

class WebDownloader01{
    //下载方法
    public void downloader(String url,String name){
        try {
            //爬取从地址到文件
            FileUtils.copyURLToFile(new URL(url),new File(name));
        }catch (IOException e){
            System.out.println("IO异常，downloader方法"+e);
        }
    }

}