[Java] 使用5种开启线程的方式

• 1. 继承Thread方式拷贝文件
• 2. 实现Runnable方式输出文件夹中所有的Java文件
• 3. 实现Callable方式统计视频文件的个数,并且输出这个线程执行的结果
• 4. 使用匿名内部类的方式输出1~100
• 5. 使用Lambda表达式的方式计算1~100的和

1. 继承Thread方式拷贝文件

// 1. 继承Thread方式拷贝文件
public class Demo01 {
    public static void main(String[] args) {
        CopyFile cf = new CopyFile("D:\\Demo\\456.txt", "D:\\Demo01\\123.txt");
        cf.start();
    }
}
class CopyFile extends Thread{
    private String srcFile;
    private String dercFile;

    public CopyFile(String srcFile, String dercFile) {
        this.srcFile = srcFile;
        this.dercFile = dercFile;
    }

    @Override
    public void run() {
        copyFile();
    }
    public void copyFile(){

        try(InputStream is = new FileInputStream(srcFile); OutputStream os = new FileOutputStream(dercFile)) {
            byte[] bytes = new byte[1024];
            int len = 0;
            while ((len = is.read(bytes)) != -1) {
                os.write(bytes,0,len);
                os.flush();
            }

        } catch (Exception e) {
            e.printStackTrace();
        } ;
    }
}

2. 实现Runnable方式输出文件夹中所有的Java文件

//*2. 实现Runnable方式输出文件夹中所有的Java文件**
public class Demo02 {
    public static void main(String[] args) {
        OpenFile of = new OpenFile(new File("D:\\Java\\project-idea"));
        Thread t = new Thread(of);
        t.start();
    }
}
class OpenFile implements Runnable{

    private File srcFolder;

    @Override
    public void run() {
        getAllJavaFile(srcFolder);
    }

    public OpenFile(File srcFolder) {
        this.srcFolder = srcFolder;
    }

    public void getAllJavaFile(File srcFolder){
        if (Objects.isNull(srcFolder)) {
            throw new NullPointerException("不能为空!");
        }
        File[] files = srcFolder.listFiles();
        if (files == null || files.length <= 0) {
            return;
        }
        for (File file : files) {
            if (file.isDirectory()) {
                getAllJavaFile(file);
            }else {
                String fileName = file.getName();
                if (fileName.endsWith(".java")) {
                    System.out.println(fileName);
                }
            }
        }
    }
}

3. 实现Callable方式统计视频文件的个数,并且输出这个线程执行的结果

//3. 实现Callable方式统计视频文件的个数,并且输出这个线程执行的结果
public class Demo03 {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        FutureTask<Integer> task = new FutureTask<Integer>(new GetVideoFileNumber(new File("D:\\Java\\video")));
        Thread t = new Thread(task);
        t.start();
        Integer videoNum= task.get();
        System.out.println(videoNum);
        
    }
}
class GetVideoFileNumber implements Callable<Integer> {

    private File videoFile;

    public GetVideoFileNumber(File videoFile) {
        this.videoFile = videoFile;
    }

    @Override
    public Integer call() throws Exception {
        return getVideoFile(videoFile);
    }

    public Integer getVideoFile(File videoFile) {
        Integer totalCount = 0;
        if (Objects.isNull(videoFile)) {
            return 0;
        }
        File[] files = videoFile.listFiles();
        if (Objects.isNull(files) || files.length <= 0) {
            return 0;
        }

        for (File file : files) {
            if (file.isDirectory()) {
                totalCount += getVideoFile(file);
            } else {
                if (file.getName().endsWith(".mp4")) {
                    totalCount++;
                }
            }
        }
        return totalCount;
    }
}

4. 使用匿名内部类的方式输出1~100

public class Demo04 {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        new Thread().start();
        new Thread(){
            @Override
            public void run() {
                for(int i = 1; i <= 100; i++){
                    System.out.println(i);
                }
            }
        }.start();
    }
}

5. 使用Lambda表达式的方式计算1~100的和

public class Demo05 {
    public static void main(String[] args) throws ExecutionException, InterruptedException {

        new Thread(()->{ int sum = 0;
            for (int i = 1;i<= 100;i++){
                sum += i;
            }
            System.out.println(sum);
        }).start();

    }
}