Java利用异常中断当前任务的技巧分享

class DownloadTask {
    public void download(Listener listener) {
        try {
            for (int i = 0; i < 100; i++) {//模拟下载过程
                Thread.sleep(1000);
                listener.onProgressUpdated(i + 1);
            }
            listener.onCompleted();
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    }
    public interface Listener {
        void onProgressUpdated(int progress);
        void onCompleted();
    }
}
public class Main {
    public static void main(String[] args) throws InterruptedException {
        DownloadTask task = new DownloadTask();
        task.download(new DownloadTask.Listener() {
            @Override
            public void onProgressUpdated(int progress) {
                System.out.println("onProgressUpdated: " + progress);
                if (isInterrupted.get()) {
                    throw new EndException();
                }
            }
            @Override
            public void onCompleted() {
            }
        });
    }
}

//DownloadTask 同上
public class Main {
    private static volatile boolean isInterrupted;
    public static void main(String[] args) throws InterruptedException {
        new Thread(() -> {//模拟外部调用，5秒后通过设置isInterrupted来取消任务，也可以把这段代码放到一个新的cancel方法中
            sleep(5000);
            isInterrupted = true;
        }).start();
        try {
            DownloadTask task = new DownloadTask();
            task.download(new DownloadTask.Listener() {
                @Override
                public void onProgressUpdated(int progress) {
                    System.out.println("onProgressUpdated: " + progress);
                    if (isInterrupted) {
                        throw new EndException();
                    }
                }
                @Override
                public void onCompleted() {
                    System.out.println("onCompleted...");
                }
            });
        }catch (EndException e){
            System.out.println("end...");
            //is interrupted, ignore
        }
        Thread.currentThread().join();
    }
    static class EndException extends RuntimeException {
    }
    public static void sleep(long time) {
        try {
            Thread.sleep(time);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    }
}

public class DownloadTask {
    public void download(Listener listener) {
        new Thread(() -> {
            try {
                for (int i = 0; i < 100; i++) {//模拟下载过程
                    Thread.sleep(1000);
                    listener.onProgressUpdated(i + 1);
                }
                listener.onCompleted();
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        }).start();
    }
    public interface Listener {
        void onProgressUpdated(int progress);
        void onCompleted();
    }
}

public class Main {
    private static volatile boolean isInterrupted;
    public static void main(String[] args) throws InterruptedException {
        Thread.UncaughtExceptionHandler handler = (t, e) -> {
            if(e instanceof EndException){
                System.out.println("end...");
                //is interrupted, ignore
            }
        };
        DownloadTask task = new DownloadTask();
        task.download(new DownloadTask.Listener() {
            @Override
            public void onProgressUpdated(int progress) {
                System.out.println("onProgressUpdated: " + progress);
                if(Thread.currentThread().getUncaughtExceptionHandler() != handler){//注意这里
                    Thread.currentThread().setUncaughtExceptionHandler(handler);
                }
                if (isInterrupted) {
                    throw new EndException();
                }
            }
            @Override
            public void onCompleted() {
                System.out.println("onCompleted...");
            }
        });
        sleep(5000);
        isInterrupted = true;
        Thread.currentThread().join();
    }
    public static class EndException extends RuntimeException {
    }
    public static void sleep(long time) {
        try {
            Thread.sleep(time);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    }
}