Java多线程之阻塞I/O如何中断

阻塞的I/O线程在关闭线程时并不会被打断，需要关闭资源才能打断。

1.执行socketInput.close();阻塞可中断。
2.执行System.in.close();阻塞没有中断。

package Thread.Interrupting;

import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class CloseResource {
    public static void main(String[] args) throws Exception {
        //堵塞的I/O线程不会被打断，需要关闭资源才能打断
        ExecutorService exec = Executors.newCachedThreadPool();
        ServerSocket server = new ServerSocket(8080);
        InputStream socketInput = new Socket("localhost", 8080)
                .getInputStream();
        exec.execute(new IOBlocked(socketInput));
        exec.execute(new IOBlocked(System.in));
        TimeUnit.MILLISECONDS.sleep(100);
        System.out.println("Shutting down all threads");
        exec.shutdownNow();
        TimeUnit.SECONDS.sleep(1);
        System.out.println("Closing " + socketInput.getClass().getName());
        socketInput.close();
        TimeUnit.SECONDS.sleep(1);
        System.out.println("Close " + System.in.getClass().getName());
        System.in.close();
    }
}

被阻塞的nio通道在关闭线程后会自动响应中断阻塞，不需要关闭底层资源。

package Thread.Interrupting;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousCloseException;
import java.nio.channels.ClosedByInterruptException;
import java.nio.channels.SocketChannel;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;

class NIOBlocked implements Runnable {
    private final SocketChannel sc;

    public NIOBlocked(SocketChannel sc) {
        this.sc = sc;
    }

    @Override
    public void run() {
        try {
            System.out.println("Waiting for read() in " + this);
            sc.read(ByteBuffer.allocate(1));
        } catch (ClosedByInterruptException e) {
            System.out.println("ClosedByInterruptException");
        } catch (AsynchronousCloseException e) {
            System.out.println("AsynchronousCloseException");
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        System.out.println("Exiting NIOBlocked.run() " + this);
    }

}

public class NIOInterruption {
    public static void main(String[] args) throws Exception {
        //被阻塞的nio通道会自动地响应中断
        ExecutorService exec = Executors.newCachedThreadPool();
        ServerSocket server = new ServerSocket(8080);
        InetSocketAddress isa = new InetSocketAddress("localhost", 8080);
        SocketChannel sc1 = SocketChannel.open(isa);
        SocketChannel sc2 = SocketChannel.open(isa);
        Future<?> f = exec.submit(new NIOBlocked(sc1));
        
        exec.execute(new NIOBlocked(sc2));
        
        exec.shutdown();
        TimeUnit.SECONDS.sleep(1);
        f.cancel(true);
        TimeUnit.SECONDS.sleep(1);
        sc2.close();
    }

}