java nio selector.select不阻塞
java nio 构建的服务端在与客户端(用ubuntu虚拟机的netcat)连接上后，
netcat直接ctrl + d(什么内容都不输入)的话，服务端的selector.select()方法的结果就一直是0
也不阻塞了。请问这是为什么。
代码如下：
package chapter4;
import org.junit.Test;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;
public class List4_2 {
@Test
public void test1(){
PlainNIOServer server = new PlainNIOServer();
try {
server.serve(12345);
} catch (IOException e) {
e.printStackTrace();
}
}
private static class PlainNIOServer {
public void serve(int port) throws IOException {//在对方连接上以后直接ctrl+d会陷入readable的死循环
ServerSocketChannel serverChannel = ServerSocketChannel.open();
serverChannel.configureBlocking(false);
serverChannel.bind(new InetSocketAddress(port));
Selector selector = Selector.open();
serverChannel.register(selector, SelectionKey.OP_ACCEPT);
while(true){
if (selector.select() == 0){
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
// continue;
}
Set<SelectionKey> keys = selector.selectedKeys();
Iterator<SelectionKey> it = keys.iterator();
while (it.hasNext()){
SelectionKey key = it.next();
it.remove();
System.out.println("acc : " + key.isAcceptable() + ", w : " + key.isWritable()
+ ", r : " + key.isReadable() + ", conn : " + key.isConnectable() + ", v : " + key.isValid());
try {
if (key.isAcceptable()) {
ServerSocketChannel server = (ServerSocketChannel) key.channel();
SocketChannel client = server.accept();
if (client != null) {
client.configureBlocking(false);
client.register(selector, SelectionKey.OP_READ);
System.out.println("Accept Connection from " + client);
}
}
if (key.isReadable()) {
SocketChannel client = (SocketChannel) key.channel();
ByteBuffer byteBuffer = ByteBuffer.allocate(5);
System.out.println("readable !!!");
int count = 0;
while (( count = client.read(byteBuffer)) > 0 ) {
byteBuffer.flip();
byte[] bytes = new byte[1024];
while (byteBuffer.hasRemaining()) {
byteBuffer.get(bytes, 0, Math.min(byteBuffer.remaining(), bytes.length));
String sentence;
System.out.println(sentence = new String(bytes, 0, count));
byteBuffer.compact();
byteBuffer.put(sentence.getBytes());
byteBuffer.flip();
client.write(byteBuffer);
}
byteBuffer.compact();
}
}
}
catch (Exception e){
e.printStackTrace();
key.channel().close();
}
}
}
}
}
}
运行如上代码以后，在虚拟机里运行netcat ， 截图如下
此时在netcat中按下ctrl + d (EOF)则服务端的selector.select方法调用之后返回结果一直为0且不再阻塞，所有连上的客户端也没办法发消息了。
服务端效果如下:
