下面列出了java.nio.channels.Selector#select() 实例代码，或者点击链接到github查看源代码，也可以在右侧发表评论。
public static void main(String[] args) throws Exception {
final Selector sel = Selector.open();
Runnable r = new Runnable() {
public void run() {
try {
sel.select();
} catch (IOException x) {
x.printStackTrace();
}
}
};
// start thread to block in Selector
Thread t = new Thread(r);
t.start();
// give thread time to start
Thread.sleep(1000);
// interrupt, close, and wakeup is the magic sequence to provoke the NPE
t.interrupt();
sel.close();
sel.wakeup();
}
public static void main(String[] args) throws Exception {
final Selector sel = Selector.open();
Runnable r = new Runnable() {
public void run() {
try {
sel.select();
} catch (IOException x) {
x.printStackTrace();
}
}
};
// start thread to block in Selector
Thread t = new Thread(r);
t.start();
// give thread time to start
Thread.sleep(1000);
// interrupt, close, and wakeup is the magic sequence to provoke the NPE
t.interrupt();
sel.close();
sel.wakeup();
}
public static void main(String[] args) throws Exception {
final Selector sel = Selector.open();
Runnable r = new Runnable() {
public void run() {
try {
sel.select();
} catch (IOException x) {
x.printStackTrace();
}
}
};
// start thread to block in Selector
Thread t = new Thread(r);
t.start();
// give thread time to start
Thread.sleep(1000);
// interrupt, close, and wakeup is the magic sequence to provoke the NPE
t.interrupt();
sel.close();
sel.wakeup();
}
public static void main(String argv[]) throws Exception {
int waitTime = 4000;
Selector selector = Selector.open();
try {
selector.wakeup();
long t1 = System.currentTimeMillis();
selector.select(waitTime);
long t2 = System.currentTimeMillis();
long totalTime = t2 - t1;
if (totalTime > waitTime)
throw new RuntimeException("Test failed");
} finally {
selector.close();
}
}
public static void main(String argv[]) throws Exception {
int waitTime = 4000;
Selector selector = Selector.open();
try {
selector.wakeup();
long t1 = System.currentTimeMillis();
selector.select(waitTime);
long t2 = System.currentTimeMillis();
long totalTime = t2 - t1;
if (totalTime > waitTime)
throw new RuntimeException("Test failed");
} finally {
selector.close();
}
}
@Override
public void run() {
final Selector selector = this.selector;
for (; ; ) {
try {
selector.select(500L);
Set<SelectionKey> keys = selector.selectedKeys();
try {
keys.forEach(this::handleKey);
} finally {
keys.clear();
}
} catch (Throwable e) {
logger.warn(getName(), e);
}
}
}
@Override
public void run() {
final Selector selector = this.selector;
for (;;) {
++acceptCount;
try {
selector.select( 1000L );
Set<SelectionKey> keys = selector.selectedKeys();
try {
for (SelectionKey key : keys) {
if (key.isValid() && key.isAcceptable()) {
accept();
} else {
key.cancel();
}
}
} finally {
keys.clear();
}
} catch (Throwable e) {
LOGGER.warn(getName(), e);
}
}
}
@Override
public void run() {
final Selector selector = this.selector;
for (;;) {
++acceptCount;
try {
selector.select(1000L);
Set<SelectionKey> keys = selector.selectedKeys();
try {
for (SelectionKey key : keys) {
if (key.isValid() && key.isAcceptable()) {
accept();
} else {
key.cancel();
}
}
} finally {
keys.clear();
}
} catch (Throwable e) {
LOGGER.warn(getName(), e);
}
}
}
public void start() throws IOException {
Selector selector = Selector.open();
//通过OPEN方法来打开一个未绑定的ServerSocketChannel 实例
ServerSocketChannel server = ServerSocketChannel.open();
//将该ServerSocketChannel绑定到指定ip
server.bind(new InetSocketAddress(NIOServer.PORT));
//设置是NIO 非阻塞模式
server.configureBlocking(false);
//将sever注册到指定Selector对象上
server.register(selector, SelectionKey.OP_ACCEPT);
while (!stop) {
selector.select(2000);
Set<SelectionKey> selectedKeys = selector.selectedKeys();
Iterator<SelectionKey> it = selectedKeys.iterator();
SelectionKey key;
while (it.hasNext()) {
key = it.next();
it.remove();
try {
handleInput(selector, key);
} catch (Exception e) {
if (key != null) {
key.cancel();
if (key.channel() != null) {
key.channel().close();
}
}
}
}
}
}
@Override
public void run() {
final Selector selector = this.selector;
for (;;) {
++reactCount;
try {
selector.select(1000L);
register(selector);
Set<SelectionKey> keys = selector.selectedKeys();
try {
for (SelectionKey key : keys) {
Object att = key.attachment();
if (att != null && key.isValid()) {
int readyOps = key.readyOps();
if ((readyOps & SelectionKey.OP_READ) != 0) {
read((NIOConnection) att);
} else if ((readyOps & SelectionKey.OP_WRITE) != 0) {
write((NIOConnection) att);
} else {
key.cancel();
}
} else {
key.cancel();
}
}
} finally {
keys.clear();
}
} catch (Throwable e) {
LOGGER.warn(name, e);
}
}
}
private void select(boolean oldWakenUp) throws IOException {
Selector selector = this.currSelector;
while (true) {
// from netty docs:
// If a task was submitted when wakenUp value was true, the task didn't get a chance to
// call
// {@link Selector#wakeup}. So we need to check task queue again before executing select
// operation.
// If we don't, the task might be pended until select operation was timed out.
// It might be pended until idle timeout if IdleStateHandler existed in pipeline.
// -- end netty notes
if (this.eventBus.hasTasks() && wakenUp.compareAndSet(false, true)) {
selector.selectNow();
break;
}
int selectedKeys = selector.select(timeoutMillis);
if (selectedKeys != 0 || oldWakenUp || wakenUp.get() || this.eventBus.hasTasks()) {
// break when we:
// 1) selected something
// 2) user submitted a task for us to run
// 3) the task queue has an already pending task
break;
}
if (Thread.interrupted()) {
break;
}
}
// TODO: handle spin lock (epoll error)
// see: <a
// href="https://github.com/netty/netty/blob/4.1/transport/src/main/java/io/netty/channel/nio/NioEventLoop.java#L738"></a>
}
/**
* Performs a write using the bytebuffer for data to be written and a
* selector to block (if blocking is requested). If the
* <code>selector</code> parameter is null, and blocking is requested then
* it will perform a busy write that could take up a lot of CPU cycles.
* @param buf The buffer containing the data, we will write as long as <code>(buf.hasRemaining()==true)</code>
* @param socket The socket to write data to
* @param selector The selector to use for blocking, if null then a busy write will be initiated
* @param writeTimeout The timeout for this write operation in milliseconds, -1 means no timeout
* @param block <code>true</code> to perform a blocking write
* otherwise a non-blocking write will be performed
* @return int - returns the number of bytes written
* @throws EOFException if write returns -1
* @throws SocketTimeoutException if the write times out
* @throws IOException if an IO Exception occurs in the underlying socket logic
*
* 将数据返回给页面。
*
*/
public int write(ByteBuffer buf, NioChannel socket, Selector selector,
long writeTimeout, boolean block) throws IOException {
if ( SHARED && block ) {
/**
* 通过NioBlockingSelector利用NioChannel将数据写入网络中。
*/
return blockingSelector.write(buf,socket,writeTimeout);
}
SelectionKey key = null;
int written = 0;
boolean timedout = false;
int keycount = 1; //assume we can write
long time = System.currentTimeMillis(); //start the timeout timer
try {
while ( (!timedout) && buf.hasRemaining() ) {
int cnt = 0;
if ( keycount > 0 ) { //only write if we were registered for a write
cnt = socket.write(buf); //write the data
if (cnt == -1) throw new EOFException();
written += cnt;
if (cnt > 0) {
time = System.currentTimeMillis(); //reset our timeout timer
continue; //we successfully wrote, try again without a selector
}
if (cnt==0 && (!block)) break; //don't block
}
if ( selector != null ) {
//register OP_WRITE to the selector
if (key==null) key = socket.getIOChannel().register(selector, SelectionKey.OP_WRITE);
else key.interestOps(SelectionKey.OP_WRITE);
if (writeTimeout==0) {
timedout = buf.hasRemaining();
} else if (writeTimeout<0) {
keycount = selector.select();
} else {
keycount = selector.select(writeTimeout);
}
}
if (writeTimeout > 0 && (selector == null || keycount == 0) ) timedout = (System.currentTimeMillis()-time)>=writeTimeout;
}//while
if ( timedout ) throw new SocketTimeoutException();
} finally {
if (key != null) {
key.cancel();
if (selector != null) selector.selectNow();//removes the key from this selector
}
}
return written;
}
public static void main(String[] args) throws Exception {
Selector selector = Selector.open();
Member mbr = new MemberImpl("localhost", 9999, 0);
byte seq = 0;
byte[] buf = new byte[50000];
Arrays.fill(buf,seq);
int len = buf.length;
BigDecimal total = new BigDecimal((double)0);
BigDecimal bytes = new BigDecimal((double)len);
NioSender sender = new NioSender();
sender.setDestination(mbr);
sender.setDirectBuffer(true);
sender.setSelector(selector);
sender.connect();
sender.setMessage(buf);
System.out.println("Writing to 9999");
long start = 0;
double mb = 0;
boolean first = true;
int count = 0;
DecimalFormat df = new DecimalFormat("##.00");
while (count<100000) {
if (first) {
first = false;
start = System.currentTimeMillis();
}
sender.setMessage(buf);
int selectedKeys = 0;
try {
selectedKeys = selector.select(0);
} catch (Exception e) {
e.printStackTrace();
continue;
}
if (selectedKeys == 0) {
continue;
}
Iterator<SelectionKey> it = selector.selectedKeys().iterator();
while (it.hasNext()) {
SelectionKey sk = it.next();
it.remove();
try {
int readyOps = sk.readyOps();
sk.interestOps(sk.interestOps() & ~readyOps);
if (sender.process(sk, false)) {
total = total.add(bytes);
sender.reset();
seq++;
Arrays.fill(buf,seq);
sender.setMessage(buf);
mb += ( (double) len) / 1024 / 1024;
if ( ( (++count) % 10000) == 0) {
long time = System.currentTimeMillis();
double seconds = ( (double) (time - start)) / 1000;
System.out.println("Throughput " + df.format(mb / seconds) + " MB/seconds, total "+mb+" MB, total "+total+" bytes.");
}
}
} catch (Throwable t) {
t.printStackTrace();
return;
}
}
}
System.out.println("Complete, sleeping 15 seconds");
Thread.sleep(15000);
}
private void select(boolean oldWakenUp) throws IOException {
Selector selector = this.selector;
try {
int selectCnt = 0;
long currentTimeNanos = System.nanoTime();
long selectDeadLineNanos = currentTimeNanos + delayNanos(currentTimeNanos);
for (;;) {
long timeoutMillis = (selectDeadLineNanos - currentTimeNanos + 500000L) / 1000000L;
if (timeoutMillis <= 0) {
if (selectCnt == 0) {
selector.selectNow();
selectCnt = 1;
}
break;
}
int selectedKeys = selector.select(timeoutMillis);
selectCnt ++;
if (selectedKeys != 0 || oldWakenUp || wakenUp.get() || hasTasks() || hasScheduledTasks()) {
// - Selected something,
// - waken up by user, or
// - the task queue has a pending task.
// - a scheduled task is ready for processing
break;
}
if (Thread.interrupted()) {
// Thread was interrupted so reset selected keys and break so we not run into a busy loop.
// As this is most likely a bug in the handler of the user or it's client library we will
// also log it.
//
// See https://github.com/netty/netty/issues/2426
if (logger.isDebugEnabled()) {
logger.debug("Selector.select() returned prematurely because " +
"Thread.currentThread().interrupt() was called. Use " +
"NioEventLoop.shutdownGracefully() to shutdown the NioEventLoop.");
}
selectCnt = 1;
break;
}
long time = System.nanoTime();
if (time - TimeUnit.MILLISECONDS.toNanos(timeoutMillis) >= currentTimeNanos) {
// timeoutMillis elapsed without anything selected.
selectCnt = 1;
} else if (SELECTOR_AUTO_REBUILD_THRESHOLD > 0 &&
selectCnt >= SELECTOR_AUTO_REBUILD_THRESHOLD) {
// The selector returned prematurely many times in a row.
// Rebuild the selector to work around the problem.
logger.warn(
"Selector.select() returned prematurely {} times in a row; rebuilding selector.",
selectCnt);
rebuildSelector();
selector = this.selector;
// Select again to populate selectedKeys.
selector.selectNow();
selectCnt = 1;
break;
}
currentTimeNanos = time;
}
if (selectCnt > MIN_PREMATURE_SELECTOR_RETURNS) {
if (logger.isDebugEnabled()) {
logger.debug("Selector.select() returned prematurely {} times in a row.", selectCnt - 1);
}
}
} catch (CancelledKeyException e) {
if (logger.isDebugEnabled()) {
logger.debug(CancelledKeyException.class.getSimpleName() + " raised by a Selector - JDK bug?", e);
}
// Harmless exception - log anyway
}
}
public <R extends Result> R expect(long timeoutMs, Matcher<R> matcher) throws IOException {
if (copierFuture == null) {
throw new IllegalStateException("Not started");
}
final long timeToStop = System.currentTimeMillis() + timeoutMs;
final boolean isInfiniteTimeout = timeoutMs == ExpectImpl.INFINITE_TIMEOUT;
long timeElapsed = timeoutMs;
ByteBuffer byteBuffer = ByteBuffer.allocate(BUFFER_SIZE);
Selector selector = Selector.open();
try {
source.register(selector, SelectionKey.OP_READ);
R result = matcher.matches(buffer.toString(), copierFuture.isDone());
if (LOG.isLoggable(Level.FINE)) {
LOG.fine(
String.format(
"Initial matcher %s result: %s",
toDebugString(matcher),
toDebugString(result)));
}
while (!(result.isSuccessful() || result.canStopMatching())
&& (isInfiniteTimeout || timeElapsed > 0)) {
int keys = isInfiniteTimeout ? selector.select() : selector.select(timeElapsed);
// if thread was interrupted the selector returns immediately
// and keep the thread status, so we need to check it
if (Thread.currentThread().isInterrupted()) {
LOG.fine("Thread was interrupted");
throw new ClosedByInterruptException();
}
if (!isInfiniteTimeout) {
timeElapsed = timeToStop - System.currentTimeMillis();
}
if (keys == 0) {
LOG.fine("Selector returns 0 key");
continue;
}
selector.selectedKeys().clear();
int len = source.read(byteBuffer);
if (len > 0) {
String string = new String(byteBuffer.array(), 0, len, charset);
processString(string);
byteBuffer.clear();
}
final boolean isEof = len == -1;
result = matcher.matches(buffer.toString(), isEof);
if (LOG.isLoggable(Level.FINE)) {
LOG.fine(
String.format(
"Matcher %s result: %s. Operation time: %d ms",
toDebugString(matcher),
toDebugString(result),
timeoutMs - timeElapsed));
}
if (isEof) {
break;
}
}
if (result.isSuccessful()) {
buffer.delete(0, result.end());
} else if (copierFuture.isDone() && buffer.length() == 0) {
throw new EOFException("Input closed");
}
return result;
} finally {
selector.close();
}
}
public static void main(String[] args) throws Exception {
Selector selector;
synchronized (Selector.class) {
// Selector.open() isn't thread safe
// http://bugs.sun.com/view_bug.do?bug_id=6427854
// Affects 1.6.0_29, fixed in 1.7.0_01
selector = Selector.open();
}
Member mbr = new MemberImpl("localhost", 9999, 0);
ChannelData data = new ChannelData();
data.setOptions(Channel.SEND_OPTIONS_BYTE_MESSAGE);
data.setAddress(mbr);
byte[] buf = new byte[8192 * 4];
data.setMessage(new XByteBuffer(buf,false));
buf = XByteBuffer.createDataPackage(data);
int len = buf.length;
BigDecimal total = new BigDecimal((double)0);
BigDecimal bytes = new BigDecimal((double)len);
NioSender sender = new NioSender();
sender.setDestination(mbr);
sender.setDirectBuffer(true);
sender.setSelector(selector);
sender.setTxBufSize(1024*1024);
sender.connect();
sender.setMessage(buf);
System.out.println("Writing to 9999");
long start = 0;
double mb = 0;
boolean first = true;
int count = 0;
DecimalFormat df = new DecimalFormat("##.00");
while (count<100000) {
if (first) {
first = false;
start = System.currentTimeMillis();
}
sender.setMessage(buf);
int selectedKeys = 0;
try {
selectedKeys = selector.select(0);
} catch (Exception e) {
e.printStackTrace();
continue;
}
if (selectedKeys == 0) {
continue;
}
Iterator<SelectionKey> it = selector.selectedKeys().iterator();
while (it.hasNext()) {
SelectionKey sk = it.next();
it.remove();
try {
int readyOps = sk.readyOps();
sk.interestOps(sk.interestOps() & ~readyOps);
if (sender.process(sk, false)) {
total = total.add(bytes);
sender.reset();
sender.setMessage(buf);
mb += ( (double) len) / 1024 / 1024;
if ( ( (++count) % 10000) == 0) {
long time = System.currentTimeMillis();
double seconds = ( (double) (time - start)) / 1000;
System.out.println("Throughput " + df.format(mb / seconds) + " MB/seconds, total "+mb+" MB, total "+total+" bytes.");
}
}
} catch (Throwable t) {
t.printStackTrace();
return;
}
}
selector.selectedKeys().clear();
}
System.out.println("Complete, sleeping 15 seconds");
Thread.sleep(15000);
}
private void select(boolean oldWakenUp) throws IOException {
// 获取选择器
Selector selector = this.selector;
try {
int selectCnt = 0;
long currentTimeNanos = System.nanoTime();
// 出来延迟队列中的任务
long selectDeadLineNanos = currentTimeNanos + delayNanos(currentTimeNanos);
for (;;) {
long timeoutMillis = (selectDeadLineNanos - currentTimeNanos + 500000L) / 1000000L;
if (timeoutMillis <= 0) {
if (selectCnt == 0) {
// 开始监听
selector.selectNow();
selectCnt = 1;
}
break;
}
// If a task was submitted when wakenUp value was true, the task didn't get a chance to call 如果在wakenUp值为true时提交了一个任务，那么这个任务就没有机会调用
// Selector#wakeup. So we need to check task queue again before executing select operation. 选择器#唤醒。因此，在执行select操作之前，我们需要再次检查任务队列。
// If we don't, the task might be pended until select operation was timed out.如果我们不这样做，任务可能会被挂起，直到选择操作超时。
// It might be pended until idle timeout if IdleStateHandler existed in pipeline.如果在管道中存在IdleStateHandler，则可能将其挂起，直到空闲超时
if (hasTasks() && wakenUp.compareAndSet(false, true)) {
selector.selectNow();
selectCnt = 1;
break;
}
// 获取监听到的事件
int selectedKeys = selector.select(timeoutMillis);
selectCnt ++;
if (selectedKeys != 0 || oldWakenUp || wakenUp.get() || hasTasks() || hasScheduledTasks()) {
// - Selected something,
// - waken up by user, or
// - the task queue has a pending task.
// - a scheduled task is ready for processing-选定的东西，
// -用户唤醒，或
// -任务队列有一个挂起的任务。
// -已安排的任务已准备好处理
break;
}
if (Thread.interrupted()) {
// Thread was interrupted so reset selected keys and break so we not run into a busy loop.
// As this is most likely a bug in the handler of the user or it's client library we will
// also log it.//线程被中断，所以重置选定的键并中断，这样我们就不会进入繁忙的循环。
//因为这很可能是一个错误的处理程序的用户或它的客户端库，我们会
//把它记录下来。
//
// See https://github.com/netty/netty/issues/2426
if (logger.isDebugEnabled()) {
logger.debug("Selector.select() returned prematurely because " +
"Thread.currentThread().interrupt() was called. Use " +
"NioEventLoop.shutdownGracefully() to shutdown the NioEventLoop.");
}
selectCnt = 1;
break;
}
long time = System.nanoTime();
if (time - TimeUnit.MILLISECONDS.toNanos(timeoutMillis) >= currentTimeNanos) {
// timeoutMillis elapsed without anything selected.timeoutMillis没有选择任何内容。
selectCnt = 1;
} else if (SELECTOR_AUTO_REBUILD_THRESHOLD > 0 &&
selectCnt >= SELECTOR_AUTO_REBUILD_THRESHOLD) {
// The selector returned prematurely many times in a row.
// Rebuild the selector to work around the problem.//选择器在一行中多次提前返回。
//重新构建选择器来解决问题。
logger.warn(
"Selector.select() returned prematurely {} times in a row; rebuilding Selector {}.",
selectCnt, selector);
// 重新构造选择器
rebuildSelector();
selector = this.selector;
// Select again to populate selectedKeys.再次选择以填充selectedKeys。
selector.selectNow();
// 重置selector轮询次数
selectCnt = 1;
break;
}
currentTimeNanos = time;
}
if (selectCnt > MIN_PREMATURE_SELECTOR_RETURNS) {
if (logger.isDebugEnabled()) {
logger.debug("Selector.select() returned prematurely {} times in a row for Selector {}.",
selectCnt - 1, selector);
}
}
} catch (CancelledKeyException e) {
if (logger.isDebugEnabled()) {
logger.debug(CancelledKeyException.class.getSimpleName() + " raised by a Selector {} - JDK bug?",
selector, e);
}
// Harmless exception - log anyway
}
}
private static boolean test(final long timeout)
throws InterruptedException, IOException {
AtomicReference<Exception> theException =
new AtomicReference<>();
AtomicBoolean isTimedOut = new AtomicBoolean();
Selector selector = Selector.open();
Thread t = new Thread(() -> {
try {
selector.select(timeout);
isTimedOut.set(true);
} catch (IOException ioe) {
theException.set(ioe);
}
});
t.start();
t.join(SLEEP_MILLIS);
boolean result;
if (theException.get() == null) {
if (timeout > SLEEP_MILLIS && isTimedOut.get()) {
System.err.printf("Test timed out early with timeout %d%n",
timeout);
result = false;
} else {
System.out.printf("Test succeeded with timeout %d%n", timeout);
result = true;
}
} else {
System.err.printf("Test failed with timeout %d%n", timeout);
theException.get().printStackTrace();
result = false;
}
t.interrupt();
selector.close();
return result;
}
public static void main(String[] args) throws Exception {
Selector selector;
synchronized (Selector.class) {
// Selector.open() isn't thread safe
// http://bugs.sun.com/view_bug.do?bug_id=6427854
// Affects 1.6.0_29, fixed in 1.7.0_01
selector = Selector.open();
}
Member mbr = new MemberImpl("localhost", 9999, 0);
byte seq = 0;
byte[] buf = new byte[50000];
Arrays.fill(buf,seq);
int len = buf.length;
BigDecimal total = new BigDecimal((double)0);
BigDecimal bytes = new BigDecimal((double)len);
NioSender sender = new NioSender();
sender.setDestination(mbr);
sender.setDirectBuffer(true);
sender.setSelector(selector);
sender.connect();
sender.setMessage(buf);
System.out.println("Writing to 9999");
long start = 0;
double mb = 0;
boolean first = true;
int count = 0;
DecimalFormat df = new DecimalFormat("##.00");
while (count<100000) {
if (first) {
first = false;
start = System.currentTimeMillis();
}
sender.setMessage(buf);
int selectedKeys = 0;
try {
selectedKeys = selector.select(0);
} catch (Exception e) {
e.printStackTrace();
continue;
}
if (selectedKeys == 0) {
continue;
}
Iterator<SelectionKey> it = selector.selectedKeys().iterator();
while (it.hasNext()) {
SelectionKey sk = it.next();
it.remove();
try {
int readyOps = sk.readyOps();
sk.interestOps(sk.interestOps() & ~readyOps);
if (sender.process(sk, false)) {
total = total.add(bytes);
sender.reset();
seq++;
Arrays.fill(buf,seq);
sender.setMessage(buf);
mb += ( (double) len) / 1024 / 1024;
if ( ( (++count) % 10000) == 0) {
long time = System.currentTimeMillis();
double seconds = ( (double) (time - start)) / 1000;
System.out.println("Throughput " + df.format(mb / seconds) + " MB/seconds, total "+mb+" MB, total "+total+" bytes.");
}
}
} catch (Throwable t) {
t.printStackTrace();
return;
}
}
}
System.out.println("Complete, sleeping 15 seconds");
Thread.sleep(15000);
}
/**
* Blocking wait for a client connection.
*
* @throws IOException
* if something goes wrong.
*/
protected void awaitAccept() throws IOException {
// blocking wait for a client connection.
final Selector serverSelector = Selector.open();
try {
final SelectionKey serverKey = server.register(serverSelector,
SelectionKey.OP_ACCEPT);
try {
serverSelector.select(); // blocks
final Set<SelectionKey> keys = serverSelector
.selectedKeys();
final Iterator<SelectionKey> iter = keys.iterator();
while (iter.hasNext()) {
final SelectionKey key = (SelectionKey) iter.next();
iter.remove();
if (key != serverKey)
throw new AssertionError();
break;
}
} finally {
serverKey.cancel();
}
} finally {
serverSelector.close();
}
}