/**
* Reactor模式简述
*
* Reactor负责轮询selector，将就绪事件分发给handler处理。
* handler大致有两种：
* 1.acceptor：负责建连，建连后注册io handler；
* 2.io handler：负责处理io读写事件；
*
* 所以Reactor模式是一种事件响应式模式。提前注册handler。selectionKey的作用是将handler与channel关联（注册事件时不能指定handler）
* 当select返回就绪事件时，可以通过selectionKey取得注册的handler。
*
* 需要注意的是：Reactor只是在编程模式上是异步的，但是底层io模型仍然是同步的。
*
* Reactor模式又可以细分为3类：
* 1.单reactor单线程模式：这种模式分发和io均由Reactor线程处理。
* 2.单reactor多线程模式：与1类似，只是io在独立的线程池里处理。reactor只负责分发。
* 3.多reactor多线程模式：在2基础上，使用了多个reactor，进行了分工。
* boss reactor只负责分发建连事件；若干worker reactor负责分发io事件。
*/
1.单reactor单线程
public class SimpleReactor implements Runnable{
private Selector selector;
public SimpleReactor(int port) {
try {
selector = Selector.open();
ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
serverSocketChannel.bind(new InetSocketAddress(port));
serverSocketChannel.configureBlocking(false);
SelectionKey key = serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
key.attach(new Acceptor(selector, serverSocketChannel));
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void run() {
while (true) {
try {
selector.select();
Set<SelectionKey> keys = selector.selectedKeys();
Iterator<SelectionKey> iterator = keys.iterator();
while (iterator.hasNext()) {
dispatch(iterator.next());
iterator.remove();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
private void dispatch(SelectionKey key) {
Runnable runnable = (Runnable) key.attachment();
runnable.run();
}
}
public class Acceptor implements Runnable{
private Selector selector;
private ServerSocketChannel serverSocketChannel;
public Acceptor(Selector selector, ServerSocketChannel serverSocketChannel) {
this.selector = selector;
this.serverSocketChannel = serverSocketChannel;
}
@Override
public void run() {
try {
SocketChannel socketChannel = serverSocketChannel.accept();
socketChannel.configureBlocking(false);
System.out.println("new client connected");
// demo仅注册read
SelectionKey key = socketChannel.register(selector, SelectionKey.OP_READ);
// single thread
key.attach(new ReadWorker(socketChannel));
// worker poll
// key.attach(new ThreadPoolReadProcessor(socketChannel));
} catch (IOException e) {
e.printStackTrace();
}
}
}
public class ReadWorker implements Runnable {
private SocketChannel socketChannel;
public ReadWorker(SocketChannel socketChannel) {
this.socketChannel = socketChannel;
}
@Override
public void run() {
ByteBuffer byteBuffer = ByteBuffer.allocate(4098);
try {
// 多线程模式下，不检测会导致读一个关闭的连接
if (!socketChannel.isOpen()) {
return;
}
int size = socketChannel.read(byteBuffer);
if (size == -1) {
return;
}
String msg = new String(byteBuffer.array()).trim();
System.out.printf("receive data: %s, size: %d \n", msg, size);
socketChannel.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
public class BootStrap {
public static void main(String[] args) {
simpleReactor();
// multiReactor();
}
public static void simpleReactor() {
SimpleReactor reactor = new SimpleReactor(15001);
reactor.run();
}
public static void multiReactor() {
BossReactor bossReactor = new BossReactor(15001);
bossReactor.run();
}
}2.单reactor多线程
public class ThreadPoolReadProcessor implements Runnable{
// singleton
private static ExecutorService poolExecutor = Executors.newFixedThreadPool(10);
private Runnable readWorker;
public ThreadPoolReadProcessor(SocketChannel socketChannel) {
this.readWorker = new ReadWorker(socketChannel);
}
@Override
public void run() {
poolExecutor.submit(readWorker);
}
}新增ThreadPoolReadProcessor，并在Acceptor中替代ReadWorker。
3.多reactor多线程
public class BossReactor implements Runnable {
private Selector selector;
public BossReactor(int port) {
try {
selector = Selector.open();
ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
serverSocketChannel.bind(new InetSocketAddress(port));
serverSocketChannel.configureBlocking(false);
SelectionKey key = serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
key.attach(new MultiThreadAcceptor(serverSocketChannel));
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void run() {
while (true) {
try {
selector.select();
Set<SelectionKey> keys = selector.selectedKeys();
Iterator<SelectionKey> iterator = keys.iterator();
while (iterator.hasNext()) {
dispatch(iterator.next());
iterator.remove();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
private void dispatch(SelectionKey key) {
Runnable runnable = (Runnable) key.attachment();
runnable.run();
}
}
public class WorkerReactor implements Runnable {
private Selector selector;
public WorkerReactor() {
try {
this.selector = Selector.open();
} catch (IOException e) {
e.printStackTrace();
}
}
public SelectionKey register(SocketChannel socketChannel, int op) {
try {
return socketChannel.register(selector, op);
} catch (ClosedChannelException e) {
throw new RuntimeException();
}
}
@Override
public void run() {
while (true) {
try {
selector.select();
Set<SelectionKey> keys = selector.selectedKeys();
Iterator<SelectionKey> iterator = keys.iterator();
while (iterator.hasNext()) {
dispatch(iterator.next());
iterator.remove();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
private void dispatch(SelectionKey key) {
Runnable runnable = (Runnable) key.attachment();
runnable.run();
}
}
public class MultiThreadAcceptor implements Runnable {
private static final int DEFAULT_SIZE = 10;
private ServerSocketChannel serverSocketChannel;
private WorkerReactor[] workerReactors;
public MultiThreadAcceptor(ServerSocketChannel serverSocketChannel) {
this.serverSocketChannel = serverSocketChannel;
this.workerReactors = new WorkerReactor[DEFAULT_SIZE];
for (int i = 0; i < DEFAULT_SIZE; i++) {
workerReactors[i] = new WorkerReactor();
// 这里简化处理，最好用线程池
new Thread(workerReactors[i]).start();
}
}
@Override
public void run() {
try {
SocketChannel socketChannel = serverSocketChannel.accept();
socketChannel.configureBlocking(false);
System.out.println("new client connected");
int index = new Random().nextInt(DEFAULT_SIZE);
SelectionKey selectionKey = workerReactors[index].register(socketChannel, SelectionKey.OP_READ);
selectionKey.attach(new ThreadPoolReadProcessor(socketChannel));
} catch (IOException e) {
e.printStackTrace();
}
}
}参考：
