NIO初学笔记

1 import java.io.IOException;
2 import java.net.InetAddress;
3 import java.net.InetSocketAddress;
4 import java.nio.channels.SelectionKey;
5 import java.nio.channels.Selector;
6 import java.nio.channels.ServerSocketChannel;
7 import java.util.Iterator;
8 import java.util.Set;
9
10 /**
11 * 反应器模式 用于解决多用户访问并发问题
12 */
13 public class Reactor implements Runnable {
14 public final Selector selector;
15 public final ServerSocketChannel serverSocketChannel;
16
17 public Reactor(int port) throws IOException {
18 selector = Selector.open();
19 serverSocketChannel = ServerSocketChannel.open();
20 InetSocketAddress inetSocketAddress = new InetSocketAddress(InetAddress.getLocalHost(), port);
21 serverSocketChannel.socket().bind(inetSocketAddress);
22 serverSocketChannel.configureBlocking(false);
23
24 // 向selector注册该channel
25 SelectionKey selectiOnKey= serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
26
27 // 利用selectionKey的attache功能绑定Acceptor 如果有事情，触发Acceptor
28 selectionKey.attach(new Acceptor(this));
29 }
30
31 @Override
32 public void run() {
33 try {
34 while (!Thread.interrupted()) {
35 selector.select();
36 Set selectiOnKeys= selector.selectedKeys();
37 Iterator it = selectionKeys.iterator();
38 // Selector如果发现channel有OP_ACCEPT或READ事件发生，下列遍历就会进行。
39 while (it.hasNext()) {
40 // 来一个事件 第一次触发一个accepter线程，SocketReadHandler
41 SelectionKey selectiOnKey= it.next();
42 dispatch(selectionKey);
43 selectionKeys.clear();
44 }
45 }
46 } catch (IOException e) {
47 e.printStackTrace();
48 }
49 }
50
51 /**
52 * 运行Acceptor或SocketReadHandler
53 *
54 * @param key
55 */
56 void dispatch(SelectionKey key) {
57 Runnable r = (Runnable) (key.attachment());
58 if (r != null) {
59 r.run();
60 }
61 }
62
63 }

1 import java.io.IOException;
2 import java.nio.channels.SocketChannel;
3
4 public class Acceptor implements Runnable {
5 private Reactor reactor;
6
7 public Acceptor(Reactor reactor) {
8 this.reactor = reactor;
9 }
10
11 @Override
12 public void run() {
13 try {
14 SocketChannel socketChannel = reactor.serverSocketChannel.accept();
15 if (socketChannel != null){
16 // 调用Handler来处理channel
17 new SocketReadHandler(reactor.selector, socketChannel);
18 }
19 } catch (IOException e) {
20 e.printStackTrace();
21 }
22 }
23 }

1 import java.io.IOException;
2 import java.nio.ByteBuffer;
3 import java.nio.channels.SelectionKey;
4 import java.nio.channels.Selector;
5 import java.nio.channels.SocketChannel;
6
7 public class SocketReadHandler implements Runnable {
8 private SocketChannel socketChannel;
9
10 public SocketReadHandler(Selector selector, SocketChannel socketChannel) throws IOException {
11 this.socketChannel = socketChannel;
12 socketChannel.configureBlocking(false);
13
14 SelectionKey selectiOnKey= socketChannel.register(selector, 0);
15
16 // 将SelectionKey绑定为本Handler 下一步有事件触发时，将调用本类的run方法。
17 // 参看dispatch(SelectionKey key)
18 selectionKey.attach(this);
19
20 // 同时将SelectionKey标记为可读，以便读取。
21 selectionKey.interestOps(SelectionKey.OP_READ);
22 selector.wakeup();
23 }
24
25 /**
26 * 处理读取数据
27 */
28 @Override
29 public void run() {
30 ByteBuffer inputBuffer = ByteBuffer.allocate(1024);
31 inputBuffer.clear();
32 try {
33 socketChannel.read(inputBuffer);
34 // 激活线程池 处理这些request
35 // requestHandle(new Request(socket,btt));
36 } catch (IOException e) {
37 e.printStackTrace();
38 }
39 }
40 }