网络编程基础(4) : IO多路复用(多线程)

1. 简述

本篇文章延续上一篇网络编程基础(3) : IO多路复用(单线程)之内容，做出了进一步的改善。

IO复用网路模型中的角色Handler，将以状态模式(State Pattern)实现，

并且将Handler接收完网络消息后的业务逻辑处理交由工作线程实现，所有的工作线程以线程池来维护。

2. 网络模型

3. 代码实现

[TCPReactor.java]

// Reactor線程package server;import java.io.IOException;import java.net.InetSocketAddress;import java.nio.channels.SelectionKey;import java.nio.channels.Selector;import java.nio.channels.ServerSocketChannel;import java.util.Iterator;import java.util.Set;public class TCPReactor implements Runnable {private final ServerSocketChannel ssc;private final Selector selector;public TCPReactor(int port) throws IOException {selector = Selector.open();ssc = ServerSocketChannel.open();InetSocketAddress addr = new InetSocketAddress(port);ssc.socket().bind(addr); // 在ServerSocketChannel綁定監聽端口ssc.configureBlocking(false); // 設置ServerSocketChannel為非阻塞SelectionKey sk = ssc.register(selector, SelectionKey.OP_ACCEPT); // ServerSocketChannel向selector註冊一個OP_ACCEPT事件，然後返回該通道的keysk.attach(new Acceptor(selector, ssc)); // 給定key一個附加的Acceptor對象}@Overridepublic void run() {while (!Thread.interrupted()) { // 在線程被中斷前持續運行System.out.println("Waiting for new event on port: " + ssc.socket().getLocalPort() + "...");try {if (selector.select() == 0) // 若沒有事件就緒則不往下執行continue;} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}Set<SelectionKey> selectedKeys = selector.selectedKeys(); // 取得所有已就緒事件的key集合Iterator<SelectionKey> it = selectedKeys.iterator();while (it.hasNext()) {dispatch((SelectionKey) (it.next())); // 根據事件的key進行調度it.remove();}}}/* * name: dispatch(SelectionKey key) * description: 調度方法，根據事件綁定的對象開新線程 */private void dispatch(SelectionKey key) {Runnable r = (Runnable) (key.attachment()); // 根據事件之key綁定的對象開新線程if (r != null)r.run();}}

[Acceptor.java]

// 接受連線請求線程package server;import java.io.IOException;import java.nio.channels.SelectionKey;import java.nio.channels.Selector;import java.nio.channels.ServerSocketChannel;import java.nio.channels.SocketChannel;public class Acceptor implements Runnable {private final ServerSocketChannel ssc;private final Selector selector;public Acceptor(Selector selector, ServerSocketChannel ssc) {this.ssc=ssc;this.selector=selector;}@Overridepublic void run() {try {SocketChannel sc= ssc.accept(); // 接受client連線請求System.out.println(sc.socket().getRemoteSocketAddress().toString() + " is connected.");if(sc!=null) {sc.configureBlocking(false); // 設置為非阻塞SelectionKey sk = sc.register(selector, SelectionKey.OP_READ); // SocketChannel向selector註冊一個OP_READ事件，然後返回該通道的keyselector.wakeup(); // 使一個阻塞住的selector操作立即返回sk.attach(new TCPHandler(sk, sc)); // 給定key一個附加的TCPHandler對象}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}

[TCPHandler.java]

// Handler線程package server;import java.io.IOException;import java.nio.channels.SelectionKey;import java.nio.channels.SocketChannel;import java.util.concurrent.LinkedBlockingQueue;import java.util.concurrent.ThreadPoolExecutor;import java.util.concurrent.TimeUnit;public class TCPHandler implements Runnable {private final SelectionKey sk;private final SocketChannel sc;private static final int THREAD_COUNTING = 10;private static ThreadPoolExecutor pool = new ThreadPoolExecutor(THREAD_COUNTING, THREAD_COUNTING, 10, TimeUnit.SECONDS,new LinkedBlockingQueue<Runnable>()); // 線程池HandlerState state; // 以狀態模式實現Handlerpublic TCPHandler(SelectionKey sk, SocketChannel sc) {this.sk = sk;this.sc = sc;state = new ReadState(); // 初始狀態設定為READINGpool.setMaximumPoolSize(32); // 設置線程池最大線程數}@Overridepublic void run() {try {state.handle(this, sk, sc, pool);} catch (IOException e) {System.out.println("[Warning!] A client has been closed.");closeChannel();}}public void closeChannel() {try {sk.cancel();sc.close();} catch (IOException e1) {e1.printStackTrace();}}public void setState(HandlerState state) {this.state = state;}}

Handler要以状态模式实现还需要定义状态接口(interface)和状态实现类(ConcreteState Class)

[HandlerState.java]

package server;import java.io.IOException;import java.nio.channels.SelectionKey;import java.nio.channels.SocketChannel;import java.util.concurrent.ThreadPoolExecutor;public interface HandlerState {public void changeState(TCPHandler h);public void handle(TCPHandler h, SelectionKey sk, SocketChannel sc,ThreadPoolExecutor pool) throws IOException ;}

[ReadState.java]

package server;import java.io.IOException;import java.nio.ByteBuffer;import java.nio.channels.SelectionKey;import java.nio.channels.SocketChannel;import java.util.concurrent.ThreadPoolExecutor;public class ReadState implements HandlerState{private SelectionKey sk;public ReadState() {}@Overridepublic void changeState(TCPHandler h) {// TODO Auto-generated method stubh.setState(new WorkState());}@Overridepublic void handle(TCPHandler h, SelectionKey sk, SocketChannel sc,ThreadPoolExecutor pool) throws IOException { // read()this.sk = sk;// non-blocking下不可用Readers，因為Readers不支援non-blockingbyte[] arr = new byte[1024];ByteBuffer buf = ByteBuffer.wrap(arr);int numBytes = sc.read(buf); // 讀取字符串if(numBytes == -1){System.out.println("[Warning!] A client has been closed.");h.closeChannel();return;}String str = new String(arr); // 將讀取到的byte內容轉為字符串型態if ((str != null) && !str.equals(" ")) {h.setState(new WorkState()); // 改變狀態(READING->WORKING)pool.execute(new WorkerThread(h, str)); // do process in worker threadSystem.out.println(sc.socket().getRemoteSocketAddress().toString()+ " > " + str);}}/* * 執行邏輯處理之函數 */synchronized void process(TCPHandler h, String str) {// do process(decode, logically process, encode)..// ..h.setState(new WriteState()); // 改變狀態(WORKING->SENDING)this.sk.interestOps(SelectionKey.OP_WRITE); // 通過key改變通道註冊的事件this.sk.selector().wakeup(); // 使一個阻塞住的selector操作立即返回}/* * 工作者線程 */class WorkerThread implements Runnable {TCPHandler h;String str;public WorkerThread(TCPHandler h, String str) {this.h = h;this.str=str;}@Overridepublic void run() {process(h, str);}}}

[WorkState.java]

package server;import java.io.IOException;import java.nio.channels.SelectionKey;import java.nio.channels.SocketChannel;import java.util.concurrent.ThreadPoolExecutor;public class WorkState implements HandlerState {public WorkState() {}@Overridepublic void changeState(TCPHandler h) {// TODO Auto-generated method stubh.setState(new WriteState());}@Overridepublic void handle(TCPHandler h, SelectionKey sk, SocketChannel sc,ThreadPoolExecutor pool) throws IOException {// TODO Auto-generated method stub}}

[WriteState.java]

package server;import java.io.IOException;import java.nio.ByteBuffer;import java.nio.channels.SelectionKey;import java.nio.channels.SocketChannel;import java.util.concurrent.ThreadPoolExecutor;public class WriteState implements HandlerState{public WriteState() {}@Overridepublic void changeState(TCPHandler h) {// TODO Auto-generated method stubh.setState(new ReadState());}@Overridepublic void handle(TCPHandler h, SelectionKey sk, SocketChannel sc,ThreadPoolExecutor pool) throws IOException { // send()// get message from message queueString str = "Your message has sent to "+ sc.socket().getLocalSocketAddress().toString() + "\r\n";ByteBuffer buf = ByteBuffer.wrap(str.getBytes()); // wrap自動把buf的position設為0，所以不需要再flip()while (buf.hasRemaining()) {sc.write(buf); // 回傳給client回應字符串，發送buf的position位置 到limit位置為止之間的內容}h.setState(new ReadState()); // 改變狀態(SENDING->READING)sk.interestOps(SelectionKey.OP_READ); // 通過key改變通道註冊的事件sk.selector().wakeup(); // 使一個阻塞住的selector操作立即返回}}

最後是主程序

[Main.java]

package server;import java.io.IOException;public class Main {public static void main(String[] args) {// TODO Auto-generated method stubtry {TCPReactor reactor = new TCPReactor(1333);reactor.run();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}

对应的客户端可以参考网络编程基础(3) : IO多路复用(单线程)中的代码

下一篇将介绍採用了多个Reactor的IO复用模型实现