reactor模式称之为响应器模式,常用于nio的网络通信框架,其服务架构图如下
不同于传统IO的串行调度方式,NIO把整个服务请求分为五个阶段
read:接收到请求,读取数据
decode:解码数据
compute:业务逻辑处理
encode:返回数据编码
send:发送数据
其中,以read和send阶段IO最为频繁
代码实现
// 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key sk.attach(new Acceptor(selector, ssc)); // 給定key一個附加的Acceptor對象 } @Override public 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 block e.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(); } }
// 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; } @Override public 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key selector.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 block e.printStackTrace(); } } }
// Handler線程 package server; import java.io.IOException; import java.nio.ByteBuffer; 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; int state; public TCPHandler(SelectionKey sk, SocketChannel sc) { this.sk = sk; this.sc = sc; state = 0; // 初始狀態設定為READING } @Override public void run() { try { if (state == 0) read(); // 讀取網絡數據 else send(); // 發送網絡數據 } catch (IOException e) { System.out.println("[Warning!] A client has been closed."); closeChannel(); } } private void closeChannel() { try { sk.cancel(); sc.close(); } catch (IOException e1) { e1.printStackTrace(); } } private synchronized void read() throws IOException { // non-blocking下不可用Readers,因為Readers不支援non-blocking byte[] 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."); 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(" ")) { process(str); // 邏輯處理 System.out.println(sc.socket().getRemoteSocketAddress().toString() + " > " + str); state = 1; // 改變狀態 sk.interestOps(SelectionKey.OP_WRITE); // 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 } } private void send() throws IOException { // get message from message queue String 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 } state = 0; // 改變狀態 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 } void process(String str) { // do process(decode, logically process, encode).. // .. } }
package server; import java.io.IOException; public class Main { public static void main(String[] args) { // TODO Auto-generated method stub try { TCPReactor reactor = new TCPReactor(1333); reactor.run(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
客户端代码
package main.pkg; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.PrintWriter; import java.net.Socket; import java.net.UnknownHostException; public class Client { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub String hostname=args[0]; int port = Integer.parseInt(args[1]); //String hostname="127.0.0.1"; //int port=1333; System.out.println("Connecting to "+ hostname +":"+port); try { Socket client = new Socket(hostname, port); // 連接至目的地 System.out.println("Connected to "+ hostname); PrintWriter out = new PrintWriter(client.getOutputStream()); BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream())); BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in)); String input; while((input=stdIn.readLine()) != null) { // 讀取輸入 out.println(input); // 發送輸入的字符串 out.flush(); // 強制將緩衝區內的數據輸出 if(input.equals("exit")) { break; } System.out.println("server: "+in.readLine()); } client.close(); System.out.println("client stop."); } catch (UnknownHostException e) { // TODO Auto-generated catch block System.err.println("Don't know about host: " + hostname); } catch (IOException e) { // TODO Auto-generated catch block System.err.println("Couldn't get I/O for the socket connection"); } } }
代码解读:
1.创建TCPReactor 类的实例,启动端口监听
2.Acceptor 类只用于处理接受请求的时候,后续的读写跟其无任何关系
3.TCPReactor.run( )一直在进行,后续selectionkey有变动,会监听到,一直执行dispatch方法
最后提醒一点,从性能来说,单线程的reactor没过多的提升,因为IO和CPU的速度还是严重不匹配
参考文章:
https://blog.csdn.net/yehjordan/article/details/51012833