同步阻塞I/O
阿新 • • 發佈:2017-07-18
tin 客戶 機制 i/o ack .get args chap 進出
TimeServer:
package netty.chapter2; import java.io.IOException; import java.net.ServerSocket; import java.net.Socket; /** * @ClassName TimeServer * @Description 同步阻塞I/O的TimeServer * @author lihk * @Date Jul 18, 2017 10:47:42 AM * @version 1.0.0 */ public class TimeServer { public static void main(String[] args) {int port = 8090; ServerSocket server = null; try { server = new ServerSocket(port); System.out.println("The time server is started in port:" + port); Socket socket = null; while (true) { socket = server.accept(); System.out.println("Accept message."); new Thread(new TimeServerHandler(socket)).start(); } } catch (Exception e) { e.printStackTrace(); } finally { if (server != null) { System.out.println("The time server close"); try{ server.close(); } catch (IOException e) { e.printStackTrace(); } server = null; } } } }
TimeServerHandler:
package netty.chapter2; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.PrintWriter; import java.net.Socket; import java.util.Date; /** * @ClassName TimeServerHandler * @Description 同步阻塞I/O的TimeServerHandler * @author lihk * @Date Jul 18, 2017 10:38:56 AM * @version 1.0.0 */ public class TimeServerHandler implements Runnable { private Socket socket; public TimeServerHandler(Socket socket) { this.socket = socket; } public void run() { BufferedReader in = null; PrintWriter out = null; try { in = new BufferedReader(new InputStreamReader(this.socket.getInputStream())); out = new PrintWriter(this.socket.getOutputStream(), true); String currentTime = null; String body = null; while (true) { body = in.readLine(); if (body == null) break; System.out.println("The time server receive order : " + body); currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body) ? new Date(System.currentTimeMillis()).toString() : "BAD ORDER"; out.println(currentTime); } } catch (Exception e) { if (in != null) { try { in.close(); } catch (IOException e1) { e1.printStackTrace(); } } if(out != null){ out.close(); out = null; } if(this.socket != null){ try { this.socket.close(); } catch (IOException e1) { e1.printStackTrace(); } this.socket = null; } } } }
TimeClient:
package netty.chapter2; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.PrintWriter; import java.net.Socket; /** * @ClassName TimeClient * @Description 同步阻塞I/O的TimeClient * @author lihk * @Date Jul 18, 2017 10:58:49 AM * @version 1.0.0 */ public class TimeClient { public static void main(String[] args) { int port = 8090; Socket socket = null; BufferedReader in = null; PrintWriter out = null; try { socket = new Socket("127.0.0.1", port); in = new BufferedReader(new InputStreamReader(socket.getInputStream())); out = new PrintWriter(socket.getOutputStream(),true); out.println("QUERY TIME ORDER"); System.out.println("Send order 2 server succeed."); String resp = in.readLine(); System.out.println("Now is:"+resp); } catch (Exception e) { e.printStackTrace(); }finally { if(out != null){ out.close(); out = null; } if(in != null){ try { in.close(); } catch (IOException e) { e.printStackTrace(); } in = null; } if(socket != null){ try { socket.close(); } catch (Exception e2) { e2.printStackTrace(); } socket = null; } } } }
BIO主要的問題在於每當一個新的客戶端請求連接時,服務器必須創建一個新的線程處理新接入的客戶端鏈路,一個線程只能處理一個客戶端連接。在高性能服務器應用領域,往往需要面向成千上萬個客戶端的並發連接,這種模型顯然無法滿足高性能、高並發的接入場景。為了改進一線程一連接模型,後來又演進出了一種通過線程池或者消息隊列實現1個或者多個線程處理N個客戶端的模型,由於它的底層通信機制依然使用同步阻塞的I/O(read(),write()方法),所以被稱為“偽異步”。
同步阻塞I/O