声明

该系列文章由书籍《Netty权威指南》第二版整理而来。只为记录学习笔记。
若认为内容侵权请及时通知本人删除相关内容。

[TOC]

时间服务器–传统的BIO

服务端代码

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public class TimeServer {
	public static void main(String[] args) throws IOException {
		int port = 1234;
		ServerSocket server = null;
		try {
			server = new ServerSocket(port);
			System.out.println("The time server is listening in port : " + port);
			Socket socket = null;
			while (true) {
				socket = server.accept();
				new Thread(new TimeServerHandler(socket)).start();
			}
		} finally {
			if (server != null) {
				System.out.println("The time server close");
				server.close();
				server = null;
			}
		}
	}
}
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public class TimeServerHandler implements Runnable {
	private Socket socket;
	private SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
	public TimeServerHandler(Socket socket) {
		this.socket = socket;
	}
	@Override
	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 body = null;
			while (true) {
				body = in.readLine();
				if (body == null)
					break;
				out.println(this.sdf.format(new Date()));
			}
		} 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();
				}
			}
		}
	}
}

客户端代码

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public class TimeClient {
	public static void main(String[] args) {
		int port = 1234;
		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");
			String resp = in.readLine();
			System.out.println("time:" + 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 (IOException e) {
					e.printStackTrace();
				}
				socket = null;
			}
		}
	}
}

总结

这种传统的BIO模型有如下特点:

  • 新的客户端连接，服务端就要开启一个线程处理–服务器的资源开销不可控
  • 无法避免线程频繁创建/销毁的开销
  • 客户端连接数量太大很容易导致服务器奔溃

参考资料: 《Netty权威指南》第二版