image.png

复习 Java 网络编程写的小 Demo

服务端

package 第17章网络编程.chapter17_03_基于TCP协议的网络编程.MultiThread.server;

public class MyServer {
    // 定义保存所有Socket的ArrayList，并将其包装为线程安全的
    public static List<Socket> socketList = Collections.synchronizedList(new ArrayList<>());

    public static void main(String[] args) throws IOException {
        ServerSocket ss = new ServerSocket(30000);
        while (true) {
            // 此行代码会阻塞，将一直等待别人的连接
            Socket s = ss.accept();
            socketList.add(s);
            // 每当客户端连接后启动一条ServerThread线程为该客户端服务
            new Thread(new ServerThread(s)).start();
        }
    }
}

服务端实现

package 第17章网络编程.chapter17_03_基于TCP协议的网络编程.MultiThread.server;

// 负责处理每个线程通信的线程类
public class ServerThread implements Runnable {
    // 定义当前线程所处理的Socket
    Socket s = null;
    // 该线程所处理的Socket所对应的输入流
    BufferedReader br = null;


    public ServerThread(Socket s) throws IOException {
        this.s = s;
        // 初始化该Socket对应的输入流
        br = new BufferedReader(new InputStreamReader(s.getInputStream()));
    }

    @Override
    public void run() {
        try {
            String content = null;
            // 采用循环不断从Socket中读取客户端发送过来的数据
            while ((content = readFromClient()) != null) {
                // 遍历socketList中的每个Socket，
                // 将读到的内容向每个Socket发送一次
                for (Socket s : MyServer.socketList) {
                    PrintStream ps = new PrintStream(s.getOutputStream());
                    ps.println(content);
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    // 定义读取客户端数据的方法
    private String readFromClient() {
        try {
            return br.readLine();
        }
        // 如果捕捉到异常，表明该Socket对应的客户端已经关闭
        catch (IOException e) {
            // 删除该Socket。
            MyServer.socketList.remove(s); // ①
        }
        return null;
    }
}

客户端

package 第17章网络编程.chapter17_03_基于TCP协议的网络编程.MultiThread.client;

public class MyClient
{
    public static void main(String[] args)throws Exception
    {
        Socket s = new Socket("127.0.0.1" , 30000);
        // 客户端启动ClientThread线程不断读取来自服务器的数据
        new Thread(new ClientThread(s)).start();   // ①
        // 获取该Socket对应的输出流
        PrintStream ps = new PrintStream(s.getOutputStream());
        String line = null;
        // 不断读取键盘输入
        BufferedReader br = new BufferedReader(
            new InputStreamReader(System.in));
        while ((line = br.readLine()) != null)
        {
            // 将用户的键盘输入内容写入Socket对应的输出流
            ps.println(line);
        }
    }
}

客户端实现

package 第17章网络编程.chapter17_03_基于TCP协议的网络编程.MultiThread.client;

public class ClientThread implements Runnable
{
    // 该线程负责处理的Socket
    private Socket s;
    // 该线程所处理的Socket所对应的输入流
    BufferedReader br = null;

    public ClientThread(Socket s)
        throws IOException
    {
        this.s = s;
        br = new BufferedReader(
            new InputStreamReader(s.getInputStream()));
    }
    @Override
    public void run()
    {
        try
        {
            String content = null;
            // 不断读取Socket输入流中的内容，并将这些内容打印输出
            while ((content = br.readLine()) != null)
            {
                System.out.println(content);
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }
}