我读过一些关于StackOverflow的问题，我们通常使用条件(c = inputStream.read()) == -1)来检测是否到达“流的结尾”。然而，我也读到过，如果套接字关闭，套接字的OutputStream只发送“流结束”消息。
这使得这个服务器代码。。

public class Server {
    public static int port = 27018;

    public static void main(String[] args) throws IOException, InterruptedException {
        char c = ' ';

        ServerSocket serverSocket = new ServerSocket(port);
        System.out.println("Server started");
        Socket connectionSocket = serverSocket.accept();
        serverSocket.close();
        String bufferOuputString = "";

        InputStream in = connectionSocket.getInputStream();
        OutputStream out = connectionSocket.getOutputStream();

        System.out.println("Connection established on port " + port);
        out.write("Welcome to my server !".getBytes());

        System.out.println("Waiting for client messages");
        while(c != '/'){
            c = (char) in.read();
            if(c == '*'){
                System.out.println(bufferOuputString);
                bufferOuputString = "";
            } else {
                bufferOuputString += c;
            }
        }

        connectionSocket.close();
    }
}

。。。和这个客户代码一起。。

public class Client {
    public static int port = 27018;

    public static void main(String[] args) throws IOException {
        try (Socket socket = new Socket("127.0.0.1", port)) {
            int c;
            Scanner sc = new Scanner(System.in);
            String bufferInputString = "";
            String bufferString = "";

            OutputStream out = socket.getOutputStream();
            InputStream in = socket.getInputStream();

            while((c = in.read()) != -1){
                bufferInputString += (char) c;
            }
            System.out.println(bufferInputString);

            while(!bufferString.contains("/")){
                System.out.println("You can write messages to server:");
                bufferString = sc.nextLine() + "*";
                out.write(bufferString.getBytes());
            }
        }
    }

}

没用因为客户端等待流结束信号（in.read() = -1），而这个信号永远不会到来，所以它一直被InputStream.read()调用阻塞。
为了记录在案，我尝试将其作为服务器代码来进一步检查套接字的“规则”：

public class Server {
    public static int port = 27018;

    public static void main(String[] args) throws IOException, InterruptedException {
        char c = ' ';

        ServerSocket serverSocket = new ServerSocket(port);
        System.out.println("Server started");
        Socket connectionSocket = serverSocket.accept();
        serverSocket.close();
        String bufferOuputString = "";

        InputStream in = connectionSocket.getInputStream();
        OutputStream out = connectionSocket.getOutputStream();

        System.out.println("Connection established on port " + port);
        out.write("Welcome to my server !".getBytes());
        Thread.sleep(3000);
        connectionSocket.close();
    }
}

3秒钟后，客户端打印出...

...然后进入无限循环，因为我忘记更改第二个while循环。因此，这确认了套接字的OutputStream对象只在Socket.close()处发送“流结束”。我的问题是：为什么选择这种设计？