Java服务端连接怎样在读取完毕后不中断连接？

无法向客户端写入数据，写入时提示连接已中断。大佬帮忙看下

        ServerSocket s = new ServerSocket(80);
        Socket ss = s.accept();

        OutputStream os = null;
        InputStream inputStream = null;
        BufferedReader in = null;

        inputStream = ss.getInputStream();
        os = ss.getOutputStream();
        in = new BufferedReader(new InputStreamReader(inputStream));

        String str = "";
        String read = "";

        read = in.readLine();
        while (str != null){
            try {
                str = in.readLine();
            } catch (IOException e) {}
            read += str + "\n";
        }

        System.out.print(read);

        os.write("Hello world!".getBytes());

是客户端主动断开了吧，你应该要修改是客户端的代码，发送完信息以后有没有去读传回来的消息。