具有单个客户端的ServerSocket

问题描述

我已经编写了以下代码，以创建一个具有恒定操作的简单ServerSocket，该ServerSocket在从数据库读取数据的同时向单个客户端发送命令。如果客户端退出并重新连接（始终使用不同的远程端口），服务器将继续向先前的“实例”发送命令。我如何区分当前客户端和断开连接的客户端，以确保将数据传递给他。您还能提出任何建议吗？

public class Server {

    private static final String connectionUrl = "jdbc:mysql://localhost:3306/testdb?serverTimezone=Europe/Athens";

    public static void main(String[] args) throws IOException {

        ServerSocket listener = new ServerSocket(50001);
        System.out.println("[SERVER 50001] Waiting for client connection...");

        try (Connection conn = DriverManager.getConnection(connectionUrl,"test","1234")) {

            String selectCommandSql = "SELECT `id`,`command` FROM `commands` WHERE (`is_sent` = 0 OR `is_sent` = NULL) LIMIT 0,1";

            while (true) {

                try {

                    Socket client = listener.accept();
                    System.out.println("[SERVER 50001] Connected to client: " + client.getRemoteSocketAddress());

                    PrintWriter out = new PrintWriter(client.getOutputStream(),true);

                    while (true) {

                        PreparedStatement ps = conn.prepareStatement(selectCommandSql);
                        ResultSet rs = ps.executeQuery();

                        if (rs.next()) {

                            int id = rs.getInt("id");
                            String command = rs.getString("command");

                            out.println(command);

                            String updateCommandStatusSql = "UPDATE `commands` SET `is_sent` = 1,`sent_at` = ? WHERE `id` = ?";
                            PreparedStatement ps2 = conn.prepareStatement(updateCommandStatusSql);
                            LocalDateTime now = LocalDateTime.now();
                            ps2.setTimestamp(1,Timestamp.valueOf(now));
                            ps2.setInt(2,id);

                            int success = ps2.executeUpdate();

                            if (success > 0 && command.equals("exit")) {

                                if (ps2 != null) ps2.close();

                                if (rs != null) rs.close();
                                if (ps != null) ps.close();

                                if (out != null) out.close();
                                client.close();
                                break;

                            }
                        }

                        if (rs != null) rs.close();
                        if (ps != null) ps.close();
                        Thread.sleep(100);
                    }

                } catch (IOException | InterruptedException e) {
                    System.err.println(e.getMessage());
                    e.printStackTrace();
                }
            }

        } catch (SQLException e) {

            System.err.println(e.getMessage());
            e.printStackTrace();

        } finally {

            listener.close();
            System.out.println("[SERVER 50001] Server closed.");
            System.exit(0);

        }
    }
}

解决方法

暂无找到可以解决该程序问题的有效方法，小编努力寻找整理中！

如果你已经找到好的解决方法，欢迎将解决方案带上本链接一起发送给小编。

小编邮箱:dio#foxmail.com (将#修改为@）