此表单导致问题。不知道为什么，但现在已经修好了。

const Urlap = () => {
      const handleSubmit = async (e) => {
        e.preventDefault();
    
        try {
          const response = await fetch("http://localhost:3000/api/members", {
            method: "POST",
            headers: {
              "Content-Type": "application/json",
            },
            body: JSON.stringify({
              name,
              birth_date,
              created_at,
              gender,
            }),
          });
        } catch (error) {
          console.log(error);
        }
      };
      const [name, setName] = useState(null);
      const [gender, setGender] = useState(null);
      const [birth_date, setBirthdate] = useState(null);
      const [created_at, setJoindate] = useState(null);
      console.log(name, birth_date, created_at);
      return (
        <Container>
          <form action="" id="form" onSubmit={handleSubmit}>
            <input type="text" onChange={(e) => setName(e.target.value)} />
            <input type="date" onChange={(e) => setBirthdate(e.target.value)} />
            <input type="date" onChange={(e) => setJoindate(e.target.value)} />
            <input type="text" onChange={(e) => setGender(e.target.value)} />
            <button type="submit">Tagfelvétel</button>
          </form>
        </Container>
      );
    };
    export default Urlap;

主要

public class Main {
    public static void main(String[] args) {
        if (Arrays.asList(args).contains("--stat")){
            Statisztika.run();
        }
        else{
            HelloApplication.main(args);
        }
    }
}

统计

public class Statisztika {

    private static List<Member> members;
    public static void run() {
        try {
            readMembersFromDatabase();
            System.out.printf("Kitiltott tagok száma: %d\n", countBannedMembers());         
        } catch (SQLException e) {
            System.out.println("nem sikerült kapcsolódni az adatbázshoz, az alkamazás leáll");
            System.out.println(e.getMessage());
        }
    }

   
    private static int countBannedMembers() {
        int count = 0;
        for (Member member: members) {
            if (member.isBanned()) {
                count++;
            }
        }
         return  count;
    }

    private static void readMembersFromDatabase() throws SQLException {
        DBHelper db = new DBHelper();
        members = db.readMembers();
    }
}

DEP

<dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.32</version>
    </dependency>

DBHELP

public class DBHelper {
    public static String DB_DRIVER = "mysql";
    public static String DB_HOST = "localhost";
    public static String DB_PORT = "3306";
    public static String DB_NAME = "vizsga";
    public static String DB_USER = "root";
    public static String DB_PASS= "";

    private Connection conn;

    public DBHelper() throws SQLException {
        String url = String.format("jdbc:%s://%s:%s/%s", DB_DRIVER, DB_HOST, DB_PORT, DB_NAME);
        conn = DriverManager.getConnection(url, DB_USER, DB_PASS);
    }

    public List<Member> readMembers() throws SQLException {
        List<Member> members = new ArrayList<>();
        String sql = "SELECT * FROM members";
        Statement statement = conn.createStatement();
        ResultSet result = statement.executeQuery(sql);
        while (result.next()) {
        int id = result.getInt("id");
        String name = result.getString("name");
        String gender = result.getString("gender");
        LocalDate birth_date = result.getDate("birth_date").toLocalDate();
        boolean banned = result.getBoolean("banned");
        Member member = new Member(id, name, gender, birth_date, banned);
        members.add(member);
        }
        return members;
    }
}

HelloContr

@FXML
    private TableColumn<Member, String> banned;

    private DBHelper db;
    public void initialize(){
       name.setCellValueFactory(new PropertyValueFactory<>("name"));
       gender.setCellValueFactory(new PropertyValueFactory<>("gender"));
        try {
            db=new DBHelper();
            refreshTable();
        } catch (SQLException e) {
          e.printStackTrace();
        }
    }

    private void refreshTable() throws SQLException {
        members.getItems().clear();
        members.getItems().addAll(db.readMembers());
    }

一对多

@OneToMany(() => Datas, (data) => data.id)
  @JoinColumn({name: 'data', referencedColumnName: 'data'})
  data: Datas[];