使用Netbeans从mysql检索数据

Question

我正在创建一个名为“图书馆管理系统”的项目。我面临的问题是，当我在ID的文本字段中输入数据以从数据库（MySql）检索数据以在其他“文本”上显示它时，它什么也没显示...

有人可以指导我吗

在代码中：

Bookidinput =文本字段名称
书名 =书名的文本名称（文本表示简单的Javafx FXML文本）
bookauthor =图书作者的文本名称

package lms.ui.main;

import com.jfoenix.effects.JFXDepthManager;
import java.io.IOException;
import java.net.URL;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ResourceBundle;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
 import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.TextField;
import javafx.scene.layout.HBox;
import javafx.scene.text.Text;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
import lms.database.databaseHandler;

public class MainController implements Initializable {

@FXML
private HBox book_info;
@FXML
private HBox member_info;
@FXML
private Text bookname;
@FXML
private Text bookauthor;
@FXML
private Text member_name;
@FXML
private Text member_email;
@FXML
private TextField bookidinput;
@FXML
private TextField memberidinput;

databaseHandler handler;

@Override
public void initialize(URL url, ResourceBundle rb) {

    JFXDepthManager.setDepth(book_info, 2);
    JFXDepthManager.setDepth(member_info, 2);

    handler = databaseHandler.getInstance();
}    

@FXML
private void AddNewMember(ActionEvent event) {

    loadWindow("/lms/ui/Add_Member/Add_Member.fxml", "Add New Member");
}

@FXML
private void AddNewBook(ActionEvent event) {

    loadWindow("/lms/FXML_AddBook.fxml", "Add New Book");
}

@FXML
private void ListMemberTable(ActionEvent event) {

    loadWindow("/lms/ui/ListMemberTable/MemberList.fxml", "Member 
Table");
}

@FXML
private void ListBooKTable(ActionEvent event) {

    loadWindow("/lms/ui/ListBookTable/BookList.fxml", "Book Table");
}

@FXML
private void Settings(ActionEvent event) {
}

    void loadWindow(String loc, String Title){

    try{
             Parent root = FXMLLoader.load(getClass().getResource(loc));
             Stage stage = new Stage(StageStyle.DECORATED);
             stage.setTitle(Title);
             stage.setScene(new Scene(root));
             stage.show();

    }
    catch(IOException e){

 Logger.getLogger(MainController.class.getName()).log(Level.SEVERE, null, 
 e);
    }
 }

 @FXML
 private void loadbookinfo(ActionEvent event) {

    String id = bookidinput.getText();
    String qu = "Select * from Books where ID = ' " + 
 bookidinput.getText() + " ' ";
    ResultSet rs = handler.exeQuery(qu) ;
   Boolean flag = false;
    try {
        while( rs.next())
        {
          String bName = rs.getString("Title");
          String bAuthor = rs.getString("Author");

          bookname.setText(rs.getString("Title"));
          bookauthor.setText(rs.getString("Author"));
          flag = true;
        }
    } catch (SQLException ex) {

 Logger.getLogger(MainController.class.getName()).log(Level.SEVERE, null, 
 ex);
    }
 }

create table Books( ID varchar(30) primary key,
Title varchar(50),
 Author varchar (60),
 Publisher varchar(60));

insert into Books values(101, "ITM", "Stephen, Coulter, Vohra", "Bloomsbury Publishing Plc");
insert into Books values(102, "The C++ Programming Language",   "Bjarne Stroustrup", "Daastan");
insert into Books values(103, "Programming: Principles and Practice Using C++", "Bjarne Stroustrup", "Pearson");
insert into Books values(104, "Modern C++ Design", "Andrei Alexandrescu", "Addison-Wesley");
insert into Books (ID,Title,Author,Publisher) values(105, "Effective C++", "Scott Meyers", "RELX Group");

我希望书名出现在“文本”中，但不会输出任何内容。强文本