如何在javaFX中将光标更改为等待的同时执行后台任务?
我有一个应用程序,它在登录时通过接口类访问数据库。登录过程会导致应用程序在访问数据库时有一段时间没有响应,因此我一直在研究线程和等待光标,以使其能够顺利运行。我曾尝试通过web和堆栈溢出上的许多示例使用线程,但我的方法似乎不起作用,我收到java.lang.IllegalStateException:不在FX应用程序线程上;currentThread=Thread-4异常,我不确定如何从这里开始。我试图做的是在后台线程运行loginLoaderything()方法时将光标更改为等待模式(尽管我没有在其中包含代码,因为它太长)。这是我的控制器类:如何在javaFX中将光标更改为等待的同时执行后台任务?,java,javafx,background-task,Java,Javafx,Background Task,我有一个应用程序,它在登录时通过接口类访问数据库。登录过程会导致应用程序在访问数据库时有一段时间没有响应,因此我一直在研究线程和等待光标,以使其能够顺利运行。我曾尝试通过web和堆栈溢出上的许多示例使用线程,但我的方法似乎不起作用,我收到java.lang.IllegalStateException:不在FX应用程序线程上;currentThread=Thread-4异常,我不确定如何从这里开始。我试图做的是在后台线程运行loginLoaderything()方法时将光标更改为等待模式(尽管我没
package main.java.gui;
import javafx.application.Platform;
import javafx.concurrent.Service;
import javafx.concurrent.Task;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.Cursor;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.stage.Stage;
import main.java.databaseInterface.BackendInterface;
import java.net.URL;
import java.util.ResourceBundle;
import java.util.concurrent.CountDownLatch;
public class LoginController implements Initializable {
private BackendInterface backendInterface;
private DashboardController dashboardController;
private StudentsController studentsController;
private ConsultationController consultationController;
private CreateStudentController createStudentController;
private CreateConsultationController createConsultationController;
@FXML
TextField username;
@FXML
PasswordField password;
@FXML
Button loginButton;
@FXML
Label loginLabel;
@FXML
public void loginButtonPress(ActionEvent event) {
Service<Void> service = new Service<Void>() {
@Override
protected Task<Void> createTask() {
return new Task<Void>() {
@Override
protected Void call() throws Exception {
loginLoadEverything();
final CountDownLatch latch = new CountDownLatch(1);
Platform.runLater(new Runnable() {
@Override
public void run() {
try {
Scene s1 = loginLabel.getScene();
s1.setCursor(Cursor.WAIT);
} finally {
latch.countDown();
}
}
});
latch.await();
return null;
}
};
}
};
service.start();
}
public void loginLoadEverything() {
//chance to true when complete
if (username.getText().isEmpty() == false || password.getText().isEmpty() == false) {
loginLabel.setText("Please enter data in the fields below");
} else {
username.setText("-----");
password.setText("-----");
//initialises backend interface with username and password
backendInterface = new BackendInterface(username.getText(), password.getText().toCharArray());
// Open a connection to the database
if (backendInterface.openConnection()) {
//return and print response
System.out.println(backendInterface.getConnectionResponse());
//directs the user to the dashboard after successful login
try {
if (backendInterface.getAllStudents() &&
backendInterface.getAllConsultations() &&
backendInterface.getCourses() &&
backendInterface.getConsultationCategories() &&
backendInterface.getConsultationPriorities()) {
FXMLLoader loader1 = new FXMLLoader();
loader1.setLocation(getClass().getResource("/main/res/dashboard.fxml"));
loader1.load();
Parent p = loader1.getRoot();
Stage stage = new Stage();
stage.setScene(new Scene(p));
stage.show();
//set instances to the dashboard controller
dashboardController = loader1.getController();
dashboardController.setBackendInterface(backendInterface); //pass backendInterface object to controller
dashboardController.setDashboardController(loader1.getController()); //pass dashboard as reference
//load images
Image logoutImage = new Image(getClass().getResourceAsStream("images/logout.png"));
Image userImage = new Image(getClass().getResourceAsStream("images/users.png"));
Image calendarImage = new Image(getClass().getResourceAsStream("images/calendar.png"));
Image leftArrowImage = new Image(getClass().getResourceAsStream("images/leftArrow.png"));
Image notepadImage = new Image(getClass().getResourceAsStream("images/notepad.png"));
//set images
dashboardController.studentLabel.setGraphic(new ImageView(userImage));
dashboardController.logoutLabel.setGraphic(new ImageView(logoutImage));
dashboardController.consultationLabel.setGraphic(new ImageView(notepadImage));
} else {
system.out.println(backendInterface.getExceptionMessage);
}
@Override
public void initialize(URL location, ResourceBundle resources) {
}
package main.java.gui;
导入javafx.application.Platform;
导入javafx.concurrent.Service;
导入javafx.concurrent.Task;
导入javafx.event.ActionEvent;
导入javafx.fxml.fxml;
导入javafx.fxml.fxmloader;
导入javafx.fxml.Initializable;
导入javafx.scene.Cursor;
导入javafx.scene.Parent;
导入javafx.scene.scene;
导入javafx.scene.control.*;
导入javafx.scene.image.image;
导入javafx.scene.image.ImageView;
导入javafx.stage.stage;
导入main.java.databaseInterface.BackendInterface;
导入java.net.URL;
导入java.util.ResourceBundle;
导入java.util.concurrent.CountDownLatch;
公共类LoginController实现可初始化{
专用后端接口后端接口;
专用仪表板控制器仪表板控制器;
私人学生控制人学生控制人;
私人咨询控制人咨询控制人;
私有CreateStudentController CreateStudentController;
私有CreateConsultationController CreateConsultationController;
@FXML
TextField用户名;
@FXML
密码字段密码;
@FXML
按钮登录按钮;
@FXML
标签登录标签;
@FXML
public void loginButtonPress(ActionEvent事件){
服务=新服务(){
@凌驾
受保护的任务createTask(){
返回新任务(){
@凌驾
受保护的Void调用()引发异常{
loginLoadEverything();
最终倒计时闩锁=新倒计时闩锁(1);
Platform.runLater(新的Runnable(){
@凌驾
公开募捐{
试一试{
场景s1=loginLabel.getScene();
s1.setCursor(Cursor.WAIT);
}最后{
倒计时();
}
}
});
satch.wait();
返回null;
}
};
}
};
service.start();
}
public void loginLoadEverything(){
//完成后有机会成为现实
if(username.getText().isEmpty()==false | | password.getText().isEmpty()==false){
loginLabel.setText(“请在下面的字段中输入数据”);
}否则{
username.setText(“----”);
password.setText(“----”);
//使用用户名和密码初始化后端接口
backendInterface=新的backendInterface(username.getText(),password.getText().toCharArray());
//打开与数据库的连接
if(backendInterface.openConnection()){
//返回和打印响应
System.out.println(backendInterface.getConnectionResponse());
//成功登录后将用户引导到仪表板
试一试{
if(backendInterface.getAllStudents()&&
backendInterface.getAllConsultations()&&
backendInterface.getCourses()&&
backendInterface.getConsultationCategories()&&
backendInterface.getConsultationPriorities()){
FXMLLoader loader1=新的FXMLLoader();
setLocation(getClass().getResource(“/main/res/dashboard.fxml”);
loader1.load();
父p=loader1.getRoot();
阶段=新阶段();
舞台场景(新场景(p));
stage.show();
//将实例设置为仪表板控制器
dashboardController=loader1.getController();
dashboardController.setBackendInterface(backendInterface);//将backendInterface对象传递给控制器
dashboardController.setDashboardController(loader1.getController());//将dashboard作为引用传递
//加载图像
Image logoutImage=新图像(getClass().getResourceAsStream(“images/logout.png”);
Image userImage=新图像(getClass().getResourceAsStream(“images/users.png”);
Image calendarImage=新图像(getClass().getResourceAsStream(“images/calendar.png”);
Image leftArrow Image=新图像(getClass().getResourceAsStream(“images/leftArrow.png”);
Image notepad Image=新图像(getClass().getResourceAsStream(“images/notepad.png”);
//设置图像
dashboardController.studentLabel.setGraphic(新的ImageView(userImage));
dashboardController.logoutLabel.setGraphic(新图像视图(logoutImage));
dashboardController.consultationLabel.setGraphic(新的ImageView(notepadImage));
}否则{
system.out.println(backendInterface.getExceptionMessage);
}
@凌驾
公共无效初始
@FXML
public void loginButtonPress(ActionEvent event) {
if (( ! username.getText().isEmpty()) || (! password.getText().isEmpty()) ) {
loginLabel.setText("Please enter data in the fields below");
} else {
// I assume you want these values before you set them to "-----", no???
final String uName = username.getText();
final char[] pw = password.getText().toCharArray();
username.setText("-----");
password.setText("-----");
// create task for retrieving data:
Task<BackendInterface> loadDataTask = new Task<BackendInterface>() {
@Override
public BackendInterface call() throws Exception {
BackendInterface backendInterface = new BackendInterface(uName, pw);
if (backendInterface.openConnection()) {
if (backendInterface.getAllStudents() &&
backendInterface.getAllConsultations() &&
backendInterface.getCourses() &&
backendInterface.getConsultationCategories() &&
backendInterface.getConsultationPriorities()) {
return backendInterface ;
}
}
// maybe throw an exception here, depending on your requirements...
return null ;
}
};
// show UI on task completion:
loadDataTask.setOnSucceeded(e -> {
BackendInterface backendInterface = loadDataTask.getValue();
if (backendInterface == null) {
// something went wrong... bail, or probably show error message...
return ;
}
FXMLLoader loader1 = new FXMLLoader();
loader1.setLocation(getClass().getResource("/main/res/dashboard.fxml"));
Parent p = loader1.load();
DashboardController controller = loader.getController();
controller.setBackendInterface(backendInterface);
Stage stage = new Stage();
stage.setScene(new Scene(p));
stage.show();
// etc etc with your Images, etc (not sure why this isn't done in DashboardController though...)
// set cursor back to default:
loginLabel.getScene().setCursor(Cursor.DEFAULT);
});
loadDataTask.setOnFailed(e -> {
// show error message or otherwise handle database exception here
});
// set cursor to WAIT:
loginLabel.getScene().setCursor(Cursor.WAIT);
// and run task in a background thread:
Thread t = new Thread(loadDataTask);
t.start();
}