java - 卡在 javafx 程序上，该程序不会将可注入(inject)字段加载到 FXML 文档中

Question

我遇到的唯一问题是 getAll() 方法，它似乎在 PersonnelController 类中的位置立即运行。我也曾在其他很多地方尝试过，但都没有成功。 setAll() 方法看起来不错，我已经测试过 setAll() 向其传递值的方法可以将正确的值返回到 main 方法。他们只是出于某种原因没有在我需要的正确时间将值返回到 Controller 。

应该发生的是，用户输入用户名和密码，然后单击登录按钮，这就是在加载第二个场景之前将可注入(inject)值传递到 FXML 的位置。根据他们输入的用户名，第二个场景中将出现一组不同的图片和标签。我有程序调用的 getter 和 setter 方法来设置文本和图像。

PersonnelController.java

package application.controller;

import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;

import application.Main;
import application.model.CrewMember;
import application.model.Starship;
import application.model.User;

public class PersonnelController implements Initializable {

    @FXML Label welcomeMsg;

    @FXML Label shipName;

    @FXML
    ImageView commandOfficer;

    @FXML
    ImageView engineOfficer;

    @FXML
    ImageView commOfficer;

    @FXML
    ImageView firstOfficer;

    @FXML
    ImageView nurse;

    @FXML
    ImageView medOfficer;

    @FXML
    ImageView navigator;

    @FXML
    ImageView helmsman;

    @FXML
    Label crew8;

    @FXML
    Label crew7;

    @FXML
    Label crew6;

    @FXML
    Label crew5;

    @FXML
    Label crew4;

    @FXML
    Label crew3;

    @FXML
    Label crew2;

    @FXML
    Label crew1;


    private Scene firstScene;

    public void getAll() {
          welcomeMsg.setText("Welcome, " + Starship.getCapt());
          shipName.setText(Starship.getShip());

          commandOfficer.setImage(CrewMember.getInput1());
          firstOfficer.setImage(CrewMember.getInput2());
          commOfficer.setImage(CrewMember.getInput3());
          engineOfficer.setImage(CrewMember.getInput4());
          helmsman.setImage(CrewMember.getInput5());
          navigator.setImage(CrewMember.getInput6());
          medOfficer.setImage(CrewMember.getInput7());
          nurse.setImage(CrewMember.getInput8());

          crew1.setText(CrewMember.getCrew1());
          crew2.setText(CrewMember.getCrew2());
          crew3.setText(CrewMember.getCrew3());
          crew4.setText(CrewMember.getCrew4());
          crew5.setText(CrewMember.getCrew5());
          crew6.setText(CrewMember.getCrew6());
          crew7.setText(CrewMember.getCrew7());
          crew8.setText(CrewMember.getCrew8());
}

    public void setFirstScene(Scene scene) {
        firstScene = scene;
    }


    public void openFirstScene(ActionEvent actionEvent) {    
        Stage primaryStage = (Stage)((Node)actionEvent.getSource()).getScene().getWindow();
        primaryStage.setScene(firstScene);
    }

    @Override
    public void initialize(URL location, ResourceBundle resources) {
                getAll();
            }
}

LoginController.java

package application.controller;

import java.io.FileNotFoundException;
import java.net.URL;
import java.util.ResourceBundle;
import java.util.Scanner;
import javafx.stage.*;
import javafx.scene.*;
import javafx.scene.layout.*;
import javafx.scene.control.*;
import javafx.geometry.*;

import application.Main;
import application.model.CrewMember;
import application.model.Starship;
import application.model.User;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.geometry.Pos;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.PasswordField;
import javafx.scene.control.TextField;
import javafx.scene.layout.VBox;
import javafx.stage.Modality;
import javafx.stage.Stage;
import javafx.stage.Window;

import java.awt.Label;
import java.io.*;

public class LoginController implements Initializable {

    @FXML 
    private Button loginButton;

    @FXML
    private TextField username;

    @FXML
    private PasswordField password;

    private static Scene secondScene;   

    private void setAll(String user) {

        Starship.setShip(user);
        Starship.setCapt(user);

        CrewMember.setInput1(user);
        CrewMember.setInput2(user);
        CrewMember.setInput3(user);
        CrewMember.setInput4(user);
        CrewMember.setInput5(user);
        CrewMember.setInput6(user);
        CrewMember.setInput7(user);
        CrewMember.setInput8(user);

        CrewMember.setCrew1(user);
        CrewMember.setCrew2(user);
        CrewMember.setCrew3(user);
        CrewMember.setCrew4(user);
        CrewMember.setCrew5(user);
        CrewMember.setCrew6(user);
        CrewMember.setCrew7(user);
        CrewMember.setCrew8(user);


}

    public void setSecondScene(Scene scene) {
        secondScene = scene;
    }

    public void openSecondScene(ActionEvent actionEvent) {

        String user = username.getText();
        String pass = password.getText();
        setAll(user);   



         /* If the username/password are valid, open the Personnel viewer. 
        Otherwise, alert the user that credentials are invalid. */
        if(User.validate(user,pass,"data/users.csv")== true) {  

            Stage primaryStage = (Stage)((Node)actionEvent.getSource()).getScene().getWindow();  
            primaryStage.setScene(secondScene);


          }
        else{

            User.invalid();

                }   
    }


    @Override
    public void initialize(URL location, ResourceBundle resources) {
        assert loginButton != null : "fx:id=\"loginButton\" was not injected: check your FXML file '/Login.fxml'.";

            }
}

Main.java

package application;

import javafx.application.Application;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.control.ButtonBase;
import javafx.scene.control.CheckBox;
import javafx.scene.layout.BorderPane;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

import application.model.CrewMember;

public class Main extends Application {
    @Override
    public void start(Stage primaryStage) {

        try {
            /* getting loader and a pane for the first scene.
            Loader will then give a possibility to get related controller */
            FXMLLoader firstPaneLoader = new FXMLLoader(getClass().getResource("/Login.fxml"));
            Parent firstPane = firstPaneLoader.load();
            Scene firstScene = new Scene(firstPane);

            // getting loader and a pane for the second scene
            FXMLLoader secondPageLoader = new FXMLLoader(getClass().getResource("/Personnel.fxml"));
            Parent secondPane = secondPageLoader.load();
            Scene secondScene = new Scene(secondPane);

            // injecting second scene into the controller of the first scene
            application.controller.LoginController firstPaneController = (application.controller.LoginController) firstPaneLoader.getController();
            firstPaneController.setSecondScene(secondScene);

            // injecting first scene into the controller of the second scene
            application.controller.PersonnelController secondPaneController = (application.controller.PersonnelController) secondPageLoader.getController();
            secondPaneController.setFirstScene(firstScene);

            // open the login screen on start       
            primaryStage.setScene(firstScene);
            primaryStage.show();

        } catch(Exception e) {
            e.printStackTrace();
        }

            }

    public static void main(String[] args) {
        launch(args);
            }
    }

这里 Starship.java 是具有 getter 和 setter 方法的两个类之一，登录屏幕的 Controller 中的 setAll() 方法和第二个屏幕的 Controller 中的 getAll() 方法调用这些方法(Personnel.java)。 FXML)。

人员.fxml

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.image.Image?>
<?import javafx.scene.image.ImageView?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.ColumnConstraints?>
<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.layout.RowConstraints?>
<?import javafx.scene.text.Font?>

<AnchorPane prefHeight="480.0" prefWidth="720.0" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.controller.PersonnelController">
   <children>
      <ImageView fitHeight="90.0" fitWidth="120.0" onMouseClicked="#getAll" pickOnBounds="true" preserveRatio="true">
         <image>
            <Image url="@../Starfleet_Command_logo.jpg" />
         </image>
      </ImageView>
      <Label fx:id="welcomeMsg" layoutX="302.0" layoutY="45.0" prefHeight="16.0" prefWidth="116.0" AnchorPane.bottomAnchor="419.0" AnchorPane.leftAnchor="302.0" AnchorPane.rightAnchor="302.0" AnchorPane.topAnchor="45.0" />
      <Label fx:id="shipName" layoutX="302.0" layoutY="74.0" prefHeight="14.0" prefWidth="91.0" AnchorPane.bottomAnchor="390.0" AnchorPane.leftAnchor="302.0" AnchorPane.rightAnchor="302.0" AnchorPane.topAnchor="74.0">
         <font>
            <Font size="10.0" />
         </font>
      </Label>
      <GridPane layoutX="8.0" layoutY="131.0" prefHeight="347.0" prefWidth="703.0">
        <columnConstraints>
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
          <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
          <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
        </columnConstraints>
        <rowConstraints>
          <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
          <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
        </rowConstraints>
         <children>
            <ImageView fx:id="commandOfficer" fitHeight="120.0" fitWidth="100.0" pickOnBounds="true" preserveRatio="true" GridPane.halignment="CENTER" GridPane.valignment="TOP" />
            <ImageView fx:id="engineOfficer" fitHeight="120.0" fitWidth="100.0" layoutX="48.0" layoutY="10.0" pickOnBounds="true" preserveRatio="true" GridPane.columnIndex="3" GridPane.halignment="CENTER" GridPane.valignment="TOP" />
            <ImageView fx:id="commOfficer" fitHeight="120.0" fitWidth="100.0" layoutX="10.0" layoutY="37.0" pickOnBounds="true" preserveRatio="true" GridPane.columnIndex="2" GridPane.halignment="CENTER" GridPane.valignment="TOP" />
            <ImageView fx:id="firstOfficer" fitHeight="120.0" fitWidth="100.0" layoutX="10.0" layoutY="37.0" pickOnBounds="true" preserveRatio="true" GridPane.columnIndex="1" GridPane.halignment="CENTER" GridPane.valignment="TOP" />
            <ImageView fx:id="nurse" fitHeight="120.0" fitWidth="100.0" layoutX="48.0" layoutY="10.0" pickOnBounds="true" preserveRatio="true" GridPane.columnIndex="3" GridPane.halignment="CENTER" GridPane.rowIndex="1" GridPane.valignment="TOP" />
            <ImageView fx:id="medOfficer" fitHeight="120.0" fitWidth="100.0" layoutX="10.0" layoutY="37.0" pickOnBounds="true" preserveRatio="true" GridPane.columnIndex="2" GridPane.halignment="CENTER" GridPane.rowIndex="1" GridPane.valignment="TOP" />
            <ImageView fx:id="navigator" fitHeight="120.0" fitWidth="100.0" layoutX="10.0" layoutY="37.0" pickOnBounds="true" preserveRatio="true" GridPane.columnIndex="1" GridPane.halignment="CENTER" GridPane.rowIndex="1" GridPane.valignment="TOP" />
            <ImageView fx:id="helmsman" fitHeight="120.0" fitWidth="100.0" layoutX="10.0" layoutY="37.0" pickOnBounds="true" preserveRatio="true" GridPane.halignment="CENTER" GridPane.rowIndex="1" GridPane.valignment="TOP" />
            <Label text="Commanding Officer" GridPane.halignment="CENTER" GridPane.valignment="BOTTOM">
               <GridPane.margin>
                  <Insets bottom="30.0" />
               </GridPane.margin>
            </Label>
            <Label layoutX="80.0" layoutY="138.0" text="Chief Medical Officer" GridPane.columnIndex="2" GridPane.halignment="CENTER" GridPane.rowIndex="1" GridPane.valignment="BOTTOM">
               <GridPane.margin>
                  <Insets bottom="30.0" />
               </GridPane.margin>
            </Label>
            <Label layoutX="10.0" layoutY="89.0" text="Navigator" GridPane.columnIndex="1" GridPane.halignment="CENTER" GridPane.rowIndex="1" GridPane.valignment="BOTTOM">
               <GridPane.margin>
                  <Insets bottom="30.0" />
               </GridPane.margin>
            </Label>
            <Label layoutX="10.0" layoutY="89.0" text="Helmsman" GridPane.halignment="CENTER" GridPane.rowIndex="1" GridPane.valignment="BOTTOM">
               <GridPane.margin>
                  <Insets bottom="30.0" />
               </GridPane.margin>
            </Label>
            <Label layoutX="10.0" layoutY="89.0" text="Chief Engineering Officer" GridPane.columnIndex="3" GridPane.halignment="CENTER" GridPane.valignment="BOTTOM">
               <padding>
                  <Insets bottom="30.0" />
               </padding>
            </Label>
            <Label layoutX="10.0" layoutY="89.0" text="Communications Officer" GridPane.columnIndex="2" GridPane.halignment="CENTER" GridPane.valignment="BOTTOM">
               <GridPane.margin>
                  <Insets bottom="30.0" />
               </GridPane.margin>
            </Label>
            <Label layoutX="10.0" layoutY="89.0" text="First Officer" GridPane.columnIndex="1" GridPane.halignment="CENTER" GridPane.valignment="BOTTOM">
               <GridPane.margin>
                  <Insets bottom="30.0" />
               </GridPane.margin>
            </Label>
            <Label layoutX="80.0" layoutY="138.0" text="Nurse" GridPane.columnIndex="3" GridPane.halignment="CENTER" GridPane.rowIndex="1" GridPane.valignment="BOTTOM">
               <GridPane.margin>
                  <Insets bottom="30.0" />
               </GridPane.margin>
            </Label>
            <Label fx:id="crew1" text="Label" GridPane.halignment="CENTER" GridPane.valignment="BOTTOM">
               <GridPane.margin>
                  <Insets bottom="10.0" />
               </GridPane.margin></Label>
            <Label fx:id="crew8" layoutX="10.0" layoutY="89.0" text="Label" GridPane.columnIndex="3" GridPane.halignment="CENTER" GridPane.rowIndex="1" GridPane.valignment="BOTTOM">
               <GridPane.margin>
                  <Insets bottom="10.0" />
               </GridPane.margin></Label>
            <Label fx:id="crew7" layoutX="10.0" layoutY="89.0" text="Label" GridPane.columnIndex="2" GridPane.halignment="CENTER" GridPane.rowIndex="1" GridPane.valignment="BOTTOM">
               <GridPane.margin>
                  <Insets bottom="10.0" />
               </GridPane.margin></Label>
            <Label fx:id="crew6" layoutX="10.0" layoutY="89.0" text="Label" GridPane.columnIndex="1" GridPane.halignment="CENTER" GridPane.rowIndex="1" GridPane.valignment="BOTTOM">
               <GridPane.margin>
                  <Insets bottom="10.0" />
               </GridPane.margin></Label>
            <Label fx:id="crew5" layoutX="10.0" layoutY="89.0" text="Label" GridPane.halignment="CENTER" GridPane.rowIndex="1" GridPane.valignment="BOTTOM">
               <GridPane.margin>
                  <Insets bottom="10.0" />
               </GridPane.margin></Label>
            <Label fx:id="crew4" layoutX="10.0" layoutY="89.0" text="Label" GridPane.columnIndex="3" GridPane.halignment="CENTER" GridPane.valignment="BOTTOM">
               <GridPane.margin>
                  <Insets bottom="10.0" />
               </GridPane.margin></Label>
            <Label fx:id="crew3" layoutX="10.0" layoutY="89.0" text="Label" GridPane.columnIndex="2" GridPane.halignment="CENTER" GridPane.valignment="BOTTOM">
               <GridPane.margin>
                  <Insets bottom="10.0" />
               </GridPane.margin></Label>
            <Label fx:id="crew2" layoutX="10.0" layoutY="89.0" text="Label" GridPane.columnIndex="1" GridPane.halignment="CENTER" GridPane.valignment="BOTTOM">
               <GridPane.margin>
                  <Insets bottom="10.0" />
               </GridPane.margin></Label>
         </children>
      </GridPane>
      <Button layoutX="627.0" layoutY="32.0" mnemonicParsing="false" onAction="#openFirstScene" text="Log Out" />
   </children>
</AnchorPane>

登录后，没有设置任何应由 getter 方法返回的标签或图像。我只收到手动输入的“欢迎”字符串。所以，标题是“欢迎，null。”

Answer 1

在调用load期间，initialize方法由FXMLLoader调用。由于您“预加载”了场景，因此当时尚未设置任何属性。

我强烈建议不要使用静态数据来传递信息。当然，能够访问数据很方便，但这是以无法控制何时/通过什么代码修改值以及永远无法同时拥有多于一艘船为代价的。

您可以使用 javafx 属性来处理这个问题。以下类设计只是缩写，缺少适当的可见性修饰符、setter、(属性)getter、初始化和构造函数，但我确信您可以自己添加:

class Starship

   StringProperty name;
   ObjectProperty<CrewMember> captain;

   // possibly replace the following property with individual properties for roles
   // or use a ObservableMap<Role, CrewMember> instead???
   ObservableList<CrewMember> crew;
}

// could we make this immutable instead??? 
class CrewMember {
    StringProperty name;
    ObjectProperty<Image> image;
}

这允许您监听船舶数据的修改:

Starship ship = new Starship();

firstPaneController.setShip(ship);
secondPaneController.setShip(ship);

登录 Controller

private Starship ship;

public void setShip(Starship ship) {
    this.ship = ship;
}

private void setAll(String user) {
    ship.setCaptain(new CrewMember(user));

    ship.getCrew().setAll(Stream.generate(() -> new CrewMember(user))
                                .limit(8)
                                .toArray(CrewMember[]::new));
}

人员 Controller

private Label[] crewNameLabels;
private ImageView[] crewImageViews;

@Override
public void initialize(URL location, ResourceBundle resources) {
    crewNameLabels = new Label[] { crew1, crew2, crew3, crew4, crew5, crew6, crew7, crew8  };
    crewImageViews = new ImageView[] {
        commandOfficer,
        firstOfficer,
        commOfficer,
        engineOfficer,
        helmsman,
        navigator,
        medOfficer,
        nurse
    };
}

private final InvalidationListener crewUpdater = o -> {
    int newCrewSize = 0;
    if (ship != null) {
        List<Crew> crew = ship.getCrew();
        newCrewSize = ship.getCrew().size();
        if (newCrewSize > crewNameLabels.length) {
            newCrewSize = crewNameLabels.length;
        }
        for (int i = 0; i < newCrewSize; i++) {
            CrewMember c = crew.get(i);
            crewNameLabels[i].textProperty().bind(c.nameProperty());
            crewImageViews[i].imageProperty().bind(c.imageProperty());
        }
    }

    // unbind everything that has no corresponding CrewMember
    for (int i = newCrewSize; i < crewNameLabels.length; i++) {
        crewNameLabels[i].textProperty().unbind();
        crewNameLabels[i].setText("");
        crewImageViews[i].imageProperty().unbind();
        crewImageViews[i].setImage(null);
    }
};

private final InvalidationListener captainUpdater = o -> {
    CrewMember captain = null;
    if (ship != null) {
        captain = ship.getCaptain();
    }
    if (captain == null) {
        welcomeMsg.textProperty().unbind();
        welcomeMsg.setText("");
    } else {
        welcomeMessage.bind(Bindings.concat("Welcome, ", captain.nameProperty()));
    }
};

private Starship ship;

public void setShip(Starship ship) {
    if (this.ship != null) {
        // remove old listener when replacing the ship
        this.ship.getCrew().removeListener(crewUpdater);
        this.ship.captainProperty().removeListener(captainUpdater);
    }

    this.ship = ship;
    if (ship != null) {
        ship.getCrew().addListener(crewUpdater);
        ship.captainProperty().addListener(captainUpdater);
        shipName.textProperty().bind(ship.nameProperty());
    } else {
        shipName.textProperty().unbind();
        shipName.setText("");
    }

    // update content
    crewUpdater.invalidated(null);
    captainUpdater.invalidated(null);
}

这应该允许您在 JavaFX 应用程序线程上的任何位置更新 Starship 对象并查看人员场景中的变化。使 CrewMember 类不可变会稍微降低更新的复杂性，因为您不再需要使用绑定(bind)，而只需要进行分配。此外，只有一个船舶+人员场景才允许您删除解除绑定(bind)逻辑，进一步简化逻辑...