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问题：

另一个FXML-controller中ImageView的Javafx setImage

吕永寿
2023-03-14

我有一个名为“AdjustmentBar”的类，它包括一个imageView、一个菜单栏和一些图片编辑函数（一个FXML文件和一个控制器）。AdjustmentBar被加载到另一个名为“ExaminationDisplayer”的类（也是一个FXML文件和一个控制器）。ExaminationDisplayer从一个在线MySQL数据库加载一些图像，我希望这些图像都显示在一个独立的ImageView中。

我已经能够将AdjustmentBar加载到ExaminationDisplayer中，但是我不知道如何对AdjustmentBar中包含的imageView进行setImage（）。我可以在ExaminationDisplayer中创建的imageview中显示数据库中的图像，如果单独运行AdjustmentBar视图，我可以在AdjustmentBar视图中显示图片。我只是无法让加载的AdjustmentBar在ExaminationDisplayer中显示图像。

当我运行它时，我得到这行代码的nullpointerexception错误：imgview.setimage（image），它位于ExaminationDisplayerController中：

public class ExaminationDisplayerController extends AdjustmentBarController {
    @FXML
    private void handlebtnFraminghamAction(ActionEvent event) throws IOException {showCardiacConditionEstimator(); }
    @FXML
    private AnchorPane anchorPane; 
    @FXML
    private LineChart<Number, Number> lcChart;
    @FXML
    private NumberAxis xAxis; // x-Axis is defined
    @FXML
    private NumberAxis yAxis; //y-Axis is defined

    public void initialize() throws ClassNotFoundException, SQLException, IOException { // Loading methods in ExaminationDisplayerController
        SPECTLoad();
    }

    public void showCardiacConditionEstimator() throws IOException { // Method for displaying CardiacConditionEstimator
        Parent parent = FXMLLoader.load(getClass().getResource("/fxml/CardiacConditionEstimator.fxml")); //Reference to the fxml file
        Stage stage = new Stage(); // creating a new stage 
        Scene scene = new Scene(parent); // creating a new scene for the file to be shown onto
        stage.setScene(scene); // sets the scene on the stage
        stage.show(); // Displaying the stage 
        stage.setMaximized(false); // maximizing the stage
    }

    public void SPECTLoad() throws SQLException, ClassNotFoundException {
        DBConnection dbConn = new DBConnection(); 
        Connection conn = dbConn.connect(); 
        PreparedStatement pstmt = null;

        try {

            for (int numberOfExaminations = 0; numberOfExaminations < 3; numberOfExaminations++) {

                String[] ID = {"1111", "1112", "1113"};
                List<String> chosenExaminations = Arrays.asList(ID);
                String SQL = "SELECT `IMAGE` FROM `SPECT` WHERE `ID` = ?;";
                pstmt = conn.prepareStatement(SQL);

                pstmt.setString(1, chosenExaminations.get(numberOfExaminations));

                ResultSet rs = pstmt.executeQuery();

                while (rs.next()) {
                    InputStream is = rs.getBinaryStream("IMAGE");
                    OutputStream os = new FileOutputStream(new File("SPECT_IMAGE.jpg"));

                    byte[] content = new byte[1024];
                    int size = 0;
                    while ((size = is.read(content)) != -1) { // Når inputstream er real passer den et -1 værdi og så stoppes loopet
                        os.write(content, 0, size);
                    }
                    os.close();
                    is.close();

                    Image image = new Image(new File("SPECT_IMAGE.jpg").toURI().toString(), 200, 200, true, true);

                    anchorPane.getChildren().add(FXMLLoader.load(getClass().getResource("/fxml/AdjustmentBar.fxml")));
                    imgView.setImage(image);
                }
            }

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

以下是AdjustmentBarController的代码：

public class AdjustmentBarController {

    @FXML
    private AnchorPane AnchorPane;
    @FXML
    private ScrollPane ScrollPane;
    @FXML
    public ImageView imgView;
    @FXML
    private Slider contrastAdjuster;
    @FXML
    private ToggleButton btnMeasure;
    @FXML
    private Pane imgContainer;
    @FXML
    private Label txtLabel;

    @FXML
    private void btnZoomInAction(ActionEvent event) {...}

    @FXML
    private void btnZoomOutAction(ActionEvent event) {...}

    @FXML
    private void btnRotateRightAction(ActionEvent event) {...}

    @FXML
    private void btnRotateLeftAction(ActionEvent event) {...}

    /**
     * Initializes the controller class.
     *
     * @param url
     * @param rb
     */
    public void initialize(URL url, ResourceBundle rb
    ) {
        contrastAdjuster.valueProperty().addListener((observable, oldValue, newValue) -> {
            double value = contrastAdjuster.getValue();
            ColorAdjust colorAdjust = new ColorAdjust();
            colorAdjust.setContrast(value);
            imgView.setEffect(colorAdjust);
        });
    }
}

我不确定AdjustmentBar的FXML文件是否相关，但如下所示：

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

<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.ScrollPane?>
<?import javafx.scene.control.Slider?>
<?import javafx.scene.control.ToggleButton?>
<?import javafx.scene.image.Image?>
<?import javafx.scene.image.ImageView?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.BorderPane?>
<?import javafx.scene.layout.HBox?>
<?import javafx.scene.layout.Pane?>

<AnchorPane id="AnchorPane" prefHeight="435.0" prefWidth="435.0" xmlns="http://javafx.com/javafx/8.0.111" xmlns:fx="http://javafx.com/fxml/1" fx:controller="Multimodality.controller.AdjustmentBarController">
    <children>
      <BorderPane prefHeight="435.0" prefWidth="435.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
         <center>
            <ScrollPane fx:id="ScrollPane" pannable="true" prefHeight="435.0" prefWidth="435.0" BorderPane.alignment="CENTER">
               <content>
                  <Pane fx:id="imgContainer">
                     <children>
                          <ImageView fx:id="imgView" fitHeight="400.0" fitWidth="400.0" nodeOrientation="INHERIT" pickOnBounds="true" preserveRatio="true" />
                        <Label fx:id="txtLabel" alignment="TOP_LEFT" layoutX="336.0" layoutY="-1.0" prefHeight="134.0" prefWidth="75.0" wrapText="true" />
                     </children>
                  </Pane>
               </content>
            </ScrollPane>
         </center>
         <bottom>
            <HBox alignment="CENTER" prefHeight="35.0" prefWidth="435.0" spacing="8.0" BorderPane.alignment="CENTER">
               <children>
                      <Button fx:id="btnZoomOut" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" mnemonicParsing="false" onAction="#btnZoomOutAction" prefHeight="25.0" prefWidth="25.0">
                          <graphic>
                              <ImageView fitHeight="20.0" fitWidth="20.0" preserveRatio="true">
                                  <image>
                                      <Image url="/img/icon_zoomout.png" />
                                  </image>
                              </ImageView>
                          </graphic>
                      </Button>
                      <Button fx:id="btnZoom100" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" mnemonicParsing="false" onAction="#btnZoom100Action" prefHeight="25.0" prefWidth="25.0">
                          <graphic>
                              <ImageView fitHeight="20.0" fitWidth="20.0" preserveRatio="true">
                                  <image>
                                      <Image url="/img/icon_fit.png" />
                                  </image>
                              </ImageView>
                          </graphic>
                      </Button>
                      <Button fx:id="btnZoomIn" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" mnemonicParsing="false" onAction="#btnZoomInAction" prefHeight="25.0" prefWidth="25.0">
                          <graphic>
                              <ImageView fitHeight="20.0" fitWidth="20.0" preserveRatio="true">
                                  <image>
                                      <Image url="/img/icon_zoomin.png" />
                                  </image>
                              </ImageView>
                          </graphic>
                      </Button>
                      <Button fx:id="btnRotateRight" contentDisplay="CENTER" graphicTextGap="0.0" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" mnemonicParsing="false" onAction="#btnRotateRightAction" prefHeight="25.0" prefWidth="25.0">
                          <graphic>
                              <ImageView fitHeight="20.0" fitWidth="20.0" preserveRatio="true">
                                  <image>
                                      <Image url="/img/shape_rotate_clockwise.png" />
                                  </image>
                              </ImageView>
                          </graphic>
                      </Button>      
                      <Button fx:id="btnRotateLeft" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" mnemonicParsing="false" onAction="#btnRotateLeftAction" prefHeight="25.0" prefWidth="25.0">
                          <graphic>
                              <ImageView fitHeight="20.0" fitWidth="20.0" preserveRatio="true">
                                  <image>
                                      <Image url="/img/shape_rotate_anticlockwise.png" />
                                  </image>
                              </ImageView>
                          </graphic>
                      </Button>
                  <ToggleButton fx:id="btnMeasure" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" mnemonicParsing="false" onAction="#btnMeasureAction" prefHeight="25.0" prefWidth="25.0">
                     <graphic>
                        <ImageView fitHeight="20.0" fitWidth="20.0" preserveRatio="true">
                            <image>
                                <Image url="/img/ruler.png" />
                            </image>
                        </ImageView>
                     </graphic>
                  </ToggleButton>
                  <ImageView fitHeight="20.0" fitWidth="20.0" preserveRatio="true">
                     <image>
                        <Image url="/img/contrast.png" />
                     </image>
                     <HBox.margin>
                        <Insets left="8.0" right="-2.0" />
                     </HBox.margin>
                  </ImageView>
                      <Slider fx:id="contrastAdjuster" blockIncrement="0.1" majorTickUnit="0.5" max="1.0" min="-1.0" minorTickCount="4" prefHeight="24.0" prefWidth="128.0" showTickMarks="true" />
               </children>
               <BorderPane.margin>
                  <Insets />
               </BorderPane.margin>
            </HBox>
         </bottom>
      </BorderPane>
    </children>
</AnchorPane>

java.lang.NullPointerException
    at Multimodality.controller.ExaminationDisplayerController.SPECTLoad(ExaminationDisplayerController.java:224)
    at Multimodality.controller.ExaminationDisplayerController.initialize(ExaminationDisplayerController.java:86)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
    at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2566)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3214)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)
    at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)
    at Multimodality.controller.ExaminationOverviewController.showExaminationDisplayer(ExaminationOverviewController.java:352)
    at Multimodality.controller.ExaminationOverviewController.btnChooseExaminationsAction(ExaminationOverviewController.java:341)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
    at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
    at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1769)
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1657)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
    at javafx.event.Event.fireEvent(Event.java:198)
    at javafx.scene.Node.fireEvent(Node.java:8413)
    at javafx.scene.control.Button.fire(Button.java:185)
    at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
    at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.event.Event.fireEvent(Event.java:198)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
    at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:381)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:417)
    at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:416)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
    at com.sun.glass.ui.View.notifyMouse(View.java:937)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
    at java.lang.Thread.run(Thread.java:745)

BUILD SUCCESSFUL

Total time: 52.909 secs

共有1个答案

谷飞星
2023-03-14

每当您有一个需求并且需要使控件public时，这就是一种代码气味。永远不要公开您的UI节点。

最好的方法是在adjustmentbarcontroller中添加一个方法来接受图像。然后，该方法将在控制器中定义的ImageView中设置此图像。

public class AdjustmentBarController {

    ...

    @FXML
    private ImageView imgView;
    ...
    public void setImage(Image image) {
        imgView.setImage(image);
    }
}

现在，一旦这件事完成了。不要从AdjustmentBarController扩展ExaminationDisplayerController。

// Do not extend from AdjustmentBarController
public class ExaminationDisplayerController {

    ...

    public void SPECTLoad() throws SQLException, ClassNotFoundException {
        DBConnection dbConn = new DBConnection(); 
        ...
        Image image = new Image(new File("SPECT_IMAGE.jpg").toURI().toString(), 200, 200, true, true);
        FXMLLoader loader = new FXMLLoader(getClass().getResource("/fxml/AdjustmentBar.fxml"));
        AnchorPane anchorPaneFromAdjustmentBar = loader.load();
        anchorPane.getChildren().add(anchorPaneFromAdjustmentBar);
        // Get the controller from the FXMLLoader
        AdjustmentBarController controller = (AdjustmentBarController) loader.getController();
        // Set the image
        controller.setImage(image);
        ...
    }
}
  • JavaFX：在实例化控制器类时传递参数（特定于您的用例）
  • 传递参数JavaFX FXML（通用方法）
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