JavaFX控制器注入不起作用 [英] JavaFX controller injection does not work

问题描述

我有两个 fxml 个文件。我用 include 语句连接它们：

I have two fxml files. I connect them with an include statement:

main fxml 文件看起来像这样：

The "main" fxmlfile looks like that:

<?import javafx.geometry.*?>
// ...

<BorderPane prefHeight="962" prefWidth="1280" xmlns="http://javafx.com/javafx/8.0.40" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.MyMainController">
    <center>
        <SplitPane dividerPositions="0.63" BorderPane.alignment="CENTER">
            <items>
                <fx:include source="AnotherFile.fxml" />
                // ...
            </items>
        </SplitPane>
    </center>
    <top>
        // ...
    </top>
</BorderPane>

第二个（=AnotherFile.fxml）就像这样：

And the second one (= "AnotherFile.fxml") like that:

<?import java.lang.*?>
// ...

<SplitPane dividerPositions="0.15" orientation="VERTICAL" prefHeight="400.0" prefWidth="500.0" xmlns="http://javafx.com/javafx/8.0.40" xmlns:fx="http://javafx.com/fxml/1">
    <items>
        // ...
        <Label fx:id="oneOfMyLabels" text="myText" GridPane.columnIndex="2" GridPane.rowIndex="1" />
    </items>
</SplitPane>

现在，我在main控制器应用程序中使用注入。 MyMainController ：

Now, I am using injections in the "main"-controller application.MyMainController:

@FXML
private Label oneOfMyLabels;

如果我运行控制器，我会得到 java.lang.NullPointerException 异常，分别是 java.lang.reflect.InvocationTargetException 一个。在调试模式中，我发现，注入的标签是 null ！

If I run the controller I get a java.lang.NullPointerException exception, respectively a java.lang.reflect.InvocationTargetException one. In debugging mode I found out, that the injected Label is null!

现在，我的问题：
无法从main fxml文件到达包含fxml文件的组件的 MyMainController ？我是否必须在每个fxml文件上使用自己的控制器，如果包含或不包含？！

Now, my question: Can't reach the MyMainController from the "main fxml file" the components of the included fxml file?? Do I have to use an own controller on each fxml file, if it is included or not?!

感谢您的帮助!!

推荐答案

您需要为每个FXML文件使用不同的控制器，并且 fx：id -annotated elements每个文件的注入将被注入对应的控制器实例。

You need to have a different controller for each FXML file, and the fx:id-annotated elements of each file will be injected into the corresponding controller instance.

当你包含FXML文件时，你可以为包含的文件注入控制器通过在 fx：include 元素上设置 fx：id 属性进入包含文件的控制器：

When you have included FXML files, you can inject the controller for the included file into the controller for the including file, by setting an fx:id attribute on the fx:include element:

mainfxml文件：

"main" fxml file:

<?import javafx.geometry.*?>
// ...

<BorderPane prefHeight="962" prefWidth="1280" xmlns="http://javafx.com/javafx/8.0.40" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.MyMainController">
    <center>
        <SplitPane dividerPositions="0.63" BorderPane.alignment="CENTER">
            <items>
                <fx:include fx:id="another" source="AnotherFile.fxml" />
                // ...
            </items>
        </SplitPane>
    </center>
    <top>
        // ...
    </top>
</BorderPane>

和主控制器：

public class MyMainController {

    @FXML
    private AnotherController anotherController ;

    // ...
}

（规则因为字段名称是 fx：id 属性的值，附加了Controller。这里 AnotherController 是 AnotherFile.fxml 的控制器类。

(the rule being that the field name is the value of the fx:id attribute with "Controller" appended). Here AnotherController is the controller class for AnotherFile.fxml.

现在，您可以在包含的控制器中公开您需要访问的数据：

Now you can, for example, expose the data you need to access in the "included controller":

public class AnotherController {

    @FXML
    private Label oneOfMyLabels ;

    public StringProperty textProperty() {
        return oneOfMyLabels.textProperty();
    }

    public final String getText() {
        return textProperty().get();
    }

    public final setText(String text) {
        textProperty().set(text);
    }

    // ...
}

然后您的主控制器可以执行以下操作：

and then your main controller can do things like

anotherController.setText(...);

当然会更新标签。这样可以保留封装，因此如果您选择使用其他控件而不是标签，则这些更改不必在直接控制器之外传播。

which will of course update the label. This preserves encapsulation, so that if you choose to use another control instead of a label, those changes do not have to propagate outside of the immediate controller.

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