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自定义对象从嵌入式FX（JFXPanel）拖放到Swing

 2023-02-16    349  

问题描述

这个问题是一个后续问题 to 自定义对象从fx到swing .

我正在为使用JAVAFX用于某些图形用户界面的swing应用程序的插件.我们添加了拖放功能以改善用户体验.首先，我们为我们的Scene使用了外部Javafx窗口(Stage)，现在我们要通过JFXPanel.

自定义对象从嵌入式FX（JFXPanel）拖放到Swing

现在，奇怪的是，对于拖放似乎完全相同的Scene是在Stage中还是在Stage中还是在JFXPanel中.

我在尝试将一些自定义的Java对象(以序列化形式)从Javafx应用程序拖动到Swing应用程序中时遇到了一些问题.但是，我在上面提到的问题中解决了我的问题.现在，使用嵌入式Javafx应用程序，我遇到了一些新问题，所以我想询问某人是否有类似的问题或对这种情况有解决方案.

我已经写了一个MVCE，这是一个简单的Java应用

public class MyApp {

    public static final DataFormat FORMAT = new DataFormat(
        // this works fine in a separate window
        //"JAVA_DATAFLAVOR:application/x-my-mime-type; class=java.lang.String",
        "application/x-my-mime-type; class=java.lang.String");

    public static final DataFlavor FLAVOR;

    static {
        try {
            FLAVOR = new DataFlavor("application/x-my-mime-type; class=java.lang.String");
        } catch (ClassNotFoundException ex) {
            throw new RuntimeException(ex);
        }
    }

    public static void main(String[] args) {
        new MyApp().run();
    }

    private void run() {
        JFrame frame = new JFrame();
        frame.setLayout(new GridLayout(1, 2));
        frame.add(buildFX());
        frame.add(buildSwing());
        frame.setSize(300, 300);
        frame.setVisible(true);
    }

    private JFXPanel buildFX() {
        BorderPane parent = new BorderPane();
        parent.setOnDragDetected(event -> {
            Dragboard dragboard = parent.startDragAndDrop(TransferMode.COPY);
            ClipboardContent content = new ClipboardContent();
            content.put(FORMAT, "Test");
            dragboard.setContent(content);
            event.consume();
        });
        JFXPanel panel = new JFXPanel();
        panel.setScene(new Scene(parent));
        return panel;
    }

    @SuppressWarnings("serial")
    private JPanel buildSwing() {
        JPanel panel = new JPanel();
        panel.setBackground(Color.ORANGE);
        panel.setTransferHandler(new TransferHandler() {

            @Override
            public boolean canImport(TransferSupport support) {
                return support.isDataFlavorSupported(FLAVOR);
            }

            @Override
            public boolean importData(TransferSupport support) {
                if (!canImport(support)) return false;
                try {
                    String data = (String) support.getTransferable().getTransferData(FLAVOR);
                    System.out.println(data);
                    return true;
                } catch (UnsupportedFlavorException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                return false;
            }

        });
        return panel;
    }
}

根据另一个问题的答案，使用DataFormat中的前缀JAVA_DATAFLAVOR:对于摇摆必须正确处理MIME类型是必要的.但是，当在A JFXPanel内使用此类DataFormat(示例中禁用)时，Java似乎试图从FX应用程序拖动时尝试构造A DataFlavor，并且未能使用前缀解析MIME类型:

Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: failed to parse:JAVA_DATAFLAVOR:application/x-my-mime-type; class=java.lang.String
    at java.awt.datatransfer.DataFlavor.<init>(Unknown Source)
    at javafx.embed.swing.SwingDnD$DnDTransferable.getTransferDataFlavors(SwingDnD.java:394)
    at sun.awt.datatransfer.DataTransferer.getFormatsForTransferable(Unknown Source)
    at sun.awt.dnd.SunDragSourceContextPeer.startDrag(Unknown Source)
    at java.awt.dnd.DragSource.startDrag(Unknown Source)
    at java.awt.dnd.DragSource.startDrag(Unknown Source)
    at java.awt.dnd.DragGestureEvent.startDrag(Unknown Source)
    at javafx.embed.swing.SwingDnD.startDrag(SwingDnD.java:280)
    at javafx.embed.swing.SwingDnD.lambda$null$66(SwingDnD.java:247)
    at java.awt.event.InvocationEvent.dispatch(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$500(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

仅使用纯MIME类型，没有前缀，拖放操作可起作用，我甚至可以接收正确的DataFlavor(java.awt.datatransfer.DataFlavor[mimetype=application/x-my-mime-type;representationclass=java.lang.String])，但是丢弃的数据始终为null.正如另一个问题所示，使用两个分离的窗口使用第二种方法，我什至无法接收DataFlavor，但是现在它以某种方式可以到此有限点.

推荐答案

可能对转移的工作方式有些误解.

试图直接检索传输数据作为字符串可能适用于”文本/普通”或其他标准文本类型，并且您注意到，对于特定的自定义未注册类型的特定情况，有一些怪癖.但是我认为自定义解决方法的努力是合理的.

由于您完全控制自定义MIME类型的内容结构以及数据生产者和消费者在同一应用程序中的两端，因此我建议不要处理内部工具包实现的前缀或类映射.可能更好的只是在没有无关的元数据和畸形前缀的情况下定义您的哑剧类型(应该是).

定义”应用程序/ x-my-mime “类型并正确解码数据应该足够.

样本1(序列化数据)

以下从样本校正的下面应将数据罚款到Java 8中的摆动框架.

package jfxtest;

import java.awt.Color;
import java.awt.GridLayout;
import java.awt.datatransfer.DataFlavor;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.util.Collections;
import javafx.embed.swing.JFXPanel;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.input.DataFormat;
import javafx.scene.input.TransferMode;
import javafx.scene.layout.BorderPane;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.TransferHandler;
import javax.swing.TransferHandler.TransferSupport;

public class MyApp {

  final static String MY_MIME_TYPE = "application/x-my-mime";
  public static final DataFormat FORMAT = new DataFormat(MY_MIME_TYPE);
  public static final DataFlavor FLAVOR = new DataFlavor(MY_MIME_TYPE, "My Mime Type");

  private void startDrag(Node node) {
    node.startDragAndDrop(TransferMode.COPY).setContent(
        Collections.singletonMap(FORMAT, "Test"));
  }

  private boolean processData(TransferSupport support) {
    try (InputStream in = (InputStream) support.getTransferable().getTransferData(FLAVOR)) {
      Object transferred = new ObjectInputStream(in).readObject();
      System.out.println("transferred: " + transferred + " (" + transferred.getClass() + ")");
      return true;
    } catch (Exception e) {
      e.printStackTrace();
    }
    return false;
  }  

  public static void main(String[] args) {
    new MyApp().run();
  }

  private void run() {
    JFrame frame = new JFrame();
    frame.setLayout(new GridLayout(1, 2));
    frame.add(buildSwing());
    SwingUtilities.invokeLater(() -> {
      frame.add(buildFX());
    });
    frame.setSize(300, 300);
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }

  private JFXPanel buildFX() {
    BorderPane parent = new BorderPane();
    parent.setOnDragDetected(event -> {
      startDrag(parent);
      event.consume();
    });
    JFXPanel panel = new JFXPanel();
    panel.setScene(new Scene(parent));
    return panel;
  }


  private JPanel buildSwing() {
    JPanel panel = new JPanel();
    panel.setBackground(Color.ORANGE);
    panel.setTransferHandler(new TransferHandler() {
      private static final long serialVersionUID = 1L;

      @Override
      public boolean canImport(TransferSupport support) {
        return support.isDataFlavorSupported(FLAVOR);
      }

      @Override
      public boolean importData(TransferSupport support) {
        if (canImport(support)) {
          return processData(support);
        }
        return false;
      }

    });
    return panel;
  }

}

输出:transferred: Test (class java.lang.String)

这里的必要摘录是:

...

  final static String MY_MIME_TYPE = "application/x-my-mime";
  public static final DataFormat FORMAT = new DataFormat(MY_MIME_TYPE);
  public static final DataFlavor FLAVOR = new DataFlavor(MY_MIME_TYPE, "My Mime Type");

  private void startDrag(Node node) {
    node.startDragAndDrop(TransferMode.COPY).setContent(
        Collections.singletonMap(FORMAT, "Test"));    
  }

  private boolean processData(TransferSupport support) {
    try (InputStream in = (InputStream) support.getTransferable().getTransferData(FLAVOR)) {
      Object transferred = new ObjectInputStream(in).readObject();
      System.out.println("transferred: " + transferred + " (" + transferred.getClass() + ")");
      return true;
    } catch (Exception e) {
      e.printStackTrace();
    }
    return false;
  }

...

请注意，数据检索是为了说明目的而简单的，对于真实的应用程序，人们可能想添加更严格的流读数，处理错误等.

样本2(带文本的自定义哑剧)

第一个示例传输一个序列化对象(通常是一个好的简单的东西，因为您可以转移任何可序列化的东西，但很难转移/接受，例如第三方JSON).在不太可能的情况下，当您希望为自定义MIME而不是序列化对象生成真实的文本或其他任意内容时，以下应完成工作:

package jfxtest;

import java.awt.Color;
import java.awt.GridLayout;
import java.awt.datatransfer.DataFlavor;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.nio.charset.StandardCharsets;
import java.util.Collections;
import javafx.embed.swing.JFXPanel;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.input.DataFormat;
import javafx.scene.input.TransferMode;
import javafx.scene.layout.BorderPane;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.TransferHandler;
import javax.swing.TransferHandler.TransferSupport;

public class MyApp {

  final static String MY_MIME_TYPE = "application/x-my-mime";
  public static final DataFormat FORMAT = new DataFormat(MY_MIME_TYPE);
  public static final DataFlavor FLAVOR = new DataFlavor(MY_MIME_TYPE, "My Mime Type");

  private void startDrag(Node node) {
    node.startDragAndDrop(TransferMode.COPY).setContent(
        // put a ByteBuffer to transfer the content unaffected
        Collections.singletonMap(FORMAT, StandardCharsets.UTF_8.encode("Test")));
  }

  private boolean processData(TransferSupport support) {
    try (InputStream in = (InputStream) support.getTransferable().getTransferData(FLAVOR)) {
      byte[] textBytes = new byte[in.available()];
      in.read(textBytes);
      String transferred = new String(textBytes, StandardCharsets.UTF_8); 
      System.out.println("transferred text: " + transferred);
      return true;
    } catch (Exception e) {
      e.printStackTrace();
    }
    return false;
  }  

  public static void main(String[] args) {
    new MyApp().run();
  }

  private void run() {
    JFrame frame = new JFrame();
    frame.setLayout(new GridLayout(1, 2));
    frame.add(buildSwing());
    SwingUtilities.invokeLater(() -> {
      frame.add(buildFX());
    });
    frame.setSize(300, 300);
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }

  private JFXPanel buildFX() {
    BorderPane parent = new BorderPane();
    parent.setOnDragDetected(event -> {
      startDrag(parent);
      event.consume();
    });
    JFXPanel panel = new JFXPanel();
    panel.setScene(new Scene(parent));
    return panel;
  }


  private JPanel buildSwing() {
    JPanel panel = new JPanel();
    panel.setBackground(Color.ORANGE);
    panel.setTransferHandler(new TransferHandler() {
      private static final long serialVersionUID = 1L;

      @Override
      public boolean canImport(TransferSupport support) {
        return support.isDataFlavorSupported(FLAVOR);
      }

      @Override
      public boolean importData(TransferSupport support) {
        if (canImport(support)) {
          return processData(support);
        }
        return false;
      }

    });
    return panel;
  }

}

输出:transferred text: Test

这里的必要部分是:

...

  private void startDrag(Node node) {
    node.startDragAndDrop(TransferMode.COPY).setContent(
        // put a ByteBuffer to transfer the content unaffected
        Collections.singletonMap(FORMAT, StandardCharsets.UTF_8.encode("Test")));
  }

  private boolean processData(TransferSupport support) {
    try (InputStream in = (InputStream) support.getTransferable().getTransferData(FLAVOR)) {
      byte[] textBytes = new byte[in.available()];
      in.read(textBytes);
      String transferred = new String(textBytes, StandardCharsets.UTF_8); 
      System.out.println("transferred text: " + transferred);
      return true;
    } catch (Exception e) {
      e.printStackTrace();
    }
    return false;
  }  

...

再次成为插图，流，错误等.在这里处理很简单.

要注意的一件事是，对于更通用，更容易的绝望化，还有一个预定义的”应用程序/x-java-serialized-object”(DataFlavor.javaSerializedObjectMimeType).但是长期的自定义哑剧似乎更灵活，更直接地处理整体.

以上所述是小编给大家介绍的自定义对象从嵌入式FX（JFXPanel）拖放到Swing,希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对77isp云服务器技术网的支持！

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