用javaswing实现文件拖拽上传，用另一个类接收swing界面上传文件的内容

首先，需要在Java Swing中添加一个JPanel组件来允许用户拖放文件。可以使用JFileChooser来选择文件并获取文件路径。然后，将文件路径传递给另一个类以进行处理。

以下是一个简单的示例：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.dnd.DnDConstants;
import java.awt.dnd.DropTarget;
import java.awt.dnd.DropTargetDragEvent;
import java.awt.dnd.DropTargetDropEvent;
import java.awt.dnd.DropTargetEvent;
import java.awt.dnd.DropTargetListener;
import java.io.File;
import java.io.IOException;
import java.util.List;

import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingConstants;
import javax.swing.TransferHandler;
import javax.swing.border.Border;
import javax.swing.border.TitledBorder;

public class FileUploadDemo extends JFrame {
    private static final long serialVersionUID = 1L;

    private JTextArea textArea;
    private JButton uploadButton;
    private FileUploadListener fileUploadListener;

    public FileUploadDemo() {
        super("File Upload Demo");

        JPanel mainPanel = new JPanel();
        mainPanel.setLayout(new BoxLayout(mainPanel, BoxLayout.PAGE_AXIS));

        // Add drop panel
        JPanel dropPanel = new JPanel();
        dropPanel.setBackground(Color.WHITE);
        dropPanel.setPreferredSize(new Dimension(500, 100));
        Border border = BorderFactory.createTitledBorder(BorderFactory.createLineBorder(Color.GRAY),
                "Drag and Drop Files Here", TitledBorder.CENTER, TitledBorder.TOP);
        dropPanel.setBorder(border);
        dropPanel.setTransferHandler(new FileDropHandler());
        dropPanel.setDropTarget(new PanelDropTarget());
        mainPanel.add(dropPanel);

        // Add text area
        textArea = new JTextArea();
        textArea.setEditable(false);
        JScrollPane scrollPane = new JScrollPane(textArea);
        scrollPane.setPreferredSize(new Dimension(500, 200));
        mainPanel.add(scrollPane);

        // Add upload button
        JPanel buttonPanel = new JPanel(new FlowLayout());
        uploadButton = new JButton("Upload");
        uploadButton.setEnabled(false);
        uploadButton.addActionListener(e -> {
            if (fileUploadListener != null) {
                fileUploadListener.onFileUploaded(textArea.getText());
            }
        });
        buttonPanel.add(uploadButton);
        mainPanel.add(buttonPanel);

        add(mainPanel, BorderLayout.CENTER);

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();
        setLocationRelativeTo(null);
    }

    public void setFileUploadListener(FileUploadListener listener) {
        this.fileUploadListener = listener;
    }

    private class PanelDropTarget implements DropTargetListener {
        @Override
        public void dragEnter(DropTargetDragEvent dtde) {
            // Check if the data flavor is supported
            if (dtde.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
                dtde.acceptDrag(DnDConstants.ACTION_COPY);
            } else {
                dtde.rejectDrag();
            }
        }

        @Override
        public void dragOver(DropTargetDragEvent dtde) {
            // Do nothing
        }

        @Override
        public void dropActionChanged(DropTargetDragEvent dtde) {
            // Do nothing
        }

        @Override
        public void dragExit(DropTargetEvent dte) {
            // Do nothing
        }

        @Override
        public void drop(DropTargetDropEvent dtde) {
            // Get the transferable and check if it contains files
            Transferable transferable = dtde.getTransferable();
            if (transferable.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
                dtde.acceptDrop(DnDConstants.ACTION_COPY);

                try {
                    // Get the list of files and add them to the text area
                    List<File> files = (List<File>) transferable.getTransferData(DataFlavor.javaFileListFlavor);
                    for (File file : files) {
                        textArea.append(file.getAbsolutePath() + "\n");
                    }
                    uploadButton.setEnabled(true);
                } catch (UnsupportedFlavorException | IOException e) {
                    e.printStackTrace();
                }
            } else {
                dtde.rejectDrop();
            }
        }
    }

    private class FileDropHandler extends TransferHandler {
        private static final long serialVersionUID = 1L;

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

        @Override
        public boolean importData(TransferSupport support) {
            if (support.isDrop()) {
                DropTargetDropEvent dtde = (DropTargetDropEvent) support.getDropEvent();
                return importFiles(dtde);
            } else {
                return false;
            }
        }

        private boolean importFiles(DropTargetDropEvent dtde) {
            // Get the transferable and check if it contains files
            Transferable transferable = dtde.getTransferable();
            if (transferable.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
                dtde.acceptDrop(DnDConstants.ACTION_COPY);

                try {
                    // Get the list of files and add them to the text area
                    List<File> files = (List<File>) transferable.getTransferData(DataFlavor.javaFileListFlavor);
                    for (File file : files) {
                        textArea.append(file.getAbsolutePath() + "\n");
                    }
                    uploadButton.setEnabled(true);
                } catch (UnsupportedFlavorException | IOException e) {
                    e.printStackTrace();
                }
                return true;
            } else {
                dtde.rejectDrop();
                return false;
            }
        }
    }

    public interface FileUploadListener {
        void onFileUploaded(String filePaths);
    }

    public static void main(String[] args) {
        FileUploadDemo demo = new FileUploadDemo();
        demo.setFileUploadListener(filePaths -> System.out.println("Uploaded files: " + filePaths));
        demo.setVisible(true);
    }
}

在这个示例中，我们使用一个JPanel作为拖放区域，并将其设置为接受文件的拖放操作。我们还添加了一个JTextArea来显示上传的文件路径，并添加了一个JButton来触发上传文件的操作。

在主方法中，我们通过设置FileUploadListener来处理上传的文件。在实际应用中，可以将上传的文件路径传递给另一个类来进行处理。