如何复制文件并使用Java将其粘贴到剪贴板？

Question

如何复制文件并将其粘贴到使用Java的剪贴板？我的程序可以复制但不能粘贴。它给

异常在线程 “主要” java.lang.ClassCastException：
java.util.Arrays中的$ ArrayList中不能转换成java.io.File

我的代码：

class FileTransferable implements Transferable { 
    private final File file; 

    public FileTransferable(File file) { 
     this.file = file; 
    } 

    @Override 
    public DataFlavor[] getTransferDataFlavors() { 
     return new DataFlavor[] { DataFlavor.javaFileListFlavor }; 
    } 

    @Override 
    public boolean isDataFlavorSupported(DataFlavor flavor) { 
     return DataFlavor.javaFileListFlavor.equals(flavor); 
    } 

    @Override 
    public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException, IOException { 
     final ArrayList<File> files = new ArrayList<File>(); 
     files.add(file); 
     return files; 
    } 
} 

Answer 1

Java无法处理特定的操作系统相关操作，如干扰剪贴板等，因为它是独立于平台的语言。在JLS和Java API中，没有用于剪贴板干涉的方法，但是有一些方法可以处理在Java API中声明的文件系统操作，作为JLS（Java语言规范）的一部分，JLS实现在大多数JVM实现中。为了做到这一点，您应该使用JNI（Java本地接口）本地开发C/C++（使用Win32 API等）或使用现成的二进制文件并在您的Java应用程序中调用它们。

Answer 2

我无法在实际代码中检测到任何问题。我想，这个投射错误发生在你实际上收到的内容从复制/粘贴操作中，你收到一个文件，包裹在一个列表中，并且可能会将列表投到File。

Answer 3

下面是从DGuitar源代码采取一个完整的示例根据您的评论

/* 
* ADropTargetListener 
* Created on 20/04/2005 
* 
* 
*/ 

import java.awt.datatransfer.DataFlavor; 
import java.awt.datatransfer.Transferable; 
import java.awt.datatransfer.UnsupportedFlavorException; 
import java.awt.dnd.DnDConstants; 
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.ArrayList; 
import java.util.List; 


/** 
* The Drop action happens in this order: 1. dragEnter = 
when the mouse enters 
* the component 2. dragOver = after the mouse has entered 
but has not been 
* released 3. drop = when the mouse is released 
* 
* @author Mauricio Gracia G 
*/ 
public class ADropTargetListener implements DropTargetListener { 
    /** 
    * creates a DropTargetListener 
    */ 
    public ADropTargetListener() { 

    } 

    /** 
    * overrides the DROP method. 
    * 
    * @see java.awt.dnd.DropTargetListener#drop(java.awt.dnd.DropTargetDropEvent) 
    */ 
    public void drop(DropTargetDropEvent dtde) { 
     Transferable transfer; 

     transfer = dtde.getTransferable(); 

     //we must accept the transfer to process it 
     dtde.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE); 

     importData(transfer); 
    } 
    /** 
    * Imports the data of the Drop action 
    * @param t the transferable object 
    */ 

    public void importData(Transferable t) { 
     if (canImport(t.getTransferDataFlavors())) { 
      try { 
       DataFlavor[] flavors = t.getTransferDataFlavors(); 
       for (int i = 0; i < flavors.length; i++) { 
        //  Drop from Windows 
        if (DataFlavor.javaFileListFlavor.equals(flavors[i])) { 

         Object gtd ; 

         gtd = t.getTransferData(DataFlavor.javaFileListFlavor) ; 
         if (gtd instanceof List) { 
          @SuppressWarnings("unchecked") 
          List<File> fileList = (List<File>) gtd; 

                 //YOUR CODE here to process the list of Files 

         } 

        } 
        //  Drop from GNOME or kde 
        // delimited by \n (\r\n) on gnome 
        // will need to remove file:// at start 
        else if (DataFlavor.stringFlavor.equals(flavors[i])) { 
         if (t.getTransferData(DataFlavor.stringFlavor) 
instanceof String) { 
          String path = (String) t 
            .getTransferData(DataFlavor.stringFlavor); 
          List<File> fileList = convertStringsToFileList(path); 
          //YOUR CODE here to process the list of Files 

         } 

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

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

      } 
     } 
    } 
    /** 
    * converts Strings in certain format to a FileList 
    * @param filestr the list of files in a single string 
    * @return   a list of files 
    */ 

    private ArrayList<File> convertStringsToFileList(String filestr) { 
     ArrayList<File> files = new ArrayList<File>(); 
     String[] tokenizedFiles = filestr.split("\n"); 
     for (int i = 0; i < tokenizedFiles.length; i++) { 
      String path = tokenizedFiles[i]; 
      if (path.startsWith("file://")) { 
       if (path.endsWith("\r")) { 
        //appears to be the case for gnome but not kde 
        path = path.substring(7); 
        path = path.replaceAll("\r", ""); 

        path = path.replaceAll("%20", " "); 
       } else { 
        path = path.substring(7); 
       } 
      } 
      files.add(new File(path)); 

     } 
     return files; 
    } 
    /** 
    * Determine if it can import certain flavor 
    * 
    * @param flavors an array of DataFlavors 
    * @return true or not depending on the flavor 
    */ 
    public boolean canImport(DataFlavor[] flavors) { 
     for (int i = 0; i < flavors.length; i++) { 
      if (DataFlavor.javaFileListFlavor.equals(flavors[i])) { 
       return true; 
      } else if (DataFlavor.stringFlavor.equals(flavors[i])) { 
       return true; 
      } 
     } 
     return false; 
    } 


    /** 
    * method that is called when the drag starts or enters the window 
    * @param dtde a DropTargetDragEvent 
    * 
    * @see java.awt.dnd.DropTargetListener#dragEnter(java.awt.dnd.DropTargetDragEvent) 
    */ 
    public void dragEnter(DropTargetDragEvent dtde) { 
     //DEBUG 
     //System.out.println("dragEnter" + ":" + dtde) ; 
    } 

    /** 
    * a method that is called when the DRAG is OVER ?? 
    * 
    * @see java.awt.dnd.DropTargetListener#dragOver(java.awt.dnd.DropTargetDragEvent) 
    */ 

    public void dragOver(DropTargetDragEvent dtde) { 
     //  DEBUG 
     //System.out.println("dragOver" + ":" + dtde) ; 
    } 

    /** 
    * when the drop action is changes this method is called 
    * 
    * @see java.awt.dnd.DropTargetListener#dropActionChanged(java.awt.dnd.DropTargetDragEvent) 
    */ 
    public void dropActionChanged(DropTargetDragEvent dtde) { 
     //  DEBUG 
     //System.out.println("dropActionChanged" + ":" + dtde) ; 
    } 

    /** 
    * method called when the drag exits the window 
    * 
    * @see java.awt.dnd.DropTargetListener#dragExit(java.awt.dnd.DropTargetEvent) 
    */ 
    public void dragExit(DropTargetEvent dte) { 
     //  DEBUG 
     //System.out.println("dragExit" + ":" + dte) ; 
    } 

}