SWT Drag to Explorer (Windows) or Finder (OS X)

问题:

I've got an SWT application with a bunch of graphical elements. I'd like for the user to be able to drag an element to their Desktop / Windows Explorer / OS X Finder. When they drop the element, I need the path that they dropped it to, so that I can create a file in that location which represents the element.

I don't think I can use a FileTransfer, because there is no source file. There is a source object which can create a file, but only once it knows where to put it.

Inlined below is a simple example of what I'm trying to achieve, there is a text box with a label to drag from. If the user drags to some folder or file, I'd like to get the path that they dragged to. If they dragged to a file, I'd like to replace the contents of that file with whatever is in the text box. If they dragged to a folder, I'd like to create a file called "TestFile" with the contents of whatever is in the text box.

import org.eclipse.swt.SWT; import org.eclipse.swt.dnd.*; import org.eclipse.swt.layout.*; import org.eclipse.swt.widgets.*;  public class DesktopDragExample {  public static void main(String[] args) {     // put together the SWT main loop     final Display display = Display.getDefault();     display.syncExec(new Runnable() {         @Override         public void run() {             Shell shell = new Shell(display, SWT.SHELL_TRIM);             initializeGui(shell);              //open the shell             shell.open();              //run the event loop             while (!shell.isDisposed()) {                 if (!display.readAndDispatch()) {                     display.sleep();                 }             }         }     }); }  // create the gui private static void initializeGui(Composite parent) {     GridLayout layout = new GridLayout(2, false);     parent.setLayout(layout);      // make the instructions label     Label infoLbl = new Label(parent, SWT.WRAP);     GridData gd = new GridData();     gd.grabExcessHorizontalSpace = true;     gd.horizontalAlignment = SWT.FILL;     gd.horizontalSpan = 2;     infoLbl.setLayoutData(gd);     infoLbl.setText(             "You should be able to drag to the desktop, Windows Explorer, or OS X Finder.\n" +             "If you drag to a file, it will replace the contents of that file with the contents of the text box.\n" +             "If you drag to a folder, it will create a file named 'TestFile' whose contents are whatever is in the text box.");      // make the text element     final Text text = new Text(parent, SWT.SINGLE | SWT.BORDER);     gd = new GridData();     gd.grabExcessHorizontalSpace = true;     gd.horizontalAlignment = SWT.FILL;     text.setLayoutData(gd);      // make the label element     Label label = new Label(parent, SWT.NONE);     label.setText("Drag me");      // listener for drags     DragSourceListener dragListener = new DragSourceListener() {         @Override         public void dragStart(DragSourceEvent e) {             e.detail = DND.DROP_COPY;         }          @Override         public void dragFinished(DragSourceEvent e) {             System.out.println("--dragFinished--");             System.out.println("e.data=" + e.data);         }          @Override         public void dragSetData(DragSourceEvent e) {             System.out.println("--dragSetData--");             System.out.println("e.data=" + e.data);         }     };       // the DragSource     DragSource dragSource = new DragSource(label, DND.DROP_COPY);     dragSource.setTransfer(new Transfer[]{FileTransfer.getInstance()});     dragSource.addDragListener(dragListener); }  private static void draggedTo(String path, String textBoxContents) {     System.out.println("Dragged the contents '" + textBoxContents + "' to '" + path + "'"); }  } 

Here are some other people with the same problem, but looks like no solution so far: Drag from SWT to Desktop, ..want destination path as String

回答1:

The only way to do it is by creating a temporary file and then using the FileTransfer. I suspect that's what you'd have to do in native code anyways. I'll see if I have enough time to sketch the sample...

回答2:

You don't get the file location from and write the file yourself. Dragging to the Desktop implies a FileTransfer (you can check what type of transfer is supported in dragSetData).

This means that SWT expecting a String[] of file paths in DragSourceEvent.data. If you set this in the dragSetData method, then SWT copies those files to your drop target - e.g. the Desktop.

        @Override         public void dragSetData(DragSourceEvent e) {             System.out.println("--dragSetData--");              System.out.println("Is supported: "  + FileTransfer.getInstance().isSupportedType(e.dataType));              FileTransfer f = FileTransfer.getInstance();             String[] filePaths = {"C:\\CamelOut\\4.xml" }  ;             e.data = filePaths;          }     }; 

文章来源: SWT Drag to Explorer (Windows) or Finder (OS X)