SWT DragSource 和 DropTarget 托拉拽

SWT 托拉拽主要由3个部分组成

DragSource - 拖拉的来源封装在这个类当中

DropTarget - 粘贴的对象封装在这个类当中

Transfer - 他们之间传输的中介就靠这个

下面来看一下例子

import org.eclipse.jface.action.MenuManager;
import org.eclipse.jface.action.StatusLineManager;
import org.eclipse.jface.action.ToolBarManager;
import org.eclipse.jface.window.ApplicationWindow;
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.DragSourceListener;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.DropTargetListener;
import org.eclipse.swt.dnd.TextTransfer;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;

public class DragAndDrog extends ApplicationWindow {
	private Text dropText;
	private Text dragText;

	/**
	 * Create the application window.
	 */
	public DragAndDrog() {
		super(null);
		createActions();
		addToolBar(SWT.FLAT | SWT.WRAP);
		addMenuBar();
		addStatusLine();
	}

	/**
	 * Create contents of the application window.
	 * @param parent
	 */
	@Override
	protected Control createContents(Composite parent) {
		Composite container = new Composite(parent, SWT.NONE);
		
		dropText = new Text(container, SWT.BORDER);
		dropText.setBounds(46, 48, 73, 21);
		
		DropTarget target = new DropTarget(dropText,DND.DROP_MOVE);
		target.setTransfer(new Transfer[]{TextTransfer.getInstance()});
		target.addDropListener(new DropTargetListener() {
			
			@Override
			public void dropAccept(DropTargetEvent event) {
				// TODO Auto-generated method stub
				
			}
			
			@Override
			public void drop(DropTargetEvent event) {
				// TODO Auto-generated method stub
				dropText.setText(String.valueOf(event.data));
			}
			
			@Override
			public void dragOver(DropTargetEvent event) {
				// TODO Auto-generated method stub
				
			}
			
			@Override
			public void dragOperationChanged(DropTargetEvent event) {
				// TODO Auto-generated method stub
				
			}
			
			@Override
			public void dragLeave(DropTargetEvent event) {
				// TODO Auto-generated method stub
				
			}
			
			@Override
			public void dragEnter(DropTargetEvent event) {
				// TODO Auto-generated method stub
				
			}
		});
		
		dragText = new Text(container, SWT.BORDER);
		dragText.setBounds(198, 48, 73, 21);
		
		DragSource dragSource = new DragSource(dragText, DND.DROP_MOVE);
		dragSource.setTransfer(new Transfer[]{TextTransfer.getInstance()});
		dragSource.addDragListener(new DragSourceListener() {
			
			@Override
			public void dragStart(DragSourceEvent event) {
				// TODO Auto-generated method stub
				
			}
			
			@Override
			public void dragSetData(DragSourceEvent event) {
				event.data = dragText.getText();
				
			}
			
			@Override
			public void dragFinished(DragSourceEvent event) {
				// TODO Auto-generated method stub
				
			}
		});

		return container;
	}

	/**
	 * Create the actions.
	 */
	private void createActions() {
		// Create the actions
	}

	/**
	 * Create the menu manager.
	 * @return the menu manager
	 */
	@Override
	protected MenuManager createMenuManager() {
		MenuManager menuManager = new MenuManager("menu");
		return menuManager;
	}

	/**
	 * Create the toolbar manager.
	 * @return the toolbar manager
	 */
	@Override
	protected ToolBarManager createToolBarManager(int style) {
		ToolBarManager toolBarManager = new ToolBarManager(style);
		return toolBarManager;
	}

	/**
	 * Create the status line manager.
	 * @return the status line manager
	 */
	@Override
	protected StatusLineManager createStatusLineManager() {
		StatusLineManager statusLineManager = new StatusLineManager();
		return statusLineManager;
	}

	/**
	 * Launch the application.
	 * @param args
	 */
	public static void main(String args[]) {
		try {
			DragAndDrog window = new DragAndDrog();
			window.setBlockOnOpen(true);
			window.open();
			Display.getCurrent().dispose();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	/**
	 * Configure the shell.
	 * @param newShell
	 */
	@Override
	protected void configureShell(Shell newShell) {
		super.configureShell(newShell);
		newShell.setText("New Application");
	}

	/**
	 * Return the initial size of the window.
	 */
	@Override
	protected Point getInitialSize() {
		return new Point(450, 300);
	}
}

　　

在上面的代码中，主要的是，必须为DragSource添加一个监听，否则会报一下的错

org.eclipse.swt.SWTException: Data does not have correct format for type
	at org.eclipse.swt.dnd.DND.error(DND.java:276)
	at org.eclipse.swt.dnd.DND.error(DND.java:227)
	at org.eclipse.swt.dnd.TextTransfer.javaToNative(TextTransfer.java:67)
	at org.eclipse.swt.dnd.DragSource.GetData(DragSource.java:472)
	at org.eclipse.swt.dnd.DragSource.access$7(DragSource.java:436)
	at org.eclipse.swt.dnd.DragSource$4.method3(DragSource.java:259)
	at org.eclipse.swt.internal.ole.win32.COMObject.callback3(COMObject.java:92)
	at org.eclipse.swt.internal.ole.win32.COM.VtblCall(Native Method)
	at org.eclipse.swt.internal.ole.win32.IDataObject.GetData(IDataObject.java:25)
	at org.eclipse.swt.dnd.Transfer.getData(Transfer.java:44)
	at org.eclipse.swt.dnd.TextTransfer.nativeToJava(TextTransfer.java:127)
	at org.eclipse.swt.dnd.DropTarget.Drop(DropTarget.java:443)
	at org.eclipse.swt.dnd.DropTarget$3.method6(DropTarget.java:258)
	at org.eclipse.swt.internal.ole.win32.COMObject.callback6(COMObject.java:119)
	at org.eclipse.swt.internal.ole.win32.COM.DoDragDrop(Native Method)
	at org.eclipse.swt.dnd.DragSource.drag(DragSource.java:363)
	at org.eclipse.swt.dnd.DragSource.access$0(DragSource.java:289)
	at org.eclipse.swt.dnd.DragSource$1.handleEvent(DragSource.java:172)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
	at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4169)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3758)
	at org.eclipse.jface.window.Window.runEventLoop(Window.java:825)
	at org.eclipse.jface.window.Window.open(Window.java:801)
	at cccccc.DragAndDrog.main(DragAndDrog.java:165)

　　

dragSource.addDragListener(new DragSourceListener() {
			
			@Override
			public void dragStart(DragSourceEvent event) {
				// TODO Auto-generated method stub
				
			}
			
			@Override
			public void dragSetData(DragSourceEvent event) {
				event.data = dragText.getText();
				
			}
			
			@Override
			public void dragFinished(DragSourceEvent event) {
				// TODO Auto-generated method stub
				
			}
		});