SWT JFace 拖曳效果

package swt_jface.demo11;
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.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.MessageBox;
import org.eclipse.swt.widgets.Shell;
public class WordJumbles {

    Display display = new Display();
    Shell shell = new Shell(display);
    String word;
    Label[] labelsRowOne;
    Label[] labelsRowTwo;
    Font font = new Font(display, "Arial", 18, SWT.BOLD);
    public void setDragSource(final Label label) {
        int operations = DND.DROP_MOVE;
        final DragSource dragSource = new DragSource(label, operations);
        Transfer[] formats = new Transfer[] { TextTransfer.getInstance()};
        dragSource.setTransfer(formats);

        dragSource.addDragListener(new DragSourceListener() {
            public void dragStart(DragSourceEvent event) {
                if (label.getText().length() == 0)
                    event.doit = false;
            }
            public void dragSetData(DragSourceEvent event) {
                if (TextTransfer.getInstance().isSupportedType(event.dataType))
                    event.data = label.getText();
            }
            public void dragFinished(DragSourceEvent event) {
                if (event.doit == true || event.detail == DND.DROP_MOVE) {
                    label.setText("");
                }
            }
        });

        label.addDisposeListener(new DisposeListener() {
            public void widgetDisposed(DisposeEvent e) {
                dragSource.dispose();
            }
        });
    }
    public void setDropTarget(final Label label) {
        int operations = DND.DROP_MOVE;
        final DropTarget dropTarget = new DropTarget(label, operations);
        Transfer[] formats = new Transfer[] { TextTransfer.getInstance()};
        dropTarget.setTransfer(formats);
        dropTarget.addDropListener(new DropTargetListener() {
            public void dragEnter(DropTargetEvent event) {
                if(label.getText().length() != 0)
                    event.detail = DND.DROP_NONE;
            }
            public void dragLeave(DropTargetEvent event) {
            }
            public void dragOperationChanged(DropTargetEvent event) {
            }
            public void dragOver(DropTargetEvent event) {
            }
            public void drop(DropTargetEvent event) {
                if (TextTransfer
                    .getInstance()
                    .isSupportedType(event.currentDataType)) {
                    String text = (String) event.data;
                    label.setText(text);
                    check();
                }
            }
            public void dropAccept(DropTargetEvent event) {
            }
        });

        label.addDisposeListener(new DisposeListener() {
            public void widgetDisposed(DisposeEvent e) {
                dropTarget.dispose();
            }
        });
    }

    private void check() {
        for(int i=0; i<word.length(); i++) {
            if(! labelsRowTwo[i].getText().equals(word.charAt(i) + ""))
                return;
        }
        MessageBox messageBox = new MessageBox(shell);
        messageBox.setMessage("Success!");
        messageBox.open();
    }
    public WordJumbles(String word) {
        this.word = word;
        shell.setText("Word Jumbles");
        labelsRowOne = new Label[word.length()];
        labelsRowTwo = new Label[word.length()];
        int width = 40;
        int[] randomPermutation = { 5, 2, 6, 3, 1, 4, 0 };
        for (int i = 0; i < word.length(); i++) {
            final Label labelRowOne = new Label(shell, SWT.BORDER);
            labelsRowOne[i] = labelRowOne;
            labelRowOne.setBounds(10 + width * i, 10, width - 5, width - 5);
            labelRowOne.setFont(font);
            labelRowOne.setText(word.charAt(randomPermutation[i]) + "");
            labelRowOne.setAlignment(SWT.CENTER);

            setDragSource(labelRowOne);
            setDropTarget(labelRowOne);
            final Label labelRowTwo = new Label(shell, SWT.BORDER);
            labelsRowTwo[i] = labelRowTwo;
            labelRowTwo.setBounds(
                10 + width * i,
                20 + width,
                width - 5,
                width - 5);
            labelRowTwo.setBackground(display.getSystemColor(SWT.COLOR_WHITE));
            labelRowTwo.setFont(font);
            labelRowTwo.setAlignment(SWT.CENTER);

            setDragSource(labelRowTwo);
            setDropTarget(labelRowTwo);
        }

        shell.pack();
        shell.open();

        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
        display.dispose();
    }
    public static void main(String[] args) {
        new WordJumbles("ECLIPSE");
    }
}