本文介绍了java拖放的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我尝试在java中拖放，但我发现的所有教程都是...（让我生气）我想要的是拖动来自JList的PublicUserLabel（包含在自制的JPanel中，名为UserPanel），并将其放在从JTabbedPanel中强制转换的自制类中。
拖动对象本身而不是其字符串表示非常重要!!!
这是我到目前为止：
PublicUserLabel
public class PublicUserLabel extends JLabel implements DragSourceListener，DragGestureListener，Transferable
{
private DragSource ds;
private PublicUser用户;
public PublicUserLabel（PublicUser user）
{
super（user.getName（））;
this.user = user;
ds = new DragSource（）;
ds.createDefaultDragGestureRecognizer（this，DnDConstants.ACTION_COPY_OR_MOVE，this）;
}
@Override
public void dragGestureRecognized（DragGestureEvent e）
{
ds.startDrag（e，DragSource.DefaultCopyDrop，this，this）;
@Override
public Object getTransferData（DataFlavor flavor）throws UnsupportedFlavorException，IOException
{
if（flavor.equals（PublicUserFlavor.publicUserFlavor））
{
return this; // TODO？
}
抛出新的UnsupportedFlavorException（flavor）;
}
@Override
public DataFlavor [] getTransferDataFlavors（）
{
DataFlavor [] df = new DataFlavor [2];
df [0] = DataFlavor.stringFlavor;
df [1] = PublicUserFlavor.publicUserFlavor;
return df;
}
@Override
public boolean isDataFlavorSupported（DataFlavor flavor）
{
return flavor.equals（PublicUserFlavor.publicUserFlavor）;
}
//更多方法
}
UserPanel：
public class UserPanel extends JPanel
{
private JTextField search;
私人列表< PublicUser> ALLUSER;
private JList< PublicUserLabel>列表;
private JScrollPane scrollPane;
private DefaultListModel< PublicUserLabel> ListModel的;
public UserPanel（）
{
allUser = new LinkedList< PublicUser>（）;
listModel = new DefaultListModel< PublicUserLabel>（）;
list = new JList< PublicUserLabel>（listModel）;
list.setDragEnabled（true）;
PublicUserFlavor：
code> public class PublicUserFlavor extends DataFlavor
{
public static DataFlavor publicUserFlavor;
static
{
publicUserFlavor = new DataFlavor（PublicUser.class，PublicUser）;
}
}
TabPanel：
public class TabPanel extends JTabbedPane implements DropTargetListener
{
public TabPanel（）
{
setTabPlacement（JTabbedPane.BOTTOM） ;
addNewTabComponent（bla）;
addNewTabComponent（blub）;
setDropTarget（new DropTarget（this，this））;
}
@Override
public void drop（DropTargetDropEvent e）
{
可传递转移= e.getTransferable（）;
if（transferable.isDataFlavorSupported（PublicUserFlavor.publicUserFlavor））
{
e.acceptDrop（DnDConstants.ACTION_COPY_OR_MOVE）;
try
{
Object o = transferable.getTransferData（PublicUserFlavor.publicUserFlavor）;
System.out.println（o）;
if（o instanceof PublicUserLabel）
{
PublicUserLabel l =（PublicUserLabel）o;
PublicUser u = l.getUser（）;
System.out.println（u）;
}
}
catch（UnsupportedFlavorException e1）
{
// TODO自动生成的catch块
e1.printStackTrace（）;
}
catch（IOException e1）
{
// TODO自动生成的catch块
e1.printStackTrace（）;
}
e.getDropTargetContext（）。dropComplete（true）;
}
}
在drop方法中有一些syso将被执行如果用户被放在面板中。但事实并非如此。我做的事情完全错了吗？
感谢您的帮助！
解决方案
我可以看到的主要问题是您正在混合两种不同的API。您正在使用低级别的D'n'D API和较新的组件D'n'DAPI。
个人而言，较新的API会让我失望，所以我倾向于避免它。
我不明白为什么你需要转移标签，最好转移底层的 PublicUser 对象，但这只是我。
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.dnd.DnDConstants;
import java.awt.dnd.DragGestureEvent;
import java.awt.dnd.DragGestureListener;
import java.awt.dnd.DragGestureRecognizer;
import java.awt.dnd.DragSource;
import java.awt.dnd.DragSourceDragEvent;
import java.awt.dnd.DragSourceDropEvent;
import java.awt.dnd.DragSourceEvent;
import java.awt.dnd.DragSourceListener;
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.IOException;
import javax.swing.DefaultListModel;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TestDnD {
public static void main（String [] args）{
new TestDnD（）;
}
public TestDnD（）{
EventQueue.invokeLater（new Runnable（）{
@Override
public void run（）{
尝试{
UIManager.setLookAndFeel（UIManager.getSystemLookAndFeelClassName（））;
} catch（ClassNotFoundException ex）{
} catch（InstantiationException ex）{
} catch（IllegalAccessException ex） {
} catch（UnsupportedLookAndFeelException ex）{
}
JFrame frame = new JFrame（Test）;
frame.setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）;
frame.setLayout（new BorderLayout（））;
frame.add（new TestPane（））;
frame.pack（）;
frame.setLocationRelativeTo（null）;
frame.setVisible（true）;
}
}）;
}
public class TestPane扩展JPanel {
private JList list;
public TestPane（）{
setLayout（new BorderLayout（））;
list = new JList（）;
DefaultListModel model = new DefaultListModel（）;
model.addElement（new User（Shaun））;
model.addElement（new User（Andy））;
model.addElement（new User（Luke））;
model.addElement（new User（Han））;
model.addElement（new User（Liea））;
model.addElement（new User（Yoda））;
list.setModel（model）;
add（new JScrollPane（list），BorderLayout.WEST）;
DragGestureRecognizer dgr = DragSource.getDefaultDragSource（）。createDefaultDragGestureRecognizer（
list，
DnDConstants.ACTION_COPY_OR_MOVE，
new DragGestureHandler（list））;
JPanel panel = new JPanel（new GridBagLayout（））;
add（panel）;
DropTarget dt = new DropTarget（
panel，
DnDConstants.ACTION_COPY_OR_MOVE，
new DropTargetHandler（panel），
true）;
}
}
public static class User {
private String name;
public User（String name）{
this.name = name;
}
public String getName（）{
return name;
}
@Override
public String toString（）{
return name;
}
}
public static class UserTransferable implements Transferable {
public static final DataFlavor USER_DATA_FLAVOR = new DataFlavor（User.class， 用户）;
私人用户用户;
public UserTransferable（用户用户）{
this.user = user;
}
@Override
public DataFlavor [] getTransferDataFlavors（）{
返回新的DataFlavor [] {USER_DATA_FLAVOR};
}
@Override
public boolean isDataFlavorSupported（DataFlavor flavor）{
return USER_DATA_FLAVOR.equals（flavor）;
}
@Override
public Object getTransferData（DataFlavor flavor）throws UnsupportedFlavorException，IOException {
Object value = null;
if（USER_DATA_FLAVOR.equals（flavor））{
value = user;
} else {
throw new UnsupportedFlavorException（flavor）;
}
返回值;
}
}
保护类DragGestureHandler实现DragGestureListener {
private JList list;
public DragGestureHandler（JList list）{
this.list = list;
}
@Override
public void dragGestureRecognized（DragGestureEvent dge）{
Object selectedValue = list.getSelectedValue（）;
if（selectedValue instanceof User）{
User user =（User）selectedValue;
可转移t = new UserTransferable（user）;
DragSource ds = dge.getDragSource（）;
ds.startDrag（
dge，
null，
t，
new DragSourceHandler（））;
}
}
}
保护类DragSourceHandler实现DragSourceListener {
public void dragEnter（DragSourceDragEvent dsde）{
}
public void dragOver（DragSourceDragEvent dsde）{
}
public void dropActionChanged（DragSourceDragEvent dsde）{
}
public void dragExit（DragSourceEvent dse）{
}
public void dragDropEnd（DragSourceDropEvent dsde）{
System.out.println （拖曳...）;
}
}
保护类DropTargetHandler实现DropTargetListener {
private JPanel panel;
public DropTargetHandler（JPanel panel）{
this.panel = panel;
}
public void dragEnter（DropTargetDragEvent dtde）{
if（dtde.getTransferable（）。isDataFlavorSupported（UserTransferable.USER_DATA_FLAVOR））{
System.out.println （接受...）;
dtde.acceptDrag（DnDConstants.ACTION_COPY_OR_MOVE）;
} else {
System.out.println（Drag ...）;
dtde.rejectDrag（）;
}
}
public void dragOver（DropTargetDragEvent dtde）{
}
public void dropActionChanged（DropTargetDragEvent dtde）{
}
public void dragExit（DropTargetEvent dte）{
}
public void drop（DropTargetDropEvent dtde）{
System.out.println（下降......）;
if（dtde.getTransferable（）。isDataFlavorSupported（UserTransferable.USER_DATA_FLAVOR））{
可传递t = dtde.getTransferable（）;
if（t.isDataFlavorSupported（UserTransferable.USER_DATA_FLAVOR））{
try {
Object transferData = t.getTransferData（UserTransferable.USER_DATA_FLAVOR）;
if（transferData instanceof User）{
User user =（User）transferData;
dtde.acceptDrop（DnDConstants.ACTION_COPY_OR_MOVE）;
panel.add（new JLabel（user.getName（）））;
panel.revalidate（）;
panel.repaint（）;
} else {
dtde.rejectDrop（）;
}
} catch（UnsupportedFlavorException ex）{
ex.printStackTrace（）;
dtde.rejectDrop（）;
} catch（IOException ex）{
ex.printStackTrace（）;
dtde.rejectDrop（）;
}
} else {
dtde.rejectDrop（）;
}
}
}
}
}
I try to get familar with drag and drop in java but all the tutorials I found were... (getting me angry)
All I want is to drag a "PublicUserLabel" from a JList (included in a selfmade JPanel called "UserPanel") and drop it in a selfmade class inerited from JTabbedPanel.It is very important to drag the object itself and not its stringrepresentation!!!
That is what I have so far:PublicUserLabel
public class PublicUserLabel extends JLabel implements DragSourceListener, DragGestureListener, Transferable
{
private DragSource ds;
private PublicUser user;
public PublicUserLabel(PublicUser user)
{
super(user.getName());
this.user = user;
ds = new DragSource();
ds.createDefaultDragGestureRecognizer(this, DnDConstants.ACTION_COPY_OR_MOVE, this);
}
@Override
public void dragGestureRecognized(DragGestureEvent e)
{
ds.startDrag(e, DragSource.DefaultCopyDrop, this, this);
}
@Override
public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException, IOException
{
if (flavor.equals(PublicUserFlavor.publicUserFlavor))
{
return this;//TODO ?
}
throw new UnsupportedFlavorException(flavor);
}
@Override
public DataFlavor[] getTransferDataFlavors()
{
DataFlavor[] df = new DataFlavor[2];
df[0] = DataFlavor.stringFlavor;
df[1] = PublicUserFlavor.publicUserFlavor;
return df;
}
@Override
public boolean isDataFlavorSupported(DataFlavor flavor)
{
return flavor.equals(PublicUserFlavor.publicUserFlavor);
}
//some more methods
}
UserPanel:
public class UserPanel extends JPanel
{
private JTextField search;
private List<PublicUser> allUser;
private JList<PublicUserLabel> list;
private JScrollPane scrollPane;
private DefaultListModel<PublicUserLabel> listModel;
public UserPanel()
{
allUser = new LinkedList<PublicUser>();
listModel = new DefaultListModel<PublicUserLabel>();
list = new JList<PublicUserLabel>(listModel);
list.setDragEnabled(true);
PublicUserFlavor:
public class PublicUserFlavor extends DataFlavor
{
public static DataFlavor publicUserFlavor;
static
{
publicUserFlavor = new DataFlavor(PublicUser.class, "PublicUser");
}
}
TabPanel:
public class TabPanel extends JTabbedPane implements DropTargetListener
{
public TabPanel()
{
setTabPlacement(JTabbedPane.BOTTOM);
addNewTabComponent("bla");
addNewTabComponent("blub");
setDropTarget(new DropTarget(this, this));
}
@Override
public void drop(DropTargetDropEvent e)
{
Transferable transferable = e.getTransferable();
if (transferable.isDataFlavorSupported(PublicUserFlavor.publicUserFlavor))
{
e.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
try
{
Object o = transferable.getTransferData(PublicUserFlavor.publicUserFlavor);
System.out.println(o);
if (o instanceof PublicUserLabel)
{
PublicUserLabel l = (PublicUserLabel)o;
PublicUser u = l.getUser();
System.out.println(u);
}
}
catch (UnsupportedFlavorException e1)
{
// TODO Auto-generated catch block
e1.printStackTrace();
}
catch (IOException e1)
{
// TODO Auto-generated catch block
e1.printStackTrace();
}
e.getDropTargetContext().dropComplete(true);
}
}
In the drop method are some syso's that shall be executed if a User is droped in the panel. But that is not the fact. Am I doing something completly wrong?Thank you for helping!
解决方案
The major issues I can see are you are mixing two different API's. You're using both the low level D'n'D API and the newer "component D'n'D" API.
Personally, the newer API annoys me, so I tend to avoid it.
I can't see why you need to transfer the label, when it would be better to transfer the underlying PublicUser object, but that's just me.
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.dnd.DnDConstants;
import java.awt.dnd.DragGestureEvent;
import java.awt.dnd.DragGestureListener;
import java.awt.dnd.DragGestureRecognizer;
import java.awt.dnd.DragSource;
import java.awt.dnd.DragSourceDragEvent;
import java.awt.dnd.DragSourceDropEvent;
import java.awt.dnd.DragSourceEvent;
import java.awt.dnd.DragSourceListener;
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.IOException;
import javax.swing.DefaultListModel;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TestDnD {
public static void main(String[] args) {
new TestDnD();
}
public TestDnD() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException ex) {
} catch (InstantiationException ex) {
} catch (IllegalAccessException ex) {
} catch (UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JList list;
public TestPane() {
setLayout(new BorderLayout());
list = new JList();
DefaultListModel model = new DefaultListModel();
model.addElement(new User("Shaun"));
model.addElement(new User("Andy"));
model.addElement(new User("Luke"));
model.addElement(new User("Han"));
model.addElement(new User("Liea"));
model.addElement(new User("Yoda"));
list.setModel(model);
add(new JScrollPane(list), BorderLayout.WEST);
DragGestureRecognizer dgr = DragSource.getDefaultDragSource().createDefaultDragGestureRecognizer(
list,
DnDConstants.ACTION_COPY_OR_MOVE,
new DragGestureHandler(list));
JPanel panel = new JPanel(new GridBagLayout());
add(panel);
DropTarget dt = new DropTarget(
panel,
DnDConstants.ACTION_COPY_OR_MOVE,
new DropTargetHandler(panel),
true);
}
}
public static class User {
private String name;
public User(String name) {
this.name = name;
}
public String getName() {
return name;
}
@Override
public String toString() {
return name;
}
}
public static class UserTransferable implements Transferable {
public static final DataFlavor USER_DATA_FLAVOR = new DataFlavor(User.class, "User");
private User user;
public UserTransferable(User user) {
this.user = user;
}
@Override
public DataFlavor[] getTransferDataFlavors() {
return new DataFlavor[]{USER_DATA_FLAVOR};
}
@Override
public boolean isDataFlavorSupported(DataFlavor flavor) {
return USER_DATA_FLAVOR.equals(flavor);
}
@Override
public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException, IOException {
Object value = null;
if (USER_DATA_FLAVOR.equals(flavor)) {
value = user;
} else {
throw new UnsupportedFlavorException(flavor);
}
return value;
}
}
protected class DragGestureHandler implements DragGestureListener {
private JList list;
public DragGestureHandler(JList list) {
this.list = list;
}
@Override
public void dragGestureRecognized(DragGestureEvent dge) {
Object selectedValue = list.getSelectedValue();
if (selectedValue instanceof User) {
User user = (User) selectedValue;
Transferable t = new UserTransferable(user);
DragSource ds = dge.getDragSource();
ds.startDrag(
dge,
null,
t,
new DragSourceHandler());
}
}
}
protected class DragSourceHandler implements DragSourceListener {
public void dragEnter(DragSourceDragEvent dsde) {
}
public void dragOver(DragSourceDragEvent dsde) {
}
public void dropActionChanged(DragSourceDragEvent dsde) {
}
public void dragExit(DragSourceEvent dse) {
}
public void dragDropEnd(DragSourceDropEvent dsde) {
System.out.println("Drag ended...");
}
}
protected class DropTargetHandler implements DropTargetListener {
private JPanel panel;
public DropTargetHandler(JPanel panel) {
this.panel = panel;
}
public void dragEnter(DropTargetDragEvent dtde) {
if (dtde.getTransferable().isDataFlavorSupported(UserTransferable.USER_DATA_FLAVOR)) {
System.out.println("Accept...");
dtde.acceptDrag(DnDConstants.ACTION_COPY_OR_MOVE);
} else {
System.out.println("Drag...");
dtde.rejectDrag();
}
}
public void dragOver(DropTargetDragEvent dtde) {
}
public void dropActionChanged(DropTargetDragEvent dtde) {
}
public void dragExit(DropTargetEvent dte) {
}
public void drop(DropTargetDropEvent dtde) {
System.out.println("Dropped...");
if (dtde.getTransferable().isDataFlavorSupported(UserTransferable.USER_DATA_FLAVOR)) {
Transferable t = dtde.getTransferable();
if (t.isDataFlavorSupported(UserTransferable.USER_DATA_FLAVOR)) {
try {
Object transferData = t.getTransferData(UserTransferable.USER_DATA_FLAVOR);
if (transferData instanceof User) {
User user = (User) transferData;
dtde.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
panel.add(new JLabel(user.getName()));
panel.revalidate();
panel.repaint();
} else {
dtde.rejectDrop();
}
} catch (UnsupportedFlavorException ex) {
ex.printStackTrace();
dtde.rejectDrop();
} catch (IOException ex) {
ex.printStackTrace();
dtde.rejectDrop();
}
} else {
dtde.rejectDrop();
}
}
}
}
}
这篇关于java拖放的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！