JAVA中怎样获取拖放的数据

[quzuoai]

我想在一个自己的窗口上面，当有用户拖放着文件到我的窗口上面松开时，就能获取到该文件的相关数据。

就好像QQ聊天窗口时，我们想发送文件时，不是也可以直接拉到上面就发送了吗？

他们是怎么得到文件的数据的呀？谢谢指教！

[ar7043]

关注~

[HL20913538]

加个监听器，然后得到文件的路径，再读出来就可以了。
我是这么想的不知道对不对！！！

[quzuoai]

怎么加个监听器呀？你是不是说侦听窗口的鼠标拖放事件吧？如果能得到文件的路径，就可以创建文件类，一切信息都可以得到啦？
可是怎么得到这个路径是最头痛的问题呀？请支教，谢谢啦

[icefire1988]

这是我写的，希望对你有帮助

import java.awt.*;
import java.awt.datatransfer.*;
import java.awt.event.*;
import java.awt.dnd.*;
import java.io.*;
import java.util.*;
import javax.swing.*;

/**
This is a test class to test drag and drop behavior. Drop items into the text area to see the
MIME types of the drop target.
*/
public class DropTargetTest
{
public static void main(String[] args)
{
JFrame frame = new DropTargetFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}

/**
This frame contains a text area that is a simple drop target.
*/
class DropTargetFrame extends JFrame
{
public DropTargetFrame()
{
setTitle("DropTarget");
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

JTextArea textArea = new JTextArea("Drop items into this text area.\n");

new DropTarget(textArea, new TextDropTargetListener(textArea));
add(new JScrollPane(textArea), "Center");
}

private static final int DEFAULT_WIDTH = 300;
private static final int DEFAULT_HEIGHT = 300;
}

/**
This listener displays the properties of a dropped object.
*/
class TextDropTargetListener implements DropTargetListener
{
/**
Constructs a listener.
@param aTextArea the text area in which to display the
properties of the dropped object.
*/
public TextDropTargetListener(JTextArea aTextArea)
{
textArea = aTextArea;
}

public void dragEnter(DropTargetDragEvent event)
{
int a = event.getDropAction();
if ((a & DnDConstants.ACTION_COPY) != 0)
textArea.append("ACTION_COPY\n");
if ((a & DnDConstants.ACTION_MOVE) != 0)
textArea.append("ACTION_MOVE\n");
if ((a & DnDConstants.ACTION_LINK) != 0)
textArea.append("ACTION_LINK\n");

if (!isDragAcceptable(event))
{
event.rejectDrag();
return;
}
}

public void dragExit(DropTargetEvent event)
{
}

public void dragOver(DropTargetDragEvent event)
{
// you can provide visual feedback here
}

public void dropActionChanged(DropTargetDragEvent event)
{
if (!isDragAcceptable(event))
{
event.rejectDrag();
return;
}
}

public void drop(DropTargetDropEvent event)
{
if (!isDropAcceptable(event))
{
event.rejectDrop();
return;
}

event.acceptDrop(DnDConstants.ACTION_COPY);

Transferable transferable = event.getTransferable();

DataFlavor[] flavors = transferable.getTransferDataFlavors();
for (int i = 0; i < flavors.length; i++)
{
DataFlavor d = flavors[i];
textArea.append("MIME type=" + d.getMimeType() + "\n");

try
{
if (d.equals(DataFlavor.javaFileListFlavor))
{
java.util.List fileList
= (java.util.List) transferable.getTransferData(d);
File f=(File) fileList.get(0);
textArea.append(f.getAbsolutePath() + "\n");
}
else if (d.equals(DataFlavor.stringFlavor))
{
String s = (String) transferable.getTransferData(d);
textArea.append(s + "\n");
}
}
catch (Exception e)
{
textArea.append(e + "\n");
}
}
textArea.append("\n");
event.dropComplete(true);
}

public boolean isDragAcceptable(DropTargetDragEvent event)
{
// usually, you check the available data flavors here
// in this program, we accept all flavors
return (event.getDropAction() & DnDConstants.ACTION_COPY_OR_MOVE) != 0;
}

public boolean isDropAcceptable(DropTargetDropEvent event)
{
// usually, you check the available data flavors here
// in this program, we accept all flavors
return (event.getDropAction() & DnDConstants.ACTION_COPY_OR_MOVE) != 0;
}

private JTextArea textArea;
}