Java 剪贴板程序

hoverlees 写道

众所周知,这个包主要是与系统剪切板相关的的软件包(还有就是与JFC里的拖曳编程相关),这个包的核心类当然是Clipborad类(个人认为),这个 类我们就看成是一个剪切板,它具有储存的内容,我们可以取得和设置它的内容.它的内容被封装在Transferable里,我们最终要取得的数据,就是在 它里面.说到Transferable接口,我不得不提一下StringSelection类,这个类就是它的一个实现,专门用来向剪切板传输文本数据 的.为什么要叫StringSelection,我想因为平时我们把文本复制到剪切板的时候,这些文本都是被选择好的,所以就会取个这个类名吧.呵 呵~~~当我们用StringSelection向Clipborad传输文本数据的时候,我们剪切板的Transferable数据就可以是一个 StringSelection对象.像这样:
StringSelection ss=new StringSelection("放入剪切板的文本");
clipboardobj.setContents(ss,ss);//两个参数都是ss,因为StringSelection既是Transferable,也是ClipboardOwner.
DataFlavor表示的是存储数据的格式,因为我们的剪切板里到底是文本,图像,还是上次复制的文件我们根本不知道,幸好有它让我们可以先知道Clipboard里存的是些什么东西.
一个剪切板还可以加入数据改变的监听器,当剪切板的数据改变时做一些操作.这主要是在Clipboard里加入监听即可.

package cn.sisy.awt;

import java.awt.Toolkit;
import java.awt.datatransfer.Clipboard;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.StringSelection;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.io.IOException;

public class CopyStringToClipboard {

	public static void main(String[] args) {

		String str = "a string for copy";

		Toolkit toolkit = Toolkit.getDefaultToolkit();
		Clipboard clipboard = toolkit.getSystemClipboard();
		StringSelection strSel = new StringSelection(str);
		clipboard.setContents(strSel, null);
		
		if(clipboard.isDataFlavorAvailable(DataFlavor.stringFlavor)){
			try {
				String content = (String) clipboard.getData(DataFlavor.stringFlavor);
				System.out.println(content);
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} 
		}
	}

}

 已复制如下：

下面看看图片如何复制：

 实现自定义的ImageSelection类用于支持图片的复制：

package cn.sisy.awt;

import java.awt.*;
import java.awt.datatransfer.*;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.io.IOException;

public class ImageSelection implements Transferable {
	
	private Image image;
	
	public ImageSelection(Image image) {
		this.image = image;
	}

	@Override
	public DataFlavor[] getTransferDataFlavors() {
		return new DataFlavor[]{DataFlavor.imageFlavor};
	}

	@Override
	public boolean isDataFlavorSupported(DataFlavor flavor) {
		// TODO Auto-generated method stub
		return flavor.equals(DataFlavor.imageFlavor);
	}

	@Override
	public Object getTransferData(DataFlavor flavor)
			throws UnsupportedFlavorException, IOException {
		if(flavor.equals(DataFlavor.imageFlavor)){
			return image;
		}else{
			throw new UnsupportedFlavorException(flavor);
		}
	}

}

 实现类CopyImage

package cn.sisy.awt;

import java.awt.*;
import java.awt.datatransfer.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.List;


public class CopyImage {
	private Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
	private final int AREA_WIDTH = 400;
	private final int AREA_HEIGHT = 400;
	private int preX = -1;
	private int preY = -1;
	BufferedImage image = new BufferedImage(AREA_WIDTH, 
			AREA_HEIGHT, BufferedImage.TYPE_INT_RGB);
	java.util.List<Image> imageList  = new java.util.ArrayList<Image>();
	Graphics g = image.getGraphics();
	private Frame f = new Frame("图形复制程序");
	private MyCanvas myCanvas = new MyCanvas();
	private Color foreColor = new Color(255,0,0);
	private Button copy = new Button("复制");
	private Button paste  = new Button("粘贴");
	public void init(){
		g.fillRect(0, 0, AREA_WIDTH, AREA_HEIGHT);
		myCanvas.setPreferredSize(new Dimension(AREA_WIDTH,
				AREA_HEIGHT));
		myCanvas.addMouseMotionListener(new MouseAdapter() {
			public void mouseDragged(MouseEvent e){
				preX = e.getX();
				preY = e.getY();
				if(preX > 0 && preY > 0){
					g.setColor(foreColor);
					g.drawLine(preX,preY,e.getX(),e.getY());
				}
				myCanvas.repaint();
			}
		});
		
		myCanvas.addMouseListener(new MouseAdapter(){
			public void mouseReleased(MouseEvent e){
				preX = -1;
				preY = -1;
			}
		});
		f.add(myCanvas);
		Panel p = new Panel();
		copy.addActionListener(new ActionListener() {		
			@Override
			public void actionPerformed(ActionEvent e) {
				ImageSelection contents = new ImageSelection(image);
				clipboard.setContents(contents, null);
			}
		});
		paste.addActionListener(new ActionListener() {		
			@Override
			public void actionPerformed(ActionEvent e) {
				if(clipboard.isDataFlavorAvailable(DataFlavor.imageFlavor)){
					try {
						imageList.add((Image)clipboard.getData(DataFlavor.imageFlavor));
						myCanvas.repaint();
					} catch (Exception e1) {
						e1.printStackTrace();
					}
				}
			}
		});
		p.add(copy);
		p.add(paste);
		f.add(p,BorderLayout.SOUTH);
		f.pack();
		f.setVisible(true);
	}
	public static void main(String[] args) {
		new CopyImage().init();
	}
	class MyCanvas extends Canvas{
		@Override
		public void paint(Graphics g) {
			g.drawImage(image,0,0,null);
			System.out.println(imageList.size());
			for(Image img : imageList){
				g.drawImage(img,0,0,null);
			}
		}
	}
}