myjtextarea.java

本程序不仅实现了记事本基本的功能

/*
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package jnotepad;

import java.awt.datatransfer.*;
import java.awt.dnd.*;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.util.Iterator;
import java.util.List;
import javax.swing.*;

/**
 *
 * @author Administrator
 */
class MyJTextArea extends JTextArea implements DropTargetListener {

    public boolean candrag = true;

    public MyJTextArea() {
        new DropTarget(this, DnDConstants.ACTION_COPY_OR_MOVE, this);
    }

    public void dragEnter(DropTargetDragEvent dtde) {
    }

    public void dragOver(DropTargetDragEvent dtde) {
    }

    public void dropActionChanged(DropTargetDragEvent dtde) {
    }

    public void dragExit(DropTargetEvent dte) {
    }

    public void drop(DropTargetDropEvent dtde) {
        if (!candrag) {
            JOptionPane.showMessageDialog(null, "请先在菜单栏中设置支持拖拽文件!",
                    "提示",
                    JOptionPane.INFORMATION_MESSAGE);
            return;
        }
        try {
            Transferable tr = dtde.getTransferable();

            if (dtde.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
                dtde.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
                List list = (List) (dtde.getTransferable().getTransferData(DataFlavor.javaFileListFlavor));
                String filepath = "";
                Iterator iterator = list.iterator();
                while (iterator.hasNext()) {
                    File f = (File) iterator.next();
                    filepath = f.getAbsolutePath();
                }
                this.setText("");
                if (filepath.endsWith(".txt")) {
                    File file = new File(filepath);
                    BufferedReader read = new BufferedReader(new FileReader(file));
                    String line = null;
                    
                    do {
                        line = read.readLine();
                        this.append(line + "\n");
                    } while (line != null);
                }
                else
                    this.setText(filepath);
                dtde.dropComplete(true);
                this.updateUI();
            } else {
                dtde.rejectDrop();
            }
        } catch (Exception ex) {
            JOptionPane.showMessageDialog(null, "        无 法 显 示!",
                    "失败",
                    JOptionPane.INFORMATION_MESSAGE);
        }
    }
}