editor.java

java编程开发技巧与实例的编译测试通过的所有例程

import java.awt.*;
import java.awt.event.*;
import java.io.*;

public class Editor extends Frame implements ActionListener, TextListener
{
	private MenuItem fileNew	=	new MenuItem("New");
	private MenuItem fileOpen	=	new MenuItem("Open...");
	private MenuItem fileSave	=	new MenuItem("Save");
	private MenuItem fileSaveAs	=	new MenuItem("Save As ...");
	private MenuItem fileExit	=	new MenuItem("Exit");
	private TextArea text		=	new TextArea();
	private String file			=	"untitled";
	private boolean	isDirty		=	false;
	public class WindowCloser extends WindowAdapter
	{
		public void windowClosing(WindowEvent we)
		{
			System.exit(0);
		}
	}
	public	Editor()
	{
		super("Text Viewer");
		setTitle("Editor: untitled");
		Menu fileMenu	=	new Menu("File");
		fileMenu.add(fileNew);
		fileNew.addActionListener(this);
		fileMenu.add(fileOpen);
		fileOpen.addActionListener(this);
		fileMenu.addSeparator();
		fileMenu.add(fileSave);
		fileSave.addActionListener(this);
		fileMenu.add(fileSaveAs);
		fileSaveAs.addActionListener(this);
		fileMenu.addSeparator();
		fileMenu.add(fileExit);
		fileExit.addActionListener(this);
		text.addTextListener(this);
		MenuBar menu	=	new MenuBar();
		menu.add(fileMenu);
		setMenuBar(menu);
		setLayout(new BorderLayout());
		add("Center", text);
		setSize(400, 400);
		setLocationRelativeTo(this);
		addWindowListener(new WindowCloser());
		setVisible(true);
	}
	public void exitProgram()
	{
		if ((isDirty) && (wantToSave()))
			saveFile();
		System.exit(0);
	}
	public void saveFile()
	{
		if (file.equals("untitled"))
			saveFileAs();
		else
			savingFile();
		isDirty	=	false;
	}
	public void saveFileAs()
	{
		FileDialog fd	=	new FileDialog(this, "Save File As", FileDialog.SAVE);
		fd.show();
		if (fd.getFile() != null)
		{
			file	=	fd.getDirectory() + fd.getFile();
			savingFile();
		}
		isDirty	=	false;
	}
	public void newFile()
	{
		if ((isDirty) && (wantToSave()))
			saveFile();
		text.setText("");
		file	=	"untitled";
		setTitle("Editor: " + file);
		isDirty	=	false;
	}
	public void openFile()
	{
		if ((isDirty) && (wantToSave()))
			saveFile();
		FileDialog fd	=	new FileDialog(this, "Open File", FileDialog.LOAD);
		fd.show();
		if (fd.getFile() != null)
		{
			file	=	fd.getDirectory() + fd.getFile();
			setTitle("Editor: " + file);
			try
			{
				BufferedReader	in	=	new BufferedReader(new FileReader(file));
				String line	=	new String(""), s = new String("");
				while ((line = in.readLine()) != null)
					s += line + "\n";
				in.close();
				text.setText(s);
				text.setCaretPosition(0);
			}
			catch	(IOException ioe)
			{
				System.err.println(ioe);	
			}
			isDirty	=	false;
		}
		fd.dispose();
	}
	public void textValueChanged(TextEvent te)
	{
		isDirty	=	true;
	}
	public void actionPerformed(ActionEvent ae)
	{
		if (ae.getSource() == fileExit)
			exitProgram();
		else if (ae.getSource() == fileNew)
			newFile();
		else if (ae.getSource() == fileOpen)
			openFile();
		else if (ae.getSource() == fileSave)
			saveFile();
		else if (ae.getSource() == fileSaveAs)
			saveFileAs();
	}
	private boolean wantToSave()
	{
		ConfirmDialog saving	=	new ConfirmDialog(this, "File not Saved", "Do you want to save " + file);
		
		return saving.isOkay;
	}
	private	void savingFile()
	{
		try
		{
			PrintWriter out = new PrintWriter(new FileWriter(file));
			out.print(text.getText());
			out.close();
		}
		catch	(IOException ioe)
		{
			System.out.println("Editor: " + file);
		}
	}
	
	public static void main(String args[])
	{
		Editor editor	=	new Editor();
	}
}