notepad.java

用java编写的记事本 具有打开保存的功能 可供大家学习

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

public class NotePad extends Frame implements ActionListener{
	TextArea textArea=new TextArea();
	MenuBar menuBar=new MenuBar();
	Menu fileMenu=new Menu("File");
	MenuItem newItem=new MenuItem("New");
	MenuItem openItem=new MenuItem("Open");
	MenuItem saveItem=new MenuItem("Save");
	MenuItem saveAsItem=new MenuItem("Save As");
	MenuItem exitItem=new MenuItem("Exit");
	String fileName=null;
	private FileDialog openFileDialog=new FileDialog(this,"Open File",FileDialog.LOAD);
	private FileDialog saveAsFileDialog=new FileDialog(this,"Save File As",FileDialog.SAVE);
	public NotePad(){
		setTitle("NotePad");
		setFont(new Font("Times New Roman",Font.PLAIN,12));
		this.setBackground(Color.white);
		this.setSize(400,300);
		fileMenu.add(newItem);
		fileMenu.add(openItem);
		fileMenu.addSeparator();
		fileMenu.add(saveItem);
		fileMenu.add(saveAsItem);
		fileMenu.addSeparator();
		fileMenu.add(exitItem);
		menuBar.add(fileMenu);
		this.setMenuBar(menuBar);
		add(textArea);
		this.addWindowListener(new WindowAdapter(){
			public void windowClosing(WindowEvent e){
				System.exit(0);
			}
		});
		newItem.addActionListener(this);
		openItem.addActionListener(this);
		saveItem.addActionListener(this);
		saveAsItem.addActionListener(this);
		exitItem.addActionListener(this);
	}
	public void actionPerformed(ActionEvent e){
		Object eventSource=e.getSource();
		if(eventSource==newItem){
			textArea.setText("");
		}
		else if(eventSource==openItem){
			openFileDialog.show();
			fileName=openFileDialog.getDirectory()+openFileDialog.getFile();
			if(fileName!=null)
			readFile(fileName);
		}
		else if(eventSource==saveItem){
			saveAsFileDialog.show();
			fileName=saveAsFileDialog.getFile();
			if(fileName!=null)
			writeFile(fileName);
		}
		else if(eventSource==saveAsItem){
			saveAsFileDialog.show();
			fileName=saveAsFileDialog.getDirectory()+saveAsFileDialog.getFile();
			if(fileName!=null)
			writeFile(fileName);
		}
		else if(eventSource==exitItem){
			System.exit(0);
		}
	}
	public void readFile(String fileName){
		try{
			File file=new File(fileName);
			FileReader readIn=new FileReader(file);
		    int size=(int)file.length();
			char[] content=new char[size];
		    int ch=readIn.read(content,0,size);
			readIn.close();
			textArea.setText(new String(content,0,ch));
		}
		catch(IOException e){
			e.printStackTrace();
		}
	}
	public void writeFile(String fileName){
		try{
			File file=new File(fileName);
			FileWriter writeOut=new FileWriter(file);
			writeOut.write(textArea.getText());
			writeOut.close();
		}
		catch(IOException e){
			e.printStackTrace();
		}
	}
	public static void main(String args[]){
		Frame frame=new NotePad();
		frame.show();
   }
}