熟悉java界面编程和IO操作的小例子

使用java做个小型的 记事本软件，主要是为了熟悉java的GUI编程，和java文件的操作，主要代码如下：

package com.hemin.fileedit;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FileDialog;
import java.awt.FlowLayout;
import java.awt.ScrollPane;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;

public class Fileedit extends JFrame{

	private JTextField selectFiled;
	private JTextArea editArea;
	private JButton saveButton;
	private JButton openButton;
	private int leavel = 0;

	//构造方法
	public Fileedit(){
		this.init();
	}
	//初始化函数
	private void init() {
		this.setTitle("Editor");
		this.setBounds(300, 50, 600, 650);
		selectFiled = new JTextField(40);
		//打开文件按钮
		openButton = new JButton("Browse");
		/*
		 * 为打开按钮添加监听事件
		 */
		openButton.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				Fileedit.this.leavel = 1;
				String path = selectFiled.getText();
				openDirorFile(path.replace("//", "\\\\"));

			}
		});



		//此处新建一个流布局
		JPanel jpanel = new JPanel(new FlowLayout(FlowLayout.LEFT));
		jpanel.setBackground(Color.gray);
		jpanel.add(selectFiled);
		jpanel.add(openButton);
		this.add(jpanel,BorderLayout.NORTH);
		editArea = new JTextArea();

		//创建滚动面板
		ScrollPane scrollPane = new ScrollPane(ScrollPane.SCROLLBARS_AS_NEEDED);
		scrollPane.add(editArea);
		this.add(scrollPane , BorderLayout.CENTER);

		saveButton = new JButton("save");
		/*
		 * 此处需添监听事件
		 */
		saveButton.addActionListener(new ActionListener() {

			@Override
			public void actionPerformed(ActionEvent e) {
				// TODO Auto-generated method stub
				saveFile();
			}
		});
		JPanel southJPanel = new JPanel();
		southJPanel.setBackground(Color.gray);
		southJPanel.add(saveButton);
		this.add(southJPanel , BorderLayout.SOUTH);
		//常规设置（退出和可视化）
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.setVisible(true);

	}

	private void openDirorFile(String absolutePath){
		File file = new File(absolutePath);
		if(!(file.exists())){
			editArea.setText("文件不存在");
		}else if(file.isDirectory()){
			editArea.setText(null);
			showDir(file); 
		}else if(file.isFile()){
			try {
				FileInputStream fis = new FileInputStream(file);
				BufferedReader br = new BufferedReader(new InputStreamReader(fis));
				String str = null;
				editArea.setText(null);
				while((str = br.readLine())!=null){
					editArea.append(str+"\r\n");
				}
				br.close();
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}

	//展示列表
    private void showDir(File directory)
    {
        File[] files = directory.listFiles();
        int len = files.length;
        for(int i = 0; i < len; i++)
        {
            if(files[i].isDirectory())
            {
                for(int j = 0; j < this.leavel; j++)
                {
                    editArea.append("    ");
                }
                editArea.append("|-- "+ files[i].getName() + " (Folder)\r\n");
                this.leavel++;
                showDir(files[i]);
                this.leavel--;
            }
            else if(files[i].isFile())
            {
                for(int j = 0; j < this.leavel; j++)
                {
                    editArea.append("    ");
                }
                editArea.append("|-- " + files[i].getAbsolutePath() + "\r\n");
            }
        }
    }

    //
    private void saveFile(){
    	//文件保存框的练习
    	FileDialog fd = new FileDialog(this, "Save File");
    	fd.setFile("untitled.txt");
    	fd.setMode(FileDialog.SAVE);
    	fd.setVisible(true);
    	String fileName = fd.getFile();
    	String dir = fd.getDirectory();
    	File  newFile = new File(dir+File.separator+fileName);
    	PrintWriter pw =null;
    	try {
			pw = new PrintWriter(new OutputStreamWriter(new FileOutputStream(newFile)));
			String str = editArea.getText();
			pw.println(str);
			pw.flush();  
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			pw.close();
		}

    }

    //主函数
	public static void main(String args[]){
		new Fileedit();
	}
}