我的第一个写字板程序 JNotePad

这个例子参考书《java 7 学习笔记》 作者 林信良

这本书挺不错的，台湾人写的书品质就是好。

只是宣传得有点夸张，比如他的另外一本书 《Servlet jsp 学习笔记》,

在 《java 7 学习笔记》中说书中有一个微博的例子，其实只是一个书签的例子。

好书是经得起考验的，不需要出版社过度的夸张宣传。

JNotePad.java

package com.xjh.swing;

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.InputEvent;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.lang.reflect.InvocationTargetException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

import javax.swing.BorderFactory;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JPopupMenu;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.KeyStroke;
import javax.swing.ScrollPaneConstants;
import javax.swing.SwingConstants;

public class JNotePad extends JFrame {

	private JMenuBar menuBar;

	private JMenu fileMenu;
	private JMenuItem menuOpen;
	private JMenuItem menuSave;
	private JMenuItem menuSaveAs;
	private JMenuItem menuClose;

	private JMenu editMenu;
	private JMenuItem menuCut;
	private JMenuItem menuCopy;
	private JMenuItem menuPaste;

	private JMenu aboutMenu;
	private JMenuItem menuAbout;
	
	private JTextArea textArea;
	private JLabel stateBar;
	
	private JPopupMenu popUpMenu;
	
	private TextDAO textDAO;
	private JFileChooser fileChooser;

	public JNotePad(TextDAO textDAO) {
		this();
		this.textDAO = textDAO;
	}
	public JNotePad() {
		initCompanents();
		initEventListeners();
	}

	private void initCompanents() {
		setTitle("新增纯文本文件");
		setSize(400, 300);

		// 设置"文件"菜单
		fileMenu = new JMenu("文件");
		menuOpen = new JMenuItem("打开文件");
		menuSave = new JMenuItem("保存文件");
		menuSaveAs = new JMenuItem("另存新文件");
		menuClose = new JMenuItem("关闭");

		fileMenu.add(menuOpen);
		fileMenu.addSeparator(); // 分隔线
		fileMenu.add(menuSave);
		fileMenu.add(menuSaveAs);
		fileMenu.addSeparator(); // 分隔线
		fileMenu.add(menuClose);

		// 设置"编辑"菜单
		editMenu = new JMenu("编辑");
		menuCut = new JMenuItem("剪贴");
		menuCopy = new JMenuItem("拷贝");
		menuPaste = new JMenuItem("粘贴");

		editMenu.add(menuCut);
		editMenu.add(menuCopy);
		editMenu.add(menuPaste);

		// 设置"关于"菜单
		aboutMenu = new JMenu("关于");
		menuAbout = new JMenuItem("关于JNotePad");
		aboutMenu.add(menuAbout);

		// 菜单列
		menuBar = new JMenuBar();
		menuBar.add(fileMenu); // 文件
		menuBar.add(editMenu); // 编辑
		menuBar.add(aboutMenu); // 关于

		// 设置菜单列
		setJMenuBar(menuBar);
		
		// 文字编辑区
		textArea = new JTextArea();
		textArea.setFont(new Font("宋体", Font.PLAIN, 16));
		textArea.setLineWrap(true); // 设置自动换行
		// 水平滚动条(不显示)和垂直滚动条(当有需要的时候显示)
		JScrollPane pane = new JScrollPane(textArea, 
				ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED, 
				ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
		Container contentPane = this.getContentPane();
		contentPane.add(pane, BorderLayout.CENTER);
		// 状态栏
		stateBar = new JLabel("未修改");
		stateBar.setHorizontalAlignment(SwingConstants.LEFT); // 文字左对齐
		stateBar.setBorder(BorderFactory.createEtchedBorder());
		contentPane.add(stateBar, BorderLayout.SOUTH); // 布局管理器
		
		popUpMenu = editMenu.getPopupMenu();
		fileChooser = new JFileChooser();
	}

	private void initEventListeners() {
		// 点击窗口开关按钮事件处理
		addWindowListener(new WindowAdapter() {
			public void windowClosing(WindowEvent e) {
				closeFile();
			}
		});
		
		// 菜单-打开文件
		menuOpen.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				openFile();
			}
		});
		
		// 菜单-保存文件
		menuSave.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				saveFile();
			}
		});
		
		// 菜单-另存新文件
		menuSaveAs.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				saveFileAs();
			}
		});
		
		// 菜单-关闭文件
		menuClose.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				closeFile();
			}
		});
		
		// 菜单-剪切
		menuCut.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				cut();
			}
		});
		
		// 菜单-复制
		menuCopy.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				copy();
			}
		});
		
		// 菜单-粘贴
		menuPaste.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				paste();
			}
		});
		
		// 菜单-关于
		menuAbout.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				// 显示对话框
				JOptionPane.showOptionDialog(null, 
						"JNotePad 0.1", 
						"关于JNotePad", 
						JOptionPane.DEFAULT_OPTION, 
						JOptionPane.INFORMATION_MESSAGE, 
						null, 
						null, 
						null);
			}
		});
		
		// 编辑区键盘事件
		textArea.addKeyListener(new KeyAdapter() {
			public void keyTyped(KeyEvent e) {
				jtextAreaActionPerformed();
			}
		});
		
		// 编辑区鼠标事件
		textArea.addMouseListener(new MouseAdapter() {
			public void mouseReleased(MouseEvent e) {
				if (e.getButton() == MouseEvent.BUTTON3) {
					popUpMenu.show(editMenu, e.getX(), e.getY());
				}
			}
			
			public void mouseClicked(MouseEvent e) {
				if (e.getButton() == MouseEvent.BUTTON1) {
					popUpMenu.setVisible(false);
				}
			}
		});
		
//		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

		// 快捷键设置
		menuOpen.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O,
				InputEvent.CTRL_MASK));
		menuSave.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S,
				InputEvent.CTRL_MASK));
		menuClose.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q,
				InputEvent.CTRL_MASK));
		menuCut.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_X,
				InputEvent.CTRL_MASK));
		menuCopy.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_C,
				InputEvent.CTRL_MASK));
		menuPaste.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_V,
				InputEvent.CTRL_MASK));

	}
	
	private void openFile() {
		if (stateBar.getText().equals("未修改")) { // 文件是否为存储状态
			showFileDialog(); // 打开文件
		} else {
			int option = JOptionPane.showConfirmDialog(null, 
					"文件已修改，是否保存？",
					"保存文件？",
					JOptionPane.YES_NO_OPTION,
					JOptionPane.WARNING_MESSAGE,
					null);
			switch (option) {
				case JOptionPane.YES_OPTION: // 确认文件保存
					saveFile(); // 保存文件
					break;
				case JOptionPane.NO_OPTION: // 放弃文件保存
					showFileDialog();
					break;
			}
					
		}
	}
	
	private void showFileDialog() {
		int option = fileChooser.showDialog(null, null); // 文件选取对话框
		// 使用者单击确认键
		if (option == JFileChooser.APPROVE_OPTION) {
			try {
				setTitle(fileChooser.getSelectedFile().toString());
				textArea.setText("");
				stateBar.setText("未修改");
				
				String text = textDAO.read(fileChooser.getSelectedFile().toString());
				textArea.setText(text);
			} catch (Throwable e) {
				JOptionPane.showMessageDialog(null, e.toString(),
						"打开文件失败", JOptionPane.ERROR_MESSAGE);
						
			}
		}
	}
	private void saveFile() {
		// 从标题栏获取文件名
		Path path = Paths.get(getTitle());
		if (Files.notExists(path)) {
			saveFileAs();
		} else {
			try {
				textDAO.save(path.toString(), textArea.getText());
				stateBar.setText("未修改");
			} catch (Throwable e) {
				JOptionPane.showMessageDialog(null, e.toString(),
						"写入文件失败", JOptionPane.ERROR_MESSAGE);
			}
		}
		
	}
	private void saveFileAs() {
		int option = fileChooser.showDialog(null, null);
		if (option == JFileChooser.APPROVE_OPTION) {
			setTitle(fileChooser.getSelectedFile().toString());
			textDAO.create(fileChooser.getSelectedFile().toString());
			saveFile();
		}
		
	}
	private void closeFile() {
		if (stateBar.getText().equals("未修改")) {
			dispose();
		} else {
			int option = JOptionPane.showConfirmDialog(null, "文件已经修改, 是否保存？",
					"保存文件？", 
					JOptionPane.YES_NO_OPTION,
					JOptionPane.WARNING_MESSAGE, 
					null);
			switch (option) {
			case JOptionPane.YES_OPTION:
				saveFile();
				break;
			case JOptionPane.NO_OPTION:
				dispose();
			}
					
		}
		
	}
	private void cut() {
		textArea.cut();
		stateBar.setText("已修改");
		popUpMenu.setVisible(false);
	}
	
	private void copy() {
		textArea.copy();
		popUpMenu.setVisible(false);
	}
	
	private void paste() {
		textArea.paste();
		stateBar.setText("已修改");
		popUpMenu.setVisible(false);
	}
	
	private void jtextAreaActionPerformed() {}

	public static void main(String[] args) throws InvocationTargetException,
			InterruptedException {
		javax.swing.SwingUtilities.invokeAndWait(new Runnable() {
			@Override
			public void run() {
				new JNotePad().setVisible(true);
			}
		});
	}

}

TextDAO.java

package com.xjh.swing;

public interface TextDAO {
	
	void create(String file);

	String read(String toString);

	void save(String file, String text);
}

FileTextDAO.java

package com.xjh.swing;

import java.io.BufferedWriter;
import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.logging.Level;
import java.util.logging.Logger;

public class FileTextDAO implements TextDAO {
	
	@Override
	public String read(String file) {
		byte[] datas = null;
		try {
			datas = Files.readAllBytes(Paths.get(file));
		} catch (IOException ex) {
			Logger.getLogger(FileTextDAO.class.getName()).log(Level.SEVERE, null, ex);
		}
		return new String(datas);
	}
	
	@Override
	public void save(String file, String text) {
		try (BufferedWriter writer = Files.newBufferedWriter(Paths.get(file), 
				Charset.forName(System.getProperty("file.endoding")))) {
					writer.write(text);
		} catch (IOException ex) {
			Logger.getLogger(FileTextDAO.class.getName()).log(Level.SEVERE, null, ex);
		}
	}

	@Override
	public void create(String file) {
		try {
			Files.createFile(Paths.get(file));
		} catch (IOException ex) {
			Logger.getLogger(FileTextDAO.class.getName()).log(Level.SEVERE, null, ex);
		}
	}
		
}