Java学习笔记——实现一个简易记事本Notepad的编写

记事本功能介绍

1.   新建：记事本清空。

2.   打开：可打开笔记本上任意文本文件。

3.   保存：将文件保存至当前文件夹。

4.   另存为：将文件保存至任意位置。

5.   退出：退出时确认退出前是否保存内容。

【注：“保存”和“另存为”时，应指明文件的后缀，如：XXX.txt】

记事本图例

打开笔记本上任意文本文件

该操作需要用到  FileDialog 类 中的 FileDialog.LOAD);

		FileDialog fd = new FileDialog(this, "打开", FileDialog.LOAD);
		fd.setVisible(true);

值得注意的是，在获取文件路径时，相关操作为：

String strFile = fd.getDirectory() + fd.getFile();

若没有 fd.getDirectory()  则只能打开当前文件夹。fd.getDirectory()  相当于取得文件的绝对路径前缀。

取得路径后，就可以将文件打开并写到文本框中。

具体操作见博客：

http://blog.csdn.net/oyuntaolianwu/article/details/9429953

代码举例

	private void jMenuItem2ActionPerformed(java.awt.event.ActionEvent evt) {
		// TODO add your handling code here:
		FileDialog fd = new FileDialog(this, "打开", FileDialog.LOAD);
		fd.setVisible(true);
		String strFile = fd.getDirectory() + fd.getFile();
		if (strFile != null) {
			try {
				FileInputStream fis = new FileInputStream(strFile);
				byte[] buf = new byte[10 * 1024];
				int len = fis.read(buf);
				jTextArea1.append(new String(buf, 0, len));
				fis.close();
			} catch (Exception e) {
				System.out.println("打开失败");
			}
		}
	}

打开图例：

将文件保存至任意位置

实际上，与上述操作相仿。只不过，是一个读一个写。

取得文件路径和内容后，相关操作就容易很多了。

代码举例：

	private void jMenuItem4ActionPerformed(java.awt.event.ActionEvent evt) {
		// TODO add your handling code here:
			FileDialog fd = new FileDialog(this, "另存为", FileDialog.SAVE);
			fd.setVisible(true);
			String string1 = jTextArea1.getText();
			String stringfile = fd.getDirectory()+fd.getFile();
			BufferedWriter bWriter = null;
			try {
				bWriter = new BufferedWriter(new FileWriter(stringfile));
				bWriter.write(string1); 
				bWriter.close(); 
			} catch (Exception e) {
				// TODO Auto-generated catch block
				System.out.println("保存失败");
			} 
	}

另存为图例

记事本 NotePad  代码

/*
 * Test_Notepad.java
 *
 * Created on __DATE__, __TIME__
 */

//package com.test;

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

import javax.swing.JOptionPane;

/**
 *
 * @author  __USER__
 */
public class Test_Notepad extends javax.swing.JFrame {

	/** Creates new form Test_Notepad */
	public Test_Notepad(String name) {
		super(name);
		initComponents();
		setLocation(450, 200);
	}

	/** This method is called from within the constructor to
	 * initialize the form.
	 * WARNING: Do NOT modify this code. The content of this method is
	 * always regenerated by the Form Editor.
	 */
	//GEN-BEGIN:initComponents
	// <editor-fold defaultstate="collapsed" desc="Generated Code">
	private void initComponents() {

		jScrollPane1 = new javax.swing.JScrollPane();
		jTextArea1 = new javax.swing.JTextArea();
		jMenuBar1 = new javax.swing.JMenuBar();
		jMenu1 = new javax.swing.JMenu();
		jMenuItem1 = new javax.swing.JMenuItem();
		jMenuItem2 = new javax.swing.JMenuItem();
		jMenuItem3 = new javax.swing.JMenuItem();
		jMenuItem4 = new javax.swing.JMenuItem();
		jSeparator1 = new javax.swing.JSeparator();
		jSeparator2 = new javax.swing.JSeparator();
		jMenuItem6 = new javax.swing.JMenuItem();
		jMenu2 = new javax.swing.JMenu();
		jMenuItem7 = new javax.swing.JMenuItem();
		jMenuItem8 = new javax.swing.JMenuItem();
		jMenuItem9 = new javax.swing.JMenuItem();
		jMenuItem10 = new javax.swing.JMenuItem();
		jMenuItem11 = new javax.swing.JMenuItem();

		setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

		jTextArea1.setColumns(20);
		jTextArea1.setRows(5);
		jScrollPane1.setViewportView(jTextArea1);

		jMenu1.setText("u6587u4ef6");
		jMenu1.setMinimumSize(new java.awt.Dimension(35, 19));

		jMenuItem1.setText("u65b0u5efa");
		jMenuItem1.addActionListener(new java.awt.event.ActionListener() {
			public void actionPerformed(java.awt.event.ActionEvent evt) {
				jMenuItem1ActionPerformed(evt);
			}
		});
		jMenu1.add(jMenuItem1);

		jMenuItem2.setText("u6253u5f00");
		jMenuItem2.addActionListener(new java.awt.event.ActionListener() {
			public void actionPerformed(java.awt.event.ActionEvent evt) {
				jMenuItem2ActionPerformed(evt);
			}
		});
		jMenu1.add(jMenuItem2);

		jMenuItem3.setText("u4fddu5b58");
		jMenuItem3.addActionListener(new java.awt.event.ActionListener() {
			public void actionPerformed(java.awt.event.ActionEvent evt) {
				jMenuItem3ActionPerformed(evt);
			}
		});
		jMenu1.add(jMenuItem3);

		jMenuItem4.setText("u53e6u5b58u4e3a");
		jMenuItem4.addActionListener(new java.awt.event.ActionListener() {
			public void actionPerformed(java.awt.event.ActionEvent evt) {
				jMenuItem4ActionPerformed(evt);
			}
		});
		jMenu1.add(jMenuItem4);
		jMenu1.add(jSeparator1);
		jMenu1.add(jSeparator2);

		jMenuItem6.setText("u9000u51fa");
		jMenuItem6.addActionListener(new java.awt.event.ActionListener() {
			public void actionPerformed(java.awt.event.ActionEvent evt) {
				jMenuItem6ActionPerformed(evt);
			}
		});
		jMenu1.add(jMenuItem6);

		jMenuBar1.add(jMenu1);

		jMenu2.setText("u7f16u8f91");

		jMenuItem7.setText("u64a4u9500");
		jMenu2.add(jMenuItem7);

		jMenuItem8.setText("u526au5207");
		jMenu2.add(jMenuItem8);

		jMenuItem9.setText("u590du5236");
		jMenu2.add(jMenuItem9);

		jMenuItem10.setText("u7c98u8d34");
		jMenu2.add(jMenuItem10);

		jMenuItem11.setText("u5220u9664");
		jMenu2.add(jMenuItem11);

		jMenuBar1.add(jMenu2);

		setJMenuBar(jMenuBar1);

		javax.swing.GroupLayout layout = new javax.swing.GroupLayout(
				getContentPane());
		getContentPane().setLayout(layout);
		layout.setHorizontalGroup(layout.createParallelGroup(
				javax.swing.GroupLayout.Alignment.LEADING).addComponent(
				jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 400,
				Short.MAX_VALUE));
		layout.setVerticalGroup(layout.createParallelGroup(
				javax.swing.GroupLayout.Alignment.LEADING).addComponent(
				jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 279,
				Short.MAX_VALUE));

		pack();
	}// </editor-fold>
	//GEN-END:initComponents

	private void jMenuItem1ActionPerformed(java.awt.event.ActionEvent evt) {
		// TODO add your handling code here:
		jTextArea1.setText(null);
	}

	private void jMenuItem4ActionPerformed(java.awt.event.ActionEvent evt) {
		// TODO add your handling code here:
			FileDialog fd = new FileDialog(this, "另存为", FileDialog.SAVE);
			fd.setVisible(true);
			String string1 = jTextArea1.getText();
			String stringfile = fd.getDirectory()+fd.getFile();
			BufferedWriter bWriter = null;
			try {
				bWriter = new BufferedWriter(new FileWriter(stringfile));
				bWriter.write(string1); 
				bWriter.close(); 
			} catch (Exception e) {
				// TODO Auto-generated catch block
				System.out.println("保存失败");
			} 
	}

	private void jMenuItem3ActionPerformed(java.awt.event.ActionEvent evt) {
		// TODO add your handling code here:
		String FileName = JOptionPane.showInputDialog("请输入保存的文件名：");
		String string1 = jTextArea1.getText();
		if (FileName != null) {
			BufferedWriter bWriter = null;
			try {
				bWriter = new BufferedWriter(new FileWriter(new File(FileName)));
				bWriter.write(string1);
				bWriter.close();
			} catch (Exception e) {
				System.out.println("保存失败");
			}
		}
	}

	private void jMenuItem6ActionPerformed(java.awt.event.ActionEvent evt) {
		// TODO add your handling code here:
		int result = JOptionPane.showConfirmDialog(null, "退出前是否保存？");
		if (result == JOptionPane.YES_OPTION) {
			String FileName = JOptionPane.showInputDialog("请输入保存的文件名：");
			String string1 = jTextArea1.getText();
			if (FileName != null) {
				BufferedWriter bWriter = null;
				try {
					bWriter = new BufferedWriter(new FileWriter(new File(
							FileName)));
					bWriter.write(string1);
					bWriter.close();
				} catch (Exception e) {
					System.out.println("保存失败");
				}
			}
			System.exit(0);
		} else if (result == JOptionPane.NO_OPTION) {
			System.exit(0);
		}
	}

	private void jMenuItem2ActionPerformed(java.awt.event.ActionEvent evt) {
		// TODO add your handling code here:
		FileDialog fd = new FileDialog(this, "打开", FileDialog.LOAD);
		fd.setVisible(true);
		String strFile = fd.getDirectory() + fd.getFile();
		if (strFile != null) {
			try {
				FileInputStream fis = new FileInputStream(strFile);
				byte[] buf = new byte[10 * 1024];
				int len = fis.read(buf);
				jTextArea1.append(new String(buf, 0, len));
				fis.close();
			} catch (Exception e) {
				System.out.println("打开失败");
			}
		}
	}

	public void SaveNotepad() {
		String FileName = JOptionPane.showInputDialog("请输入保存的文件名：");
		String string1 = jTextArea1.getText();
		if (FileName != null) {
			BufferedWriter bWriter = null;
			try {
				bWriter = new BufferedWriter(new FileWriter(new File(FileName)));
				bWriter.write(string1);
				bWriter.close();
				//				Thread.sleep(1000);
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}

	/**
	 * @param args the command line arguments
	 */
	public static void main(String args[]) {
		java.awt.EventQueue.invokeLater(new Runnable() {
			public void run() {
				Test_Notepad notepad = new Test_Notepad("决Jue的记事本");
				notepad.setVisible(true);
			}
		});
	}

	//GEN-BEGIN:variables
	// Variables declaration - do not modify
	private javax.swing.JMenu jMenu1;
	private javax.swing.JMenu jMenu2;
	private javax.swing.JMenuBar jMenuBar1;
	private javax.swing.JMenuItem jMenuItem1;
	private javax.swing.JMenuItem jMenuItem10;
	private javax.swing.JMenuItem jMenuItem11;
	private javax.swing.JMenuItem jMenuItem2;
	private javax.swing.JMenuItem jMenuItem3;
	private javax.swing.JMenuItem jMenuItem4;
	private javax.swing.JMenuItem jMenuItem6;
	private javax.swing.JMenuItem jMenuItem7;
	private javax.swing.JMenuItem jMenuItem8;
	private javax.swing.JMenuItem jMenuItem9;
	private javax.swing.JScrollPane jScrollPane1;
	private javax.swing.JSeparator jSeparator1;
	private javax.swing.JSeparator jSeparator2;
	private javax.swing.JTextArea jTextArea1;
	// End of variables declaration//GEN-END:variables

}