Java实现记事本功能

import java.awt.Color;

import java.awt.Dimension;

import java.awt.Toolkit;

import java.io.FileReader;

import java.io.IOException;



import javax.swing.GroupLayout;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.JScrollPane;

import javax.swing.JTextArea;

import javax.swing.JTextField;

import javax.swing.SwingUtilities;

import javax.swing.event.CaretEvent;

import javax.swing.event.CaretListener;

import javax.swing.event.DocumentEvent;

import javax.swing.event.DocumentListener;

import javax.swing.text.BadLocationException;

import javax.swing.text.DefaultHighlighter;

import javax.swing.text.Highlighter;

import javax.swing.text.Highlighter.HighlightPainter;



// 高亮: 

// 1. text area 先设置setHighlighter为hilit

// 2. 添加要高亮字符的下标到hilit里 



@SuppressWarnings("serial")

public final class Finder extends JFrame implements DocumentListener, CaretListener {

	private JLabel status;

	private JTextField entry;

	private JTextArea textArea;

	private JScrollPane scroller;

	

	private Highlighter hilit;

	private HighlightPainter painter;

	private final Color NO_FOUND_COLOR = Color.PINK;

	private final Color HILIT_COLOR = Color.YELLOW;



	public Finder() {

		initComponents();

		entry.getDocument().addDocumentListener(this);

		

		try {

			FileReader reader = new FileReader("Finder.java");

			textArea.read(reader, null);

		} catch (IOException e) {

			e.printStackTrace();

		}

		textArea.setLineWrap(true);

		textArea.setWrapStyleWord(true);

		textArea.setTabSize(4);

		textArea.addCaretListener(this);

		

		hilit = new DefaultHighlighter();

		painter = new DefaultHighlighter.DefaultHighlightPainter(HILIT_COLOR);

		textArea.setHighlighter(hilit);

	}



	private void initComponents() {

		status = new JLabel("");

		entry = new JTextField();

		textArea = new JTextArea();

		scroller = new JScrollPane(textArea);



		JLabel label1 = new JLabel("Enter text to search:");

		// Layouts components using group layout

		GroupLayout layout = new GroupLayout(getContentPane());

		layout.setAutoCreateGaps(true);

		layout.setAutoCreateContainerGaps(true);

		getContentPane().setLayout(layout);



		// Horizontal axis

		GroupLayout.SequentialGroup hGroup = layout.createSequentialGroup();

		GroupLayout.SequentialGroup topSGroup = layout.createSequentialGroup();

		topSGroup.addComponent(label1).addComponent(entry);

		hGroup.addGroup(layout.createParallelGroup().addGroup(topSGroup).addComponent(scroller)

				.addComponent(status));

		layout.setHorizontalGroup(hGroup);



		// Vertical axis

		GroupLayout.SequentialGroup vGroup = layout.createSequentialGroup();

		GroupLayout.ParallelGroup topPGroup = layout.createParallelGroup(GroupLayout.Alignment.BASELINE);

		topPGroup.addComponent(label1).addComponent(entry);

		vGroup.addGroup(topPGroup).addComponent(scroller).addComponent(status);

		layout.setVerticalGroup(vGroup);



		// Setting frame

		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

		int width = 600;

		int height = 700;

		int x, y;

		Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();

		x = (screenSize.width - width) / 2;

		y = (screenSize.height - height) / 2 - 600;

		x = x > 0 ? x : 0;

		y = y > 0 ? y : 0;

		setLocation(x, y);

		setSize(width, height);

	}

	

	public void search(String s) {

		if (s == null) {

			return;

		}

		

		hilit.removeAllHighlights();

		

		if (s.length() <= 0) {

			status.setText("No text to search.");

			return;

		}

		

		// 高亮: 

		// 1. text area 先设置setHighlighter为hilit

		// 2. 添加要高亮字符的下标到hilit里 



		String content = textArea.getText();

		int start = content.indexOf(s);

		if (start >= 0) {

			entry.setBackground(Color.WHITE);

			while (start >= 0) {

				int end = start + s.length();

				try {

					hilit.addHighlight(start, end, painter);

				} catch (BadLocationException e) {

					e.printStackTrace();

				}



				start = content.indexOf(s, end);

			}

			status.setText(s + " found.");

		} else {

			status.setText(s + " not found.");

			entry.setBackground(NO_FOUND_COLOR);

		}

	}

	

	public void changedUpdate(DocumentEvent e) {

	}

	

	public void insertUpdate(DocumentEvent e) {

		search(entry.getText());

	}

	

	public void removeUpdate(DocumentEvent e) {

		search(entry.getText());

	}

	

	public void caretUpdate(CaretEvent e) {

		search(textArea.getSelectedText());

	}



	public static void main(String[] args) {

		SwingUtilities.invokeLater(new Runnable() {

			public void run() {

				new Finder().setVisible(true);

			}

		});

	}

}