editor.java

Java程序设计大学教程程序源代码

/*
 * Editor.java
 * 参见教程295页 示例程序10-5
 * Created on 2005年8月1日, 下午2:42
 */

package jbookch10;

import javax.swing.*;
import javax.swing.border.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;

public class Editor extends JFrame implements ActionListener{

    public Editor() {
        fileChooser.setSize( 400,300 );
        newfile.addActionListener(this);
        open.addActionListener(this);
        save.addActionListener(this);
        buttonPanel.add(newfile);
        buttonPanel.add(open);
        buttonPanel.add(save);
        //主面板的BorderLayout布局
        mainPanel.setLayout(new BorderLayout(0,0));
        mainPanel.add(new JScrollPane(display),"Center");
        mainPanel.add(new JLabel("编辑词库文件（每行格式为：英文单词=中文注释）："),"North");
        mainPanel.add( buttonPanel,"South");
        setContentPane(mainPanel);
        setSize(280,240);
        setTitle("词库文件编辑器");
    }
    
    public void actionPerformed(ActionEvent evt) {
        if (evt.getSource()==open ) {
            open();//打开文件
            return;
        }
        if (evt.getSource()==save ) {
            save();//保存文件
            return;
        }
        if (evt.getSource()==newfile ) {
            newfile();//新建文件
            return;
        }
    }
    
    private void newfile(){
        display.setText("");
        choice = fileChooser.showSaveDialog( this );
        if ( choice == JFileChooser.APPROVE_OPTION ) {
            chosenFile = fileChooser.getSelectedFile();
            writeToFile(chosenFile);
        }
    }
    
    private void open(){
        choice = fileChooser.showOpenDialog( this );
        if ( choice == JFileChooser.APPROVE_OPTION ) {
            chosenFile = fileChooser.getSelectedFile();
        }
        readFromFile(chosenFile);//读入文件
    }
    
    private void save(){
        if (chosenFile == null ) {
            newfile();
        }
        writeToFile(chosenFile);
    }
    
    private void readFromFile(File file) {
        display.setText("");// 清除编辑区
        String fileName=file.getAbsolutePath();
        try {
            BufferedReader inStream
                    = new BufferedReader(new FileReader(fileName));// 新建或打开流
            String line = inStream.readLine();            // 读入文本行
            while (line != null) {                        //多行文本需要循环读入
                display.append(line + "\n");              // 写入到文本域组件中
                line = inStream.readLine();               // 读入下一行
            }
            inStream.close();                             // 关闭流
        } catch (FileNotFoundException e) {
            JOptionPane.showConfirmDialog(this,fileName +
                    "文件找不到！","操作提示",JOptionPane.DEFAULT_OPTION, JOptionPane.ERROR_MESSAGE);
        } catch (IOException e) {
            JOptionPane.showConfirmDialog(this,"无法预料的异常: " + e.getMessage(),
                    "操作提示",JOptionPane.DEFAULT_OPTION, JOptionPane.ERROR_MESSAGE);
        }
    }
    
    private void writeToFile(File file) {
        String fileName=file.getAbsolutePath();
        try {
            FileWriter outStream =  new FileWriter(fileName);
            outStream.write(display.getText());
            outStream.close();
        } catch (IOException e) {
            JOptionPane.showConfirmDialog(this,"无法预料的异常: " + e.getMessage(),
                    "操作提示",JOptionPane.DEFAULT_OPTION, JOptionPane.ERROR_MESSAGE);
        } 
    }
     
    public static void main(String args[]) {
        Editor editor=new Editor();
        editor.setSize( 400,400);
        editor.setVisible(true);
        editor.addWindowListener(new WindowAdapter() {      // 退出程序
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
    }
    
    private JPanel mainPanel = new JPanel(),
            buttonPanel = new JPanel();
    private JTextArea display = new JTextArea();
    private JButton open = new JButton("打开文件");
    private JButton save = new JButton("保存文件");
    private JButton newfile = new JButton("新建文件");
    private File chosenFile;
    private int choice;
    private JFileChooser  fileChooser = new JFileChooser();

}