本段程序结合I/O和Swing图形界面进行编写 源代码如下
package IO; import java.awt.BorderLayout; import java.awt.Container; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.io.BufferedReader; import java.io.File; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JTextArea; import javax.swing.SwingConstants; public class SwingText extends JFrame{ private JFrame frame; private JTextArea jt; private JPanel jp1; private JPanel jp2; private Container c; private JButton read; private JButton write; private File file; /* * 此方法实例化文件对象，如果文件不存在，则新建文件 */ public void createFile(){ file=new File("D:/2.txt");//实例化文件对象 if (!file.exists()) {//判断文件是否存在 try { file.createNewFile(); } catch (IOException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } } } /* * 此方法返回一个“读取文件”按钮 */ public JButton createReadButton(){ JButton read=new JButton("读取文件"); read.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { // TODO Auto-generated method stub try { FileReader fr=new FileReader(file);//读取文件内容 BufferedReader br=new BufferedReader(fr);//新建缓存 String s=null; while ((s=br.readLine())!=null) { jt.append(s);//设置文本框内容 jt.append("\n");//增加换行符 } } catch (Exception e1) { // TODO Auto-generated catch block e1.printStackTrace(); } } }); return read; } /* * 此方法返回一个“写入文件”按钮 */ public JButton createWriteButton(){ JButton write=new JButton("写入文件"); write.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { // TODO Auto-generated method stub try { FileWriter fw=new FileWriter(file); fw.write(jt.getText());//将文本框内容全部写入文件 fw.close(); System.out.println("写入文件成功");//在控制台输出提示“文件写入成功” jt.setText("");//清空文本框内容 } catch (IOException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } } }); return write; } private void go(){ createFile(); frame=new JFrame("文件读取器"); c=frame.getContentPane(); read=createReadButton();//调用方法返回“读取文件”按钮 read.setSize(50, 30); write=createWriteButton();//调用方法返回“写入文件”按钮 write.setSize(50,30); jt=new JTextArea(20, 40);//设置文本框行数 jt.setLineWrap(true);// 激活自动换行功能 jt.setWrapStyleWord(true);// 激活断行不断字功能 jp1=new JPanel(); jp1.add(jt); jp2=new JPanel(); jp2.add(read); jp2.add(write); c.add(BorderLayout.NORTH,jp1); c.add(BorderLayout.SOUTH,jp2); frame.setVisible(true); frame.setSize(500,500); } public static void main(String[] args) { new SwingText().go(); } }文件运行效果图如下
