txt.java

① 在窗口上放置一个菜单条和一个文本区

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

import javax.swing.*; 

import com.sun.tools.hat.internal.parser.Reader; 
public class txt extends JFrame implements ActionListener 
{ 
JTextArea ta; 
JMenuItem open,save,myexit,open1,save1; 

JMenuBar mb; 
JPopupMenu popm; 
JScrollPane sp; 
public void createmenu() 
{ 
mb=new JMenuBar(); 

JMenu m1=new JMenu("编辑"); 
 
mb.add(m1); 

open=new JMenuItem("打开"); 

open.addActionListener(this); 
save=new JMenuItem("保存"); 
save.addActionListener(this); 
myexit=new JMenuItem("退出"); 
myexit.addActionListener(this); 
m1.add(open);m1.add(save);m1.addSeparator(); m1.add(myexit);



} 



public txt () 
{ 
addWindowListener(new WindowAdapter() 
{ 
public void windowClosing(WindowEvent e) 
{ 
dispose(); 
System.exit(0); 
} 
}); 

ta=new JTextArea(10,20); 
add(ta,BorderLayout.CENTER); 
Panel p1=new Panel(); 
add(p1,BorderLayout.SOUTH); 
setVisible(true); 
setSize(400,400); 

Dimension dim = Toolkit.getDefaultToolkit().getScreenSize(); 
int w = getSize().width; 
int h = getSize().height; 
int x = (dim.width-w)/2; 
int y = (dim.height-h)/2; 
setLocation(x,y); 
createmenu(); 
setJMenuBar(mb); 
sp = new JScrollPane(ta); 
getContentPane().add(sp); 
} 
public void actionPerformed(ActionEvent e) 
{ 
if(e.getActionCommand()=="打开") 
try 
{ 
openfile(); 
} 
catch(IOException ex){} 
if(e.getActionCommand()=="保存") 
{ 
try { 
savefile(); 
} catch (IOException e1) { 

e1.printStackTrace(); 
} 
} 
if(e.getActionCommand()=="退出") 
{ 
dispose(); 
System.exit(0); 
} 


} 
public void savefile() throws IOException 
{ 
FileDialog fd=new FileDialog(this,"保存",FileDialog.SAVE); 
fd.setVisible(true); 
FileWriter fw=new FileWriter( fd.getDirectory()+fd.getFile()); 
for(int i=0;i<ta.getText().length();i++) 
{ 
fw.write(ta.getText().charAt(i)); 
} 
fw.close(); 
} 
public void openfile() throws IOException 
{ 
FileDialog fd=new FileDialog(this,"打开",FileDialog.LOAD); 
fd.setVisible(true); 
FileReader fr=new FileReader( fd.getDirectory()+fd.getFile()); 
int n=0; 
int row=10; 
while((n=fr.read())!=-1) 
{ 
ta.append(""+(char)n); 
row--; 
if(row==0) 
{ 
ta.append("\n"); 
row=20; 
} 
} 
fr.close(); 
} 
public static void main(String []args) 
{ 
txt t=new txt(); 
} 
}