虚心求教：关于第22天的保存程序的疑惑 - 黑马程序员技术交流社区

/*
需求：在文本区域内输入一些字符，点保存后能存到硬盘上，
注意若文件存在不弹出对话框直接覆盖，若文件不存在直接弹出对话框。
在原有程序的基础上监听保存条目
*/
import java.awt.*;
import java.awt.event.*;
import java.io.*;
class Run
{
private Frame frame=null;
private Menu menu=null,submenu=null;
private MenuItem closeitem =null,subitem=null,openitem=null,saveitem=null;
private MenuBar bar =null;
private TextArea ta= null;
private FileDialog openDia,saveDia;
private File file =null;
Run()
{
init();
}
private void init()
{
frame = new Frame("我的窗");
menu = new Menu("文件菜单");
submenu = new Menu("子菜单");
closeitem = new MenuItem("关闭条目");
subitem = new MenuItem("子条目");
openitem = new MenuItem("打开条目");
saveitem = new MenuItem("保存条目");
bar = new MenuBar();
ta = new TextArea();
openDia = new FileDialog(frame,"我要打开",FileDialog.LOAD);
saveDia = new FileDialog(frame,"我要保存",FileDialog.SAVE);//保存模式
frame.setMenuBar(bar);
frame.add(ta);
bar.add(menu);
menu.add(openitem);
menu.add(saveitem);
menu.add(submenu);
submenu.add(subitem);
menu.add(closeitem);
frame.setBounds(500,50,500,650);
frame.setVisible(true);
myEvent();
}
private void myEvent()
{
//保存
saveitem.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent ae)
{
if(file==null)//如果为空就弹出对话框，并将来当前文本区域内的文件封装成对象
{
saveDia.setVisible(true);
String dirPath = saveDia.getDirectory();
String fileName = saveDia.getFile();
/*
System.out.println("dirPath:"+dirPath); // dirPath:C:\Documents and Settings\Administrator\桌面\
System.out.println("getFile:"+file); // getFile:null
*/
if (dirPath == null || fileName ==null)
return;
//有 null
file = new File(dirPath,fileName);
}
try
{
BufferedWriter bfw = new BufferedWriter(new FileWriter(file));
String text = ta.getText();//获取输入内容
bfw.write(text);
bfw.close();
}
catch (Exception asd)
{
throw new RuntimeException();
}
}
});
//打开
openitem.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent ae)
{
openDia.setVisible(true);
String dirPath = openDia.getDirectory();
String fileName = openDia.getFile();
if(dirPath==null || fileName==null)
return;
ta.setText("");
file = new File(dirPath,fileName);
try
{
BufferedReader br = new BufferedReader(new FileReader(file));
String text=null;
while((text=br.readLine())!=null)
ta.append(text+"\r\n");
}
catch (IOException e)
{
throw new RuntimeException("读取失败");
}
}
});
closeitem.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent ae)
{
System.exit(0);
}
});
frame.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent we)
{
System.exit(0);
}
});
}
public static void main(String[] args)
{
new Run();
}
}

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