Java 文件操作简单demo

两小时写了这么一个小的demo，不过很惭愧的说，里面有一点bug，程序有时工作有时又不太工作……不过初学者还可以看看的说……如果有大牛能够指出到底哪有问题，必定感激不尽。

界面大致如下所示：



共有两个源文件，Frame.java

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.TextArea;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;

import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;

/**
*
* @author lwfcgz
*
*/
public class Frame extends JFrame{

/**
*
*/
private static final long serialVersionUID = 1L;
private JPanel northPanel,southPanel;
private TextArea textArea;
private JButton openButton;
private JButton createButton;
private JButton deleteButton;
private JButton closeButton;
private JButton readButton;
private JButton writeButton;
private JButton pointerButton;
private JButton propertyButton;
private File file;
private JFileChooser fileChooser;
private RandomAccessFile randomAccessFile;
private int screenWidth,screenHeight;
private int frameWidth,frameHeight;
private String path;
private String content;

//	constructor
public Frame(){
this.northPanel=new JPanel(new BorderLayout());
this.southPanel=new JPanel(new GridLayout(2,4));
this.fileChooser=new JFileChooser();
this.fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);

//		set property of north panel
this.textArea=new TextArea("", 10, 70,TextArea.SCROLLBARS_BOTH);
this.textArea.setEditable(false);
this.textArea.setText("");
this.northPanel.add(this.textArea,BorderLayout.CENTER);

//		set property of south panel
this.openButton=new JButton("打开");
this.openButton.addActionListener(new ActionListener(){

@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
int result=fileChooser.showOpenDialog(null);
if((result==JFileChooser.APPROVE_OPTION)){
file=fileChooser.getSelectedFile();
try {
if(randomAccessFile!=null)
randomAccessFile.close();
randomAccessFile=new RandomAccessFile(file,"rw");
} catch (FileNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
path=fileChooser.getSelectedFile().getAbsolutePath();
textArea.setText("已打开文件： "+path);
}
}

});//end openButton action listener
this.southPanel.add(openButton);
this.createButton=new JButton("创建");
this.createButton.addActionListener(new ActionListener(){

@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
String tmpPath=JOptionPane.showInputDialog(null, "请输入新建文件名", "创建文件", JOptionPane.INFORMATION_MESSAGE);
if(tmpPath==null){
JOptionPane.showMessageDialog(null, "创建新文件失败", "Error", JOptionPane.ERROR_MESSAGE);
}
else{
path=tmpPath;
textArea.setText("已创建新文件"+path);
file=new File(path);
try {
if(randomAccessFile!=null)
randomAccessFile.close();
randomAccessFile=null;
randomAccessFile=new RandomAccessFile(file,"rw");
} catch (FileNotFoundException e2) {
// TODO Auto-generated catch block
e2.printStackTrace();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
file.createNewFile();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}//end try catch
}//end else
}//end method action performed

});//end createButton action listener
this.southPanel.add(createButton);
this.deleteButton=new JButton("删除");
this.deleteButton.addActionListener(new ActionListener(){

@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
if(file==null){
JOptionPane.showMessageDialog(null, "当前文件为空", "Error", JOptionPane.ERROR_MESSAGE);
textArea.setText("删除文件失败");
return;
}
if(randomAccessFile!=null)
try {
randomAccessFile.close();
randomAccessFile=null;
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
file=new File(path);
if(file.delete()==true){
textArea.setText("已成功删除文件"+path);
path=null;
file=null;
}
else{
textArea.setText("由于未知原因，删除文件失败"+path);
}
}//end method actionPerformed

});//end action listener for delete button
this.southPanel.add(deleteButton);
this.closeButton=new JButton("关闭");
this.closeButton.addActionListener(new ActionListener(){

@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
if(file==null){
JOptionPane.showMessageDialog(null, "当前文件为空", "Error", JOptionPane.ERROR_MESSAGE);
textArea.setText("关闭文件失败");
return;
}
else{
JOptionPane.showMessageDialog(null, "成功关闭文件", "Info", JOptionPane.INFORMATION_MESSAGE);
try {
if(randomAccessFile!=null)
randomAccessFile.close();
randomAccessFile=null;
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
file=null;
path=null;
textArea.setText("");
}
}//end method actionPerformed

});//end closeButton action listener
this.southPanel.add(closeButton);
this.readButton=new JButton("读取");
this.readButton.addActionListener(new ActionListener(){

@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
if(file==null){
JOptionPane.showMessageDialog(null, "当前文件为空", "Error", JOptionPane.ERROR_MESSAGE);
textArea.setText("读取文件失败");
return;
}
try {
if(randomAccessFile==null)
randomAccessFile=new RandomAccessFile(file,"rw");
} catch (FileNotFoundException e2) {
// TODO Auto-generated catch block
e2.printStackTrace();
}
content="";
byte[] buffer=new byte[5000];
int hasRead=0;
try {
while((hasRead=randomAccessFile.read(buffer))>0){
content+=new String(buffer,0,hasRead);
}
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
textArea.setText(content);
}//end method action performed

});//end read button action listener
this.southPanel.add(readButton);
this.writeButton=new JButton("写入");
this.writeButton.addActionListener(new ActionListener(){

@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
if(file==null){
JOptionPane.showMessageDialog(null, "当前文件为空", "Error", JOptionPane.ERROR_MESSAGE);
textArea.setText("写入文件失败");
return;
}
try {
if(randomAccessFile==null)
randomAccessFile=new RandomAccessFile(file,"rw");
} catch (FileNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
String tmp=JOptionPane.showInputDialog(null,"请输入要写的内容","输入",JOptionPane.INFORMATION_MESSAGE);
if(tmp==null || tmp.length()==0){
JOptionPane.showMessageDialog(null, "没有要写入的内容", "Error", JOptionPane.ERROR_MESSAGE);
return;
}
try {
randomAccessFile.seek(file.length());
randomAccessFile.write(tmp.getBytes());
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
textArea.setText("已成功写入文件："+file.getName());
}//end method action performed

});//end write button action listener
this.southPanel.add(writeButton);
this.pointerButton=new JButton("定位");
this.pointerButton.addActionListener(new ActionListener(){

@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
if(file==null){
JOptionPane.showMessageDialog(null, "当前文件为空", "Error", JOptionPane.ERROR_MESSAGE);
textArea.setText("定位文件失败");
return;
}
//				get user's input value
String tmp=JOptionPane.showInputDialog(null,"请输入定位目标","指针定位",JOptionPane.INFORMATION_MESSAGE);
int result=Integer.valueOf(tmp).intValue();
if(result<0 || result>file.length()){
JOptionPane.showMessageDialog(null, "无效指针位置", "Error", JOptionPane.ERROR_MESSAGE);
textArea.setText("定位文件失败");
return;
}
try {
if(randomAccessFile==null)
randomAccessFile=new RandomAccessFile(file,"rw");
randomAccessFile.seek(result);
textArea.setText("定位文件成功"+'\n'+"当前指针位置："+result);
JOptionPane.showMessageDialog(null, "成功定位指针位置", "Info", JOptionPane.INFORMATION_MESSAGE);
} catch (FileNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (Exception e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}//end method action performed

});//end pointer button listener
this.southPanel.add(pointerButton);
this.propertyButton=new JButton("属性");
this.propertyButton.addActionListener(new ActionListener(){

@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
if(file==null){
JOptionPane.showMessageDialog(null, "当前文件为空", "Error", JOptionPane.ERROR_MESSAGE);
textArea.setText("文件属性查看失败");
return;
}
else{
textArea.setText("文件名："+file.getName()+'\n'
+"文件长度："+file.length()+'\n'
+"文件路径："+file.getAbsolutePath()+'\n'
+"最后修改日期："+file.lastModified()+'\n'
+"文件可读性："+file.canRead()+'\n'
+"文件可写性："+file.canWrite()+'\n');
}
}//end method action performed

});//end property button action listener
this.southPanel.add(propertyButton);

//		add panels into frame
this.frameHeight=300;
this.frameWidth=350;
this.add(northPanel,BorderLayout.NORTH);
this.add(this.southPanel,BorderLayout.SOUTH);
this.setSize(this.frameWidth,this.frameHeight);
this.setTitle("Demo by lwfcgz");

//      get screen size and set the location in the center of the screen
this.screenWidth=(int)Toolkit.getDefaultToolkit().getScreenSize().getWidth();
this.screenHeight=(int)Toolkit.getDefaultToolkit().getScreenSize().getHeight();
this.setLocation((this.screenWidth-this.frameWidth)/2, (this.screenHeight-this.frameHeight)/2);
this.setVisible(true);

}//end constructor

}//end class Frame

Main.java

import javax.swing.JFrame;

/**
*
* @author lwfcgz
*
*/
public class Main {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Frame frame=new Frame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}//end method main

}//end class Main