java实现打开文件和保存文件功能

本人是新手，在学习java如何打开文件和保存文件，功能很简单，实现起来也不麻烦。

附源代码：

public class FileOpenAndSave extends JFrame{

private static final long serialVersionUID = 4029562126308556571L;

private JPanel panel1, panel2;

private TextArea ta;

private JButton open, save;

private JLabel label;

public FileOpenAndSave() {

setSize(400, 300);

setTitle("FileOpenDemo");

setLocation(400, 400);

panel1 = new JPanel(new BorderLayout());

panel1.setPreferredSize(new Dimension(280, 280));

ta = new TextArea();

panel1.add(ta, BorderLayout.CENTER);

open = new JButton("Open File");
// 打开文件按钮

save = new JButton("Save File");
// 保存文件按钮

// 为打开文件按钮注册监听器

open.addActionListener(new ActionListener() {

@Override

public void actionPerformed(ActionEvent e) {

JFileChooser chooser = new JFileChooser("请选择文件");

FileNameExtensionFilter filter = new FileNameExtensionFilter("文本文件(*.txt)", "txt");

chooser.setFileFilter(filter);

int res = chooser.showOpenDialog(null);

if(res == JFileChooser.APPROVE_OPTION){

File file = chooser.getSelectedFile();

String path = file.getAbsolutePath();

try {

// 注意编码问题

InputStreamReader reader = new InputStreamReader(new FileInputStream(path), "utf-8");

char[] buf = new char[1024];

int len = 0;

CharBuffer cb = CharBuffer.allocate((int) file.length());

while((len = reader.read(buf)) > -1){

cb.put(buf, 0, len);

}

reader.close();

String str = new String(cb.array());

// 此段代码功能是将所读文件复制到相同路径下

/*int sep = path.lastIndexOf("\\");

path = path.substring(0, sep + 1) + "copy.txt";

OutputStreamWriter writer = new OutputStreamWriter(new FileOutputStream(path));

writer.write(cb.array());

writer.close();*/

ta.setEditable(false);

ta.setText(str);

} catch (Exception e1) {

e1.printStackTrace();

}

}

}

});

// 为保存文件按钮注册监听器

save.addActionListener(new ActionListener() {

@Override

public void actionPerformed(ActionEvent e) {

String path;

String content = ta.getText();

JFileChooser chooser = new JFileChooser();

FileNameExtensionFilter filter = new FileNameExtensionFilter("文本文件(*.txt)", "txt");

chooser.setFileFilter(filter);

int res =chooser.showSaveDialog(null);

if(res == JFileChooser.APPROVE_OPTION){

path = chooser.getSelectedFile().getAbsolutePath() + ".txt";// 获得保存路径

try {

// 注意编码问题

OutputStreamWriter writer = new OutputStreamWriter(new FileOutputStream(path), "gbk");

writer.write(content);

writer.close();

} catch (IOException e1) {

e1.printStackTrace();

}

}

}

});

label = new JLabel("hhshhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh");

label.setVisible(false);

panel2 = new JPanel(new FlowLayout());

panel2.add(label);

panel2.add(open);

panel2.add(save);

add(panel1, BorderLayout.CENTER);

add(panel2, BorderLayout.SOUTH);

setResizable(false);

enableInputMethods(false);

setDefaultCloseOperation(EXIT_ON_CLOSE);

setVisible(true);

}

public static void main(String[] args) {

new FileOpenAndSave();

}

}