java JFileChooser

 

 

import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.filechooser.FileFilter;

public class JFileChooserTest {

	public static void main(String[] args) {
		FrameFileDialog f = new FrameFileDialog();
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}

}

class FrameFileDialog extends JFrame implements ActionListener {
	private JFileChooser fileDialog = null;
	private Label label = new Label("INFO:", Label.CENTER);
	private JButton b1, b2;
	private JTextArea textArea = null;

	public FrameFileDialog() {
		super("带文件对话框的窗口");
		Container con = this.getContentPane();
		con.setLayout(new BorderLayout());
		con.setSize(40, 50);

		b1 = new JButton("打开文件");
		b2 = new JButton("保存文件");
		b1.addActionListener(this);
		b2.addActionListener(this);

		JPanel p = new JPanel();
		p.add(b1);
		p.add(b2);

		textArea = new JTextArea(20, 30);
		JScrollPane jsp = new JScrollPane(textArea);
		fileDialog = new JFileChooser("C:\\");
		fileDialog.setControlButtonsAreShown(true);
		// 设置过滤条件
		fileDialog.setFileFilter(new MyFileFilter("java"));
		fileDialog.setFileFilter(new MyFileFilter("txt"));

		con.add(jsp, BorderLayout.CENTER);
		con.add(label, BorderLayout.NORTH);
		con.add(p, BorderLayout.SOUTH);
		this.setSize(380,280);
		this.setVisible(true);
		//this.pack();

	}

	@Override
	// 监听器
	public void actionPerformed(ActionEvent e) {
		File file = null;
		int result;
		if (e.getSource() == b1) {// OPEN
			fileDialog.setDialogTitle("打开文件");
			result = fileDialog.showOpenDialog(this);
			textArea.setText("");
			if (result == JFileChooser.APPROVE_OPTION) {
				file = fileDialog.getSelectedFile();
				label.setText("选择的文件是：" + file.getName());
			} else if (result == JFileChooser.CANCEL_OPTION) {
				//JOptionPane.showMessageDialog(this, "你还未选择文件");
				label.setText("未选中文件");
				return;
			} 
			//选择了文件
			FileInputStream fileStream = null;
			
			try {
				fileStream = new FileInputStream(file);
				
			} catch (FileNotFoundException e1) {
				label.setText("文件没找到");
				e1.printStackTrace();
				return;
			}
			int readByte;
			byte buffer[]=new byte[1024];
			try {
				while ((readByte = fileStream.read(buffer)) !=-1) {
					textArea.append(new String(buffer,0,readByte));
				}
				//流使用完后关闭
				fileStream.close();

			} catch (IOException e1) {
				label.setText("读取文件出错");
				e1.printStackTrace();
			}

		} else if (e.getSource() == b2) {// 保存文件
			fileDialog.setDialogTitle("保存文件");
			result = fileDialog.showSaveDialog(this);
			file = null;
			if (result == JFileChooser.APPROVE_OPTION) {
				file = fileDialog.getSelectedFile();
				label.setText("保存的文件是：" + file.getName());
			} else if (result == JFileChooser.CANCEL_OPTION) {
				label.setText("没有选择任何文件");
			}
			FileOutputStream fileStream1 = null;
			PrintWriter pw=null;
			if (file != null) {
				try {
					fileStream1 = new FileOutputStream(file);
				} catch (FileNotFoundException e1) {
					label.setText("文件没有发现");
					e1.printStackTrace();
					return;
				}
				String content = textArea.getText();
				try {
					pw=new PrintWriter(fileStream1);
					pw.print(content);
					pw.close();
//					fileStream1.write(content.getBytes());
					fileStream1.close();
				} catch (IOException e1) {
					label.setText("写文件出错");
					e1.printStackTrace();
				}

			}

		}

	}

}
/**
 * 文件过滤器,让文件打开对话框只显示特定格式的文件
 * @author Administrator
 *
 */
class MyFileFilter extends FileFilter {
	private String ext;

	MyFileFilter(String ext) {
		this.ext = ext;
	}

	@Override
	public boolean accept(File file) {
		if (file.isDirectory())
			return true;
		String fileName = file.getName();
		int index = fileName.lastIndexOf(".");
		if (index > 0 && index < fileName.length() - 1) {
			String extension = fileName.substring(index + 1);
			if (extension.toLowerCase().equals(ext))
				return true;
		}
		return false;
	}

	@Override
	public String getDescription() {
		if (ext.equals("java")) {
			return "Java source file(*.java)";
		}
		if (ext.equals("txt")) {
			return "TXT file(*.txt)";
		}
		return "";
	}

}