java 弹出文件保存对话框

package test;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;

import javax.swing.JFileChooser;
import javax.swing.filechooser.FileNameExtensionFilter;

public class readfile {
public static void main(String args[])throws IOException {

FileNameExtensionFilter filter=new FileNameExtensionFilter("*.txt","txt");
JFileChooser fc=new JFileChooser();
fc.setFileFilter(filter);
fc.setMultiSelectionEnabled(false);
int result=fc.showSaveDialog(null);
if (result==JFileChooser.APPROVE_OPTION) {
File file=fc.getSelectedFile();
if (!file.getPath().endsWith(".txt")) {
file=new File(file.getPath()+".txt");
}
System.out.println("file path="+file.getPath());
FileOutputStream fos=null;
try {
if (!file.exists()) {//文件不存在 则创建一个
file.createNewFile();
}
fos=new FileOutputStream(file);
fos.write("文件内容".getBytes());
fos.flush();
} catch (IOException e) {
System.err.println("文件创建失败：");
e.printStackTrace();
}finally{
if (fos!=null) {
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}}}