//文件过滤器

import java.io.File;

import javax.swing.filechooser.FileFilter;

public class MyFilter extends FileFilter{
    private String[] filterString = null;
    public MyFilter(String[] filStrings){
        this.filterString = filStrings;
    }
    public boolean accept(File file){
           if(file.isDirectory()) return true;
           for(int i=0; i<filterString.length; ++i)
               if(file.getName().endsWith(filterString[i]))
                   return true;
           /* 返回要显示的文件类型 */
           /*
            *   File.isDirectory()测试此抽象路径名表示的文件是否是一个目录
           */
           return false;
      }
      
      public String getDescription() {
          String ss = "";
          for(int i=0; i<filterString.length; ++i)
              ss += " *" + filterString[i];
          return("Txt Files(" + ss + ")");                  //返回显示文件类型的描述
      }
}

//文件的选择

JFileChooser jfc = new JFileChooser();
                //设置文件的过滤器
                String[] filterString = {".cpp", ".c"};
                MyFilter filter = new MyFilter(filterString);
                //获取jar包位置，设置JFileChooser当前路径
                String jarFilePath = Main.class.getProtectionDomain().getCodeSource().getLocation().getFile();
                try {
                    jarFilePath = URLDecoder.decode(jarFilePath, "UTF-8");
                } catch (UnsupportedEncodingException ex) {
                    ex.printStackTrace();
                }
                jfc.setCurrentDirectory(new File(jarFilePath));
                jfc.setFileFilter(filter);
                jfc.showOpenDialog(null);
                File fl = jfc.getSelectedFile();
                if(fl != null){
                    String code = "";
                    try {
                        BufferedReader br = new BufferedReader(new FileReader(fl));
                        String newLine = null;
                        boolean flag = true;
                        while((newLine=br.readLine()) != null){
                        }
                    } catch (FileNotFoundException ex) {
                        ex.printStackTrace();
                    } catch (IOException ex) {
                        ex.printStackTrace();
                    }
                }

//文件的保存

JFileChooser jfc = new JFileChooser();
                    String[] filterString = {".txt"};
                    //设置文件的过滤器
                    MyFilter filter = new MyFilter(filterString);
                    //获取jar包位置，设置JFileChooser当前路径
                    String jarFilePath = LexicalAnalyzer.class.getProtectionDomain().getCodeSource().getLocation().getFile();
                    try {
                        jarFilePath = URLDecoder.decode(jarFilePath, "UTF-8");
                    } catch (UnsupportedEncodingException e) {
                        e.printStackTrace();
                    }
                    jfc.setCurrentDirectory(new File(jarFilePath));
                    jfc.setFileFilter(filter);
                    jfc.showSaveDialog(null);
                    File fl = jfc.getSelectedFile();
                    OutputStreamWriter osw;
                    try {
                        osw = new OutputStreamWriter(new FileOutputStream(fl));
                        String text = textPane.getText();
                        osw.write(text, 0, text.length());
                        osw.flush();
                        osw.close();
                    } catch (FileNotFoundException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }