I/O 获取指定目录下的指定文件和目录

import java.io.File;import java.io.FilenameFilter;import java.util.ArrayList;import java.util.Iterator;import java.util.List;import java.util.regex.Pattern;public final class Directory { public static File[] local(File dir, final String regex) {     return dir.listFiles(new FilenameFilter() {         private Pattern pattern = Pattern.compile(regex);         public boolean accept(File dir, String name) {           return pattern.matcher(             new File(name).getName()).matches();         }       });     } public static File[] local(String path, final String regex) { // Overloaded     return local(new File(path), regex); }    // A two-tuple for returning a pair of objects:   public static class TreeInfo implements Iterable<File> {     public List<File> files = new ArrayList<File>();     public List<File> dirs = new ArrayList<File>();     // The default iterable element is the file list:     public Iterator<File> iterator() {       return files.iterator();     }     void addAll(TreeInfo other) {       files.addAll(other.files);       dirs.addAll(other.dirs);     }     public String toString() {       return "dirs: " + PPrint.pformat(dirs) +         "\n\nfiles: " + PPrint.pformat(files);     }   }   public static TreeInfo walk(String start, String regex) { // Begin recursion     return recurseDirs(new File(start), regex);   }   public static TreeInfo walk(File start, String regex) { // Overloaded     return recurseDirs(start, regex);   }   public static TreeInfo walk(File start) { // Everything     return recurseDirs(start, ".*");   }   public static TreeInfo walk(String start) {     return recurseDirs(new File(start), ".*");   }     static TreeInfo recurseDirs(File startDir, String regex){     TreeInfo result = new TreeInfo();     for(File item : startDir.listFiles()) {       if(item.isDirectory()) {         result.dirs.add(item);         result.addAll(recurseDirs(item, regex));       } else // Regular file         if(item.getName().matches(regex))           result.files.add(item);    }    return result;   }     // Simple validation test:   public static void main(String[] args) {     if(args.length == 0)       System.out.println(walk("."));     else       for(String arg : args)        System.out.println(walk(arg));  }    static class PPrint{  static String pformat(List<File> list){  String s = "";  for(int i=0;i<list.size();i++){  s += list.get(i).getName()+"\r\n";  }  return s;  }  }}