列出文件和目录

File dir = new File("directoryName");
    String[] children = dir.list();
if (children == null) {
// Either dir does not exist or is not a directory
    } else {
        for (int i=0; i < children.length; i++) {
// Get filename of file or directory
            String filename = children[i];
        }
    }
    // It is also possible to filter the list of returned files.
// This example does not return any files that start with `.'.
    FilenameFilter filter = new FilenameFilter() {
        public boolean accept(File dir, String name) {
            return !name.startsWith(".");
        }
    };
    children = dir.list(filter);
    // The list of files can also be retrieved as File objects
    File[] files = dir.listFiles();
    // This filter only returns directories
    FileFilter fileFilter = new FileFilter() {
        public boolean accept(File file) {
            return file.isDirectory();
        }
    };
    files = dir.listFiles(fileFilter);