src/org/nutz/lang/Files.java
public static boolean deleteDir(File dir) {
        if (null == dir || !dir.exists())
            return false;
        if (!dir.isDirectory())
            throw new RuntimeException("\"" + dir.getAbsolutePath() + "\" should be a directory!");
        File[] files = dir.listFiles();
        boolean re = false;
        if (null != files) {
            if (files.length == 0)
                return dir.delete();
            for (File f : files) {
                if (f.isDirectory())
                    re |= deleteDir(f);
                else
                    re |= deleteFile(f);
            }
            re |= dir.delete();
        }
        return re;
    }
public static boolean deleteDir(File dir) {
        if (null == dir || !dir.exists())
            return false;
        if (!dir.isDirectory())
            throw new RuntimeException("\"" + dir.getAbsolutePath() + "\" should be a directory!");
        File[] files = dir.listFiles();
        boolean re = false;
        if (null != files) {
            if (files.length == 0)
                return dir.delete();
            for (File f : files) {
                if (f.isDirectory())
                    re |= deleteDir(f);
                else
                    re |= deleteFile(f);
            }
            re |= dir.delete();
        }
        return re;
    }
强行删除一个目录，包括这个目录下所有的子目录和文件

@param dir
目录
@return 是否删除成功