Freemarker

Freemarker中有类TemplateCache其中方法：

 private static String normalizeName(String name) {
        // Disallow 0 for security reasons.
        if (name.indexOf(0) != -1) return null;

        for(;;) {
            int parentDirPathLoc = name.indexOf(PARENT_DIR_PATH);
            if(parentDirPathLoc == 0) {
                // If it starts with /../, then it reaches outside the template
                // root.
                return null;
            }
            if(parentDirPathLoc == -1) {
                if(name.startsWith(PARENT_DIR_PATH_PREFIX)) {
                    // Another attempt to reach out of template root.
                    return null;
                }
                break;
            }
            int previousSlashLoc = name.lastIndexOf(SLASH, parentDirPathLoc - 1);
            name = name.substring(0, previousSlashLoc + 1) +
                   name.substring(parentDirPathLoc + PARENT_DIR_PATH.length());
        }
        for(;;) {
            int currentDirPathLoc = name.indexOf(CURRENT_DIR_PATH);
            if(currentDirPathLoc == -1) {
                if(name.startsWith(CURRENT_DIR_PATH_PREFIX)) {
                    name = name.substring(CURRENT_DIR_PATH_PREFIX.length());
                }
                break;
            }
            name = name.substring(0, currentDirPathLoc) +
                   name.substring(currentDirPathLoc + CURRENT_DIR_PATH.length() - 1);
        }
        // Editing can leave us with a leading slash; strip it.
        if(name.length() > 1 && name.charAt(0) == SLASH) {
            name = name.substring(1);
        }
        return name;
    }

 先记下来以后再研究