java代码保藏:获取HttpServletRequest中某一前缀的参数

public static Map getParametersStartingWith(ServletRequest request, String prefix)
    {
        Enumeration paramNames = request.getParameterNames();
        Map params = new TreeMap();
        if(prefix == null)prefix = "";
        while(paramNames != null && paramNames.hasMoreElements()) 
        {
            String paramName = (String)paramNames.nextElement();
            if("".equals(prefix) || paramName.startsWith(prefix))
            {
                String unprefixed = paramName.substring(prefix.length());
                String values[] = request.getParameterValues(paramName);
                if(values != null && values.length != 0)
                    if(values.length > 1)
                        params.put(unprefixed, values);
                    else
                        params.put(unprefixed, values[0]);
            }
        }
        return params;
    }