使用jdk1.8 stream特性对参数名称进行排序

String param = "x=4&a=&ca=2&acb=3&sign=xxx";
Object result = sortParamByKey(param.split("&"));

public static String sortParamByKey(String[] param) {
        if(param != null) {
            List<String> params = Arrays.asList(param);
            String result = params.stream()        
            .collect(Collectors.toMap(v->v.split("=")[0],v->v.substring(v.indexOf("=")+1)))
            .entrySet().stream()
            .filter(e->!(e.getValue()==null || "".equals(e.getValue())))
            .filter(e->!"sign".equalsIgnoreCase(e.getKey()))//sign为key的时候,去除
            .sorted(Map.Entry.comparingByKey())
            .map(e->new StringBuilder(e.getKey()).append("=").append(e.getValue()))
            .collect(Collectors.joining("&"))
            ;
            return result;
        }
        return null;
    }