Java后台获取前端POST请求中Json数据的乱码问题

Question

前端上传的Json数据如下所示：

 {
    "name":"百度跳线",//产品名字
    "data":[

        {"num": 1, "gongxu": "bq"}//gongxu：工序名称,名字已经统一。num：排名顺序

        {"num": 2, "gongxu": "rs"}

        {"num": 3, "gongxu": "slsjzp"}
        //.......
        //.......
    ]
}

在Java后台的Servlet中通过以下代码获取请求体：

 request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        // 1. 获取请求体中的内容
        BufferedReader br = new BufferedReader(
                new InputStreamReader(request.getInputStream(), "utf-8"));
        StringBuffer sb = new StringBuffer("");
        String temp;
        while ((temp = br.readLine()) != null) {
            sb.append(temp);
        }
        br.close();
        String params = sb.toString();
        System.out.println(params);

最后得出的结果却包含乱码：

 name=%E6%9D%A1%E7%BA%BF&data%5B0%5D%5Bnum%5D=1&data%5B0%5D%5Bgongxu%5D=ym&data%5B1%5D%5Bnum%5D=2&data%5B1%5D%5Bgongxu%5D=yj&data%5B2%5D%5Bnum%5D=3&data%5B2%5D%5Bgongxu%5D=yinddj

这里不仅有乱码，而且data字段也有好几个，请问怎么样才能把前端传的数据原封不动的取出来呢？