fastjson

<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.75</version>
</dependency>

SysUser sysUser = new SysUser(12L);
        String ss = JSONObject.toJSONString(sysUser);
        System.out.println(ss);

        String aa = "{"admin":false,"params":{"admin":false,"params":{},"userId":4545},"userId":12}";

        SysUser sysUser = JSON.parseObject(aa, SysUser.class);

        System.out.println(sysUser);

        String s = JSONObject.toJSONString(sysUser);

        System.out.println(s);

        ArrayList<String> strings = new ArrayList<>();
        strings.add("aa");
        strings.add("afd");
        strings.add("adsfds");
        strings.add("asdfdsa");

        LinkedList<String> strings1 = new LinkedList<>();
        strings1.add("sdfdsf");
        strings1.add("sdfdsf");
        strings1.add("sdfdsf");
        strings1.add("sdfdfdsfds");

        for (String string : strings1) {
            System.out.println(string);
        }

        JSONObject jsonObject = JSONObject.parseObject(aa);

        System.out.println(jsonObject.getString("userId"));
        System.out.println(jsonObject.getString("admin"));
        System.out.println(JSONObject.parseObject(jsonObject.getString("params")).getString("userId"));