Java Object to Class

User user = new User(username,password);
//添加构成JWT的参数
JwtBuilder builder = Jwts.builder().setHeaderParam("typ", "JWT")
                .claim("key",user)
                .signWith(signatureAlgorithm, signingKey);

Object object = claims.get(“key”);
ObjectMapper mapper = new ObjectMapper();
User u = mapper.convertValue(object,User.class);