Json 和 Java - 循环引用

如何在Java中处理循环引用的问题

java
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.databind.ObjectMapper;
public class Main {
    public static void main(String[] args) throws Exception {
        ObjectMapper mapper = new ObjectMapper();
        
        User user1 = new User("John");
        User user2 = new User("Alice");
        
        user1.setFriend(user2);
        user2.setFriend(user1);
        
        String json = mapper.writeValueAsString(user1);
        System.out.println(json);
        
        User deserializedUser = mapper.readValue(json, User.class);
        System.out.println(deserializedUser.getName());
        System.out.println(deserializedUser.getFriend().getName());
    }
}
class User {
    private String name;
    
    @JsonIgnore
    private User friend;
    
    // getters and setters
    
    public User(String name) {
        this.name = name;
    }
}