如何将另一个类对象添加到列表中

Posted 2023-01-09

我有一个播放器类和一个朋友类，播放器类中有一个朋友对象。但是，朋友类别也与玩家类别具有相同的字段。如何将好友列表添加到播放器。就像在Facebook上，用户的朋友列表中有朋友。如何使PlayerController类中的已注释方法起作用？

//@CrossOrigin(origins = "http://localhost:4200")
@RestController
@RequestMapping(value = "/players", produces =  MediaType.APPLICATION_JSON_VALUE )
public class PlayerController 

    @Autowired
    private PlayerReopsitory playerReopsitory;

    @GetMapping(produces = "application/json")
    public List<Player> getAllPlayers()
        return playerReopsitory.findAll();
    

    @PostMapping
//  @ResponseStatus(HttpStatus.OK)
    public void create(@RequestBody Player player) 
        playerReopsitory.save(player);
    

    @GetMapping("/id")
    public Player getOne(@PathVariable("id") Long id) 
        return playerReopsitory.getOne(id);
    

    @DeleteMapping("/id")
    void deletePlayer(@PathVariable Long id) 
        playerReopsitory.deleteById(id);
    

    @PutMapping("/id")
    Player updatePlayer(@RequestBody Player newPlayer, @PathVariable Long id) 

        return playerReopsitory.findById(id).map(player -> 
            player.setName(newPlayer.getName());
            player.setEmail(newPlayer.getEmail());
            player.setPhone(newPlayer.getPhone());
            return playerReopsitory.save(player);
         ).orElseGet(() -> 
                newPlayer.setId(id);
                return playerReopsitory.save(newPlayer);
            );
        


//  how to make this function work?
//  @GetMapping("/id/friends")
//  public List<Friend> getAllFriendFromList(@PathVariable Long id) 
//      return playerReopsitory.findById(id).get();
//  
//  

@Entity
@Table(name= "user", schema = "rabbit")
@JsonIgnoreProperties("hibernateLazyInitializer", "handler")
public class Friend 

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column(name="userName")
    private String userName;

    @Column(name="playername")
    private String name;

    @Column(name="email")
    private String email;

    @Column(name="phone")
    private String phone;

    public Long getId() 
        return id;
    

    public void setId(Long id) 
        this.id = id;
    

    public String getUserName() 
        return userName;
    

    public void setUserName(String userName) 
        this.userName = userName;
    

    public String getName() 
        return name;
    

    public void setName(String name) 
        this.name = name;
    

    public String getEmail() 
        return email;
    

    public void setEmail(String email) 
        this.email = email;
    

    public String getPhone() 
        return phone;
    

    public void setPhone(String phone) 
        this.phone = phone;
    

    @Override
    public String toString() 
        return "Friend [id=" + id + ", userName=" + userName + ", name=" + name + ", email=" + email + ", phone="
                + phone + "]";
    

@Entity
@Table(name= "user", schema = "rabbit")
@JsonIgnoreProperties("hibernateLazyInitializer", "handler")
public class Player 

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column(name="userName")
    private String userName;

    @Column(name="playername")
    private String name;

    @Column(name="email")
    private String email;

    @Column(name="phone")
    private String phone;

    private Friend friend;




    public Friend getFriend() 
        return friend;
    

    public void setFriend(Friend friend) 
        this.friend = friend;
    

    public String getUserName() 
        return userName;
    

    public void setUserName(String userName) 
        this.userName = userName;
    

    public String getName() 
        return name;
    

    public void setName(String name) 
        this.name = name;
    

    public String getEmail() 
        return email;
    

    public void setEmail(String email) 
        this.email = email;
    

    public String getPhone() 
        return phone;
    

    public void setPhone(String phone) 
        this.phone = phone;
    


    public Long getId() 
        return id;
    

    public void setId(Long id) 
        this.id = id;
    



    @Override
    public String toString() 
        return "Player [id=" + id + ", userName=" + userName + ", name=" + name + ", email=" + email + ", phone="
                + phone + ", friend=" + friend + "]";
    

public interface FriendReopsitory extends JpaRepository<Player, Long> 

public interface PlayerReopsitory extends JpaRepository<Player, Long> 

@Component
public class FriendService 


    private static Map<Friend, Long> getFriends = new HashMap<>();

    

答案

[因为朋友也是玩家，所以我建议您将模型重构为只有一个类别的玩家，并且与自己之间存在多对多的关系。

@Entity
public class Player 

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    /*
    * Add other fields
    */

    @ManyToMany()
    @JoinTable(name = "player_friends", joinColumns = 
            @JoinColumn(name = "PLAYER_ID", referencedColumnName = "ID")
    , inverseJoinColumns = 
            @JoinColumn(name = "FRIEND_ID", referencedColumnName = "ID")
    )
    private List<Player> friends;

    /*
    * Add other getters and setters
    */

    public List<Player> getFriends() 
        return this.friends;
    

    /*
    * Implement addFriend and removeFriend methods
    */

然后您将需要处理集合加载（LAZY或EAGER），添加和删除好友方法。但这不在此问题的范围内，您可以在线找到有关此主题的大量资源。