java - 如何将另一个类对象添加到列表中
问题描述
我有一个玩家类和朋友类,玩家类中有朋友对象。但是朋友类也有与玩家类相同的字段。如何将好友列表添加到播放器。就像在 facebook 上用户在他的朋友列表中有朋友一样。如何使 PlayerController 类中的注释方法起作用?
//@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<>();{
}
}
解决方案
由于 Friends 也是玩家,我建议您将模型重构为只有一个 Player 类,与自身具有多对多关系。
@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),添加和删除友元方法。但这不在这个问题的范围内,你可以在网上找到关于这个主题的大量资源。
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