JSON 解析错误：无法从 START_OBJECT 令牌中反序列化 java.util.ArrayList 的实例

Question

我在我的项目中使用 spring boot 和 spring 数据，我有两个类：

@Entity
public class Mission implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue( strategy = GenerationType.IDENTITY )
    private Long              id;
    private String            departure;
    private String            arrival;
    private Boolean           isFreeWayEnabled;
    @OneToMany( mappedBy = "mission" )
    private List<Station>     stations;
    // getters and setters
}

第二类：

@Entity
public class Station implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue( strategy = GenerationType.IDENTITY )
    private Long              id;
    private String            station;

    @ManyToOne( fetch = FetchType.LAZY )
    @JsonBackReference
    private Mission           mission;
    //getters and setters
}

和控制器：

@RequestMapping( value = "mission/addMission", method = RequestMethod.POST, consumes = "application/json;charset=UTF-8" )
public Reponse addMission( @RequestBody Mission mission ) throws ServletException {
    if ( messages != null ) {
        return new Reponse( -1, messages );
    }
    boolean flag = false;
    try {
        application.addMision( mission );
        application.addStation( mission.getStations(), mission.getId() );
        flag = true;
    } catch ( Exception e ) {
        return new Reponse( 5, Static.getErreursForException( e ) );
    }
    return new Reponse( 0, flag );
}

问题是当我尝试使用 JSON 添加新任务时：

{"departure":"fff","arrival":"ffff","isFreeWayEnabled":false,stations:{"id":1}

Answer 1

您正在尝试将对象反序列化为列表。您需要将 Stations 设为 JSON 数组

{"departure":"fff","arrival":"ffff","isFreeWayEnabled":false,stations:[{"id":1}, {"id":2}]}