使用主键连接表：org.hibernate.mapping.SimpleValue无法强制转换为org.hibernate.mapping.Component

Question

public class Employee implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "employee_id")
private Integer employeeId;

@Column(name = "doj")
@Temporal(TemporalType.DATE)
private Date doj;

@Column(name = "first_name")
private String firstName;

@Column(name = "last_name")
private String lastName;

@OneToMany(cascade = CascadeType.ALL, mappedBy = "id.employee")
private Set<EmployeeProject> employeeProject;
// 

Project.java

public class Project implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "project_id")
private Integer projectId;

@Column(name = "exp_end_date")
@Temporal(TemporalType.DATE)
private Date expEndDate;

@Column(name = "project_name")
private String projectName;

@Column(name = "start_date")
@Temporal(TemporalType.DATE)
private Date startDate;

@OneToMany(cascade = CascadeType.ALL, mappedBy = "id.project")
private Set<EmployeeProject> employeeProject;

EmployeeProject.java

@IdClass(EmployeeProjectPK.class)
public class EmployeeProject implements Serializable {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;

@Id
@Column(name = "PROJECT_ID", insertable = false, updatable = false)
private int projectId;    

@Id
@Column(name = "employee_id", insertable = false, updatable = false)
private int employeeId;    


@ManyToOne
@JoinColumn(name = "employee_id")
private Employee employee;

@ManyToOne
@JoinColumn(name = "project_id")
private Project project;

EmployeeProjectPK.Java

public class EmployeeProjectPK implements Serializable {

private static final long serialVersionUID = 1L;
private Integer id;
private Integer projectId;
private Integer employeeId;

基于上面的实体设计，当我试图坚持一个'员工'时，我得到了以下异常。任何想法？

  

引起：java.lang.ClassCastException：org.hibernate.mapping.SimpleValue无法强制转换为org.hibernate.mapping.Component

Answer 1

我认为您在Employee实体中映射的问题

你可以尝试使用

@OneToMany(cascade = CascadeType.ALL, mappedBy = "employee")
private Set<EmployeeProject> employeeProject;

而不是

@OneToMany(cascade = CascadeType.ALL, mappedBy = "id.employee")
private Set<EmployeeProject> employeeProject;

也尝试在Project实体中更改它并使用

@OneToMany(cascade = CascadeType.ALL, mappedBy = "project")
private Set<EmployeeProject> employeeProject;

而不是

@OneToMany(cascade = CascadeType.ALL, mappedBy = "id.project")
private Set<EmployeeProject> employeeProject;

  

所以最后你应该替换

     

mappedBy =＆＃34; id.project＆＃34; 由 mappedBy =＆＃34;项目＆＃34;

     

和

     

mappedBy =＆＃34; id.employee＆＃34; mappedBy =＆＃34;员工＆＃34;