Java 如何使用hibernate与现有对象创建组合键对象

假设我有以下数据库模式

CREATE TABLE employee(
    id BIGINT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50) NOT NULL,
    hrid VARCHAR (50)
);
CREATE TABLE territory(
    id BIGINT PRIMARY KEY,
    name varchar (50)
);
CREATE TABLE transcode(
    id BIGINT AUTO_INCREMENT PRIMARY KEY,
    code VARCHAR (10) NOT NULL
);
create table employee_territory_function(
  employee_id BIGINT NOT NULL,
  territory_id BIGINT NOT NULL,
  transcode_id BIGINT NOT NULL,
  PRIMARY KEY (employee_id,territory_id),
  CONSTRAINT employeeref FOREIGN KEY (employee_id) REFERENCES employee (id),
  CONSTRAINT territoryref FOREIGN KEY (territory_id) REFERENCES territory (id) ,
  CONSTRAINT transcoderef FOREIGN KEY (transcode_id) REFERENCES transcode (id)
);

现在我有了以下JPA映射实体

员工实体

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

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String name;
    private String hrid;
    @OneToMany(fetch = FetchType.LAZY, mappedBy = "employee", cascade = CascadeType.ALL)
    private Set<EmployeeTerritoryFunction> employeeTerritoryFunctionList = new HashSet<>();
    //getters and setters
}

转码实体：

@Entity
public class Territory implements Serializable {
    @Id
    private long id;
    private String name;
    //getters and setters
}

EmployeeTerritoryFunction实体（复合键表）

EmployeeTerrityFunction pk

public class EmployeeTerritoryFunctionPK implements Serializable {
    private static final long serialVersionUID = 1L;

    private Long employee;
    private Long territory;
    //getters and setters, no args constructor, equals and hashcode
}

以下样本插入

Employee employee = this.employeeRepository.findByHrid("111");
        if (employee == null) {
            employee = new Employee();
            employee.setName("Marie");
            employee.setHrid("333");
        }

        Territory territory = new Territory();
        territory.setId(2L);
        territory.setName("T2");

        Territory territory2 = new Territory();
        territory2.setId(3L);
        territory2.setName("T3");


        Transcode transcode = this.transcodeRepository.findByCode("ASC");
        Transcode transcode2 = this.transcodeRepository.findByCode("CC");


        EmployeeTerritoryFunction employeeTerritoryFunction1 = new EmployeeTerritoryFunction();

        employeeTerritoryFunction1.setTranscode(transcode);
        employeeTerritoryFunction1.setTerritory(territory);
        employeeTerritoryFunction1.setEmployee(employee);
        employee.getEmployeeTerritoryFunctionList().add(employeeTerritoryFunction1);

        EmployeeTerritoryFunction employeeTerritoryFunction2 = new EmployeeTerritoryFunction();
        employeeTerritoryFunction2.setTranscode(transcode2);
        employeeTerritoryFunction2.setTerritory(territory2);
        employeeTerritoryFunction2.setEmployee(employee);
        employee.getEmployeeTerritoryFunctionList().add(employeeTerritoryFunction2);

        employeeRepository.save(employee);

当我只使用新对象运行上述代码时，我没有问题，因为hibernate会自动插入employee、territory和employee\u territory\u函数列表，但当我首先删除所有现有territory、employee\u territory\u函数并尝试使用现有employee插入时，hibernate无法自动插入或更新employee，自动插入区域，员工区域功能。 低于误差

Caused by: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.example.demo.Employee.employeeTerritoryFunctionList, could not initialize proxy - no Session

当我将oneToMany fetch类型替换为EAGER时，我得到了以下错误

Caused by: javax.persistence.EntityNotFoundException: Unable to find com.example.demo.Territory with id 3

hibernate可能会尝试查询Territory表，但当他这样做时，我不会这样做，因为我删除了Territory和EmployeeTerritoryFunction表上的所有数据，并且只有员工现有数据不会被删除

---

如何修复请？

EmployeeTerrityFunction和EmployeeTerrityFunctionPK两个类中的字段的名称应该完全相同，并且具有您没有的相同类型。试着这样做：

@Entity
@IdClass(EmployeeTerritoryFunctionPK.class)
public class EmployeeTerritoryFunction implements Serializable {

    @Id
    @ManyToOne
    private Employee employee;

    @Id
    @ManyToOne
    private Territory territory;
}

public class EmployeeTerritoryFunctionPK implements Serializable {
    private Employee employee;
    private Territory territory;

    public int hashCode() { //TODO }
    public boolean equals(Object obj) { //TODO }

}

---

你可以看看这个答案：谢谢你的回答。根据链接的答案，我应该使用EAGER-oneToMany-fetch类型。但还是有另一个错误。请在我编辑的问题@BrianVosburghThanks@Conrad中查找，但是我如何使用EmployeeTerritoryFunction类型的对象，然后设置Territory和Employee类型的字段？现在我得到了这个异常

DuplicateMappingException:Table[Employee_Territory_function]包含物理列名[Employee_id]由多个逻辑列名引用：[employee_id]，[employeeId]

再次更新了我的答案，我希望这一个会有所帮助。现在我完成了问题中的第一次执行，当我将fetchtype设置为EAGER时，Territory将插入，主键由数据库自动生成，但名称的值为空（我将其他属性设置为空）即使我设置了示例插入中所示的值，您能举个例子吗？如果你打字不正确，就很难理解你的问题。

Caused by: javax.persistence.EntityNotFoundException: Unable to find com.example.demo.Territory with id 3

@Entity
@IdClass(EmployeeTerritoryFunctionPK.class)
public class EmployeeTerritoryFunction implements Serializable {

    @Id
    @ManyToOne
    private Employee employee;

    @Id
    @ManyToOne
    private Territory territory;
}

public class EmployeeTerritoryFunctionPK implements Serializable {
    private Employee employee;
    private Territory territory;

    public int hashCode() { //TODO }
    public boolean equals(Object obj) { //TODO }

}