【发布时间】：2020-08-19 14:38:49
【问题描述】：
有两个实体Permission 和Role 与@ManyToMany 有关系；我想在他们的连接表中添加一些额外的字段，我在这篇文章 enter link description here 之后编码，这里是我的代码：
角色实体
@Setter
@Getter
@AllArgsConstructor
@NoArgsConstructor
@Entity
@GenericGenerator(name = "jpa-uuid", strategy = "uuid")
public class Role {
@Id
@GeneratedValue(generator = "jpa-uuid")
private String id;
@JsonIgnore @ToString.Exclude
@OneToMany(mappedBy = "role",cascade = CascadeType.ALL,orphanRemoval = false,fetch = FetchType.EAGER)
private Set<RolePermission> role_permission;
public void addPermission(Permission permission){
RolePermission rolePermission = new RolePermission(this,permission);
role_permission.add(rolePermission);
permission.getRole_permission().add(rolePermission);
}
public void removePermission(Permission permission){
for(Iterator<RolePermission> iterator = role_permission.iterator();iterator.hasNext();){
RolePermission rolePermission = iterator.next();
if(rolePermission.getRole().equals(this) && rolePermission.getPermission().equals(permission)){
iterator.remove();
rolePermission.getRole().role_permission.remove(rolePermission);
rolePermission.setRole(null);
rolePermission.setPermission(null);
}
}
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Role role = (Role) o;
return Objects.equals(id, role.id);
}
@Override
public int hashCode() {
return Objects.hash(id);
}
}
权限实体
@Setter
@Getter
@AllArgsConstructor
@NoArgsConstructor
@Entity
@GenericGenerator(name = "jpa-uuid", strategy = "uuid")
public class Permission {
@Id
@GeneratedValue(generator = "jpa-uuid")
private String id;
@JsonIgnore @ToString.Exclude
@OneToMany(mappedBy = "permission",cascade = CascadeType.ALL,orphanRemoval = true,fetch = FetchType.EAGER)
private Set<RolePermission> role_permission;
public void addRole(Role role){
RolePermission rolePermission = new RolePermission(role,this);
role_permission.add(rolePermission);
role.getRole_permission().add(rolePermission);
}
public void removeRole(Role role){
for(Iterator<RolePermission> iterator = role_permission.iterator(); iterator.hasNext();){
RolePermission rolePermission = iterator.next();
if(rolePermission.getRole().equals(role) && rolePermission.getPermission().equals(this)){
iterator.remove();
rolePermission.getRole().getRole_permission().remove(rolePermission);
rolePermission.setRole(null);
rolePermission.setPermission(null);
}
}
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Permission that = (Permission) o;
return Objects.equals(id, that.id);
}
@Override
public int hashCode() {
return Objects.hash(id);
}
}
角色权限密钥
@Embeddable
@Setter
@Getter
@NoArgsConstructor
public class RolePermissionKey implements Serializable {
private static final long serialVersionUID = 4686642987484483168L;
@Column(name = "role_id")
private String role_id;
@Column(name = "permission_id")
private String permission_id;
public RolePermissionKey(String roleId, String permissionId) {
this.role_id=roleId;
this.permission_id=permissionId;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
RolePermissionKey that = (RolePermissionKey) o;
return role_id.equals(that.role_id) &&
permission_id.equals(that.permission_id);
}
@Override
public int hashCode() {
return Objects.hash(role_id, permission_id);
}
}
带有额外字段的关系表
@Entity
@Setter
@Getter
@NoArgsConstructor
public class RolePermission implements Serializable {
private static final long serialVersionUID = 8274025418699729303L;
@EmbeddedId
RolePermissionKey id;
@ManyToOne(fetch = FetchType.LAZY)
@MapsId("role_id")
Role role;
@ManyToOne(fetch = FetchType.LAZY)
@MapsId("permission_id")
Permission permission;
Date create_date =new Date();
public RolePermission(Role role,Permission permission) {
this.role=role;
this.permission=permission;
this.id = new RolePermissionKey(role.getId(),permission.getId());
this.create_date=new Date();
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
RolePermission that = (RolePermission) o;
return Objects.equals(role, that.role) &&
Objects.equals(permission, that.permission);
}
@Override
public int hashCode() {
return Objects.hash(role, permission);
}
}
测试代码
Role role5 = roleRepository.findByTitle("Role5");
Permission permission6 = permissionRepository.findByTitle("Permission6");
role5.addPermission(permission6);
permission6.addRole(role5);
roleRepository.save(role5);
permissionRepository.save(permission6);
然后，我在四个地方使用了相同的测试代码进行测试：
1.一个类实现了ApplicationRunner；在spring boot启动前初始化数据，no exception
2.一个 Spring Boot 测试类 @SpringBootTest;no exception
3.控制器类 @Controller ； exception thrown
4.服务类 @Service ； exception thrown
这里例外：
2020-05-05 09:11:35.952 WARN 17000 --- [nio-8080-exec-1] .m.m.a.ExceptionHandlerExceptionResolver : Resolved [org.springframework.dao.DataIntegrityViolationException: A different object with the same identifier value was already associated with the session : [com.xxx.model.authentication.RolePermission#com.xxx.model.authentication.RolePermissionKey@9e2c8771]; nested exception is javax.persistence.EntityExistsException: A different object with the same identifier value was already associated with the session : [com.xxx.model.authentication.RolePermission#com.xxx.model.authentication.RolePermissionKey@9e2c8771]]
现在我很困惑问题是代码还是其他问题。我在 1,2 中使用了测试代码来添加之间的关系
一个角色和一个权限susscessfully，并得到了预期的结果。但代码在3,4中不起作用。
我需要一些提示和建议；顺便问一下，有没有使用spring data jpa的开源真实世界项目值得学习？
，谢谢。
#################################################################
感谢@Olivier Depriester 的帮助。
我在调试模型中研究了 Role 和 Permission Entity 中 RolePermission Set 的元素；
维护两个实体关系的集合类型是set，我已经覆盖了equals() 和
hashCode() 方法可以确保具有相同 ID 的关系实体（RolePermission）不会出现在同一个集合中。
在save() 执行之前，Set of Role 和 Permision 中实际上只包含一个 RolePermission 对象。
在测试代码中，有两个.save() action，即使我注释其中一个，也会抛出异常。
我想知道cascade 是否有问题。
奇怪的是，测试代码可以在某处成功执行。
【问题讨论】：