我在 Customer 和 BusinessUnit 之间有多对多的关系：
public class Customer extends AbstractEntity {
@JoinTable(name = "CUS_BUS_UNITS",
joinColumns = {
@JoinColumn(name = "CUS_ID", referencedColumnName = "CUS_ID")},
inverseJoinColumns = {
@JoinColumn(name = "BUS_ID", referencedColumnName = "BUS_ID")})
@ManyToMany
private Collection<BusinessUnit> businessUnits;
}
public class BusinessUnit extends AbstractEntity {
@ManyToMany(mappedBy = "businessUnits")
private Collection<Customer> customers;
}
当我调用 entityManager.merge(customer); 在客户（已经在数据库中，未更改）我在日志中看到这两个 sql 命令：
休眠：更新 CUSTOMERS 设置 CUS_DESCR=?、CUS_NAME=?、CUS_ENABLED=? CUS_ID=? 休眠：从 CUS_BUS_UNITS 中删除 CUS_ID=?
为什么休眠试图从连接表中删除记录？我只需要更新连接表中的客户记录和可能的记录 - 取决于我是否添加或删除了客户的业务部门。不应更新、删除或插入业务单位。
编辑： 我的 equals/hashCode 是（在 AbstractEntity 中定义）：
public int hashCode() {
if (getId() != null) {
return getId().hashCode();
}
return super.hashCode();
}
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
AbstractEntity other = (AbstractEntity) obj;
if (getId() == null || other.getId() == null) {
return false;
}
if (!getId().equals(other.getId())) {
return false;
}
return true;
}
编辑 2 表格转换器：
@FacesConverter("businessUnitConverter")
public class BusinessUnitConverter implements Converter {
/**
* {@inheritDoc}
*/
@Override
public String getAsString(FacesContext context, UIComponent component, Object object) {
return ((BusinessUnit) object).getId().toString();
}
@Override
public Object getAsObject(FacesContext context, UIComponent component, String value) {
BusinessUnit businessUnit = new BusinessUnit();
businessUnit.setId(Long.parseLong(value));
return businessUnit;
}
}