JPA在需要类型转换的字段上定义关系

Question

我想在列"供应商"上加入两个表,在发票表供应商类型是整数,在供应商表中,供应商是类型varchar(10).

是否可以进行类型转换并且还有关系？

@Entity
public class Vendor
{
    private String id;

    @Id(Column="vendor")
    public String getId(){ ... }
}

@Entity
public class Invoice
{
    private Vendor vendor;

    @One-to-one
    public Vendor getVendor() { ... }
}

Answer 1

也许这可以使用瞬态场来完成

@Entity
public class Employee {
    ...
    private boolean isActive;
    ...
    @Transient
    public boolean getIsActive() {
        return isActive;
    }
    public void setIsActive(boolean isActive) {
        this.isActive = isActive;
    }
    @Basic
    private String getIsActiveValue() {
        if (isActive) {
            return "T";
        } else {
            return "F";
        }
    }
    private void setIsActiveValue(String isActive) {
        this.isActive = "T".equals(isActive);
    }
}

http://en.wikibooks.org/wiki/Java_Persistence/Basic_Attributes#Conversion