小编Cha*_*nia的帖子

我正在使用App Engine的JDO实现的本地开发版本.当我查询包含其他对象作为嵌入字段的对象时,嵌入字段将返回null.

例如,假设这是我坚持的主要对象:

@PersistenceCapable
public class Branch {

    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
    private Long id;

    @Persistent
    private String name;

    @Persistent
    private Address address;

            ...
}

这是我的嵌入对象:

@PersistenceCapable(embeddedOnly="true")
public class Address {

    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
    private Long id;

    @Persistent
    private String street;

    @Persistent
    private String city;

            ...
}

以下代码不检索嵌入对象:

    PersistenceManager pm = MyPersistenceManagerFactory.get().getPersistenceManager();

    Branch branch = null;
    try {
        branch = pm.getObjectById(Branch.class, branchId);
    }
    catch (JDOObjectNotFoundException onfe) {
        // not found
    }
    catch (Exception e) {
        // failed
    }
    finally …