Roo 的持久性上下文

Question

对于事物何时分离以及持久性上下文的范围，我有点困惑。我的实体是否仅在 roo 生成的每个方法中“管理”？我之所以问，是因为我已经读过在分离的实例上调用 refresh() 应该会引发异常，但是然后我在没有先合并实体的情况下调用 refresh() 我似乎没有收到错误...

有人可以根据实体管理器的生命周期以及何时在单个合并、持久化、删除方法中管理和分离对象来解释 Roo 代码...

// WARNING: DO NOT EDIT THIS FILE. THIS FILE IS MANAGED BY SPRING ROO.
// You may push code into the target .java compilation unit if you wish to edit any member(s).


import java.math.BigDecimal;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import org.springframework.transaction.annotation.Transactional;

privileged aspect AdminDirectRole_Roo_Jpa_ActiveRecord {

    @PersistenceContext
    transient EntityManager AdminDirectRole.entityManager;

    public static final EntityManager AdminDirectRole.entityManager() {
        EntityManager em = new AdminDirectRole().entityManager;
        if (em == null) throw new IllegalStateException("Entity manager has not been injected (is the Spring Aspects JAR configured as an AJC/AJDT aspects library?)");
        return em;
    }

    public static long AdminDirectRole.countAdminDirectRoles() {
        return entityManager().createQuery("SELECT COUNT(o) FROM AdminDirectRole o", Long.class).getSingleResult();
    }

    public static List<AdminDirectRole> AdminDirectRole.findAllAdminDirectRoles() {
        return entityManager().createQuery("SELECT o FROM AdminDirectRole o", AdminDirectRole.class).getResultList();
    }

    public static AdminDirectRole AdminDirectRole.findAdminDirectRole(BigDecimal id) {
        if (id == null) return null;
        return entityManager().find(AdminDirectRole.class, id);
    }

    public static List<AdminDirectRole> AdminDirectRole.findAdminDirectRoleEntries(int firstResult, int maxResults) {
        return entityManager().createQuery("SELECT o FROM AdminDirectRole o", AdminDirectRole.class).setFirstResult(firstResult).setMaxResults(maxResults).getResultList();
    }

    @Transactional
    public void AdminDirectRole.persist() {
        if (this.entityManager == null) this.entityManager = entityManager();
        this.entityManager.persist(this);
    }

    @Transactional
    public void AdminDirectRole.remove() {
        if (this.entityManager == null) this.entityManager = entityManager();
        if (this.entityManager.contains(this)) {
            this.entityManager.remove(this);
        } else {
            AdminDirectRole attached = AdminDirectRole.findAdminDirectRole(this.id);
            this.entityManager.remove(attached);
        }
    }

    @Transactional
    public void AdminDirectRole.flush() {
        if (this.entityManager == null) this.entityManager = entityManager();
        this.entityManager.flush();
    }

    @Transactional
    public void AdminDirectRole.clear() {
        if (this.entityManager == null) this.entityManager = entityManager();
        this.entityManager.clear();
    }

    @Transactional
    public AdminDirectRole AdminDirectRole.merge() {
        if (this.entityManager == null) this.entityManager = entityManager();
        AdminDirectRole merged = this.entityManager.merge(this);
        this.entityManager.flush();
        return merged;
    }

}

任何建议表示赞赏。我创建了这个方法，期望它由于我没有将实体合并到任何持久性上下文中而失败，并且没有引发异常？

@Transactional
    public void refresh() {
        if (this.entityManager == null) this.entityManager = entityManager();
        entityManager.refresh(this);
    }

Answer 1

持久化上下文默认绑定到事务。我假设任何代码检索 AdminDirectRole 的实例并调用刷新方法都用@Transactional 包装？换句话说：

//Will not throw an exception
@Transactional
public void foo(AdminDirectRole detached) {
  detached.merge();
  detached.refresh();
}

//Will throw an exception unless whatever is calling bar() has an @Transactional annotation (or whatever is calling whatever is calling bar and so on)
public void bar(AdminDirectRole detached) {
  detached.merge();
  detached.refresh();
}