javax.xml.ws.WebServiceException: javax.xml.bind.MarshalException - 带有链接异常：

Question

我正在开发一个肥皂网络服务。我将 JPA 与 namedquery 注释一起用于数据查询。但是，在我的查询中将 sum 之类的聚合函数与 group by 结合使用会导致一些异常。我的代码如下所示。

@Entity
@Cacheable(false)
@Table(name = "criteriatable")
@XmlRootElement
@NamedQueries(
{
@NamedQuery(name = "Criteriatable.findAll", query = "SELECT c FROM Criteriatable c"),
@NamedQuery(name = "Criteriatable.findById", query = "SELECT c FROM Criteriatable c WHERE c.id =    :id"),
@NamedQuery(name = "Criteriatable.findByCriteriaid", query = "SELECT c FROM Criteriatable c WHERE c.criteriaid = :criteriaid"),
@NamedQuery(name = "Criteriatable.findBySubcriteriaid", query = "SELECT c FROM Criteriatable c WHERE c.subcriteriaid = :subcriteriaid"),
@NamedQuery(name = "Criteriatable.findByProjectid", query = "SELECT c FROM Criteriatable c WHERE c.projectid = :projectid"),
@NamedQuery(name = "Criteriatable.findAllCriteriatableGroup", query = "SELECT c.criteriagroupname AS groupname, SUM(c.weight) AS groupweight  FROM Criteriatable c WHERE c.projectid = :projectid GROUP BY c.criteriagroupname"),
@NamedQuery(name = "Criteriatable.SumAllWeightByProjectid", query = "SELECT SUM(c.weight) AS TotalProjectWeight FROM Criteriatable c WHERE c.projectid = :projectid")    
})
  public class Criteriatable implements Serializable
{
@Basic(optional = false)
@NotNull
@Column(name = "weight")
private double weight;
@Basic(optional = false)
@NotNull
@Column(name = "status")
private int status;
@Basic(optional = false)
@NotNull
@Lob
@Size(min = 1, max = 65535)
@Column(name = "criteriagroupname")

WS方法

@WebMethod(operationName = "getAllCriteriaGroupByProjectid")
public List<Criteriatable> getAllCriteriaGroupByProjectid(@WebParam(name = "projectid") int projectid)
{
    EntityManager em = emf.createEntityManager();
    String find = "Criteriatable.findAllCriteriatableGroup";
    TypedQuery<Criteriatable> query = em.createNamedQuery(find, Criteriatable.class);
    query.setParameter("projectid", projectid);
    return query.getResultList();
}

我收到的错误是：

SEVERE:   Error occured
javax.xml.ws.WebServiceException: javax.xml.bind.MarshalException
- with linked exception:
[com.sun.istack.SAXException2: class [Ljava.lang.Object; nor any of its super class is known to this context.
javax.xml.bind.JAXBException: class [Ljava.lang.Object; nor any of its super class is known to this context.]

我需要帮助。谢谢。

Answer 1

您的查询 Criteriatable.findAllCriteriatableGroup 未返回 Criteriatable 对象。

它返回一个 [groupName, groupweight] 元组列表。

请记住，泛型类型信息在运行时不可用，因此您在运行时的List<Criteriatable> 集合将是List<Object[]>（实际上是List<Object[2]>，但您不能那样写）。

这随后会导致 JAXB 映射失败。

你需要为你的结果定义一个 POJO：

@XmlRootElement
public class GroupTotal {

    private String groupName;

    private double groupTotal;

    public GroupTotal(String groupName, double groupTotal) {
         this.groupName = groupName;
         this.groupTotal = groupTotal;
    }

    // getters and setters ...
}

修改您的查询：

SELECT NEW your.package.GroupTotal (c.criteriagroupname, SUM(c.weight))
  FROM Criteriatable c WHERE c.projectid = :projectid GROUP BY c.criteriagroupname

最后执行：

TypedQuery<GroupTotal> query = em.createNamedQuery(find, GroupTotal.class);

我还没有尝试过，但它应该能让你指出正确的方向。

Answer 2

我认为问题在于您从 Web 方法返回 List。尝试返回您自己的包装类，该类将在其中包含列表作为字段。像这样的

public class CriteriatablesWrapper {
    private List<Criteriatable> criteriatableList;
    // getter and setter
}

并将您的服务方法签名更改为

@WebMethod(operationName = "getAllCriteriaGroupByProjectid")
public CriteriatablesWrapper getAllCriteriaGroupByProjectid(@WebParam(name = "projectid") int projectid) {
    ...
}