java - 无法持久化实体。 EJB异常

Question

尝试学习 JPA、EJB、ManagedBeans、JSF 等，但在尝试持久化实体时遇到错误。那是通过我的facelet 调用BlogManager 保存方法。这里是 JSF、ManagedBean、EJB 和实体。

@Entity
@Table(name = "BLOG")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "Blog.findAll", query = "SELECT b FROM Blog b"),
@NamedQuery(name = "Blog.findByBlogid", query = "SELECT b FROM Blog b WHERE b.blogid = :blogid"),
@NamedQuery(name = "Blog.findByText", query = "SELECT b FROM Blog b WHERE b.text = :text"),
@NamedQuery(name = "Blog.findByTimestamp", query = "SELECT b FROM Blog b WHERE b.timestamp = :timestamp")})
public class Blog implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@Basic(optional = false)
@NotNull
@Column(name = "BLOGID")
private Integer blogid;
@Size(max = 5000)
@Column(name = "TEXT")
private String text;
@Column(name = "TIMESTAMP")
@Temporal(TemporalType.TIMESTAMP)
private Date timestamp;

public Blog() {
}

public Blog(Integer blogid) {
    this.blogid = blogid;
}
Getters and Setters...

EJB:

@Stateless
public class BlogFacade extends AbstractFacade<Blog> {
@PersistenceContext(unitName = "MyBlogPU")
private EntityManager em;

@Override
protected EntityManager getEntityManager() {
    return em;
}

public BlogFacade() {
    super(Blog.class);
}

public List<Blog> getBlogs(){
    em.createNativeQuery("USE Blog").executeUpdate();
    Query query = em.createNamedQuery("Blog.findAll");
    return query.getResultList();
}

public void deleteBlog(int id){
    Query query = em.createNativeQuery("DELETE FROM blog WHERE blogid = :blogid");
    query.setParameter(":blogid", id);
    query.executeUpdate();
}
}

托管Bean

@Named("blogManager")
@ManagedBean
@SessionScoped
public class BlogManager implements Serializable {
private Blog BlogEntity;

@EJB
private BlogFacade BlogFacade;

@PostConstruct
public void init(){
    BlogEntity = new Blog();
}

public Blog getBlogEntity(){
    return this.BlogEntity;
}

public void setBlogEntity(Blog BlogEntity){
    this.BlogEntity = BlogEntity;
}

public void save(){
    BlogFacade.create(BlogEntity);
}

public void delete(){
    BlogFacade.remove(BlogEntity);
}

public void deleteBlog(@QueryParam("blogid") int id){
    BlogFacade.deleteBlog(id);
}

public List<Blog> getBlogs(){
    return BlogFacade.getBlogs();
}
}

小面

<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE composition PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<ui:composition xmlns:ui="http://xmlns.jcp.org/jsf/facelets"
            xmlns:h="http://xmlns.jcp.org/jsf/html"
            xmlns:p="http://xmlns.jcp.org/jsf/passthrough"
            xmlns:c="http://java.sun.com/jsp/jstl/core"
            xmlns="http://www.w3.org/1999/xhtml"
            template="./template.xhtml"
            xmlns:f="http://xmlns.jcp.org/jsf/core">

<ui:define name="left">
    <h:form>
        <h:inputTextarea value="#{blogManager.blogEntity.text}" p:placeholder="Tweet max 30 chars." style="width: 100%; height:150px; resize: none;" /><br/><br/>
        <h:commandButton value="Tweet" action="#{blogManager.save}" />
    </h:form>
</ui:define>

<ui:define name="right">
    <c:forEach items="#{blogManager.getBlogs()}" var="item">
        <h:outputText value="#{item.getText()}" />&nbsp;&nbsp;
        Likes: &nbsp;&nbsp;<h:outputText value="" />&nbsp;&nbsp;&nbsp;
        <h:commandLink action="" value="like">
            <f:param name="tweetid" value="" />
            <f:param name="username" value="" />
        </h:commandLink>&nbsp;<br />
        <textarea>
            <h:outputText value="" />
        </textarea>
    </c:forEach>
</ui:define>

</ui:composition>

不确定这是否允许，但我已将 strack 跟踪上传到 http://pastebin.com/7Mp0J7yG而不是把它弄乱在这篇文章中。是的，我遇到了 EJB 错误。

Answer 1

您的应用程序在 Bean 验证上失败。所以看看吧。您在 id 字段上有 @NotNull 注释(为什么？主键无论如何都不应该为空)，但从您提供的来源来看，我无法弄清楚 id 是如何生成的。没有定义策略。添加@GeneratedValue