Question

我有以下课程

public class RSS 
{
    private Integer id;
    private String title;
    private String description;
    private String link;
    private Date dateCreated;
    private Collection rssItems;
    private String  url;
    private String language;
    private String rating;
    private Date pubDate;
    private Date lastBuildDate;
    private User user;
    private Date dateModified;

    public RSS() {
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public void setDescription(String description){
        this.description = description;
    }

    public String getDescription(){
        return this.description;
    }

    public void setLink(String link){
        this.link = link;
    }

    public String getLink(){
        return this.link;
    }

    public void setUrl(String url){
        this.url = url;
    }

    public String getUrl(){
        return this.url;
    }

    public void setLanguage(String language){
        this.language = language;
    }

    public String getLanguage(){
        return this.language;
    }

    public void setRating(String rating){
        this.rating = rating;
    }

    public String getRating(){
        return this.rating;
    }

    public Date getPubDate() {
        return pubDate;
    }

    public void setPubDate(Date pubDate) {
        this.pubDate = pubDate;
    }

    public Date getLastBuildDate() {
        return lastBuildDate;
    }

    public void setLastBuildDate(Date lastBuildDate) {
        this.lastBuildDate = lastBuildDate;
    }

    public Date getDateModified() {
        return dateModified;
    }

    public void setDateModified(Date dateModified) {
        this.dateModified = dateModified;
    }

    public Date getDateCreated() {
        return dateCreated;
    }

    public void setDateCreated(Date dateCreated) {
        this.dateCreated = dateCreated;
    }

    public Collection getRssItems() {
        return rssItems;
    }

    public void setRssItems(Collection rssItems) {
        this.rssItems = rssItems;
    }
}

public class RSSItem {

    private RSS rss;

    private Integer id;
    private String title;
    private String description;
    private String link;
    private Date dateCreated;
    private Date dateModified;
    private int rss_id;

    public RSSItem() {}

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public String getLink() {
        return link;
    }

    public void setLink(String link) {
        this.link = link;
    }

    public Date getDateCreated() {
        return dateCreated;
    }

    public void setDateCreated(Date dateCreated) {
        this.dateCreated = dateCreated;
    }

    public Date getDateModified() {
        return dateModified;
    }

    public void setDateModified(Date dateModified) {
        this.dateModified = dateModified;
    }

    public RSS getRss() {
        return rss;
    }

    public void setRss(RSS rss) {
        this.rss = rss;
    }
}

我映射为

    <hibernate-mapping>
  <class name="com.rssFeed.domain.RSS"  schema="PUBLIC" table="RSS">
    <id name="id" type="int">
      <column name="ID"/>
      <generator class="native"/>
    </id>
    <property name="title" type="string">
      <column name="TITLE" not-null="true"/>
    </property>        
    <property name="lastBuildDate" type="java.util.Date">
      <column name="LASTBUILDDATE"/>
    </property>
    <property name="pubDate" type="java.util.Date">
      <column name="PUBDATE" />
    </property>
    <property name="dateCreated" type="java.util.Date">
      <column name="DATECREATED" not-null="true"/>
    </property>
    <property name="dateModified" type="java.util.Date">
      <column name="DATEMODIFIED" not-null="true"/>
    </property>
    <property name="description" type="string">
      <column name="DESCRIPTION" not-null="true"/>
    </property>
    <property name="link" type="string">
      <column name="LINK" not-null="true"/>
    </property>
    <property name="url" type="string">
      <column name="URL" not-null="true"/>
    </property>
    <property name="language" type="string">
      <column name="LANGUAGE" not-null="true"/>
    </property>
    <property name="rating" type="string">
      <column name="RATING"/>
    </property>
     <set inverse="true" lazy="false" name="rssItems">
      <key>
        <column name="RSS_ID"/>
      </key>
      <one-to-many class="com.rssFeed.domain.RSSItem"/>
    </set>
  </class>
</hibernate-mapping>


<hibernate-mapping>
  <class name="com.rssFeed.domain.RSSItem" schema="PUBLIC" table="RSSItem">
    <id name="id" type="int">
      <column name="ID"/>
      <generator class="native"/>
    </id>
    <property name="title" type="string">
      <column name="TITLE" not-null="true"/>
    </property>
    <property name="description" type="string">
      <column name="DESCRIPTION" not-null="true"/>
    </property>
    <property name="link" type="string">
      <column name="LINK" not-null="true"/>
    </property>
    <property name="dateCreated" type="java.util.Date">
      <column name="DATECREATED"/>
    </property>
    <property name="dateModified" type="java.util.Date">
      <column name="DATEMODIFIED"/>
    </property>
    <many-to-one class="com.rssFeed.domain.RSS" fetch="select" name="rss">
      <column name="RSS_ID"/>
    </many-to-one>
  </class>
</hibernate-mapping>

但是当我尝试获取RSS时，我收到以下错误

目标VM发生异常：无法懒惰地初始化角色集合：com.rssFeed.domain.RSS.rssItems，没有会话或会话已关闭 org.hibernate.LazyInitializationException：无法懒惰地初始化角色集合：com.rssFeed.domain.RSS.rssItems，没有会话或会话被关闭 at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException（AbstractPersistentCollection.java:358） at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected（AbstractPersistentCollection.java:350） at org.hibernate.collection.AbstractPersistentCollection.readSize（AbstractPersistentCollection.java:97） at org.hibernate.collection.PersistentSet.size（PersistentSet.java:139）在com.rssFeed.dao.hibernate.HibernateRssDao.get（HibernateRssDao.java:47）在com.rssFeed.ServiceImplementation.RssServiceImplementation.get（RssServiceImplementation.java:46）在com.rssFeed.mvc.ViewRssController.handleRequest（ViewRssController.java:20）在org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle（SimpleControllerHandlerAdapter.java:48）在org.springframework.web.servlet.DispatcherServlet.doDispatch（DispatcherServlet.java:875）在org.springframework.web.servlet.DispatcherServlet.doService（DispatcherServlet.java:809）在org.springframework.web.servlet.FrameworkServlet.processRequest（FrameworkServlet.java:476）在org.springframework.web.servlet.FrameworkServlet.doGet（FrameworkServlet.java:431）在javax.servlet.http.HttpServlet.service（HttpServlet.java:734）在javax.servlet.http.HttpServlet.service（HttpServlet.java:847）在org.apache.catalina.core.StandardWrapper.service（StandardWrapper.java:1523）在org.apache.catalina.core.StandardWrapperValve.invoke（StandardWrapperValve.java:279）在org.apache.catalina.core.StandardContextValve.invoke（StandardContextValve.java:188）在org.apache.catalina.core.StandardPipeline.invoke（StandardPipeline.java:641）在com.sun.enterprise.web.WebPipeline.invoke（WebPipeline.java:97）在com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke（PESessionLockingStandardPipeline.java:85）在org.apache.catalina.core.StandardHostValve.invoke（StandardHostValve.java:185）在org.apache.catalina.connector.CoyoteAdapter.doService（CoyoteAdapter.java:332）在org.apache.catalina.connector.CoyoteAdapter.service（CoyoteAdapter.java:233） at com.sun.enterprise.v3.services.impl.ContainerMapper.service（ContainerMapper.java:165） at com.sun.grizzly.http.ProcessorTask.invokeAdapter（ProcessorTask.java:791） at com.sun.grizzly.http.ProcessorTask.doProcess（ProcessorTask.java:693）在com.sun.grizzly.http.ProcessorTask.process（ProcessorTask.java:954） at com.sun.grizzly.http.DefaultProtocolFilter.execute（DefaultProtocolFilter.java:170） at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter（DefaultProtocolChain.java:135）在com.sun.grizzly.DefaultProtocolChain.execute（DefaultProtocolChain.java:102） at com.sun.grizzly.DefaultProtocolChain.execute（DefaultProtocolChain.java:88）在com.sun.grizzly.http.HttpProtocolChain.execute（HttpProtocolChain.java:76） at com.sun.grizzly.ProtocolChainContextTask.doCall（ProtocolChainContextTask.java:53）在com.sun.grizzly.SelectionKeyContextTask.call（SelectionKeyContextTask.java:57）在com.sun.grizzly.ContextTask.run（ContextTask.java:69）在com.sun.grizzly.util.AbstractThreadPool $ Worker.doWork（AbstractThreadPool.java:330）在com.sun.grizzly.util.AbstractThreadPool $ Worker.run（AbstractThreadPool.java:309）在java.lang.Thread.run（Thread.java:619）＆LT;

这是什么意思？

由于

我根据Pascal Thivent的建议修改了我的代码

现在我得到以下异常

type Exception report

message

descriptionThe server encountered an internal error () that prevented it from fulfilling this request.

exception

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.dao.InvalidDataAccessResourceUsageException: could not initialize a collection: [com.rssFeed.domain.RSS.rssItems#3]; nested exception is org.hibernate.exception.SQLGrammarException: could not initialize a collection: [com.rssFeed.domain.RSS.rssItems#3]

root cause

org.springframework.dao.InvalidDataAccessResourceUsageException: could not initialize a collection: [com.rssFeed.domain.RSS.rssItems#3]; nested exception is org.hibernate.exception.SQLGrammarException: could not initialize a collection: [com.rssFeed.domain.RSS.rssItems#3]

root cause

org.hibernate.exception.SQLGrammarException: could not initialize a collection: [com.rssFeed.domain.RSS.rssItems#3]

root cause

java.sql.SQLException: Table not found in statement [select rssitems0_.RSS_ID as RSS7_1_, rssitems0_.ID as ID1_, rssitems0_.ID as ID2_0_, rssitems0_.TITLE as TITLE2_0_, rssitems0_.DESCRIPTION as DESCRIPT3_2_0_, rssitems0_.LINK as LINK2_0_, rssitems0_.DATECREATED as DATECREA5_2_0_, rssitems0_.DATEMODIFIED as DATEMODI6_2_0_, rssitems0_.RSS_ID as RSS7_2_0_ from PUBLIC.RSSItem rssitems0_ where rssitems0_.RSS_ID=?]

note The full stack traces of the exception and its root causes are available in the GlassFish v3 logs.

只有当我删除lazyLoad =“false”时才会收到上一个错误

顺便说一下这是我的表定义

drop table RSS_ITEM if exists
drop table RSS if exists

create table RSS (
   id integer identity primary key,
   title varchar(128) not null, 
   description varchar(2048) not null,
   link varchar(1024) not null,
   url varchar(1024) not null,
   language  varchar(63) not null,
   rating  varchar(63),
   pubDate date,
   lastBuildDate date,
   user_id integer,
   dateCreated date not null,
   dateModified date not null   
);


create table RSS_ITEM (
   id integer identity primary key,
   title varchar(128) not null,
   description varchar(2048) not null,
   link varchar(1024) not null,
   rss_id integer not null,
   dateCreated date not null,
   dateModified date not null   
);


alter table RSS_ITEM add constraint item_rss foreign key (rss_id) references RSS;
alter table RSS add constraint rss_user foreign key (user_id) references RSS_USER;

Answer 1

基本上，当您尝试访问延迟加载的属性并且Hibernate Session已经关闭时，会抛出LazyInitializationException（因此无法加载属性，因此异常）。这正是跟踪报告的rssItems属性。

奇怪的是，您使用lazy="false"标记了此属性，并且根据文档，此禁用延迟提取并指定始终急切地提取关联以便{{1}应该急切地获取，你不应该得到rssItems。

话虽如此，我并非确定映射是正确的，我不确定在映射LazyInitializationException时是否可以使用<set>。我找不到官方参考，但如果我记得很清楚，你应该使用java.util.Collection来映射<bag>。所以你可以尝试：

将Collection属性的类型更改为rssItems〜或〜
更改您的映射以使用java.util.Set

完成后，检查<bag>在检索rssItems实体时是否按预期急切加载（激活Hibernate SQL日志记录在这里会有所帮助）。

Answer 2

您的表在DB中命名为RSS_ITEM，但hibernate在SQL查询中查找RSSItem（检查错误）。您需要在映射中修复表名。请参阅hbm XML中的第二类映射。表名应该是RSS_ITEM。

帮助Hibernate映射

2 个答案: