hibernate一对多取到的set集合 failed to lazily initialize a collection of role

SGroup ,SGroupPrv 一对多关系

在   SGroup .hbm.xml中部门配置

<set name="SGroupPrvs" inverse="true" cascade="all" lazy="true">
    <key>
        <column name="GROUPID" precision="22" scale="0"/>
    </key>
    <one-to-many class="com.news.Hibernate.SGroupPrv"/>
</set>

JAVA其中代码：

String groupid=request.getParameter("groupid");
   System.out.print("组名id:"+groupid); 
    SGroup groups=groupManager.getSGroup(groupid);
    groups.setGroupid(Integer.parseInt(groupid));
    System.out.println("groupid:"+groups.getGroupid());
    System.out.println("groupname:"+groups.getName());
    System.out.print("是否实例化："+Hibernate.isInitialized(groups));
    if(!Hibernate.isInitialized(groups)) 
     Hibernate.initialize(groups); 

    //Hibernate.initialize(groups.getSGroupPrvs());
    Set<SGroupPrv> set=groups.getSGroupPrvs(); 
    System.out.print("是否实例化："+Hibernate.isInitialized(set));
    if(!Hibernate.isInitialized(set)) 
     Hibernate.initialize(set); 
    System.out.print("是否实例化："+Hibernate.isInitialized(set));
    System.out.println(set.size());

运行出现failed to lazily initialize a collection of role异常

主要原因是：SGroup 采用了延迟加载策略，根据主键搜索出SGroup 对象时，并没有把Set<SGroupPrv>集合一并的搜索出来，得用到时才加载Set<SGroupPrv>，当用到Set<SGroupPrv>集合时无法获取到SGroup 对象的主键值

 

解决方法：

1.web.xml中加入OpenSessionInViewFilter过滤机制

  <filter>  
       <filter-name>OpenSessionInViewFilter</filter-name>  
       <filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class> 
    <init-param>
   <param-name>singleSession</param-name>
   <param-value>false</param-value>
  </init-param> 
   </filter>     
   <filter-mapping>  
       <filter-name>OpenSessionInViewFilter</filter-name>  
       <url-pattern>/*</url-pattern>  
   </filter-mapping> 

2.把LOAD(**.class,主键)方法改成GET(**.class,主键)方法，根据主键得到对应的对象

3.观察项目中cglib所属哪个版本的，如果是cglib_2.1.3.jar版本请升级至cglib_2.2.jar