解决JPA延迟加载异常

当统计子分类个数时，entity对象已经处于session之外的游离状态，Hibernate的transaction默认lazy=”true”，所以，程序在取数据时会出现错误

解决：

在web.xml文件中设置Filter

<!-- To Solve an org.hibernate.LazyInitalizationException -->
    <filter>
        <filter-name>Spring penEntityManagerInViewFilter</filter-name>
        <!-- Include this if you are using Hibernate -->
        <!-- org.springframework.orm.hibernate3.support.OpenSessionInViewFilter 用于hibernate+spring -->
    <filter-class>org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>SpringOpenEntityManagerInViewFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>