关于Web项目出现懒加载异常的解决方案

manytomany关系中，使用 fetch = FetchType.LAZY 来做懒加载，加快些性能。但是却一直出错，原因是session被关闭，要保持session，需要事务。

• Hibernate

1. 使用xml配置文件

   <!-- 配置opensessionInViewFilter 用于解决懒加载问题-->
     <filter>
        <filter-name>OpenSessionInViewFilter</filter-name>
        <filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class>
     </filter>
   <filter-mapping>
       <filter-name>openSessionInViewFilter</filter-name>
       <url-pattern>/*</url-pattern>
   </filter-mapping>

2. 使用的是Java配置
   

   /**
    * 处理hibernate的懒加载异常，延长hibernate的session再回话结束后关闭
    * @Title: customOpenEntityManagerInViewFilter 
    * @Description: TODO
    * @return FilterRegistrationBean
    * @throws
    */
   @Bean
   public FilterRegistrationBean OpenSessionInViewFilter() {
     FilterRegistrationBean registration = new FilterRegistrationBean();
     registration.setFilter(new OpenSessionInViewFilter());
     registration.addUrlPatterns("/*");
     registration.setName("openSessionInViewFilter");
     registration.setOrder(1);//设置优先级，必须大于shiro的fiter，不然会出现session周期的问题
     return registration;
   }

• JPA

1. 使用xml配置文件

   <!--在页面开启session，解决懒加载异常的问题-->
   <filter>
       <filter-name>OpenEntityManagerInViewFilter</filter-name>
       <filter-class>org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter</filter-class>
   </filter>
   <filter-mapping>
       <filter-name>openEntityManagerInViewFilter</filter-name>
       <url-pattern>/*</url-pattern>
   </filter-mapping>

2. 使用的是Java配置

   /**
    * @Description: 处理JPA的懒加载异常，延长hibernate的session再回话结束后关闭
    * @Title: customOpenEntityManagerInViewFilter
    * @throws
    * @return FilterRegistrationBean
    */
   @Bean
   public FilterRegistrationBean customOpenEntityManagerInViewFilter() {
       FilterRegistrationBean registration = new FilterRegistrationBean();
       registration.setFilter(new OpenEntityManagerInViewFilter());
       registration.addUrlPatterns("/*");
       registration.setName("openEntityManagerInViewFilter");
       registration.setOrder(1);// 设置优先级，必须大于shiro的fiter，不然会出现session周期的问题
       return registration;
   }