hibernate - OpenEntityManagerInViewFilter 问题

Question

我已经在这个网站和其他网站上搜索过让 OpenEntityManagerInViewFilter 工作的答案。我有一个标准的 User 对象，它引用具有多对多关系的角色对象作为一个集合。当我尝试从 Controller 编辑我的用户时，我收到了可怕的延迟初始化异常。在大多数情况下，通过简单地将其添加到您的 web.xml 中，这似乎应该是非常简单的:

<filter>
    <filter-name>oemInViewFilter</filter-name>
    <filter-class>
        org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter
    </filter-class>
</filter>

<filter-mapping>
    <filter-name>oemInViewFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

现在我尝试过但没有成功的事情(这些是来自网络的各种建议)

1. 将上述声明移至 web.xml 的最顶部
2. 在我的 Controller 方法和/或整个类周围使用@Transactional
3. 显然将获取类型切换为 Eager Works，但这里违背了我的意图
4. 使用我定义的entityManagerFacorty
5. 已验证 OpenEntityManager 存在于惰性初始化异常中，因此它被触发

我读过的唯一一件事对我来说有意义，因为为什么这不起作用是我正在加载两个不同的 session ，因为我的持久层是如何设置的，并且过滤器抓取了错误的 session 。

这是我的 Controller 中的方法，我从数据库中查找用户并导致惰性初始化异常，因为它没有从用户对象中检索角色。

@RequestMapping(value = "/edit/{id}", method = RequestMethod.GET)
   public String edit(@PathVariable final Integer id, final ModelMap modelMap)
   {
      final User user = userDao.find(id); ******This causes the lazy init exception

      if (user != null)
      {
         modelMap.addAttribute("userInstance", user);
         modelMap.addAttribute("validRoles",  new HashSet<Role>(roleDao.findAll()));
         return "/user/edit";
      }
      return "redirect:/user/list";
   }

这是我的相关设置:

Web.xml:

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns="http://java.sun.com/xml/ns/javaee"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
         id="WebApp_ID" version="2.5">

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            /WEB-INF/board-servlet.xml  *****This file references the file with entityManager declared*****
            /WEB-INF/board-security.xml
        </param-value>
    </context-param>

    <filter>
        <filter-name>springSecurityFilterChain</filter-name>
        <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
    </filter>

    <filter-mapping>
        <filter-name>springSecurityFilterChain</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <servlet>
        <servlet-name>board</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>board</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

    <servlet-mapping>
        <servlet-name>default</servlet-name>
        <url-pattern>*.css</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>default</servlet-name>
        <url-pattern>*.js</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>default</servlet-name>
        <url-pattern>*.jpg</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>default</servlet-name>
        <url-pattern>*.png</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>default</servlet-name>
        <url-pattern>*.gif</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>default</servlet-name>
        <url-pattern>*.ico</url-pattern>
    </servlet-mapping>

    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>

    <filter>
        <filter-name>oemInViewFilter</filter-name>
        <filter-class>
            org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter
        </filter-class>
    </filter>

    <filter-mapping>
        <filter-name>oemInViewFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <filter>
        <filter-name>sitemesh</filter-name>
        <filter-class>
            com.opensymphony.module.sitemesh.filter.PageFilter
        </filter-class>
    </filter>

    <filter-mapping>
        <filter-name>sitemesh</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

</web-app>

board-servlet.xml

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd">

  ****This is what pulls in my entityManager  
 <import resource="classpath:persistence-spring-beans.xml"/> 

    <mvc:annotation-driven/>

    <bean id="viewResolver" class="org.springframework.web.servlet.view.UrlBasedViewResolver">
        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="maxUploadSize" value="100000"/>
    </bean>

    <bean id="messageSource"
          class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
        <property name="basename" value="classpath:message"/>
        <property name="defaultEncoding" value="UTF-8"/>
    </bean>

</beans>

持久性-spring-beans.xml

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
            http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
            http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd">

    <context:annotation-config/>
    <context:component-scan base-package="com.something" use-default-filters="true"/>
    <aop:aspectj-autoproxy proxy-target-class="true"/>

    <tx:annotation-driven transaction-manager="transactionManager"/>

    <bean class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean" id="entityManagerFactory">
        <property name="persistenceUnitName" value="prodPersistenceUnit"/>
        <property name="dataSource" ref="c3p0PostgresDataSource"/>
        <property name="packagesToScan" value="com.something.persistence.dto"/>
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"/>
        </property>
    </bean>

    <bean class="org.springframework.orm.jpa.JpaTransactionManager" id="transactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory"/>
    </bean>

    <bean id="c3p0PostgresDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
        <property name="driverClass" value="org.postgresql.Driver"/>
        <property name="jdbcUrl" value="jdbc:postgresql://localhost:5432/yellow_hammer"/>
        <property name="user" value="yellow"/>
        <property name="password" value="hammer"/>
        <property name="initialPoolSize" value="3"/>
        <property name="minPoolSize" value="3"/>
        <property name="maxPoolSize" value="50"/>
        <property name="idleConnectionTestPeriod" value="200"/>
        <property name="acquireIncrement" value="1"/>
        <property name="maxStatements" value="0"/>
        <!-- 0 means: statement caching is turned off.  -->
        <property name="numHelperThreads" value="3"/>
        <!-- 3 is default -->
    </bean>
</beans>

如果相关信息还不够，请告诉我。

编辑UserDao - 这扩展了 GenericDao，我将在下面发布它。

@Dao
public class UserDao extends GenericDao<User>
{
   public User findByUsernameAndPassword(final String username, final String password)
   {
      final Query query = entityManager.createQuery("from User user " + "where user.username = :user " + "and user.password = :pass ")
         .setParameter("user", username)
         .setParameter("pass", password);

      return uniqueResult(query);
   }

   public List<User> findByRole(final Role roleIn)
   {
      if (roleIn == null)
      {
         return null;
      }

      final Query query = entityManager.createQuery("select user from User user, Role role where role = :roleParam ").
         setParameter("roleParam", roleIn);

      return query.getResultList();
   }
}

通用Dao

public class GenericDao<T extends BaseDto>
{
   protected Class<T> entityClass;

   @PersistenceContext
   protected EntityManager entityManager;

   public GenericDao()
   {
      final ParameterizedType genericSuperclass = (ParameterizedType) getClass().getGenericSuperclass();
      this.entityClass = (Class<T>) genericSuperclass.getActualTypeArguments()[0];
   }

   public T find(final Integer id)
   {
      return entityManager.find(entityClass, id);
   }

   public List<T> findAll()
   {
      final Query query = entityManager.createQuery("from " + entityClass.getSimpleName());
      return query.getResultList();
   }

   public T save(final T t)
   {
      if (t != null)
      {
         return t.getId() != null && t.getVersion() != null ? update(t) : create(t);
      }

      return null;
   }

   private T create(final T t)
   {
      entityManager.persist(t);
      return t;
   }

   private T update(final T t)
   {
      return entityManager.merge(t);
   }

   public void delete(T t)
   {
      t = entityManager.merge(t);
      entityManager.remove(t);
   }

   protected T uniqueResult(final Query query)
   {
      final List results = query.getResultList();
      if (results.isEmpty())
      {
         return null;
      }
      else if (results.size() == 1)
      {
         return entityClass.cast(results.get(0));
      }

      // TODO send notification, multiple results found
      return null;
   }
}

Answer 1

但是现在!!

让我猜猜:你的应用程序的名称是:board？

正确吗？然后继续阅读剩下的答案!

是的，您有两个实体管理器，甚至两个相同的应用程序上下文(一个应用程序上下文和一个 Web 上下文)——因此您拥有每个 bean 两次!

发生的事情是:你只有一个(相关的)spring 配置文件:'board-servlet.xml'('persistence-spring-beans.xml'包含在该文件中，因此至少它是一个大的逻辑文件)

并且您在“web.xml”中两次从此文件创建上下文:

第一:

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>
        /WEB-INF/board-servlet.xml  *****This file references the file with entityManager declared*****
        /WEB-INF/board-security.xml
    </param-value>
</context-param>
...
<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

ContextLoaderListener 加载“contextConfigLocation”参数中的文件指定的应用程序上下文。

第二个:

<servlet>
    <servlet-name>board</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>

Dispatcher Servlet 创建 Web 应用程序上下文，其 xml 文件为:

• 由初始化参数“contextConfigLocation”命名
• 或者，如果没有这样的参数，它会查找名为“/WEB-INF/-servlet.xml”的文件

(更多详细信息请查看 FrameworkServlet 的 Java 文档)

在您的情况下，没有明确命名的文件，因此它会再次读取“board-servlet.xml”。

你需要做的就是将它们分开:

• 删除 <import resource="classpath:persistence-spring-beans.xml"/>来自board-servlet.xml
• 更改 contextConfigLocation在web.xml它指的是 classpath:persistence-spring-beans.xml和/WEB-INF/board-security.xml直接
• (不是 100% 必要)将“context:component-scan”分开，以便组件扫描 board-servlet.xml仅扫描@Controller以及 persistence-spring-beans.xml 中的组件扫描扫描其他( @Service 、 @Component 、 @Repository 和 @Dao )
• 最后一步:请告诉我现在可以使用了