如何在Spring MVC中使用延迟加载 [英] How to use lazy loading in Spring MVC

查看：197
本文介绍了如何在Spring MVC中使用延迟加载的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

如何在Spring MVC中使用延迟加载？此刻我正在使用，但这使得我的应用程序运行速度变慢。
这是我的域名的一部分：

pre $ @ $ c $ @ManyToMany（fetch = FetchType.EAGER）
@JoinTable （name =NEWS_TAG，joinColumns = @JoinColumn（name =NEWS_ID），inverseJoinColumns = @JoinColumn（name =TAG_ID））
private List< Tags> tags = new ArrayList< Tags>（）;

公共列表<标签> getTags（）{
返回this.tags;
}

和dao： 

  public List< News> getSomeNews（long b，long hm）{
 
 List< News> news =（List< News>）sessionFactory 
 .getCurrentSession（）
 .createQuery（
from News WHERE title！='About'ORDER BY publish_time）
 .setMaxResults （int）hm）.setFirstResult（（int）b）.list（）; 
回报消息; 
}

Servlet-context： 

 < context：annotation-config /> 
 
< context：component-scan base-package =net.babobka.blog/> 
 
 
 
< import resource =../../ db / db-config.xml/> 
 
< bean id =urlForwardController
 class =org.springframework.web.servlet.mvc.UrlFilenameViewController/> 
 
< bean id =tilesConfigurer
 class =org.springframework.web.servlet.view.tiles2.TilesConfigurer> 
< property name =definitions> 
< list> 
<值> /WEB-INF/tiles.xml< /值> 
< / list> 
< / property> 
< / bean> 
 
< bean id =viewResolver
 class =org.springframework.web.servlet.view.UrlBasedViewResolver> 
< property name =viewClass
 value =org.springframework.web.servlet.view.tiles2.TilesView/> 
< / bean> 
 
< / beans>

Db-config： 

 < bean id =propertyConfigurer
 class =org.springframework.beans.factory.config.PropertyPlaceholderConfigurer
p：location =/ WEB-INF / db / jdbc .properties/> 
 
  destroy-method =closep：driverClassName =$ {jdbc.driverClassName }
p：url =$ {jdbc.databaseurl}p：username =$ {jdbc.username}p：password =$ {jdbc.password}/> 
 
< bean id =sessionFactory
 class =org.springframework.orm.hibernate3.LocalSessionFactoryBean> 
< property name =dataSourceref =dataSource/> 
< property name =configLocation> 
<值> /WEB-INF/db/hibernate.cfg.xml< /值> 
< / property> 
< property name =configurationClass> 
< value> org.hibernate.cfg.AnnotationConfiguration< / value> 
< / property> 
< property name =hibernateProperties> 
<道具> 
< prop key =hibernate.dialect> $ {jdbc.dialect}< / prop> 
< prop key =hibernate.show_sql> $ {jdbc.show_sql}< / prop> 
< /道具> 
< / property> 
< / bean> 
 
< bean id =transactionManager
 class =org.springframework.orm.hibernate3.HibernateTransactionManager> 
< property name =sessionFactoryref =sessionFactory/> 
< / bean> 
 
< tx：annotation-driven /> 
 
< / beans>

Web.xml： 

 <？xml version =1.0encoding =UTF-8？> 
< web-app version =2.5xmlns =http://java.sun.com/xml/ns/javaee
 xmlns：xsi =http：//www.w3。 org / 2001 / XMLSchema-instance
 xsi：schemaLocation =http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web- app_2_5.xsd> 
 
 <！ - 所有Servlet共享的Root Spring容器的定义
和Filters  - > 
< context-param> 
< param-name> contextConfigLocation< / param-name> 
 
< param-value> 
 /WEB-INF/spring/root-context.xml 
 /WEB-INF/spring/application-security.xml 
< /参数值> 
< / context-param> 
 
 
 
 <！ - 创建所有Servlet和过滤器共享的Spring容器 - > 
< listener> 
< listener-class> org.springframework.web.context.ContextLoaderListener< / listener-class> 
< / listener> 
 
 
 
 <！ - 处理应用程序请求 - > 
< servlet> 
< servlet-name> appServlet< / servlet-name> 
< servlet-class> org.springframework.web.servlet.DispatcherServlet< / servlet-class> 
< init-param> 
< param-name> contextConfigLocation< / param-name> 
< param-value> /WEB-INF/spring/appServlet/servlet-context.xml< / param-value> 
< / init-param> 
  1< / load-on-startup> 
< / servlet> 
 
< servlet-mapping> 
< servlet-name> appServlet< / servlet-name> 
< url-pattern> /< / url-pattern> 
< / servlet-mapping> 
 
< servlet-mapping> 
< servlet-name> appServlet< / servlet-name> 
< url-pattern> * .gif< / url-pattern> 
< / servlet-mapping> 
< 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> 
 
< filter> 
< filter-name> hibernateFilterChain< / filter-name> 
< filter-class> org.springframework.orm.hibernate3.support.OpenSessionInViewFilter< / filter-class> 
< / filter> 
< filter-mapping> 
< filter-name> hibernateFilterChain< / filter-name> 
< url-pattern> / *< / url-pattern> 
< / filter-mapping> 
 
 
 
 
< / web-app>

我需要做些什么来解决我的问题？您可以使用 OpenSessionInViewFilter 来防止休眠会话关闭。

将此添加到 web.xml ：

 < filter> 
< filter-name> hibernateFilterChain< / filter-name> 
< filter-class> org.springframework.orm.hibernate4.support.OpenSessionInViewFilter< / filter-class> 
< / filter> 
< filter-mapping> 
< filter-name> hibernateFilterChain< / filter-name> 
< url-pattern> / *< / url-pattern> 
< / filter-mapping>

@see阅读更多信息： OpenSessionInViewFilter



code> fetch = FetchType.EAGER 。 @ManyToMany 默认为LAZY。


How to use lazy loading in Spring MVC? I'm using eager at this moment, but this makes my app works slowler. This is part of my domain:

@ManyToMany(fetch = FetchType.EAGER)
@JoinTable(name = "NEWS_TAG", joinColumns = @JoinColumn(name = "NEWS_ID"), inverseJoinColumns = @JoinColumn(name = "TAG_ID"))
private List<Tags> tags = new ArrayList<Tags>();

public List<Tags> getTags() {
    return this.tags;
}

And dao:

public List<News> getSomeNews(long b, long hm) {

    List<News> news = (List<News>) sessionFactory
            .getCurrentSession()
            .createQuery(
                    "from News WHERE title!='About' ORDER BY publish_time")
            .setMaxResults((int) hm).setFirstResult((int) b).list();
    return news;
}

Servlet-context: 

    <context:annotation-config />

    <context:component-scan base-package="net.babobka.blog" />



    <import resource="../../db/db-config.xml" />

    <bean id="urlForwardController"
        class="org.springframework.web.servlet.mvc.UrlFilenameViewController" />

    <bean id="tilesConfigurer"
        class="org.springframework.web.servlet.view.tiles2.TilesConfigurer">
        <property name="definitions">
            <list>
                <value>/WEB-INF/tiles.xml</value>
            </list>
        </property>
    </bean>

    <bean id="viewResolver"
        class="org.springframework.web.servlet.view.UrlBasedViewResolver">
        <property name="viewClass"
            value="org.springframework.web.servlet.view.tiles2.TilesView" />
    </bean>

</beans>

Db-config:

<bean id="propertyConfigurer"
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"
        p:location="/WEB-INF/db/jdbc.properties" />

    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
        destroy-method="close" p:driverClassName="${jdbc.driverClassName}"
        p:url="${jdbc.databaseurl}" p:username="${jdbc.username}" p:password="${jdbc.password}" />

    <bean id="sessionFactory"
        class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="configLocation">
            <value>/WEB-INF/db/hibernate.cfg.xml</value>
        </property>
        <property name="configurationClass">
            <value>org.hibernate.cfg.AnnotationConfiguration</value>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">${jdbc.dialect}</prop>
                <prop key="hibernate.show_sql">${jdbc.show_sql}</prop>
            </props>
        </property>
    </bean>

    <bean id="transactionManager"
        class="org.springframework.orm.hibernate3.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactory" />
    </bean>

    <tx:annotation-driven />

</beans>

Web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

    <!-- The definition of the Root Spring Container shared by all Servlets 
        and Filters -->
    <context-param>
        <param-name>contextConfigLocation</param-name>

        <param-value>
        /WEB-INF/spring/root-context.xml
        /WEB-INF/spring/application-security.xml
        </param-value>
    </context-param>



    <!-- Creates the Spring Container shared by all Servlets and Filters -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>



    <!-- Processes application requests -->
    <servlet>
        <servlet-name>appServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring/appServlet/servlet-context.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

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

    <servlet-mapping>
        <servlet-name>appServlet</servlet-name>
        <url-pattern>*.gif</url-pattern>
    </servlet-mapping>
    <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>

    <filter>
        <filter-name>hibernateFilterChain</filter-name>
        <filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>hibernateFilterChain</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>




</web-app>

What I have to do to solve my problem?

解决方案

You can use OpenSessionInViewFilter to prevent hibernate session get closed. Add this to web.xml:

  <filter>
    <filter-name>hibernateFilterChain</filter-name>
    <filter-class>org.springframework.orm.hibernate4.support.OpenSessionInViewFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>hibernateFilterChain</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

@see read more here: OpenSessionInViewFilter

And remove fetch = FetchType.EAGER. @ManyToMany is LAZY by default.

这篇关于如何在Spring MVC中使用延迟加载的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

查看全文
相关文章
Java开发最新文章
热门教程
热门工具
登录 关闭
扫码关注1秒登录
发送“验证码”获取 | 15天全站免登陆