BlogJava-Kevin.Zhong-随笔分类-Jpahttp://www.blogjava.net/sway/category/35107.html彪悍的人生不需要解释，彪悍的代码不需要注释。zh-cnThu, 23 Oct 2008 02:15:03 GMTThu, 23 Oct 2008 02:15:03 GMT60JPA2级缓存的配置http://www.blogjava.net/sway/archive/2008/10/23/236094.htmlin.Zhongin.ZhongThu, 23 Oct 2008 01:55:00 GMThttp://www.blogjava.net/sway/archive/2008/10/23/236094.htmlhttp://www.blogjava.net/sway/comments/236094.htmlhttp://www.blogjava.net/sway/archive/2008/10/23/236094.html#Feedback0http://www.blogjava.net/sway/comments/commentRss/236094.htmlhttp://www.blogjava.net/sway/services/trackbacks/236094.html
2.在applicationContext.xml中配置
............
    <bean id="entityManagerFactory"
        class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="jpaVendorAdapter">
            <bean
                class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <property name="showSql" value="${jpa.showSql}" />
                <property name="generateDdl" value="${jpa.generateDdl}" />
                <property name="database">
                    <util:constant
                        static-field="org.springframework.orm.jpa.vendor.Database.ORACLE" />
                </property>
            </bean>
        </property>
        <property name="jpaProperties">
            <props>
                <prop key="hibernate.max_fetch_depth">3</prop>
                <prop key="hibernate.cache.use_second_level_cache">
                    true
                </prop>
                <prop key="hibernate.cache.use_structured_entries">
                    true
                </prop>
                <prop key="hibernate.cache.use_query_cache">true</prop>
                <prop key="hibernate.cache.provider_class">
                    com.googlecode.hibernate.memcached.MemcachedCacheProvider
                </prop>
                <prop key="hibernate.memcached.servers">
                    10.1.19.132:33001 10.1.19.132:33002 10.1.19.132:33003
                </prop>
            </props>
        </property>
    </bean>
............

3.在实体类上配置缓存策略
如@org.hibernate.annotations.Cache(usage = CacheConcurrencyStrategy.READ_WRITE)   

下面这几种情况就不适合加载到二级缓存中:
  1.经常被修改的数据
  2.绝对不允许出现并发访问的数据
  3.与其他应用共享的数据
  下面这己种情况合适加载到二级缓存中:
  1.数据更新频率低
  2.允许偶尔出现并发问题的非重要数据
  3.不会被并发访问的数据
  4.常量数据
  5.不会被第三方修改的数据



in.Zhong 2008-10-23 09:55 发表评论
]]>JPA的@Version标记的意义http://www.blogjava.net/sway/archive/2008/10/10/233569.htmlin.Zhongin.ZhongFri, 10 Oct 2008 05:05:00 GMThttp://www.blogjava.net/sway/archive/2008/10/10/233569.htmlhttp://www.blogjava.net/sway/comments/233569.htmlhttp://www.blogjava.net/sway/archive/2008/10/10/233569.html#Feedback0http://www.blogjava.net/sway/comments/commentRss/233569.htmlhttp://www.blogjava.net/sway/services/trackbacks/233569.html
   例：假设当前数据的版本为1，余额为100

a. 操作员A此时将其读出(version=1),并从其账户余额中扣除$50(100-50)。

b. 在操作员A操作的过程中，操作员B也要读入此用户信息(version=1),并从其账户余额中扣除$20(100-20)。

c. 操作员A完成修改工作，将数据版本号加1(version=2)，连同余额$50一并提交数据库更新，此时由于提交数据版本大于数据库记录的当前版本，数据被更新，数据库记录版本更新为2。

d. 操作员B完成操作，也将版本号加1(version=2)试图向数据库提交数据$80，但此时比对数据库记录版本时发现，操作员B提交的数据版本号为2，数据库记录当前版本也为2，不满足“提交版本必须大于记录当前版本才能执行更新”的乐观锁策略，因此，操作员B的操作被驳回。

in.Zhong 2008-10-10 13:05 发表评论
]]>Jpa的诡异异常http://www.blogjava.net/sway/archive/2008/10/10/233537.htmlin.Zhongin.ZhongFri, 10 Oct 2008 03:12:00 GMThttp://www.blogjava.net/sway/archive/2008/10/10/233537.htmlhttp://www.blogjava.net/sway/comments/233537.htmlhttp://www.blogjava.net/sway/archive/2008/10/10/233537.html#Feedback0http://www.blogjava.net/sway/comments/commentRss/233537.htmlhttp://www.blogjava.net/sway/services/trackbacks/233537.htmlorg.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [com/jl/framework/identity/idm/service/spring/conf/applicationContext.xml]: Invocation of init method failed; nested exception is java.lang.IllegalStateException: No data type for node: org.hibernate.hql.ast.tree.IdentNode
 \-[IDENT] IdentNode: 'out' {originalText=out}

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1337)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:473)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBeanFactory.java:409)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:380)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:264)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:221)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:261)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:185)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:164)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:423)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:729)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:381)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:93)
    at com.jl.framework.identity.idm.service.spring.DIContainerLoader.<init>(DIContainerLoader.java:42)
    at com.jl.framework.identity.idm.service.spring.DIContainerLoader.instance(DIContainerLoader.java:51)
    at com.jl.framework.identity.idm.service.spring.DIContainerLoader.getInstance(DIContainerLoader.java:46)
    at com.jl.framework.identity.idm.service.ContainerLoaderFactory.getContainerLoader(ContainerLoaderFactory.java:25)
    at com.jl.framework.identity.idm.dao.DaoServiceLocator.getMenuItemDao(DaoServiceLocator.java:103)
    at com.jl.framework.identity.idm.Menu.getMenuItemDao(Menu.java:61)
    at com.jl.framework.identity.idm.Menu.getRoot(Menu.java:69)
    at com.jl.framework.identity.idm.MenuTest.testGetRoot(MenuTest.java:36)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.junit.internal.runners.TestMethodRunner.executeMethodBody(TestMethodRunner.java:99)
    at org.junit.internal.runners.TestMethodRunner.runUnprotected(TestMethodRunner.java:81)
    at org.junit.internal.runners.BeforeAndAfterRunner.runProtected(BeforeAndAfterRunner.java:34)
    at org.junit.internal.runners.TestMethodRunner.runMethod(TestMethodRunner.java:75)
    at org.junit.internal.runners.TestMethodRunner.run(TestMethodRunner.java:45)
    at org.junit.internal.runners.TestClassMethodsRunner.invokeTestMethod(TestClassMethodsRunner.java:66)
    at org.junit.internal.runners.TestClassMethodsRunner.run(TestClassMethodsRunner.java:35)
    at org.junit.internal.runners.TestClassRunner$1.runUnprotected(TestClassRunner.java:42)
    at org.junit.internal.runners.BeforeAndAfterRunner.runProtected(BeforeAndAfterRunner.java:34)
    at org.junit.internal.runners.TestClassRunner.run(TestClassRunner.java:52)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:38)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)
Caused by: java.lang.IllegalStateException: No data type for node: org.hibernate.hql.ast.tree.IdentNode
 \-[IDENT] IdentNode: 'out' {originalText=out}
遇到这种异常就要小心了,很可能是你的jsql的问题.经过查找发现某类下有如下语句
@NamedQuery(name="getMenuItemRoot",query="SELECT out FROM MenuItem mi WHERE mi.parent IS NULL")
jpa可不知道这个out是干什么的.

in.Zhong 2008-10-10 11:12 发表评论
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