正在调用@PrePersist并修改实体，但不会将其写入数据库

Question

我正在使用Hibernate和MySQL在Spring MVC中开发一个应用程序，我遇到了一个问题。我正在尝试使用@PrePersist注释填充我的Java实体中的最后一个修改字段。我调试了代码，方法被调用，值得设置。但是，数据库抛出了null违例，因为它没有写出@PrePersist方法添加的值。有谁知道如何修复此问题将数据写入数据库？

仅供参考，除了更改日期之外，我还想使用这些JPA注释来执行某些业务逻辑或使用与注释类似的内容。

代码：

@Entity
@Table(name = "account")
public class Account {
    @Column(name = "modified_on")
    @Temporal(TemporalType.TIMESTAMP)
    @DateTimeFormat(style = "MM")
    @NotNull()
    private Calendar modifiedOn;
... getters, setter and other stuff

    @PrePersist
    public void prePersist() {
        Calendar now = Calendar.getInstance();
        this.createdOn = now;
        this.modifiedOn = now;
    }


    @PreUpdate
    public void preUpdate() {
        Calendar now = Calendar.getInstance();
        this.modifiedOn = now;
    }

的applicationContext-的persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns:beans="http://www.springframework.org/schema/beans" 
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
             xmlns:jdbc="http://www.springframework.org/schema/jdbc"
             xmlns:jee="http://www.springframework.org/schema/jee" 
             xmlns="http://www.springframework.org/schema/data/jpa"
        xsi:schemaLocation="http://www.springframework.org/schema/beans 
                            http://www.springframework.org/schema/beans/spring-beans.xsd
                            http://www.springframework.org/schema/jdbc
                            http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd
                            http://www.springframework.org/schema/jee
                            http://www.springframework.org/schema/jee/spring-jee-3.2.xsd                            
                            http://www.springframework.org/schema/data/jpa 
                            http://www.springframework.org/schema/data/jpa/spring-jpa.xsd">
     <repositories base-package="${repositoryPackageName}" />
    <beans:bean id="hibernateJpaVendorAdapter" class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
    <beans:bean id="exceptionTranslator" class="org.springframework.orm.hibernate4.HibernateExceptionTranslator" />
    <beans:bean class="org.springframework.orm.jpa.JpaTransactionManager" id="transactionManager">
        <beans:property name="entityManagerFactory" ref="entityManagerFactory" />
    </beans:bean>
    <beans:bean id="persistenceExceptionTranslationPostProcessor" class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />
        <beans:bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
            <beans:property name="driverClassName" value="${database.driverClassName}" />
            <beans:property name="url" value="${database.url}" />
            <beans:property name="username" value="${database.username}" />
            <beans:property name="password" value="${database.password}" />
        </beans:bean>
        <beans:bean class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean" id="entityManagerFactory">
            <beans:property name="dataSource" ref="dataSource" />
            <beans:property name="jpaVendorAdapter" ref="hibernateJpaVendorAdapter" />
            <beans:property name="packagesToScan" value="${scanPackageName}" />
            <beans:property name="jpaProperties">
                <beans:props>
                    <beans:prop key="hbm2ddl.auto">validate</beans:prop>
                    <beans:prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</beans:prop>
                    <beans:prop key="hibernate.query.substitutions">true '1', false '0'</beans:prop>
                    <beans:prop key="hibernate.generate_statistics">true</beans:prop>
                    <beans:prop key="hibernate.show_sql">false</beans:prop>
                    <beans:prop key="hibernate.format_sql">true</beans:prop>
                    <beans:prop key="hibernate.hbm2ddl.auto">validate</beans:prop>
                </beans:props>
            </beans:property>
        </beans:bean>
</beans:beans>

的applicationContext.xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:aop="http://www.springframework.org/schema/aop" 
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:jee="http://www.springframework.org/schema/jee" 
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:util="http://www.springframework.org/schema/util"
    xsi:schemaLocation=
    "http://www.springframework.org/schema/aop 
    http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
    http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans-3.2.xsd 
    http://www.springframework.org/schema/context 
    http://www.springframework.org/schema/context/spring-context-3.2.xsd 
    http://www.springframework.org/schema/jee
    http://www.springframework.org/schema/jee/spring-jee-3.2.xsd
    http://www.springframework.org/schema/tx 
    http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
    http://www.springframework.org/schema/util
    http://www.springframework.org/schema/util/spring-util-3.2.xsd"
    >
    <context:property-placeholder location="classpath:META-INF/spring/*.properties" />
    <context:property-placeholder location="classpath:META-INF/properties/*.properties"/>    
    <context:component-scan base-package="${doaminPackageName}"/>
    <context:component-scan base-package="${repositoryPackagename}"/>
    <context:component-scan base-package="${repositoryPackageName}" >
    <context:exclude-filter type="custom" expression="ourapp.util.TestClassFilter"/>
    </context:component-scan>
    <context:component-scan base-package="${utilBeanPackageName}"/>
    <tx:annotation-driven transaction-manager="transactionManager" />
    <bean id="mailSender" class="org.springframework.mail.javamail.JavaMailSenderImpl">
        <property name="host" value="${mail.server.host}" />
        <property name="port" value="${mail.server.port}" />
        <property name="protocol" value="${mail.server.protocol}" />
        <property name="username" value="${mail.server.username}" />
        <property name="password" value="${mail.server.password}" />
        <property name="javaMailProperties">
            <util:properties location="classpath:META-INF/spring/javamail.properties" />
        </property>
    </bean> 
</beans>

的applicationContext-web.xml中

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:aop="http://www.springframework.org/schema/aop" 
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:jee="http://www.springframework.org/schema/jee" 
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:util="http://www.springframework.org/schema/util"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:p="http://www.springframework.org/schema/p" 

    xsi:schemaLocation=
    "http://www.springframework.org/schema/aop 
    http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
    http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans-3.2.xsd 
    http://www.springframework.org/schema/context 
    http://www.springframework.org/schema/context/spring-context-3.2.xsd 
    http://www.springframework.org/schema/jee
    http://www.springframework.org/schema/jee/spring-jee-3.2.xsd
    http://www.springframework.org/schema/tx 
    http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
    http://www.springframework.org/schema/mvc 
    http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
    http://www.springframework.org/schema/util
    http://www.springframework.org/schema/util/spring-util-3.2.xsd"
    >
    <context:component-scan base-package="${controllerPackageName}"/>
    <mvc:annotation-driven/>
    <mvc:default-servlet-handler/>

    <mvc:resources location="/, classpath:/META-INF/web-resources/" mapping="/resources/**"/>

    <mvc:interceptors>
        <bean class="org.springframework.web.servlet.theme.ThemeChangeInterceptor"/>
        <bean class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor" p:paramName="lang"/>
    </mvc:interceptors>
    <mvc:view-controller path="/uncaughtException"/>
    <mvc:view-controller path="/resourceNotFound"/>
    <mvc:view-controller path="/dataAccessFailure"/>

    <bean class="org.springframework.context.support.ReloadableResourceBundleMessageSource" id="messageSource"  p:fallbackToSystemLocale="false">
        <property name="basenames">
            <list>
                <value>META-INF/web-resources/i18n/accountCreation/messages</value>
                <value>META-INF/web-resources/i18n/accountCreation/application</value>
                <value>META-INF/web-resources/i18n/accountCreation/errors</value>
                <!-- Keep Global resource bundles at the bottom, they are checked last -->
                <value>META-INF/web-resources/i18n/global_messages</value>
                <value>META-INF/web-resources/i18n/global_application</value>
                <value>META-INF/web-resources/i18n/global_errors</value>
            </list>
        </property>
    </bean>
    <bean class="org.springframework.web.servlet.i18n.CookieLocaleResolver" id="localeResolver" p:cookieName="locale">
        <property name="defaultLocale" value="en"/>
    </bean>
    <bean class="org.springframework.ui.context.support.ResourceBundleThemeSource" id="themeSource"/>
    <bean class="org.springframework.web.servlet.theme.CookieThemeResolver" id="themeResolver" p:cookieName="theme" p:defaultThemeName="standard"/>
    <bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver" p:defaultErrorView="exceptions/uncaughtException">
        <property name="exceptionMappings">
            <props>
                <prop key=".DataAccessException">exceptions/dataAccessFailure</prop>
                <prop key=".NoSuchRequestHandlingMethodException">exceptions/resourceNotFound</prop>
                <prop key=".TypeMismatchException">exceptions/resourceNotFound</prop>
                <prop key=".MissingServletRequestParameterException">exceptions/resourceNotFound</prop>
            </props>
        </property>
    </bean>

    <!-- Enable this for integration of file upload functionality -->
    <bean class="org.springframework.web.multipart.commons.CommonsMultipartResolver" id="multipartResolver"/>
<!-- TymeLeaf Settings -->
<!-- THYMELEAF: Template Resolver for webapp pages   --> 
    <bean class="org.thymeleaf.templateresolver.ServletContextTemplateResolver" id="templateResolver">
      <property name="prefix" value="/WEB-INF/templates/"/>
      <property name="suffix" value=".html"/>
      <property name="templateMode" value="HTML5"/>
    </bean>
<!-- THYMELEAF: Template Engine (Spring3-specific version) -->     
    <bean class="org.thymeleaf.spring3.SpringTemplateEngine" id="templateEngine">
      <qualifier value="templateEngine"/>
      <property name="templateResolver" ref="templateResolver"/>
    </bean>
<!-- THYMELEAF: View Resolver - implementation of Spring's ViewResolver interface --> 
    <bean class="org.thymeleaf.spring3.view.ThymeleafViewResolver">
      <property name="templateEngine" ref="templateEngine"/>
    </bean>
</beans>

Answer 1

如果您的应用程序配置为挂钩JPA实体的方法，则如果直接设置字段，它可能无法跟踪更改。尝试使用setter方法：

@PrePersist
public void prePersist() {
    Calendar now = Calendar.getInstance();
    this.setCreatedOn(now);
    this.setModifiedOn(now);
}


@PreUpdate
public void preUpdate() {
    Calendar now = Calendar.getInstance();
    this.setModifiedOn(now);
}

此外，正如a simily question的答案中所述，这些注释行为依赖于实现：

  

请注意，在实体被持久化并随后在单个事务中进行修改或者在单个事务中修改实体并随后将其删除时，是否依赖于实现来确定是否发生PreUpdate和PostUpdate回调。便携式应用程序不应该依赖这种行为。

所以它可能取决于你如何加载和保存你的实体。