Spring Data Cassandra LocalDateTime 转换答案

【问题标题】：Spring Data Cassandra LocalDateTime ConversionSpring Data Cassandra LocalDateTime 转换
【发布时间】：2015-04-20 18:53:33
【问题描述】：

我正在做一个项目，我们有一个实体，我们想要使用类型为 LocalDateTime 的字段进行持久化，我们知道 cassandra 没有对这种类型转换的本机支持，我们使用 Spring 的支持创建了自己的自定义转换器对于转换器，但是 Spring-Data-Cassandra 似乎无法识别它们或理解该字段应映射到列。

这就是我们向 Spring 的转换服务注册转换器的方式。

<bean id="conversionService" class="org.springframework.context.support.ConversionServiceFactoryBean">
        <property name="converters">
            <set>
                <!-- list of converters-->
                <bean class="com.klappo.userservice.api.persistence.converters.DateToLocalDateTimeConverter" />
                <bean class="com.klappo.userservice.api.persistence.converters.LocalDateTimeToDateConverter" />
                <bean class="com.klappo.userservice.api.persistence.converters.DateToLocalDateConverter" />
                <bean class="com.klappo.userservice.api.persistence.converters.LocalDateToDateConverter" />
            </set>
        </property>
    </bean>

最终结果是我们的应用程序启动时抛出以下异常：

    Caused by: 
org.springframework.data.cassandra.mapping.VerifierMappingExceptions: java.time.LocalDate:|Cassandra entities must have the @Table, @Persistent or @PrimaryKeyClass Annotation|
    at org.springframework.data.cassandra.mapping.BasicCassandraPersistentEntityMetadataVerifier.verify(BasicCassandraPersistentEntityMetadataVerifier.java:45)
    at org.springframework.data.cassandra.mapping.BasicCassandraPersistentEntity.verify(BasicCassandraPersistentEntity.java:198)
    at org.springframework.data.mapping.context.AbstractMappingContext.addPersistentEntity(AbstractMappingContext.java:297)
    at org.springframework.data.mapping.context.AbstractMappingContext$PersistentPropertyCreator.createAndRegisterProperty(AbstractMappingContext.java:469)
    at org.springframework.data.mapping.context.AbstractMappingContext$PersistentPropertyCreator.doWith(AbstractMappingContext.java:426)
    at org.springframework.util.ReflectionUtils.doWithFields(ReflectionUtils.java:607)
    at org.springframework.data.mapping.context.AbstractMappingContext.addPersistentEntity(AbstractMappingContext.java:294)
    at org.springframework.data.mapping.context.AbstractMappingContext$PersistentPropertyCreator.createAndRegisterProperty(AbstractMappingContext.java:469)
    at org.springframework.data.mapping.context.AbstractMappingContext$PersistentPropertyCreator.doWith(AbstractMappingContext.java:426)
    at org.springframework.util.ReflectionUtils.doWithFields(ReflectionUtils.java:607)
    at org.springframework.data.mapping.context.AbstractMappingContext.addPersistentEntity(AbstractMappingContext.java:294)
    at org.springframework.data.mapping.context.AbstractMappingContext.addPersistentEntity(AbstractMappingContext.java:256)
    at org.springframework.data.mapping.context.AbstractMappingContext.initialize(AbstractMappingContext.java:372)
    at org.springframework.data.cassandra.mapping.BasicCassandraMappingContext.initialize(BasicCassandraMappingContext.java:79)
    at org.springframework.data.mapping.context.AbstractMappingContext.afterPropertiesSet(AbstractMappingContext.java:362)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1612)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1549)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:539)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:328)
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:108)
    at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorArguments(ConstructorResolver.java:632)
    at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:140)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1114)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1017)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:504)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:328)
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:108)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1456)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1197)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:328)
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:108)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1456)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1197)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:328)
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:108)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1456)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1197)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1017)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:960)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:858)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:480)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:289)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1185)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:703)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:760)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106)
    at org.eclipse.jetty.server.handler.ContextHandler.callContextInitialized(ContextHandler.java:800)
    at org.eclipse.jetty.servlet.ServletContextHandler.callContextInitialized(ServletContextHandler.java:444)
    at org.eclipse.jetty.server.handler.ContextHandler.startContext(ContextHandler.java:791)
    at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:294)
    at org.eclipse.jetty.webapp.WebAppContext.startWebapp(WebAppContext.java:1349)
    at org.eclipse.jetty.maven.plugin.JettyWebAppContext.startWebapp(JettyWebAppContext.java:296)
    at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1342)
    at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:741)
    at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:505)
    at org.eclipse.jetty.maven.plugin.JettyWebAppContext.doStart(JettyWebAppContext.java:365)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
    at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)
    at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:114)
    at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
    at org.eclipse.jetty.server.handler.ContextHandlerCollection.doStart(ContextHandlerCollection.java:163)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
    at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)
    at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:114)
    at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
    at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)
    at org.eclipse.jetty.server.Server.start(Server.java:387)
    at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:114)
    at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
    at org.eclipse.jetty.server.Server.doStart(Server.java:354)
    at org.eclipse.jetty.maven.plugin.JettyServer.doStart(JettyServer.java:73)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
    at org.eclipse.jetty.maven.plugin.AbstractJettyMojo.startJetty(AbstractJettyMojo.java:534)
    at org.eclipse.jetty.maven.plugin.AbstractJettyMojo.execute(AbstractJettyMojo.java:357)
    at org.eclipse.jetty.maven.plugin.JettyRunMojo.execute(JettyRunMojo.java:167)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:132)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:208)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:120)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:347)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:154)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:582)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:214)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:158)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
    at org.codehaus.classworlds.Launcher.main(Launcher.java:46)

Spring 在这方面的数据文档缺乏很多，所以我们想知道是否有人尝试将自定义类型转换器与 spring-data-cassandra 一起使用，如果是，我们想知道正确的做法是什么它。

提前致谢。

【问题讨论】：

标签： java datetime converter java-8 spring-data-cassandra

【解决方案1】：

由于我有同样的问题，我想分享一些我的进一步调查结果：

spring data cassandra的验证器检查实体类的有效性，失败，因为字段类型LocalDateTime不是有效的简单类型
由于 cassandra 映射的糟糕实现，用自己的实现覆盖/扩展功能非常麻烦。特别是 CassandraSimpleTypeHolder 有一些 final 和 static 方法，可以直接在其他类中使用。
我尝试提供我自己的CassandraMappingContext、CassandraPersistentProperty 等的实现。这允许“验证”实体，但无法写入。这是由于使用的 datastax 驱动程序在其内部映射 TypeCode 中不知道 LocalDateTime。所以你必须提供 LocalDateTime 和 Date 之间的映射。这通常由 ConversionService 完成。但目前我没有找到任何使用它的地方。

不过，另一种选择是等待官方解决方案：

在内部使用 datastax 驱动程序。当前版本 3.0 可以使用额外模块来处理 jdk8 内容：http://www.datastax.com/dev/blog/datastax-java-driver-3-0-0-released
但是，当前的 spring 数据版本不支持 3.0 驱动程序和对 JSR310 的兼容性。它将成为下一个春季数据发布的一部分：https://github.com/spring-projects/spring-data-commons/wiki/Release-Train-Ingalls

【讨论】：

【解决方案2】：

不幸的是 spring-data-cassandra 版本。 http://www.datastax.com/documentation/developer/java-driver/1.0/java-driver/reference/javaClass2Cql3Datatypes_r.html

我遇到了同样的问题，因为想将我的类映射到 Cassandra 中的 TEXT 字段，但做不到。经过几天的尝试，我得出的结论是不可能在 Spring-Data for Cassandra 中使用自定义类型转换器（使用版本 1.2.0.M1 测试）。

CassandraTemplate 使用了 MappingCassandraConverter，它嵌入了 DefaultConversionService，但是这个 DefaultConversionService 并没有在 spring-data-cassandra 模块的任何地方使用。它只是为了与 SpringData API 集成而引入的。

您可以在库的代码中找到conversionService 仅在使用的库

BeanWrapper<S> wrapper = BeanWrapper.create(instance, conversionService);

只是跳过转换服务：

@Deprecated
public static <T> BeanWrapper<T> create(T bean, ConversionService conversionService) {
    return new BeanWrapper<T>(bean);
}

您可以在 MappingCassandraConverter.readPropertyFromRow(...) 中看到它使用 ColumnReader.get(int i) 仅支持 Cassandra 的 MAP、LIST、SET 和主要数据类型（文本、数字、UUID、java.util.Date、布尔值，字节缓冲区）。

此外，BasicCassandraMappingContext.verifier (BasicCassandraPersistentEntityMetadataVerifier) 在尝试写入任何无法映射到支持的 Cassandra 类型或不是 @Table 的字段时抛出异常。

这就是为什么你有例外

// it was attempt to check conversion of an embedded field 'date' in LocalDateTime    
org.springframework.data.cassandra.mapping.VerifierMappingExceptions: java.time.LocalDate

所以解决它的唯一方法是在 spring-data-cassandra 之上使用 ConversionService 来满足您的需求。

转换服务部分的示例代码：

import org.springframework.data.convert.Jsr310Converters;

...    

@Bean
public ConversionService getConversionService() {
    // creates DefaultConversionService
    ConversionServiceFactoryBean bean = new ConversionServiceFactoryBean();
    bean.setConverters(new HashSet<>(getConverters()));
    bean.afterPropertiesSet();
    ConversionService service = bean.getObject();
    return service;
}

private Set<Converter<?, ?>> getConverters() {
    Set<Converter<?,?>> converters = new HashSet<Converter<?,?>>();
    converters.addAll(Jsr310Converters.getConvertersToRegister());
    converters.add(new TimeWriteConverter());
    converters.add(new TimeReadConverter());

    return converters;
}

public static class TimeWriteConverter implements Converter<LocalDateTime, Long> {
    @Override
    public Long convert(LocalDateTime source) {
        return source.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli();
    }
}
public static class TimeReadConverter implements Converter<Long, LocalDateTime> {
    @Override
    public LocalDateTime convert(Long source) {
        return LocalDateTime.ofInstant(Instant.ofEpochMilli(source), ZoneId.systemDefault());
    }
}

【讨论】：

您是否找到任何解决方法，或者您在发现此问题后是如何实现映射的？
是的，我添加了额外的服务层，它以编程方式使用 ConversionService。这对我来说很好，因为在我的项目中需要某种时间序列 API（findLatest、findRange）。看起来像docs.spring.io/spring/docs/current/spring-framework-reference/…

【解决方案3】：

我可以看到与我的配置有些不同。

当你可以使用标准配置容器list时，首先为什么要使用set。

第二个：如果不行，试试java code config看看是否可行：

@Configuration
public class ConversionConfiguration {

    @Bean
    public ConversionService getConversionService() {
        ConversionServiceFactoryBean bean = new ConversionServiceFactoryBean();
        bean.setConverters(getConverters());
        bean.afterPropertiesSet();
        ConversionService object = bean.getObject();
        return object;
    }

    private Set<Converter> getConverters() {
        Set<Converter> converters = new HashSet<Converter>();

        converters.add(new DateToLocalDateTimeConverter());
        converters.add(new LocalDateTimeToDateConverter());
        converters.add(new DateToLocalDateConverter());
        converters.add(new LocalDateToDateConverter());

        return converters;
    }
}

【讨论】：

您能解释一下为什么在这种情况下 java config 的行为与 xml 不同吗？
@JörnHorstmann XML 的唯一问题是您必须等到运行时才能发现 bean 中的拼写错误或其他一些愚蠢的 boo-boo。另一方面，使用 Spring IDE 插件（或集成的 Spring Tools Suite）绝对可以帮助您解决错误并确保配置的完整性。
在我看来，XML 和基于注释的配置之间没有实际区别，因为任何现代 IDE 都支持检查配置（Intelij IDEA - Spring* 插件，Eclipse - Spring Tool Suite 插件） .例如，Spring 配置中的任何 XML 通常都被 XSD 模式很好地覆盖，因此在开发的早期阶段就发现了拼写错误。
@DmitryBuykin 你体贴的 cmets 大大扩大了我的无知范围。