Springboot 之JPA查询报错
在 CatDao中添加自定义查询方法后，启动报错
2019-06-11 11:06:13.874 INFO 14700 --- [ restartedMain] org.hibernate.Version : HHH000412: Hibernate Core {5.3.7.Final}
2019-06-11 11:06:13.890 INFO 14700 --- [ restartedMain] org.hibernate.cfg.Environment : HHH000206: hibernate.properties not found
2019-06-11 11:06:16.270 INFO 14700 --- [ restartedMain] o.hibernate.annotations.common.Version : HCANN000001: Hibernate Commons Annotations {5.0.4.Final}
2019-06-11 11:06:17.403 INFO 14700 --- [ restartedMain] org.hibernate.dialect.Dialect : HHH000400: Using dialect: org.hibernate.dialect.MySQL5InnoDBDialect
2019-06-11 11:06:23.144 INFO 14700 --- [ restartedMain] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default'
2019-06-11 11:06:23.318 INFO 14700 --- [ restartedMain] o.s.b.d.a.OptionalLiveReloadServer : LiveReload server is running on port 35729
2019-06-11 11:06:25.815 WARN 14700 --- [ restartedMain] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'catController': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'catService': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'catDao': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Failed to create query for method public abstract java.util.List com.demo.dao.CatDao.findByCatName(java.lang.String)! Unable to locate Attribute with the the given name [catName] on this ManagedType [com.demo.bean.Cat]
2019-06-11 11:06:25.816 INFO 14700 --- [ restartedMain] j.LocalContainerEntityManagerFactoryBean : Closing JPA EntityManagerFactory for persistence unit 'default'
2019-06-11 11:06:25.842 INFO 14700 --- [ restartedMain] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Shutdown initiated...
2019-06-11 11:06:25.855 INFO 14700 --- [ restartedMain] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Shutdown completed.
2019-06-11 11:06:25.858 INFO 14700 --- [ restartedMain] o.apache.catalina.core.StandardService : Stopping service [Tomcat]
2019-06-11 11:06:26.021 INFO 14700 --- [ restartedMain] ConditionEvaluationReportLoggingListener :
Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2019-06-11 11:06:26.228 ERROR 14700 --- [ restartedMain] o.s.boot.SpringApplication : Application run failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'catController': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'catService': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'catDao': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Failed to create query for method public abstract java.util.List com.demo.dao.CatDao.findByCatName(java.lang.String)! Unable to locate Attribute with the the given name [catName] on this ManagedType [com.demo.bean.Cat]
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:324) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1395) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:592) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:849) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:877) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142) ~[spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775) [spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) [spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260) [spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248) [spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
at com.SpringBootHelloApplication.main(SpringBootHelloApplication.java:16) [classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_121]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_121]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_121]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_121]
at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-2.1.3.RELEASE.jar:2.1.3.RELEASE]
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'catService': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'catDao': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Failed to create query for method public abstract java.util.List com.demo.dao.CatDao.findByCatName(java.lang.String)! Unable to locate Attribute with the the given name [catName] on this ManagedType [com.demo.bean.Cat]
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:324) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1395) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:592) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:204) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.resolveBeanByName(AbstractAutowireCapableBeanFactory.java:452) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:526) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:496) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:636) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:180) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:321) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
... 22 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'catDao': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Failed to create query for method public abstract java.util.List com.demo.dao.CatDao.findByCatName(java.lang.String)! Unable to locate Attribute with the the given name [catName] on this ManagedType [com.demo.bean.Cat]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1762) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:593) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:277) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1247) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1167) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:520) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:496) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:636) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:180) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:321) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
... 36 common frames omitted
Caused by: java.lang.IllegalArgumentException: Failed to create query for method public abstract java.util.List com.demo.dao.CatDao.findByCatName(java.lang.String)! Unable to locate Attribute with the the given name [catName] on this ManagedType [com.demo.bean.Cat]
at org.springframework.data.jpa.repository.query.PartTreeJpaQuery.<init>(PartTreeJpaQuery.java:82) ~[spring-data-jpa-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$CreateQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:103) ~[spring-data-jpa-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$CreateIfNotFoundQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:208) ~[spring-data-jpa-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$AbstractQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:79) ~[spring-data-jpa-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lookupQuery(RepositoryFactorySupport.java:566) ~[spring-data-commons-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$mapMethodsToQuery$1(RepositoryFactorySupport.java:559) ~[spring-data-commons-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193) ~[na:1.8.0_121]
at java.util.Iterator.forEachRemaining(Iterator.java:116) ~[na:1.8.0_121]
at java.util.Collections$UnmodifiableCollection$1.forEachRemaining(Collections.java:1049) ~[na:1.8.0_121]
at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801) ~[na:1.8.0_121]
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481) ~[na:1.8.0_121]
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471) ~[na:1.8.0_121]
at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708) ~[na:1.8.0_121]
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:1.8.0_121]
at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499) ~[na:1.8.0_121]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.mapMethodsToQuery(RepositoryFactorySupport.java:561) ~[spring-data-commons-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$new$0(RepositoryFactorySupport.java:551) ~[spring-data-commons-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at java.util.Optional.map(Optional.java:215) ~[na:1.8.0_121]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.<init>(RepositoryFactorySupport.java:551) ~[spring-data-commons-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport.getRepository(RepositoryFactorySupport.java:324) ~[spring-data-commons-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.lambda$afterPropertiesSet$5(RepositoryFactoryBeanSupport.java:297) ~[spring-data-commons-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.util.Lazy.getNullable(Lazy.java:211) ~[spring-data-commons-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.util.Lazy.get(Lazy.java:94) ~[spring-data-commons-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.afterPropertiesSet(RepositoryFactoryBeanSupport.java:300) ~[spring-data-commons-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean.afterPropertiesSet(JpaRepositoryFactoryBean.java:119) ~[spring-data-jpa-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1821) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1758) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
... 51 common frames omitted
Caused by: java.lang.IllegalArgumentException: Unable to locate Attribute with the the given name [catName] on this ManagedType [com.demo.bean.Cat]
at org.hibernate.metamodel.internal.AbstractManagedType.checkNotNull(AbstractManagedType.java:128) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.metamodel.internal.AbstractManagedType.getAttribute(AbstractManagedType.java:113) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.springframework.data.jpa.repository.query.QueryUtils.toExpressionRecursively(QueryUtils.java:593) ~[spring-data-jpa-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.jpa.repository.query.QueryUtils.toExpressionRecursively(QueryUtils.java:577) ~[spring-data-jpa-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.jpa.repository.query.JpaQueryCreator$PredicateBuilder.getTypedPath(JpaQueryCreator.java:379) ~[spring-data-jpa-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.jpa.repository.query.JpaQueryCreator$PredicateBuilder.build(JpaQueryCreator.java:302) ~[spring-data-jpa-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.jpa.repository.query.JpaQueryCreator.toPredicate(JpaQueryCreator.java:207) ~[spring-data-jpa-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.jpa.repository.query.JpaQueryCreator.create(JpaQueryCreator.java:120) ~[spring-data-jpa-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.jpa.repository.query.JpaQueryCreator.create(JpaQueryCreator.java:57) ~[spring-data-jpa-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.repository.query.parser.AbstractQueryCreator.createCriteria(AbstractQueryCreator.java:119) ~[spring-data-commons-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.repository.query.parser.AbstractQueryCreator.createQuery(AbstractQueryCreator.java:95) ~[spring-data-commons-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.repository.query.parser.AbstractQueryCreator.createQuery(AbstractQueryCreator.java:81) ~[spring-data-commons-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.jpa.repository.query.PartTreeJpaQuery$QueryPreparer.<init>(PartTreeJpaQuery.java:145) ~[spring-data-jpa-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.jpa.repository.query.PartTreeJpaQuery$CountQueryPreparer.<init>(PartTreeJpaQuery.java:268) ~[spring-data-jpa-2.1.5.RELEASE.jar:2.1.5.RELEASE]
at org.springframework.data.jpa.repository.query.PartTreeJpaQuery.<init>(PartTreeJpaQuery.java:77) ~[spring-data-jpa-2.1.5.RELEASE.jar:2.1.5.RELEASE]
... 77 common frames omitted
Process finished with exit code 0
1.controller层
@RestController @RequestMapping("/cat") public class CatController { @Resource private CatService catService; @GetMapping(value = "/findByCatName") public List<Cat> findByCatName(String catName){ return catService.findByCatName(catName); } }
2.service层
@Service public class CatService { @Resource private CatDao catRepository; public List<Cat> findByCatName(String catName){ return catRepository.findByCatName(catName); } }
3.dao层
public interface CatDao extends JpaRepository<Cat,Integer> { //根据名称查询 List<Cat> findByCatName(String catName); }
这样看着代码是没什么问题，而且之前在启动项目的时候，我可以通过代码生成数据库表了，所以就很自然的认为，实体是没有问题的；
但是在网上查了很多资料都是说dao层的字段名称和实体的不一致的问题，所以我就把注意力放在dao层上面去查问题，就这样查了好久，依然觉得代码没问题（很无奈啊….）
后来实在没有办法了就又去检查实体字段名称的定义，终于找到问题了，是因为字段的定义不符合规范，虽然之前已经可以通过实体生成表结构，但是在使用查询的时候，不知道为
什么还是注入不了（这个目前还没有搞清楚），最后把正确的实体贴出来，以来警醒自己吧
之前定义的变量名称是：CatAge/CatName
@Entity public class Cat { @Id @GeneratedValue(strategy = GenerationType.AUTO) private int id ;//主键 private String catName;//姓名 private int catAge; //年龄 public int getId() { return id; } public void setId(int id) { this.id = id; } public String getCatName() { return catName; } public void setCatName(String catName) { this.catName = catName; } public int getCatAge() { return catAge; } public void setCatAge(int catAge) { this.catAge = catAge; } }
总结：
这次的错误主要是在创建实体的时候，变量的命名不规范造成的，所以简单总结下java的常用的几个命名规则：
1.包： 所有包的命名必须采用小写英文字母；
2. 类：参照java驼峰命名法，类名的首字母必须采用大写的形式，如果类名为多词组合而成的话，那么每个词的首字母必须采用大写。eg:CatDao；
3.方法：参照java驼峰命名法，首字母以小写开头，每个单词首字母大写（第一个单词除外）；
4.变量：首字母以小写开头，每个单词首字母大写（第一个单词除外）；
CatDao
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