Spring Boot Spring Data JPA 和存储库

【问题标题】：Spring Boot Spring Data JPA and RepositoriesSpring Boot Spring Data JPA 和存储库
【发布时间】：2018-08-06 08:58:40
【问题描述】：

我非常熟悉“旧版”Spring 4 应用程序。 “遗留”是指不使用 Spring Boot 并使用 application-context.xml 文件和注释。但是，我是 Spring Boot 和 Configuration 类的新手。

我正在创建一个新的 Spring Boot 应用程序，并将一些代码移动到我的旧 Spring 应用程序到这个新的 Spring Boot 应用程序。有了这个，我正在实现 Spring Data JPA？

我已经有了实体，所以我只是把它带进来。我有一个正确的 application.properties 设置。我按照我看到的所有示例中的描述创建了存储库，因此我有一个如下所示的存储库：

@Repository("contactDao")
public interface ContactDao extends CrudRepository<ContactEntity, Long>
{
}

所以，据我了解，findOne(Long id) 和 findAll() 等有很多函数。所有这些方法都是内置的。我什至能够对读取、写入到数据库，一切都很好。

所以，我现在想知道......我需要创建实现吗？我的意思是，因为我没有 EntityManager ...我需要一个吗？

我现在看到的所有示例，都显示了与上面类似的界面，但没有@Repository 注释：

 public interface ContactDao extends CrudRepository<ContactEntity, Long>
 {
 }

我现在看到需要实现的示例：

@Repository("contactDao")
public class ContactDaoImpl implements ContactDao 
{
    @PersistenceContext 
    private EntityManager entityManager;    

    @Override
    public ContactEntity findOne(Long contactId)
    {
          return entityManager.findOne(contactId);
    }
}

我认为 Spring Data JPA 的承诺是不必有 Impl，但接口就足够了????????????

出现这种情况的原因是因为我现在正在测试我的业务服务，它抱怨我缺少 EntityManagerFactory ...我认为我不需要一个。

在澄清方面的任何帮助将不胜感激。我正在查看 Google 并访问所有类型的站点和 github 项目，但其中一些站点和项目....如果它们不是从 2017 年开始的，它们很可能已经过时了。

我只想要按照当前标准构建这个项目的正确方法。

更新：

1) 放回我的接口 2) 删除了实现代码 3) DAO/Repository 代码测试正常 4) 新增业务服务：

public interface ContactService
{
    List<ContactEntity> getAllContacts();
    List<ContactEntity> getContactsByUserId(long userId);
    ContactEntity getContactById(long contactId);
    ContactEntity add(ContactEntity newContact);
    ContactEntity update(ContactEntity newContact);
    void remove(long contactId);
}

这是服务的实际实现：

@Transactional
@Service("contactService")
public class ContactServiceImpl implements ContactService
{
    @Autowired
    private ContactDao contactDao;   // THIS ERRORS

    @Override
    public List<ContactEntity> getAllContacts()
    {
        List<ContactEntity> contactList = (List<ContactEntity>) contactDao.findAll();
        return contactList;
     }

     @Override
     public List<ContactEntity> getContactsByUserId(long userId)
     {
          UserEntity userEntity = new UserEntity();
          userEntity.setUserId(userId);
          List<ContactEntity> contactList = contactDao.findByUser(userEntity);
          return contactList;
      }

      ... other methods ...
}

这是测试设置：

@Configuration
@ComponentScan("com.tomholmes.springboot.phonebook.server")
@EnableJpaRepositories(basePackages=
{"com.tomholmes.springboot.phonebook.server"})
@PropertySource(value = "classpath:application.properties")
public class TestServiceContextConfiguration
{     }

 @RunWith(SpringRunner.class)
 @SpringBootTest(classes = TestServiceContextConfiguration.class)
 @Transactional
 public class BaseServiceImplTests
 {     }

最后，这是测试本身：

public class ContactServiceImplTest extends BaseServiceImplTests
{
    @Autowired
    private ContactService service;

     @Test
     public void testFetchAll() throws Exception
    {
        List<ContactEntity> contactEntityList = service.getAllContacts();
        assertNotNull(contactEntityList);
     }
}

这是错误：

 java.lang.IllegalStateException: Failed to load ApplicationContext
at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:124)
at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:83)
at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:117)
at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:83)
at org.springframework.boot.test.autoconfigure.SpringBootDependencyInjectionTestExecutionListener.prepareTestInstance(SpringBootDependencyInjectionTestExecutionListener.java:44)
at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:230)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:228)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:287)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:289)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:247)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'contactEmailService': Unsatisfied dependency expressed through field 'contactEmailDao'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'contactEmailDao': Cannot create inner bean '(inner bean)#70ab80e3' of type [org.springframework.orm.jpa.SharedEntityManagerCreator] while setting bean property 'entityManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#70ab80e3': Cannot resolve reference to bean 'entityManagerFactory' while setting constructor argument; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'entityManagerFactory' available
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:303)
at org.springframework.boot.test.context.SpringBootContextLoader.loadContext(SpringBootContextLoader.java:120)
at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContextInternal(DefaultCacheAwareContextLoaderDelegate.java:98)
at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:116)
... 26 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'contactEmailDao': Cannot create inner bean '(inner bean)#70ab80e3' of type [org.springframework.orm.jpa.SharedEntityManagerCreator] while setting bean property 'entityManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#70ab80e3': Cannot resolve reference to bean 'entityManagerFactory' while setting constructor argument; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'entityManagerFactory' available
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:313)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:129)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1531)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1276)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585)
... 44 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#70ab80e3': Cannot resolve reference to bean 'entityManagerFactory' while setting constructor argument; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'entityManagerFactory' available
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:359)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:108)
at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorArguments(ConstructorResolver.java:634)
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:448)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1173)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1067)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:299)
... 57 more
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'entityManagerFactory' available
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:687)
at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:1207)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:284)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:351)
... 65 more

【问题讨论】：

  • 阅读参考文档。不是随机的例子（我们一无所知）。您的最后一个示例甚至无法编译，因此您找到它的来源不可靠。如果您有异常，并且想知道原因，请发布错误堆栈跟踪以及相关代码/配置。不要随意尝试或随意猜测。
  • 你不需要 Spring Data 接口上的 `@Repository´ 注释。如果您看到使用该注释的实现类，则它不是 Spring Data。参见例如本指南：spring.io/guides/gs/accessing-data-jpa
  • @JBNizet 我已阅读参考文档，但不是很清楚，如果是，就不会有这些问题。是的，我有一个例外，即自动装配 ContactDao 时我的服务代码没有找到 entityManagerFactoryBean ......那么它在哪里？它不在 Repository 中，是否需要在 Service 中？
  • 添加@Reposity 似乎并没有伤害任何东西，但它并没有解决我在哪里、为什么、如何需要 EntityManagerFactory 的问题。就像我说的，我是从一个遗留应用程序移植过来的，并试图通过使用“遗留”Spring 应用程序来学习 Spring Boot。
  • 这是我查看的页面之一：concretepage.com/spring-boot/…，这一页：mkyong.com/spring-boot/spring-boot-hibernate-search-example，这一页：callicoder.com/…

标签： java spring spring-boot spring-data-jpa


【解决方案1】：

你不需要实现 ContactDao 接口。

假设您有一个员工数据库。 举个例子：

@Repository
public interface ContactDao extends CrudRepository<ContactEntity, Long>{
    Employee findOne(Long id);
    List<Employee> findByName(String name);
    //etc...
}

然后在你的类中实现业务逻辑或者你可以在任何你想要的地方编写代码：

@Service
public class ServiceImpl implement Service{
    Autowired
    ContactDao contactDao;

    public Employee getEmployee(Long id){
        return contactDao.findOne(id);
    }
}

@Repository 或 @Service 或其他注释，您对 Spring Boot 说这些是 bean，因此它必须管理它们。

关于 EntityManager 的异常，请仔细阅读错误消息。也许你创建的 bean 有问题，或者你没有。谷歌它或发布它。

【讨论】：

  • 是的，这就是我最初所做的......所有接口，没有实现，当我尝试测试我的业务服务时，我得到了一个巨大的错误。
  • 那么你应该告诉我们你的错误。否则我们无法提供帮助。
  • @dunni 我刚刚发布了错误....我以前做过....虽然当我提出问题时，我并不经常有态度。我以为我们是来互相帮助的？这并不是说我没有研究过这一切，并且阅读了几本书试图找到答案。当我第一次学习 Spring 时，我不得不做很多相同的事情......大量的研究和反复试验，直到我发现所有的问题是什么。
【解决方案2】： 
package com.wisdom.spring.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;


import com.wisdom.spring.model.students;
import com.wisdom.spring.repo.students_repo;

@RestController
@RequestMapping("/students")
public class studentController {
    @Autowired
    students_repo STDRepo;

    @GetMapping(value = "/a")
    public String a() {
        return "hello";
    }

    @GetMapping(value = "/save")
    public List<students> getStudents(){

        System.out.println("Data returned");
        return STDRepo.findAll();
    }

    @PostMapping(value = "/savestd")
    public void saveBurger(students student) {
        STDRepo.save(student);
    }

}



package com.wisdom.spring.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class students {
    @Id
    @Column
    private int s_id;

    @Column
    private String name;

    @Column
    private String address;

    public students() {

    }

    public students(int s_id, String name, String address) {
        this.s_id = s_id;
        this.name = name;
        this.address = address;
    }

    public int getS_id() {
        return s_id;
    }

    public void setS_id(int s_id) {
        this.s_id = s_id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }



}



package com.wisdom.spring.repo;

import org.springframework.data.jpa.repository.JpaRepository;

import com.wisdom.spring.model.students;

public interface students_repo extends JpaRepository<students,String> {

}

//pom
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.wisdom.spring</groupId>
    <artifactId>myspringjpa</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>my-spring-jpa</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

//application config

spring.datasource.driverClassName=org.postgresql.Driver
spring.datasource.url=jdbc:postgresql://localhost:5433/finalproject
spring.datasource.username=postgres
spring.datasource.password=8855
spring.jpa.hibernate.ddl-auto=update
spring.jpa.generate-ddl=true
spring.jpa.show-sql=true
server.port=8585

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