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弹簧启动：不能使用持久性

java hibernate spring jpa spring-boot
2022-09-04 19:37:35

我已经进入了这个日子，虽然我学到了很多东西，但开始绝望。

我已经尝试了这个优秀问题的所有建议：

没有名为 EntityManager 的持久性提供程序

我曾经使用无处不在的HibernateUtil类进行过这项工作，但被告知要在这里转向普通的JPA风格：

弹簧控制器方法改进建议

不幸的是，我无法让豆类注射在弹簧靴中正常工作。这是我的尝试：

Spring JPA （Hibernate） 没有符合条件的 Bean 类型：javax.persistence.EntityManagerFactory

经过大量的工作，我最终得到了一个空实体管理器。我发现了这个，并开始认为它不起作用：

在 Tomcat 6 中使用 JPA2：@PersitenceContext不起作用，EntityManager 为 null

在我看来，EntityManagerFactory绝对应该在Spring-boot创造的任何上下文中成为一个豆子，但是......无论什么。我认为至少这可以工作：

应用程序启动：

@Configuration
@ComponentScan
@EnableAutoConfiguration
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

控制器：

@Controller
public class GetController {

    private static final String PERSISTENCE_UNIT_NAME = "cpJpaPu";  

    @RequestMapping(value = "/user", method = RequestMethod.GET)
    public @ResponseBody User getUser(@RequestParam(value="id", required=true) int id) {
        User user = null;

        EntityManagerFactory emf = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);
        EntityManager em = emf.createEntityManager();
        UserDAO userDao = new UserDAO();
        userDao.setEntityManager(em);
        user = userDao.load(id);

        return user;
    }
}

道：

public class UserDAO {

    public EntityManager entityManager;

    public void setEntityManager(EntityManager entityManager) {
        this.entityManager = entityManager;
    }

    public EntityManager getEntityManager() {
        return entityManager;
    }   

    public void insert(User user) {
        entityManager.persist(user);
    }

    public User load(int id) {
        return entityManager.find(User.class, id);
    }
}

/src/main/resources/persistence.xml：

<persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" version="1.0">
  <persistence-unit name="cpJpaPu" transaction-type="RESOURCE_LOCAL">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <class>com.mydomain.User</class>
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect"/>
      <property name="hibernate.connection.driver_class" value="org.postgresql.Driver"/>
      <property name="hibernate.show_sql" value="false"/>
      <property name="hibernate.connection.username" value="user"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:postgresql://localhost:5432/mydb"/>
    </properties>
  </persistence-unit>
</persistence>

它不起作用：

javax.persistence.PersistenceException: No Persistence provider for EntityManager named cpJpaPu
    javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:61)
    javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:39)
    com.mydomain.GetController.getUser(GetController.java:25)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    java.lang.reflect.Method.invoke(Unknown Source)
    org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:214)
    org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:748)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:689)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:947)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:878)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:946)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:837)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:822)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)

--- 新增信息---

聚 甲醛：

<?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>

    <groupId>com.mygroup</groupId>
    <artifactId>myartifact</artifactId>
    <version>0.1.0</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>0.5.0.M6</version>
    </parent>

    <dependencies>
        <!--  Spring framework -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!--  Hibernate -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>4.3.0.Final</version>
        </dependency>

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <!-- Must override version or face stack traces -->
            <version>4.3.0.Final</version>
        </dependency>

        <!-- Spring ORM, works with Hibernate -->   
        <dependency>
           <groupId>org.springframework</groupId>
           <artifactId>spring-orm</artifactId>
        </dependency>

        <!--  Spring implementation of Jackson for RESTful JSON -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>         
        </dependency>

        <!--  JDBC -->
        <dependency>
            <groupId>postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>9.1-901.jdbc4</version>
        </dependency>

        <!-- Logging -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
        </dependency>

        <!-- Prevent logging conflicts -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-logging</artifactId>
            <scope>compile</scope>
            <exclusions>                
                <exclusion>
                    <groupId>ch.qos.logback</groupId>
                    <artifactId>logback-classic</artifactId>
                </exclusion>
            </exclusions> 
        </dependency>
    </dependencies>

    <properties>
        <start-class>com.cloudfordev.controlpanel.Application</start-class>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

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

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>          
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <repositories>
        <repository>
            <id>spring-snapshots</id>
            <url>http://repo.spring.io/libs-snapshot</url>
            <snapshots><enabled>true</enabled></snapshots>
        </repository>
    </repositories>

    <pluginRepositories>
        <pluginRepository>
            <id>spring-snapshots</id>
            <url>http://repo.spring.io/libs-snapshot</url>
            <snapshots><enabled>true</enabled></snapshots>
        </pluginRepository>
    </pluginRepositories>
</project>

答案 1

spring boot 不读取持久性.xml文件缺省情况下，请参阅此处的文档

https://docs.spring.io/spring-boot/docs/current/reference/html/howto-data-access.html

因此，如果您想继续使用持久性.xml文件只需将以下代码添加到您的AppConfig类中即可

@Bean
public LocalEntityManagerFactoryBean entityManagerFactory(){
     LocalEntityManagerFactoryBean factoryBean = new LocalEntityManagerFactoryBean();
    factoryBean.setPersistenceUnitName("cpJpaPu");
    return factoryBean;
}

答案 2

不幸的是，JPA的某些功能只能在XML配置中工作，但我在你的功能中看不到类似的东西。我不认为是默认加载的，所以可能这就是问题所在。那么，为什么不顺应流程，使用 Java 和 application.properties 来配置实体管理器呢？Spring Boot 的 JPA 示例包含您入门所需的一切。它使用Spring Data JPA，而您的代码仅使用JPA API，但您可以通过删除示例中的Spring Data依赖项轻松恢复到该级别。persistence.xml

最近的Spring Boot快照具有一项功能，可让您创建自己的快照，以便您可以添加自定义XML配置，但是一旦需要自定义，就必须手动执行所有JPA配置。LocalEntityManagerFactoryBeanEntityManager

注意：你并没有真正在你的控制器中非常有效地使用依赖注入 - 你为什么不直接注入？UserDao


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