如何使用 Spring Boot 配置 JPA + HIBERNATE

Question

我想使用 entiies 和 jpa 来处理我的数据库。

当我只是想在 SpringConfig.java 中创建 bean 时：

    @Bean
    @Singleton
    public EntityManager getEntityManager(){
        return Persistence.createEntityManagerFactory("collection").createEntityManager();
    }

我有：

Caused by: javax.persistence.PersistenceException: No Persistence provider for EntityManager named collection:  No META-INF/persistence.xml was found in classpath.

但名称“collection”与 persistence-unit 中的名称相同

我的 persistence.xml 位于 resources (src/main/resources) 并配置为 jpa in弹簧靴

更新：

当我尝试将 persistence.xml 放入资源/META-INF/ 时，我遇到了另一个例外：

Caused by: javax.persistence.PersistenceException: No Persistence provider for EntityManager named collection: Provider named org.hibernate.jpa.HibernatePersistenceProvider threw unexpected exception at create EntityManagerFactory: 
java.lang.NoSuchMethodError

Answer 1

在这种情况下，最好使用 application.properties 作为属性文件。

#spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/concretepage
spring.datasource.username=root
spring.datasource.password=
spring.datasource.tomcat.max-wait=20000
spring.datasource.tomcat.max-active=50
spring.datasource.tomcat.max-idle=20
spring.datasource.tomcat.min-idle=15

spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQLDialect
spring.jpa.properties.hibernate.id.new_generator_mappings = false
spring.jpa.properties.hibernate.format_sql = true

logging.level.org.hibernate.SQL=DEBUG
logging.level.org.hibernate.type.descriptor.sql.BasicBinder=TRACE 

并且在 Dao 实现类中注入这样的依赖：

@PersistenceContext
    private EntityManager entityManager;

pom.xml 内容应该如下：

<?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.concretepage</groupId>
    <artifactId>spring-boot-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>spring-demo</name>
    <description>Spring Boot Demo Project</description>
    <parent>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-parent</artifactId>
       <version>1.5.2.RELEASE</version>
    </parent>
    <properties>
       <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>   
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>    
            <dependency>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-devtools</artifactId>
                    <optional>true</optional>
            </dependency> 
    </dependencies> 
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>