如何在 Spring Boot 应用程序中从数据库表中填充实体

Question

**我正在尝试创建一个springboot应用程序并创建了数据库和表。现在需要从创建的数据库表中填充实体。 Spring sts 是我的编辑器。我没有创建任何单独的配置类来设置数据源等，因为我希望 springboot 能够做到这一点。我是否需要有单独的配置类来建立连接。但是在尝试填充实体时会出现以下错误。 **

org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set
Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set

下面给出的是应用程序文件

> 这是 application.properties 文件。

spring.jpa.hibernate.ddl-auto=none
spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.username=root
spring.datasource.password=root

spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect
spring.jpa.show-sql=false
spring.jpa.hibernate.ddl-auto=update

server.port=${PORT:8081

}

>这是我的 pom.xml 文件

    <?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 https://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>2.3.0.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>io.javabrains.com</groupId>
    <artifactId>spring-security-jdbc</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>spring-security-jdbc</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-jdbc</artifactId>
        </dependency>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-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>

>主类

    @SpringBootApplication
public class SpringSecurityJdbcApplication {

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

}

请帮助解决此问题。提前致谢。

Answer 1

我认为问题出在您的 application.properties 文件中。

你有：

spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect

但是jpa 上没有properties 属性。 尝试删除属性，您的行应如下所示：

spring.jpa.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect