1. pom.xml

<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.example</groupId>
    <artifactId>my-springboot1</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.0.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <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-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <version>1.4.197</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>6.0.6</version>
        </dependency>
        <dependency>
            <groupId>com.oracle</groupId>
            <artifactId>ojdbc6</artifactId>
            <version>11.2.0.4.0-atlassian-hosted</version>
        </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>

2. application.properties

server.port=9000
db=oracle
################JPA-DATA的配置############################
##此处不能使用${db}替换
spring.jpa.database-platform=${oracle.dialect}
spring.jpa.generate-ddl=true
spring.jpa.show-sql=true
spring.jpa.hibernate.ddl-auto=create

################ DataSource的配置 ############################
spring.datasource.url=${${db}.url}
spring.datasource.driverClassName=${${db}.driverClassName}
spring.datasource.username=${${db}.username}
spring.datasource.password=${${db}.password}
spring.datasource.platform=${${db}.platform}

#打开h2的管理控制台（http://localhost:9000/h2-console）
spring.h2.console.enabled=true

########### h2 #####################################
#h2.url=jdbc:h2:mem:test
h2.url=jdbc:h2:file:./db/test01
#h2.url=jdbc:h2:mem:test;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE
h2.driverClassName=org.h2.Driver
h2.username=sa
h2.password=
h2.platform=h2
h2.dialect=org.hibernate.dialect.H2Dialect
########### mysql #####################################
mysql.url=jdbc:mysql://localhost:3306/test
mysql.driverClassName=com.mysql.cj.jdbc.Driver
mysql.username=root
mysql.password=123
mysql.platform=mysql
mysql.dialect=org.hibernate.dialect.MySQL57Dialect

########### oracle #####################################
oracle.url=jdbc:oracle:thin:@10.211.55.4:1521:xe
oracle.driverClassName=oracle.jdbc.OracleDriver
oracle.username=john
oracle.password=123
oracle.platform=oracle
oralce.dialect=org.hibernate.dialect.Oracle10gDialect

#########库及数据的初始化####################################
#spring.datasource.schema=classpath:db/schema.sql
#spring.datasource.data=classpath:db/data.sql

4. 测试

@RunWith(SpringRunner.class)
@SpringBootTest
public class DemoApplicationTests {
    @Autowired private BookRepository br;
    @Test public void test1(){
        Book book=new Book();
        book.setBname("tom");
        br.save(book);
    }
}