SpringBoot无法自动创建数据库，请求排查启动异常与配置问题

我刚开始学习SpringBoot，按照教授指导的步骤操作，但无法自动创建数据库。日志显示无法加载MySQL驱动类com.mysql.cj.jdbc.Driver，导致数据源创建失败，应用启动终止。我的目标是在MySQL Workbench中生成对应的数据表。

配置文件（application.properties） #

spring.datasource.url = jdbc:mysql://localhost:3306/dbLastNameDemo
spring.datasource.username = root
spring.datasource.password = password

spring.jpa.database-platform = org.hibernate.dialect.MySQL5InnoDBDialect
spring.jpa.hibernate.ddl-auto = update

spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5InnoDBDialect

server.error.include.stacktrace=never

控制台启动日志 #

2023-10-04 21:24:10.672  INFO 24832 --- [  restartedMain] c.c.delapena.DelapenaApplication         : Starting DelapenaApplication using Java 19.0.1 on Daesut with PID 24832 (C:\Users\Daesut\Downloads\delapena\delapena\target\classes started by Daesut in C:\Users\Daesut\Downloads\delapena\delapena)
2023-10-04 21:24:10.673  INFO 24832 --- [  restartedMain] c.c.delapena.DelapenaApplication         : No active profile set, falling back to 1 default profile: "default"
2023-10-04 21:24:10.717  INFO 24832 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2023-10-04 21:24:10.717  INFO 24832 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2023-10-04 21:24:11.134  INFO 24832 --- [  restartedMain] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data JPA repositories in DEFAULT mode.
2023-10-04 21:24:11.145  INFO 24832 --- [  restartedMain] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 4 ms. Found 0 JPA repository interfaces.
2023-10-04 21:24:11.702  INFO 24832 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2023-10-04 21:24:11.714  INFO 24832 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2023-10-04 21:24:11.714  INFO 24832 --- [  restartedMain] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.80]
2023-10-04 21:24:11.774  INFO 24832 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2023-10-04 21:24:11.774  INFO 24832 --- [  restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1057 ms
2023-10-04 21:24:11.821 ERROR 24832 --- [  restartedMain] com.zaxxer.hikari.HikariConfig           : Failed to load driver class com.mysql.cj.jdbc.Driver from HikariConfig class classloader jdk.internal.loader.ClassLoaders$AppClassLoader@c387f44
2023-10-04 21:24:11.823  WARN 24832 --- [  restartedMain] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'dataSourceScriptDatabaseInitializer' defined in class path resource [org/springframework/boot/autoconfigure/sql/init/DataSourceInitializationConfiguration.class]: Unsatisfied dependency expressed through method 'dataSourceScriptDatabaseInitializer' parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [org/springframework/boot/autoconfigure/jdbc/DataSourceConfiguration$Hikari.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.zaxxer.hikari.HikariDataSource]: Factory method 'dataSource' threw exception; nested exception is java.lang.RuntimeException: Failed to load driver class com.mysql.cj.jdbc.Driver in either of HikariConfig class loader or Thread context classloader
2023-10-04 21:24:11.825  INFO 24832 --- [  restartedMain] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2023-10-04 21:24:11.835  INFO 24832 --- [  restartedMain] ConditionEvaluationReportLoggingListener : 

解决方案 #

• 添加MySQL驱动依赖：项目缺少MySQL JDBC驱动包，这是核心问题。

  • Maven项目：在pom.xml中添加以下依赖

    <dependency>
        <groupId>com.mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <scope>runtime</scope>
    </dependency>
    

  • Gradle项目：在build.gradle中添加

    runtimeOnly 'com.mysql:mysql-connector-j'
    

  注：Spring Boot 2.4及以上版本推荐使用mysql-connector-j，旧版本用mysql-connector-java。

• 提前创建数据库：Spring Boot只能自动生成数据表，无法自动创建数据库。需先在MySQL Workbench中执行SQL：CREATE DATABASE dbLastNameDemo;

• 可选：显式指定驱动类：虽然Spring Boot会自动推断，但可在application.properties中添加配置确保正确性：

  spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
  

• 检查MySQL服务状态：确认本地MySQL服务正在运行，端口3306未被占用。

• 同步依赖：添加依赖后，执行Maven的clean install或Gradle的build命令，确保依赖下载完成。

内容的提问来源于stack exchange，提问作者Daniel Gilbert Dela Peña