SpringBoot整合MySQL启动失败：无法配置DataSource的url属性

报错信息 #

***************************
APPLICATION FAILED TO START
***************************

Description:

Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.

Reason: Failed to determine a suitable driver class

已排查项 #

• application.properties中指定的数据库已存在
• MySQL服务器正在运行
• pom.xml中已引入mysql-connector-j依赖
• Maven依赖中已包含mysql-connector-j-8.031.jar

环境版本 #

• java version "17.0.6" 2023-01-17 LTS
• Apache Maven 3.6.3
• Eclipse Version: 2022-12 (4.26.0)

相关配置 #

src/main/resources/application.properties #

spring.datasource.url=jdbc:mysql://localhost:3306/database_name
spring.datasource.username=
spring.datasource.password=
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

spring.jpa.database-platform = org.hibernate.dialect.MySQL5Dialect
spring.jpa.generate-ddl=true
spring.jpa.hibernate.ddl-auto=create
spring.jpa.show-sql=true

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

pom.xml #

<?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">

    <!-- The basics -->
    <modelVersion>4.0.0</modelVersion>
    
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.7</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    
    <groupId>com.example</groupId>
    <artifactId>MyProjectApplication</artifactId>
    <version>1.0.0</version>

    <!-- Dependencies -->
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</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-web</artifactId>
        </dependency>
                
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
                
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
        </dependency>

    </dependencies>

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

</project>

MyProjectApplication.java #

package com.springboot;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication()
public class MyProjectApplication {

    public static void main(String[] args) {
        SpringApplication.run(MyProjectApplication.class, "--debug");
    }

}

项目结构 #

src/
├── main/
│   ├── java/
│   │   └── com/
│   │       └── example/
│   │           └── myproject/
│   │               ├── MyProjectApplication.java
│   │               └── controllers/
│   │                   └── MyController.java
│   │               └── dao/
│                   ...
│                   ...  
│   ├── resources/
│   │   ├── application.properties
target/
pom.xml

解决方案 #

1. 补全数据库账号密码 #

application.properties中spring.datasource.username和spring.datasource.password为空，必须填入MySQL的有效账号密码，示例：

spring.datasource.username=root
spring.datasource.password=your_mysql_password

2. 修正主类包扫描范围 #

主类MyProjectApplication.java所在包为com.springboot，但业务类均在com.example.myproject下。@SpringBootApplication默认仅扫描主类所在包及其子包，导致数据源配置无法被正确识别。两种解决方式：

• 将MyProjectApplication.java移动到com.example.myproject包下
• 在@SpringBootApplication中显式指定扫描范围：

  @SpringBootApplication(scanBasePackages = "com.example.myproject")
  

3. 调整MySQL驱动依赖作用域 #

为mysql-connector-j添加runtime作用域，符合SpringBoot依赖规范，确保运行时能正确加载驱动：

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

4. 匹配MySQL 8.0对应的Hibernate方言 #

将spring.jpa.database-platform修改为适配MySQL 8.0的方言：

spring.jpa.database-platform = org.hibernate.dialect.MySQL8Dialect

5. 清理Eclipse缓存并重载Maven #

• 执行Project -> Clean清理项目
• 右键项目选择Maven -> Update Project，勾选Force Update of Snapshots/Releases后点击OK

6. 验证配置文件位置 #

确认application.properties位于src/main/resources目录下，文件名无拼写错误（如不要写成application.properites）。

内容的提问来源于stack exchange，提问作者alienko