Spring Boot通过STS连接MySQL失败，寻求解决方案

错误日志 #

[2m2023-03-13T08:40:09.974+05:30[0;39m [32m INFO[0;39m [35m9720[0;39m [2m---[0;39m [2m[           main][0;39m [36mcom.zaxxer.hikari.HikariDataSource      [0;39m [2m:[0;39m root - Starting...
[2m2023-03-13T08:40:11.259+05:30[0;39m [31mERROR[0;39m [35m9720[0;39m [2m---[0;39m [2m[           main][0;39m [36mcom.zaxxer.hikari.pool.HikariPool       [0;39m [2m:[0;39m root - Exception during pool initialization.

com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-java-8.0.30.jar:8.0.30]
    at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-java-8.0.30.jar:8.0.30]
    at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:828) ~[mysql-connector-java-8.0.30.jar:8.0.30]
    at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:448) ~[mysql-connector-java-8.0.30.jar:8.0.30]

配置文件 #

application.properties #

spring.datasource.url=jdbc:mysql://localhost:3307/learn
spring.datasource.name=root
spring.datasource.password=2071
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL57Dialect;
spring.jpa.show-sql=true
spring.jpa.hibernate.ddl-auto=update

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 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>3.0.4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.jpa.test</groupId>
    <artifactId>bootjpaexample</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>bootjpaexample</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.30</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>

解决方法 #

1. 修正数据源用户名配置项 #

配置中错误使用了spring.datasource.name，Spring Boot中正确的用户名配置键是spring.datasource.username，修改后：

spring.datasource.username=root

2. 验证MySQL端口正确性 #

默认MySQL端口是3306，你配置的是3307，需要确认本地MySQL服务确实运行在3307端口。可以用MySQL客户端（如MySQL Workbench）尝试连接localhost:3307，验证端口是否可用。

3. 修复Hibernate方言配置 #

方言配置末尾多了一个分号，会导致解析错误，去掉分号：

spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL57Dialect

另外，Spring Boot 3.x搭配MySQL 8.x更推荐使用org.hibernate.dialect.MySQL8Dialect，适配性更好。

4. 确认MySQL服务状态 #

确保本地MySQL服务已经启动：

• Windows：执行net start mysql
• Linux/macOS：执行sudo systemctl start mysql

5. 调整MySQL驱动兼容性 #

Spring Boot 3.0.4默认适配的MySQL驱动版本高于8.0.30，建议去掉手动指定的版本号，让Spring Boot自动管理适配版本：

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>

或者改用MySQL官方新坐标（8.0.33+版本推荐）：

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

6. 补充URL连接参数（可选） #

MySQL 8.x连接时建议添加时区、SSL相关参数，避免时区错误和连接问题：

spring.datasource.url=jdbc:mysql://localhost:3307/learn?useSSL=false&serverTimezone=Asia/Shanghai&allowPublicKeyRetrieval=true

内容的提问来源于stack exchange，提问作者Praveen Kumar