Spring Boot 项目 Mysql数据库连接问题

记录一次搭建SpringBoot项目时连接数据库的问题，版本：SpringBoot 2.3.1/mysql 5.6.47

启动项目时出现警告：

2020-06-22 10:19:21.704  INFO 8720 --- [           main] o.a.catalina.core.AprLifecycleListener   : OpenSSL successfully initialized [OpenSSL 1.1.1c  28 May 2019]
2020-06-22 10:19:21.777  INFO 8720 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2020-06-22 10:19:21.777  INFO 8720 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1120 ms
Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.
2020-06-22 10:19:22.184  INFO 8720 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2020-06-22 10:19:22.247  INFO 8720 --- [           main] o.s.b.a.w.s.WelcomePageHandlerMapping    : Adding welcome page template: index
2020-06-22 10:19:22.419  INFO 8720 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''

请求数据库时异常日志如下：

java.sql.SQLException: The server time zone value '�й���׼ʱ��' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the 'serverTimezone' configuration property) to use a more specifc time zone value if you want to utilize time zone support.
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129) ~[mysql-connector-java-8.0.20.jar:8.0.20]
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) ~[mysql-connector-java-8.0.20.jar:8.0.20]
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89) ~[mysql-connector-java-8.0.20.jar:8.0.20]
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63) ~[mysql-connector-java-8.0.20.jar:8.0.20]
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:73) ~[mysql-connector-java-8.0.20.jar:8.0.20]
    at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:76) ~[mysql-connector-java-8.0.20.jar:8.0.20]
    at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836) ~[mysql-connector-java-8.0.20.jar:8.0.20]
    at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456) ~[mysql-connector-java-8.0.20.jar:8.0.20]
    at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246) ~[mysql-connector-java-8.0.20.jar:8.0.20]
    at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:197) ~[mysql-connector-java-8.0.20.jar:8.0.20]
    at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:138) ~[HikariCP-3.4.5.jar:na]
    at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:358) ~[HikariCP-3.4.5.jar:na]
    at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:206) ~[HikariCP-3.4.5.jar:na]
    at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:477) [HikariCP-3.4.5.jar:na]

部分配置如下：

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/test?setUnicode=true&characterEncoding=utf8
    username: root
    password: root

解决过程：

1. 警告日志提示新的驱动名称为  com.mysql.cj.jdbc.Driver 

2. 根据错误日志提示的信息，网上好多博主都是设置serverTimezone

于是修改配置文件为：

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/test?setUnicode=true&characterEncoding=utf8&serverTimezone=UTC
    username: root
    password: root

测试发现还是不行，想到之前项目很多出错的原因都是maven依赖导致的，于是查看mysql的依赖

<!-- mysql连接 -->
<dependency>
       <groupId>mysql</groupId>
       <artifactId>mysql-connector-java</artifactId>
       <scope>runtime</scope>
</dependency>

Ctrl + 左键 点击 mysql-connector-java  查看详细信息

<modelVersion>4.0.0</modelVersion>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.20</version>
<packaging>jar</packaging>

发现版本为8.0.20，这样就明白为什么会有上面的警告日志了，再考虑到我的数据库是5.6版本，于是尝试降低mysql依赖的版本，最终的解决方式如下

pom文件，指定mysql依赖版本

<!-- mysql连接 -->
<dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.20</version>
        <scope>runtime</scope>
</dependency>

修改yml配置文件

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/test?setUnicode=true&characterEncoding=utf8
    username: root
    password: root

 建议还是要设置一下serverTimezone时区问题 

url: jdbc:mysql://localhost:3306/test?setUnicode=true&characterEncoding=utf8&serverTimezone=UTC