Could not open JDBC Connection for transaction; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (Could not create connection to database server.-服务器

报错信息：Could not open JDBC Connection for transaction; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (Could not create connection to databa...

报错信息：Could not open JDBC Connection for transaction; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (Could not create connection to database server.)

问题来源mysql-connecter-java 版本过低如果你mysql的版本是mysql 8.0+ 而你的mysql-connecter-java 为5.x.x的时候就会报错这个错误所以如果你是maven环境更换如下版本还要更换数据库连接配置

            <!--
             https://mvnrepository.com/artifact/mysql/mysql-connector-java 
            -->
            <
            dependency
            >
            <
            groupId
            >mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.11</version></dependency>

数据库连接配置更新

driverClassName 配置 com.mysql.jdbc.Driver 替换为 com.mysql.cj.jdbc.Driver

url 配置 增加为 ?serverTimezone=UTC&amp;useUnicode=true&amp;characterEncoding=utf8&amp;useSSL=false"

效果：

            driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/XXXX?serverTimezone=UTC
            &useUnicode=true&characterEncoding=utf8&useSSL=false
username=root
password=

拓展

在上面配置：

url=jdbc:mysql://localhost:3306/XXXX?serverTimezone=UTC&useUnicode=true&characterEncoding=utf8&useSSL=false

中如果

serverTimezone配置为UTC 那么会比中国早八个小时 如果在中国你可以配置成ShangHai或者Hongkong 如下面所示

url=jdbc:mysql://localhost:3306/test?serverTimezone=Shanghai&useUnicode=true&characterEncoding=utf8&useSSL=false

报错信息： java.sql.SQLException: Unknown system variable ‘query_cache_size‘

问题来源mysql-connecter-java 版本过低如果你mysql的版本是mysql 8.0+ 而你的mysql-connecter-java 为6.x.x的就会报错这个错误所以如果你是maven环境更换如下版本就好了

如果错误依然为解决请参考上面更换数据库连接配置

            <!--
             https://mvnrepository.com/artifact/mysql/mysql-connector-java 
            -->
            <
            dependency
            >
            <
            groupId
            >mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.11</version></dependency>