springboot初始化activiti表失败——mysql8.xxx的坑

2021-04-09 14:47:48.732 ERROR 5088 --- [ main] o.a.e.impl.interceptor.CommandContext : Error while closing command context

org.apache.ibatis.exceptions.PersistenceException:
### Error querying database. Cause: java.sql.SQLSyntaxErrorException: Table 'activiti.act_ge_property' doesn't exist
### The error may exist in org/activiti/db/mapping/entity/Property.xml
### The error may involve org.activiti.engine.impl.persistence.entity.PropertyEntityImpl.selectProperty-Inline
### The error occurred while setting parameters
### SQL: select * from ACT_GE_PROPERTY where NAME_ = ?
### Cause: java.sql.SQLSyntaxErrorException: Table 'activiti.act_ge_property' doesn't exist
at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30) ~[mybatis-3.5.6.jar:3.5.6]

问题分析：

因为mysql使用schema标识库名而不是catalog，因此mysql会扫描所有的库来找表，如果其他库中有相同名称的表，activiti就以为找到了，本质上这个表在当前数据库中并不存在。
设置nullCatalogMeansCurrent=true，表示mysql默认当前数据库操作，在mysql-connector-java 5.xxx该参数默认为true，在6.xxx以上默认为false，因此需要设置nullCatalogMeansCurrent=true

解决办法：

yml数据源配置：

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql:///activiti?useUnicode=true&characterEncoding=utf8&nullCatalogMeansCurrent=true&useSSL=false&useLegacyDatetimeCode=false&serverTimezone=UTC
    username: root
    password: root