1. 首先切记！！：

mybatis多数据源的原理是根据不同包，调用不同的数据源，只需要把mapper.java和mapper.xml写在某个package中，springboot自动帮你实现数据源切换，这个不要弄错

2 配置双数据源报错

2.1.1 问题描述

org.springframework.beans.factory.BeanDefinitionStoreException: 
Failed to process import candidates for configuration class [com.telecom.SpBookActApplication]; 
nested exception is java.io.FileNotFoundException: class path resource [org/springframework/security/config/annotation/authentication/configurers/GlobalAuthenticationConfigurerAdapter.class] cannot be opened because it does not exist

2.1.2 解决方法

启动类中添加：

@SpringBootApplication(exclude = {
		org.activiti.spring.boot.SecurityAutoConfiguration.class,
	org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration.class})

2.2.1 问题描述

Failed to instantiate [org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean]:Factory method 'entityManagerFactory' threw exception;
nested exception is java.lang.IllegalArgumentException: jdbcUrl is required with driverClassName.

2.2.2 解决方法

将配置文件Application.yml中的 url:jdbc:mysql… 改为：jdbc-url: jdbc:mysql…

2.3.1 问题描述

Error creating bean with name 'bookInfoController': Unsatisfied dependency expressed through field 'iBookInfoService'; 
nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: 
Error creating bean with name 'bookInfoServiceImpl': Unsatisfied dependency expressed through field 'baseMapper'; 

2.3.2 解决方法

可能性1：实现类(XxxServiceImpl)没有加@Service注解，没有的话把这个注解加上。
可能性2：mapper类没有注入进去，可以在项目启动类上面加个全盘扫描或者指定扫描其下的任何包，注解使用它即可@MapperScan(“path”)，其中path为扫描路径。

2.4.1 问题描述

NoSuchBeanDefinitionException:
No qualifying bean of type ‘com.telecom.dao.BookDao’ available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

2.4.2 解决方法

在写了mapper层的情况下还忘记删掉之前写的的dao层，导致重复了

2.5.1 问题描述

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

Description:

An attempt was made to call a method that does not exist. The attempt was made from the following location:

   org.mybatis.spring.SqlSessionFactoryBean.buildSqlSessionFactory(SqlSessionFactoryBean.java:564)

The following method did not exist:

'void org.apache.ibatis.session.Configuration.setDefaultEnumTypeHandler(java.lang.Class)'

2.5.2 解决方法

这种一般都是由于版本依赖冲突引起的问题，用maven-helper检查一下依赖冲突，exclude一下，但是发现还是不行，但是删了本地重复的版本文件也不行。

2.6.1 问题描述

jar:file:/D:/programs/apache-maven-3.6.1/mvn_resp/org/mybatis/mybatis-spring/2.0.6/mybatis-spring-2.0.6.jar!/org/mybatis/spring/SqlSessionFactoryBean.class

The called method’s class, org.apache.ibatis.session.Configuration, is available from the following locations:

jar:file:/D:/programs/apache-maven-3.6.1/mvn_resp/org/mybatis/mybatis/3.4.2/mybatis-3.4.2.jar!/org/apache/ibatis/session/Configuration.class

The called method’s class hierarchy was loaded from the following locations:

org.apache.ibatis.session.Configuration: file:/D:/programs/apache-maven-3.6.1/mvn_resp/org/mybatis/mybatis/3.4.2/mybatis-3.4.2.jar
Action:

Correct the classpath of your application so that it contains compatible versions of the classes org.mybatis.spring.SqlSessionFactoryBean and org.apache.ibatis.session.Configuration

2.6.2 解决方法

这是因为多个版本的依赖，找到mybatis-spring这个2.0.6依赖删除即可

2.7.1 问题描述

java.lang.IllegalStateException:
Failed to introspect Class [com.telecom.config.PrimaryDataSourceConfig] from ClassLoader [jdk.internal.loader.ClassLoaders$AppClassLoader@2f0e140b]
Caused by: java.lang.NoClassDefFoundError: org/apache/ibatis/session/SqlSessionFactory
Caused by: java.lang.ClassNotFoundException: org.apache.ibatis.session.SqlSessionFactory

2.7.2 解决方法

这个报错其实就是没有找到要加载的类，一般在启动的时候报错。
加载不到的类有两种情况，一种是直接找不到要加载的依赖包，或者添加了依赖包后没有加载进入，需要看看是不是 maven 的设置问题，重新刷新加载一下 maven 的依赖，或者清一下 idea 的缓存；
另外一种是导入了依赖包，但是依赖包中又引入了其他的依赖包中的类，这个类找不到。

2.8.1 问题描述

An attempt was made to call a method that does not exist. The attempt was made from the following location：

com.baomidou.mybatisplus.core.MybatisMapperAnnotationBuilder.getLanguageDriver(MybatisMapperAnnotationBuilder.java:384)

2.8.2 解决方法

com.baomidou.mybatisplus.core.MybatisMapperAnnotationBuilder.getLanguageDriver方法不存在
原因：activiti包中的 org.mybatis 包 和 mybatisPlus中的org.mybatis 包冲突。
需要排除掉activiti包中的 org.mybatis 包。

       <dependency>
            <groupId>org.activiti</groupId>
            <artifactId>activiti-spring-boot-starter-basic</artifactId>
            <version>6.0.0</version>
            <exclusions>
                <exclusion>
                    <artifactId>mybatis</artifactId>
                    <groupId>org.mybatis</groupId>
                </exclusion>
            </exclusions>
        </dependency>

2.9.1 问题描述

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘deployApplications’ defined in class path resource [org/activiti/application/conf/ApplicationAutoConfiguration.class]:
Unsatisfied dependency expressed through method ‘deployApplications’ parameter 2;

nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘processEntryDeployer’ defined in class path resource [org/activiti/application/conf/ApplicationProcessAutoConfiguration.class]: Unsatisfied dependency expressed through method ‘processEntryDeployer’ parameter 0;

nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘repositoryServiceBean’ defined in class path resource [org/activiti/spring/boot/JpaProcessEngineAutoConfiguration/JpaConfiguration.class]: Unsatisfied dependency expressed through method ‘repositoryServiceBean’ parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘processEngine’ defined in class path resource [org/activiti/spring/boot/JpaProcessEngineAutoConfiguration$JpaConfiguration.class]: Unsatisfied dependency expressed through method ‘processEngine’ parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘springProcessEngineConfiguration’ defined in class path resource [org/activiti/spring/boot/JpaProcessEngineAutoConfig

2.9.2 解决方法

在创建SqlSessionFactoryBean bean = new SqlSessionFactoryBean();针对mybatis；若是项目中使用了mybatis，则需要替换成：MybatisSqlSessionFactoryBean bean = new MybatisSqlSessionFactoryBean(); 否则会报错：找不到baseMapper中的方法；

3 整合Activiti工作流报错

3.1.1 问题描述

Parameter 1 of method springProcessEngineConfiguration in org.activiti.spring.boot.JpaProcessEngineAutoConfiguration$JpaConfiguration required a bean of type 'javax.persistence.EntityManagerFactory' that could not be found.

3.1.2 解决方法

// 第一种方式 指定工作流单独的数据源
@Configuration
public class ActivitiDatasourceConfig extends AbstractProcessEngineAutoConfiguration {
 
  @Bean
  @Primary
  @ConfigurationProperties(prefix = "spring.datasource.activiti")
  public DataSource activitiDataSource() {
    return DataSourceBuilder.create().build();
  }
 
  @Bean
  public SpringProcessEngineConfiguration springProcessEngineConfiguration(
      PlatformTransactionManager transactionManager,
      SpringAsyncExecutor springAsyncExecutor) throws IOException {
 
    return baseSpringProcessEngineConfiguration(activitiDataSource(), transactionManager, springAsyncExecutor);
  }
 
}
 
 
 
// 第二种方式 使用已有的数据源
@Configuration
public class ActivitiConfig extends AbstractProcessEngineAutoConfiguration {
    static final String NAME = "master";
    //注入数据源和事务管理器
    @Bean
    public SpringProcessEngineConfiguration springProcessEngineConfiguration(
            SpringAsyncExecutor springAsyncExecutor) throws IOException {
            @Qualifier(NAME + "DataSource") DataSource dataSource,
            @Qualifier(NAME + "TransactionManager") PlatformTransactionManager transactionManager,
            
        return this.baseSpringProcessEngineConfiguration(dataSource, transactionManager, springAsyncExecutor);
    }
}

此问题参考博客： https://blog.csdn.net/weixin_29300375/article/details/81181333

3.2.1 问题描述

***************************
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

3.2.2 解决方法

八成是application.yml文件中配置数据源啥的有问题
我是因为改动了配置数据源的路径spring.datasource.dynamic.datasource 后，但是忘记在项目的其他地方改一下这个配置文件中的路径
也可能是其他问题引起的：https://blog.csdn.net/qq_45498460/article/details/112860809

3.3.1 问题描述

Could not update Activiti database schema: unknown version from database: '7.0.0.0'

3.3.2 解决方法

这个可能是activiti下activiti-spring-boot-starter-basic包版本异常引起的数据库错误，需要如下图检查一下ProcessEngine.java里和数据库里的act_ge_property表里版本号是否一致，不一致的话将数据库中act_ge_property表中的版本号中的的版本和和pom.xml中activiti-spring-boot-starter-basic包下db.create下sql 文件中的版本对应。

这个问题也是苦苦寻找好久解决方法，最后参考的这个文章找到的这个解决办法https://blog.csdn.net/qq_41169544/article/details/122810066
，瞬间柳暗花明又一村了。