springBoot双数据源动态配置

问题：
在实际开发过程中，会遇到调用两个数据库的操作，开发到一半，不能将配置文件大改，要不改变原开发模式的情况下，动态调用另一个数据库。
做法：
设置一个主数据库，在什么也不写的情况下，调用的是主数据库。如果调用另一个数据库，则加上一句说明即可。

1.修改配置文件

#---------------------------------------------------------------------------------
#master 数据源配置
master.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
master.datasource.url=jdbc:mysql://xxx:3306/xxx?useSSL=false&serverTimezone=GMT%2B8
master.datasource.username=xxx
master.datasource.password=xxx
#assert 数据源配置
assert.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
assert.datasource.url=jdbc:mysql://yyy:3306/yyy?useSSL=false&serverTimezone=GMT%2B8
assert.datasource.username=yyy
assert.datasource.password=yyy

2.修改mybatis加载类

修改主数据库的配置类

    @Value("${master.datasource.driver-class-name}")
    private String driverClassName;
    @Value("${master.datasource.url}")
    private String url;
    @Value("${master.datasource.username}")
    private String username;
    @Value("${master.datasource.password}")
    private String password;
    @Bean(name = "masterDataSource")
    @Primary
    public DataSource dataSource() {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName(this.driverClassName);
        dataSource.setUrl(this.url);
        dataSource.setUsername(this.username);
        dataSource.setPassword(this.password);
        return dataSource;
    }
//设置主数据库
     @Bean(name = "masterSqlSessionFactory")
    @Primary
    public SqlSessionFactory sqlSessionFactoryBean(@Qualifier("masterDataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean factory = new SqlSessionFactoryBean();
        factory.setDataSource(dataSource);
        factory.setTypeAliasesPackage(MODEL_PACKAGE);
        //配置分页插件，详情请查阅官方文档
        PageHelper pageHelper = new PageHelper();
        Properties properties = new Properties();
        properties.setProperty("pageSizeZero", "true");//分页尺寸为0时查询所有纪录不再执行分页
        properties.setProperty("reasonable", "true");//页码<=0 查询第一页，页码>=总页数查询最后一页
        properties.setProperty("supportMethodsArguments", "true");//支持通过 Mapper 接口参数来传递分页参数
        pageHelper.setProperties(properties);
        //添加插件
        factory.setPlugins(new Interceptor[]{pageHelper});
        //添加XML目录
        ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        factory.setMapperLocations(resolver.getResources("classpath*:mapper/*.xml"));
        factory.getObject().getConfiguration().setMapUnderscoreToCamelCase(true);
        return factory.getObject();
    }
//设置主事务
    @Bean(name = "masterTransactionManager")
    @Primary
    public DataSourceTransactionManager transactionManager(@Qualifier("masterDataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

增加另一个数据库的配置类

import javax.sql.DataSource;
@Configuration
public class MyBatisAssertConfigurer {
    @Value("${assert.datasource.driver-class-name}")
    private String driverClassName;
    @Value("${assert.datasource.url}")
    private String url;
    @Value("${assert.datasource.username}")
    private String username;
    @Value("${assert.datasource.password}")
    private String password;
    @Bean(name = "assertDataSource")
    public DataSource dataSource() {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName(this.driverClassName);
        dataSource.setUrl(this.url);
        dataSource.setUsername(this.username);
        dataSource.setPassword(this.password);
        return dataSource;
    }
    @Bean(name = "assertSqlSessionFactory")
    public SqlSessionFactory sqlSessionFactory(@Qualifier("assertDataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        bean.setMapperLocations(
                new PathMatchingResourcePatternResolver().getResources("classpath*:assert/*.xml"));
        return bean.getObject();
    }
    @Bean(name = "assertTransactionManager")
    public DataSourceTransactionManager transactionManager(@Qualifier("assertDataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }
}

修改mybatis的动态加载

@Configuration
public class MapperScanConfigurer {
    @Bean
    public MapperScannerConfigurer primaryMapperScannerConfigurer() {
        MapperScannerConfigurer mapperScannerConfigurer = new MapperScannerConfigurer();
        mapperScannerConfigurer.setSqlSessionFactoryBeanName("masterSqlSessionFactory");
        mapperScannerConfigurer.setBasePackage(MAPPER_PACKAGE);
        buildProperties(mapperScannerConfigurer);
        return mapperScannerConfigurer;
    }
    @Bean
    public MapperScannerConfigurer assertMapperScannerConfigurer() {
        MapperScannerConfigurer mapperScannerConfigurer = new MapperScannerConfigurer();
        mapperScannerConfigurer.setSqlSessionFactoryBeanName("assertSqlSessionFactory");
        mapperScannerConfigurer.setBasePackage("com.bonc.fengxing.assertdao");
        buildProperties(mapperScannerConfigurer);
        return mapperScannerConfigurer;
    }
    private void buildProperties(MapperScannerConfigurer mapperScannerConfigurer) {
        //初始化扫描器的相关配置，这里我们要创建一个Mapper的父类
        Properties properties = new Properties();
        properties.setProperty("mappers", MAPPER_INTERFACE_REFERENCE);
        properties.setProperty("notEmpty", "false");//insert、update是否判断字符串类型!='' 即 test="str != null"表达式内是否追加 and str != ''
        properties.setProperty("IDENTITY", "MYSQL");
        mapperScannerConfigurer.setProperties(properties);
    }
}

3.实际使用

创建一个assertdao跟dao同级，以及xml资源文件。目录结构如下：

在项目中使用时

直接引用即可