SpringBoot使用mybatis，发生：Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured

最近，配置项目，使用SpringBoot2.2.1，配置mybatis访问db，配好后，使用自定义的数据源。启动发生：

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


Action:

Consider the following:
	If you want an embedded database (H2, HSQL or Derby), please put it on the classpath.
	If you have database settings to be loaded from a particular profile you may need to activate it (no profiles are currently active).

　　虽然，我知道，是因为我没有在application.yml文件中配置：spring.datasource。但是因为我是自定义的数据源，配置项不在spring.datasource，所以希望，不配置spring.datasource，也能启动项目。单纯在@SpringBootApplication(exclude = {DataSourceAutoConfigure.class})中排除DataSourceAutoConfigure是不行的。

       下面是解决方案：

        方案1:

        在自定义数据源中，添加自定义自动配置类。见下面的例子：

import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;

import javax.annotation.Resource;
import javax.sql.DataSource;
import java.util.Properties;

/**
 * 自定义自动配置类
 * 1. 自定义数据源，自定义数据源是为了，防止因为没有在配置文件中，配置spring.datasource，
 * 出现：Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.
 * 2. 切面类，用来切换主从数据源
 *
 */
@EnableAspectJAutoProxy
@Configuration
public class CustomDataSourceAutoConfiguration {


    @Bean
    @ConditionalOnMissingBean
    public DataSource defaultDataSource() {
            return new CustomDataSource());
        }
    }

    @Bean
    @ConditionalOnBean({DataSource.class})
    public CustomDataSourceAspect CustomDsAspect() {
        return new CustomDataSourceAspect();
    }
}

　　别忘了，在META-INF/spring.factories文件中配置：

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.xxx.framework.datasource.masterslave.CustomDataSourceAutoConfiguration 

　　方案2:

       在启动类上，添加如下代码：

import com.lzj.framework.datasource.multi.MultiDatabaseMapperFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
@MapperScan(basePackages = {"com.xxx.test.dao"}, factoryBean = MultiDatabaseMapperFactoryBean.class)
public class LzjFrameworkTestApplication {

    public static void main(String[] args) {
         SpringApplication.run(LzjFrameworkTestApplication.class, args);
    }

}

　　第一要在@SpringBootApplication中排除DataSourceAutoConfiguration类的配置；第二，要配置@MapperScan，在参数中指出，扫描标准@Mapper注解的dao接口的包位置，和自定义factoryBean的实现类。factoryBean需要自己实现，需要继承MapperFactoryBean接口。

       当然，你要是不使用数据库，只需把DataSourceAutoConfiguration排除就可以了。

       项目，就可以正常启动了。