springboot 集成mybatis，解决【warn】No MyBatis mapper was found in '[*.*.*]' package

springboot+mybatis+druid集成，同时解决warn警告

1. springboot 集成druid

增加DataSource配置文件

#用户中心数据源
spring.datasource.url=jdbc:mysql://localhost:3306/mysql?serverTimezone=UTC
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
# 下面为连接池的补充设置，应用到上面所有数据源中
spring.datasource.initialSize=5
spring.datasource.minIdle=5
spring.datasource.maxActive=20
# 配置获取连接等待超时的时间
spring.datasource.maxWait=6000
# 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒
spring.datasource.timeBetweenEvictionRunsMillis=6000
# 配置一个连接在池中最小生存的时间，单位是毫秒
spring.datasource.minEvictableIdleTimeMillis=300000
spring.datasource.validationQuery=SELECT 1
spring.datasource.testWhileIdle=true
spring.datasource.testOnBorrow=false
spring.datasource.testOnReturn=false
# 配置监控统计拦截的filters，去掉后监控界面sql无法统计，'wall'用于防火墙
spring.datasource.filters=stat,wall
spring.datasource.logSlowSql=true

#druid监控台配置信息
spring.druid.allow=127.0.0.1
spring.druid.loginUsername=root
spring.druid.loginPassword=root
spring.druid.logSlowSql=true

配置dataSource的Bean

@Configuration
@PropertySource("classpath:dataSource.properties")
public class DataSourceConfiguration {

    @ConfigurationProperties(prefix = "spring.datasource")
    public DataSource dataSource() {
        return new DruidDataSource();
    }
    
    @Bean
    @ConfigurationProperties(prefix="spring.druid")
    public HashMap druidProperties() {
        return new HashMap();
    }

    /**
     * Title: druidServlet
     * Description: druid监控servlet
     *
     * @param
     * @return org.springframework.boot.web.servlet.ServletRegistrationBean
     * @date 2019-01-21 14:44
     */
    @Bean
    public ServletRegistrationBean druidServlet(@Qualifier("druidProperties") HashMap druidProperties) {
        ServletRegistrationBean reg = new ServletRegistrationBean();
        reg.setServlet(new StatViewServlet());
        reg.addUrlMappings("/druid/*");
        reg.setInitParameters(druidProperties);
        return reg;
    }

    /**
     * Title: filterRegistrationBean
     * Description: druid监控请求拦截
     *
     * @param
     * @return org.springframework.boot.web.servlet.FilterRegistrationBean
     * @date 2019-01-21 14:46
     */
    @Bean
    public FilterRegistrationBean filterRegistrationBean() {
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
        filterRegistrationBean.setFilter(new WebStatFilter());
        filterRegistrationBean.addUrlPatterns("/*");
        filterRegistrationBean.addInitParameter("exclusions", "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*");
        filterRegistrationBean.addInitParameter("profileEnable", "true");
        return filterRegistrationBean;
    }
}

第一步已完成，springboot集成Druid完成。

2. 集成mybatis

@Configuration
public class MybatisConfiguration {
    
    @Bean
    public SqlSessionFactory sqlSessionFactory(@Autowired DataSource dataSource) {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource);
        try {
            // 加载MyBatis配置文件
            PathMatchingResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
            // 能加载多个，所以可以配置通配符(如：classpath*:mapper/**/*.xml)
            sqlSessionFactoryBean.setMapperLocations(
                    resourcePatternResolver.getResources("classpath:com/seeyon/capp/orderservice/**/*.xml"));
            return sqlSessionFactoryBean.getObject();
        } catch (Exception e) {
            log.error("SqlSessionFactory create error!", e);
        }
        return null;
    }

    @Bean
    public DataSourceTransactionManager dataSourceTransactionManager(@Autowired DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }
}

第二步基本完成，一般还需要配置mapper自动扫描。
这里有两种方式

	@Bean
    public MapperScannerConfigurer mapperScannerConfigurer() {
        MapperScannerConfigurer mapperScannerConfigurer = new MapperScannerConfigurer();
        mapperScannerConfigurer.setBasePackage("com.seeyon.capp.orderservice.**.*mapper");
        mapperScannerConfigurer.setSqlSessionFactoryBeanName("sqlSessionFactory");
        return mapperScannerConfigurer;
    }

或者

@SpringBootApplication()
@MapperScan(basePackages = "com.seeyon.capp.orderservice.**.*mapper")
public class MainApplication {

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

如果使用第一种@Bean的方式配置，springboot启动会调用MybatisAutoConfiguration.AutoConfiguredMapperScannerRegistrar类的registerBeanDefinitions方法初始化mapper，也就是按照默认路径初始化，所以如果默认路径下没有mapper的interface就会报警告。源代码如下

 @Override
    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {

      logger.debug("Searching for mappers annotated with @Mapper");

      ClassPathMapperScanner scanner = new ClassPathMapperScanner(registry);

      try {
        if (this.resourceLoader != null) {
          scanner.setResourceLoader(this.resourceLoader);
        }

		//获取路径(Main类所在的包路径)
        List packages = AutoConfigurationPackages.get(this.beanFactory);
        if (logger.isDebugEnabled()) {
          for (String pkg : packages) {
            logger.debug("Using auto-configuration base package '{}'", pkg);
          }
        }

        scanner.setAnnotationClass(Mapper.class);
        scanner.registerFilters();
        scanner.doScan(StringUtils.toStringArray(packages));
      } catch (IllegalStateException ex) {
        logger.debug("Could not determine auto-configuration package, automatic mapper scanning disabled.", ex);
      }
    }

所以使用第二种方法配置，可以覆盖springboot的自动配置，就不会报WARN org.mybatis.spring.mapper.ClassPathMapperScanner - No MyBatis mapper was found in…的警告了。

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备注：idea里面用 @Autowired注入mapper的时候，会报找不到bean的错误，网上很多解决办法都是关闭idea的注入检查，个人觉得这个办法不好，所以我找到一个另外的办法，用@Resource注入可以解决。