Spring boot似乎找不到mybatis映射器配置（Mapped statements集合不包含值）

Question

我正在使用 mybatis 和 spring-boot。

我已经忍受了几个小时的关注消息。

2018-02-18 15:25:13.774 ERROR 77556 --- [nio-8080-exec-5] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for org.owls.mybatis.mapper.TestMapper.selectTimestamp
### Cause: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for org.owls.mybatis.mapper.TestMapper.selectTimestamp] with root cause

java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for org.owls.mybatis.mapper.TestMapper.selectTimestamp

我的源码是基于这个（Spring boot入门项目）并添加Mybatis设置的。

我想不知何故mybatis找不到映射器信息，所以我想在控制台中打印注册的mybatis映射器列表。（是否可以？）

仅供参考，以下是我实施的事情。

我用的application.yml是添加mybatis

mybatis:
    type-aliases-package: org.owls.mybatis.model
    type-handlers-package: org.owls.mybatis.handler
    mapper-locations: classpath:/resources/mybatis/mapper/*_mapper.xml 
    configuration:
        map-underscore-to-camel-case: true
        default-fetch-size: 100
        default-statement-timeout: 30

这是/resources/mybatis/mapper/test_mapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.owls.mybatis.mapper.TestMapper">
    <select id="selectTimestamp" resultType="map">
        SELECT NOW() FROM DUAL
    </select>
</mapper>

这里是Java代码。

首先是Mapper接口，包TestMapper中是org.owls.mybatis.mapper

public interface TestMapper {
    @Select("SELECT NOW() FROM DUAL")
    public Map selectTimestamp() throws Exception;
}

其次，我制作了一个生成SqlSessionTemplate. 这是代码

@Service
public class MybatisService implements ApplicationContextAware {

    private Logger logger = Logger.getLogger(MybatisService.class);
    private ApplicationContext context;

    @Autowired
    DBService dbService;


    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.context = applicationContext;
    }


    // Register a Object with a name, if not exists
    private void registerBean(String beanName, Object newBean){
        BeanDefinitionRegistry registry = (BeanDefinitionRegistry)  context.getAutowireCapableBeanFactory();
        BeanDefinitionBuilder builder = BeanDefinitionBuilder.rootBeanDefinition(newBean.getClass());
        BeanDefinition def = builder.getBeanDefinition();
        if(!registry.containsBeanDefinition(beanName)) registry.registerBeanDefinition(beanName, def);
    }


    /*
    * Managing SqlSessionFactory
    * */
    private SqlSessionFactory generateSqlSessionFactory(String dsId, DataSource ds) throws Exception {
        String beanName = dsId + "SqlSessionFactory";

        SqlSessionFactory sqlSessionFactory = null;
        try {
            Object registeredBean = context.getBean(beanName);
            logger.info("Found SqlSessionFactory bean [ " + beanName + " ]. Returns the instance");
            sqlSessionFactory = (SqlSessionFactory) registeredBean;
        } catch (NoSuchBeanDefinitionException e) {
            logger.info("Not found SqlSessionFactory bean [ " + beanName + " ]. Generate new one");
            SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
            sqlSessionFactoryBean.setDataSource(ds);
            sqlSessionFactory = (SqlSessionFactory) sqlSessionFactoryBean.getObject();
            registerBean(beanName, sqlSessionFactory);
        }
        return sqlSessionFactory;
    }


    /*
    * Managing SqlSessionTemplate
    * */
    private SqlSessionTemplate generateSqlSessionTemplate(String dsId, SqlSessionFactory sqlSessionFactory) throws Exception {
        String beanName = dsId + "SqlSessionTemplate";
        SqlSessionTemplate sqlSessionTemplate = null;
        try {
            Object registeredBean = context.getBean(beanName);
            logger.info("Found SqlSessionTemplate bean [ " + beanName + " ]. Returns the instance");
            sqlSessionTemplate = (SqlSessionTemplate) registeredBean;
        } catch (NoSuchBeanDefinitionException e) {
            logger.info("Not found SqlSessionTemplate bean [ " + beanName + " ]. Generate new one");
            sqlSessionTemplate = new SqlSessionTemplate(sqlSessionFactory);
            registerBean(beanName, sqlSessionFactory);
        }
        return sqlSessionTemplate;
    }


    public SqlSessionTemplate getSqlSessionTemplate(String dsId) {
        SqlSessionTemplate template = null;
        try {
            DataSource ds = dbService.getDS(dsId);
            SqlSessionFactory sqlSessionFactory = generateSqlSessionFactory(dsId, ds);
            template = generateSqlSessionTemplate(dsId, sqlSessionFactory);
        } catch (Exception e) {
            logger.error("Failed to fetch SqlSessionFactory. returns null value ", e);
        }
        return template;
    }
}

最后，在控制器中，我用...调用它

@Controller
@RequestMapping(value = {"/test"})
public class TestController {

    @Autowired
    MybatisService mybatisService;
    private SqlSessionTemplate sqlSessionTemplate;

    private Logger logger = Logger.getLogger(TestController.class);

    @PostConstruct
    public void init(){
        sqlSessionTemplate = mybatisService.getSqlSessionTemplate("test");
    }

    @RequestMapping(value = {"getCurrentTimestamp"})
    public @ResponseBody String getCurrentTimestamp() throws Exception {

        logger.info("=== SqlSessionTemplate Info in Controller :: " + sqlSessionTemplate);

        Map<String, Object> data = (Map) sqlSessionTemplate.selectOne("org.owls.mybatis.mapper.TestMapper.selectTimestamp");
        ObjectMapper mapper = new ObjectMapper();
        return mapper.writeValueAsString(data);
    }
};

我认为错误消息有点含糊。（我找不到任何设置错误的线索 - mapper xml, application.yml, db connection）

感谢您的回答。 访问完整源代码

======================== 编辑＃1。2 月 19 日 ===============================

我发现SqlSessionFactory Configuration根本没有任何映射器。

我可以通过以下方式打印映射器列表。在代码中生成SqlSessionFactory...

// FOR TEST 0219
MapperRegistry registry = sqlSessionFactory.getConfiguration().getMapperRegistry();


logger.info("=== Printing Mapper Registry starts");
registry.getMappers().forEach(mapper -> {
    logger.info("Mapper Registry :: " +  mapper.getName());
});
logger.info("=== Printing Mapper Registry ends");
// FOR TEST 0219

就我而言，它不打印任何内容，但它可以通过MapperRegistry实例添加映射器或包。

这是我的想法

1. SqlSessionFactory（ibatis提供）需要DataSource
2. SqlSessionTemplate（ibatis提供）是端点，它需要SqlSessionFactory
3. 总之，SqlSessionTemplate取决于SqlSessionFactory哪个取决于DataSource。

如果是这样，我如何SqlSession*在使用动态数据源的项目中正确生成为 bean？

在我上面的代码（编辑过的代码）中，我能够将映射器添加为bean，但每个SqlSessionFactory都有相同的映射器（重复，因为MapperRegistry获取包名称作为参数）

我怎样才能设置不同的映射器来对应SqlSessionFactory？