環(huán)境：mybatis-spring 2.0.3

可以通過如下方式向在Spring中集成Mybatis，通過向Spring注冊SqlSessionFactoryBean和@MapperScan啟用Mybatis的功能

@Configuration
@MapperScan("com.holybell.mybatis.mapper") // Mapper接口掃描路徑
public class Config {
    /**
     * 通過SqlSessionFactoryBean獲得SqlSessionFactory
     */
    @Bean
    public SqlSessionFactory sqlSessionFactory() throws Exception {
        SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
        factoryBean.setDataSource(dataSource());
        return factoryBean.getObject();
    }

    @Bean
    public DataSource dataSource() {
        // ... 省略創(chuàng)建一個DataSource
    }
}

Mybatis利用Spring提供的BeanFactory接口球恤，實現(xiàn)了SqlSessionFactoryBean辜昵，簡單來說它就是一個構(gòu)建SqlSessionFactory的工廠類，雖然注冊的是SqlSessionFactoryBean咽斧，但是它生產(chǎn)的對象也會注冊到Spring容器中

public class SqlSessionFactoryBean 
        implements FactoryBean<SqlSessionFactory>, InitializingBean, 
                   ApplicationListener<ApplicationEvent> {

    // spring的資源加載器
    private static final ResourcePatternResolver RESOURCE_PATTERN_RESOLVER 
                                                    = new PathMatchingResourcePatternResolver();
    // spring的類注解解析器
    private static final MetadataReaderFactory METADATA_READER_FACTORY 
                                                    = new CachingMetadataReaderFactory();

    private SqlSessionFactory sqlSessionFactory;

    /**
     * FactoryBean向Spring容器注冊之后堪置，
     * Spring會回調(diào)這個方法獲得它生產(chǎn)的bean
     */
    public SqlSessionFactory getObject() throws Exception {
        if (this.sqlSessionFactory == null) {
            afterPropertiesSet();    
        }
        return this.sqlSessionFactory;
    }
    /**
     * Spring會在bean初始化完成之后回調(diào)這個方法
     */
    public void afterPropertiesSet() throws Exception {
        // 省略Assert校驗...
        this.sqlSessionFactory = buildSqlSessionFactory();
    }
    /**
     * 構(gòu)造Mybatis的SqlSessionFactory
     */
    protected SqlSessionFactory buildSqlSessionFactory() throws IOException {
    
       final Configuration targetConfiguration;

        // 省略其他屬性的裝配

        // 掃描路徑躬存，向mybatis注冊TypeHandler
        if (hasLength(this.typeHandlersPackage)) {
            scanClasses(this.typeHandlersPackage, 
                    TypeHandler.class).stream().filter(clazz -> !clazz.isAnonymousClass())
                    .filter(clazz -> !clazz.isInterface())
                    .filter(clazz -> !Modifier.isAbstract(clazz.getModifiers()))
                    .forEach(targetConfiguration.getTypeHandlerRegistry()::register);
        }

        // 如果注冊SqlSessionFactoryBean的時候配置了Mapper文件地址
        // 那么就會去解析Mapper文件，生成Configruation中的各種配置信息舀锨，如MapperStatement
        for (Resource mapperLocation : this.mapperLocations) {
            if (mapperLocation == null) {
                continue;
            }

            try {
                // 這里就和不集成Spring的Mybatis操作一樣
                // 解析Mapper文件的配置岭洲，生產(chǎn)MappedStatement等信息
                XMLMapperBuilder xmlMapperBuilder 
                        = new XMLMapperBuilder(mapperLocation.getInputStream(),
                                configuration, mapperLocation.toString(), 
                                configuration.getSqlFragments());
                xmlMapperBuilder.parse();
            } catch (Exception e) {
                // ...省略異常
            } finally {
              ErrorContext.instance().reset();
            }
        }
        // ...
        return this.sqlSessionFactoryBuilder.build(configuration);
    }
    /**
     * 從指定的路徑packagePatterns加載指定assignableType注解的類
     */
    private Set<Class<?>> scanClasses(String packagePatterns, Class<?> assignableType)
          throws IOException {

        Set<Class<?>> classes = new HashSet<>();
        String[] packagePatternArray = tokenizeToStringArray(packagePatterns,
                ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS);
        for (String packagePattern : packagePatternArray) {
            // 加載類資源，每個Resource對象表示一個被加載的文件資源坎匿，此處為class文件
            Resource[] resources = RESOURCE_PATTERN_RESOLVER
                    .getResources(ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX
                            + ClassUtils.convertClassNameToResourcePath(packagePattern) 
                            + "/**/*.class");
            // 遍歷每個加載到的Class文件盾剩，解析注解信息
            for (Resource resource : resources) {
                try {
                    // 解析類的注解信息
                    ClassMetadata classMetadata = METADATA_READER_FACTORY
                            .getMetadataReader(resource).getClassMetadata();
                    Class<?> clazz = Resources.classForName(classMetadata.getClassName());
                    if (assignableType == null || assignableType.isAssignableFrom(clazz)) {
                        // 符合條件的類加入集合返回
                        classes.add(clazz);
                    }
                } catch (Throwable e) {
                    // ... 省略異常日志
                }
            }
        }
        return classes;
    }
}

簡而言之，Mybatis借助SqlSessionFactoryBean完成了在不集成Spring的情況下SqlSessionFactory的創(chuàng)建替蔬，同時可以借助這個類裝配Interceptor告私、TypeHandler等組件