1.声明
当前内容主要为复习和理解如何在当前的SpringBoot中MyBatis
2. 查看解析
1.通过查看源码方式发现了mybatis-spring-boot-starter中存在一个org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration
发现注释：
/**
* {@link EnableAutoConfiguration Auto-Configuration} for Mybatis. Contributes a
* {@link SqlSessionFactory} and a {@link SqlSessionTemplate}.
*
* If {@link org.mybatis.spring.annotation.MapperScan} is used, or a
* configuration file is specified as a property, those will be considered,
* otherwise this auto-configuration will attempt to register mappers based on
* the interface definitions in or under the root auto-configuration package.
*
* @author Eddú Meléndez
* @author Josh Long
* @author Kazuki Shimizu
* @author Eduardo Macarrón
*/
如果使用了@org.mybatis.spring.annotation.MapperScan,注解就可以扫描dao层并创建代理了
2.查看创建sqlSessionFactory的bean创建方法
@Bean
@ConditionalOnMissingBean
public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
SqlSessionFactoryBean factory = new SqlSessionFactoryBean();
factory.setDataSource(dataSource);
factory.setVfs(SpringBootVFS.class);
if (StringUtils.hasText(this.properties.getConfigLocation())) {
factory.setConfigLocation(this.resourceLoader.getResource(this.properties.getConfigLocation()));
}
factory.setConfiguration(properties.getConfiguration());
if (!ObjectUtils.isEmpty(this.interceptors)) {
factory.setPlugins(this.interceptors);
}
if (this.databaseIdProvider != null) {
factory.setDatabaseIdProvider(this.databaseIdProvider);
}
if (StringUtils.hasLength(this.properties.getTypeAliasesPackage())) {
factory.setTypeAliasesPackage(this.properties.getTypeAliasesPackage());
}
if (StringUtils.hasLength(this.properties.getTypeHandlersPackage())) {
factory.setTypeHandlersPackage(this.properties.getTypeHandlersPackage());
}
if (!ObjectUtils.isEmpty(this.properties.resolveMapperLocations())) {
factory.setMapperLocations(this.properties.resolveMapperLocations());
}
return factory.getObject();
}
发现一个非常明显的属性this.properties,然后找到MybatisProperties这个类
@ConfigurationProperties(prefix = MybatisProperties.MYBATIS_PREFIX)
// 即使用mybatis.属性方式在application.properties就可注入到这个配置类中
然后通过查看代码发现：AutoConfiguredMapperScannerRegistrar这个东西
public static class AutoConfiguredMapperScannerRegistrar
implements BeanFactoryAware, ImportBeanDefinitionRegistrar, ResourceLoaderAware {
private BeanFactory beanFactory;
private ResourceLoader resourceLoader;
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
log.debug("Searching for mappers annotated with @Mapper'");
ClassPathMapperScanner scanner = new ClassPathMapperScanner(registry);
try {
if (this.resourceLoader != null) {
scanner.setResourceLoader(this.resourceLoader);
}
List<String> pkgs = AutoConfigurationPackages.get(this.beanFactory);
for (String pkg : pkgs) {
log.debug("Using auto-configuration base package '" + pkg + "'");
}
scanner.setAnnotationClass(Mapper.class);
scanner.registerFilters();
scanner.doScan(StringUtils.toStringArray(pkgs));
} catch (IllegalStateException ex) {
log.debug("Could not determine auto-configuration " + "package, automatic mapper scanning disabled.");
}
}
@Override
public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
this.beanFactory = beanFactory;
}
@Override
public void setResourceLoader(ResourceLoader resourceLoader) {
this.resourceLoader = resourceLoader;
}
}
发现了这样一句话:Searching for mappers annotated with @Mapper,也就是说没有@MapperScan,但是mapper接口上游@Mapper也是可以创建接口代理的，实现MapperScan同样的方法
3.总结
-
在SpringBoot中的application.properties配置扫描的映射文件Mapper.xml即可加载配置文件
mybatis.mapper-locations=classpath:com/hy/filesys/mapper/*Mapper.xml -
扫描dao层的接口可以使用两种方式：
使用配置类上面添加@MapperScan或者在接口上添加@Mapper都可以实现扫描 -
还可以手动创建类似Spring和MyBatis整合时候的bean
-
所以为了方便，一般在application.properties中配置扫描的mapper.xml文件，在配置类上面添加@MapperScan或者在dao接口上面配置@Mapper