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原理:
- FactoryBean的自定义对象
- jdk动态代理Mapper接口对象
目录结构:
public class Test {
public static void main(String[] args) {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
context.register(AppConfig.class);
context.refresh();
UserService userService = (UserService)context.getBean("userService");
userService.test();
}
}
@CondorHeroMapperScan("com.athome.tulin.springmybatis.mapper")
@ComponentScan("com.athome.tulin.springmybatis")
public class AppConfig {
@Bean
public SqlSessionFactory sqlSessionFactory() throws IOException {
System.out.println("4.依赖注入MemberMapper需要先创建对象………AppConfig…………SqlSessionFactory………");
InputStream inputStream = Resources.getResourceAsStream("mybatis.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
return sqlSessionFactory;
}
}
@Component public class UserService { public UserService() { System.out.println("3.…………创建UserService…………"); } //如何把mybatis生成的UserMapper的代理对象赋值给UserMapper @Autowired private UserMapper userMapper; @Autowired private OrderMapper orderMapper; @Autowired private MemberMapper memberMapper; public void test(){ System.out.println("7.……UserService…test…"); System.out.println(userMapper.selectById()); System.out.println(orderMapper.selectById()); System.out.println(memberMapper.selectById()); } }
public interface MemberMapper {
@Select("select 'member' ")
String selectById();
}
public interface OrderMapper {
@Select("select 'order' ")
String selectById();
}
public interface UserMapper {
@Select("select 'user' ")
String selectById();
}
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Import(CondorHeroImportBeanDefinitionRegistrar.class)
public @interface CondorHeroMapperScan {
String value();
}
public class CondorHeroFactoryBean implements FactoryBean { private Class mapperInterface; private SqlSession sqlSession; public CondorHeroFactoryBean(Class mapperInterface) { this.mapperInterface = mapperInterface; } /** * 从容器查找SqlSessionFactory 并获取sqlSession 赋值于sqlSession * 扫描的时候有 beanDefinition.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_TYPE); * 那他就会自动找set方法 * @param sqlSessionFactory */ public void setSqlSession(SqlSessionFactory sqlSessionFactory) { System.out.println("5.……setSqlSession……"); sqlSessionFactory.getConfiguration().addMapper(mapperInterface); this.sqlSession = sqlSessionFactory.openSession(); } @Override public Object getObject() throws Exception { //动态代理获取UserMapper接口对象 System.out.println("6.……getObject……"); return sqlSession.getMapper(mapperInterface); } @Override public Class<?> getObjectType() { return mapperInterface; } }
public class CondorHeroImportBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar { @Override public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry, BeanNameGenerator importBeanNameGenerator) { System.out.println("1.……registerBeanDefinitions……"); //1.获取注解上的指定路径 Map<String, Object> annotationAttributes = importingClassMetadata.getAnnotationAttributes(CondorHeroMapperScan.class.getName()); String path = (String)annotationAttributes.get("value"); //2.扫描 CondorHeroBeanDefinitionScanner scanner = new CondorHeroBeanDefinitionScanner(registry); scanner.addIncludeFilter(new TypeFilter() { @Override public boolean match(MetadataReader metadataReader, MetadataReaderFactory metadataReaderFactory) throws IOException { return true; } }); scanner.scan(path); } }
public class CondorHeroBeanDefinitionScanner extends ClassPathBeanDefinitionScanner { public CondorHeroBeanDefinitionScanner(BeanDefinitionRegistry registry) { super(registry); } @Override protected boolean isCandidateComponent(AnnotatedBeanDefinition beanDefinition) { //只关心接口(判断是否是接口) return beanDefinition.getMetadata().isInterface(); } /** * 扫描路径并得到beanDefinition * @param basePackages * @return */ @Override protected Set<BeanDefinitionHolder> doScan(String... basePackages) { System.out.println("2.……doScan……"); Set<BeanDefinitionHolder> beanDefinitionHolders = super.doScan(basePackages); for (BeanDefinitionHolder beanDefinitionHolder: beanDefinitionHolders) { GenericBeanDefinition beanDefinition = (GenericBeanDefinition)beanDefinitionHolder.getBeanDefinition(); //设置值 beanDefinition.getConstructorArgumentValues().addGenericArgumentValue(beanDefinition.getBeanClassName()); //设置名称 beanDefinition.setBeanClassName(CondorHeroFactoryBean.class.getName()); //将MapperFactoryBean的注入模型设置为By-Type。也就是说,MapperFactoryBean中的setXxx中的属性会从容器中来进行查找 beanDefinition.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_TYPE); } return beanDefinitionHolders; } }
运行结果是:
1.……registerBeanDefinitions……
2.……doScan……
3.…………创建UserService…………
4.依赖注入MemberMapper需要先创建对象………AppConfig…………SqlSessionFactory………
5.……setSqlSession……
6.……getObject……
5.……setSqlSession……
6.……getObject……
5.……setSqlSession……
6.……getObject……
7.……UserService…test… user order member
MapperScannerConfigurer
类型的BeanDefinitionprivate void processBeanDefinitions(Set<BeanDefinitionHolder> beanDefinitions) { GenericBeanDefinition definition; for (BeanDefinitionHolder holder : beanDefinitions) { definition = (GenericBeanDefinition) holder.getBeanDefinition(); String beanClassName = definition.getBeanClassName(); LOGGER.debug(() -> "Creating MapperFactoryBean with name '" + holder.getBeanName() + "' and '" + beanClassName + "' mapperInterface"); // the mapper interface is the original class of the bean // but, the actual class of the bean is MapperFactoryBean //设置值 definition.getConstructorArgumentValues().addGenericArgumentValue(beanClassName); // issue #59 //设置名称 definition.setBeanClass(this.mapperFactoryBeanClass); definition.getPropertyValues().add("addToConfig", this.addToConfig); boolean explicitFactoryUsed = false; if (StringUtils.hasText(this.sqlSessionFactoryBeanName)) { definition.getPropertyValues().add("sqlSessionFactory", new RuntimeBeanReference(this.sqlSessionFactoryBeanName)); explicitFactoryUsed = true; } else if (this.sqlSessionFactory != null) { definition.getPropertyValues().add("sqlSessionFactory", this.sqlSessionFactory); explicitFactoryUsed = true; } if (StringUtils.hasText(this.sqlSessionTemplateBeanName)) { if (explicitFactoryUsed) { LOGGER.warn( () -> "Cannot use both: sqlSessionTemplate and sqlSessionFactory together. sqlSessionFactory is ignored."); } definition.getPropertyValues().add("sqlSessionTemplate", new RuntimeBeanReference(this.sqlSessionTemplateBeanName)); explicitFactoryUsed = true; } else if (this.sqlSessionTemplate != null) { if (explicitFactoryUsed) { LOGGER.warn( () -> "Cannot use both: sqlSessionTemplate and sqlSessionFactory together. sqlSessionFactory is ignored."); } definition.getPropertyValues().add("sqlSessionTemplate", this.sqlSessionTemplate); explicitFactoryUsed = true; } if (!explicitFactoryUsed) { LOGGER.debug(() -> "Enabling autowire by type for MapperFactoryBean with name '" + holder.getBeanName() + "'."); //将MapperFactoryBean的注入模型设置为By-Type。也就是说,MapperFactoryBean中的setXxx中的属性会从容器中来进行查找 definition.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_TYPE); } definition.setLazyInit(lazyInitialization); } }
public class MapperFactoryBean<T> extends SqlSessionDaoSupport implements FactoryBean<T> {}
@Override
public T getObject() throws Exception {
return getSqlSession().getMapper(this.mapperInterface);
}
@Override
public Class<T> getObjectType() {
return this.mapperInterface;
}
注意:这里的getObject调用时机是,在创建的对象依赖了Mapper对象就会去创建该Mapper对象,此时通过MapperFactoryBean去获取
上面的getSqlSession()对应源码是:
这一步是程序员自己定义一个SqlSessionFactory,例如:
@CondorHeroMapperScan("com.athome.tulin.springmybatis.mapper")
@ComponentScan("com.athome.tulin.springmybatis")
public class AppConfig {
@Bean
public SqlSessionFactory sqlSessionFactory() throws IOException {
System.out.println("4.依赖注入MemberMapper需要先创建对象………AppConfig…………SqlSessionFactory………");
InputStream inputStream = Resources.getResourceAsStream("mybatis.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
return sqlSessionFactory;
}
}
这里定义的SqlSessionFactory 会赋值于2.10的sqlSessionTemplate
至此:业务类中的引入Mapper对象就复制成功。
@Autowired
private OrderMapper orderMapper;
即:这时候的orderMapper就 是赋值了代理对象的对象是有值 的。
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