携手创作，共同成长！这是我参与「掘金日新计划 · 8 月更文挑战」的第24天，点击查看活动详情
1. Spring扩展点
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BeanFactoryPostProcessor
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- BeanDefinitionRegistryPostProcessor
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BeanPostProcessor
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- InstantiationAwareBeanPostProcessor
- AbstractAutoProxyCreator
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@Import
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- ImportBeanDefinitionRegistrar
- ImportSelector
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Aware
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InitializingBean
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FactoryBean
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SmartInitializingSingleton
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ApplicationListener
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Lifecycle
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- SmartLifecycle
- LifecycleProcessor
-
HandlerInterceptor
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MethodInterceptor
2. Spring扩展点应用场景
2.1 整合Nacos
思考： 为什么整合Nacos注册中心后，服务启动就会自动注册，Nacos是如何实现自动服务注册的？
NacosAutoServiceRegistration
# 对ApplicationListener的扩展
AbstractAutoServiceRegistration#onApplicationEvent
# 服务注册
》NacosServiceRegistry#register
NacosWatch：
#对SmartLifecycle的扩展
NacosWatch#start
#订阅服务接收实例更改的事件
》NamingService#subscribe
扩展： Eureka Server端上下文的初始化是在SmartLifecycle#start中实现的
EurekaServerInitializerConfiguration
2.2 整合Feign
思考：为什么Feign接口可以通过@Autowired直接注入使用？Feign接口是如何交给Spring管理的？
@FeignClient(value = "mall-order",path = "/order")
public interface OrderFeignService {
@RequestMapping("/findOrderByUserId/{userId}")
R findOrderByUserId(@PathVariable("userId") Integer userId);
}
@RestController
@RequestMapping("/user")
public class UserController {
@Autowired
OrderFeignService orderFeignService;
@RequestMapping(value = "/findOrderByUserId/{id}")
public R findOrderByUserId(@PathVariable("id") Integer id) {
//feign调用
R result = orderFeignService.findOrderByUserId(id);
return result;
}
}
FeignClientsRegistrar
FeignClientFactorybean
2.3 整合Ribbon
思考：为什么@Bean修饰的RestTemplate加上@LoadBalanced就能实现负载均衡功能？
@Bean
@LoadBalanced
public RestTemplate restTemplate() {
return new RestTemplate();
}
LoadBalancerAutoConfiguration
对SmartInitializingSingleton的扩展，为所有用@LaodBalanced修饰的restTemplate（利用了@Qualifier）绑定实现了负载均衡逻辑的拦截器LoadBalancerInterceptor
LoadBalancerInterceptor
2.4 整合sentinel
AbstractSentinelInterceptor
# Webmvc接口资源保护入口
AbstractSentinelInterceptor#preHandle
SentinelDataSourceHandler
#Sentinel持久化读数据源设计，利用了SmartInitializingSingleton扩展点
SentinelDataSourceHandler#afterSingletonsInstantiated
# 注册一个FactoryBean类型的数据源
》SentinelDataSourceHandler#registerBean
》》NacosDataSourceFactoryBean#getObject
# 利用FactoryBean获取到读数据源
》》new NacosDataSource(properties, groupId, dataId, converter)
NacosDataSourceFactoryBean
2.5 整合seata
GlobalTransactionScanner
GlobalTransactionalInterceptor
