spring注解

一、

//当配置文件 user.enable=1时才会创建bean，否则不会创建

@ConditionalOnProperty(prefix = "user", name = "enable",havingValue = "1")

二、

@Bean
@ConditionalOnMissingBean
public HomeService defaultHomeService(){
    HomeServiceImpl homeService=new HomeServiceImpl();
    return homeService;
}