@Import, conditional and @importresource annotations

 @Import

@Import({User.class, DBHelper.class})
@Configuration(proxyBeanMethods = false) // tell SpringBoot This is a configuration class  ==  The configuration file 
public class MyConfig {
}

import Import the class of the specified type , And you can automatically create a parameterless constructor for these two components , And objects of the specified type are placed in containers

@Conditional

ctrl+h Open the inheritance tree of the annotation , There are many derived annotations

condition Translation is conditional , As the name suggests, it is to inject components through various conditions

such as ConditionOnBean, and ConditionOnMissionBean The two notes are opposite

One is if there is a Bean Then inject the current Bean, Another is that there is no one Bean Then inject the current Bean

If the annotation is written on the class name , If there are components in the container Bean Complete assembly , On the contrary, do not assemble .

Be careful :

  The situation will be judged first , Because it has not been assembled into the container at the time of judgment , So two of the classes Bean All failed to assemble

 @ImportResourse

We are not using springboot When developing a project , Using all of these xml Writing , To register bean, If we need to use xml The way is springboot On the project , I just need to add an annotation in config Class

@ImportResource("classpath:bean.xml")

These components are contained in the container