springboot源码理解十、自定义starter改造

自定义starter改造

热插拔技术

新增标记类ConfigMarker

package com.duohoob.config;

public class ConfigMarker {

}
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新增@EnableRegisterServer注解

package com.duohoob.config;

import org.springframework.context.annotation.Import;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Import(ConfigMarker.class) // spring的底层注解，给容器导入一个组件。
public @interface EnableRegisterServer {

}

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修改自动配置类

向MyAutoConfiguration添加注解@ConditionalOnBean(ConfigMarker.class)

package com.duohoob.config;

import com.duohoob.bean.SimpleBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@ConditionalOnBean(ConfigMarker.class) // 上下文中存在某个bean才会生效
public class MyAutoConfiguration {

	@Bean
	public SimpleBean simpleBean() {
		return new SimpleBean();
	}

}

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在spring-boot-mytest启动类添加注解

package com.duohoob.springbootmytest;

import com.duohoob.config.EnableRegisterServer;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@EnableRegisterServer
@SpringBootApplication
public class SpringBootMytestApplication {

	public static void main(String[] args) {
		SpringApplication.run(SpringBootMytestApplication.class, args);
	}

}

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如果不加我们不想simpleBean被注册到容器中，不加@EnableRegisterServer就好了。