【SpringBoot3】Bean管理

1.Bean扫描

1.1传统Spring

标签：<context:component-scan base-package="com. example "/>
注解：@ComponentScan(basePackages = "com.example")

1.2SpringBoot

SpringBoot默认扫描启动类所在的包及其子包

2.Bean注册

如果要注册的bean对象来自于第三方（不是自定义的,可能无法修改，则不能为添加注解），是无法用 @Component 及衍生注解声明bean的

解决

2.1@Bean

2.1.1下载jar包

2.1.2导入依赖

2.1.3配置类

如果要注册第三方bean，建议在配置类中集中注册

2.2@Import

2.2.1导入配置类

2.2.2导入 ImportSelector 接口实现类

package com.aaa.config;import org.springframework.context.annotation.ImportSelector;
import org.springframework.core.type.AnnotationMetadata;import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;public class CommonImportSelector implements ImportSelector {@Overridepublic String[] selectImports(AnnotationMetadata importingClassMetadata) {//读取配置文件的内容List<String> imports = new ArrayList<>();InputStream is = CommonImportSelector.class.getClassLoader().getResourceAsStream("common.imports");BufferedReader br = new BufferedReader(new InputStreamReader(is));String line = null;try {while((line = br.readLine())!=null){imports.add(line);}} catch (IOException e) {throw new RuntimeException(e);} finally {if (br!=null){try {br.close();} catch (IOException e) {throw new RuntimeException(e);}}}return imports.toArray(new String[0]);}
}