Spring源码分析：List集合注入

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.example</groupId><artifactId>spring-boot-test</artifactId><version>1.0-SNAPSHOT</version><properties><maven.compiler.source>11</maven.compiler.source><maven.compiler.target>11</maven.compiler.target><java.version>11</java.version><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><spring-boot.version>2.4.2</spring-boot.version><spring-cloud.version>2020.0.1</spring-cloud.version><spring-cloud-alibaba.version>2021.1</spring-cloud-alibaba.version><knife4j.version>4.1.0</knife4j.version><hutool.version>5.6.1</hutool.version><lombok.version>1.18.22</lombok.version><maven.plugin.version>2.7.8</maven.plugin.version></properties><!-- 依赖声明 --><dependencyManagement><dependencies><!-- SpringCloud 微服务 --><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>${spring-cloud.version}</version><type>pom</type><scope>import</scope></dependency><!-- SpringCloud Alibaba 微服务 --><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-alibaba-dependencies</artifactId><version>${spring-cloud-alibaba.version}</version><type>pom</type><scope>import</scope></dependency><!-- SpringBoot 依赖配置 --><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-dependencies</artifactId><version>${spring-boot.version}</version><type>pom</type><scope>import</scope></dependency><!--文档插件--><dependency><groupId>com.github.xiaoymin</groupId><artifactId>knife4j-openapi2-spring-boot-starter</artifactId><version>${knife4j.version}</version></dependency><!-- hutool工具 --><dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId><version>${hutool.version}</version></dependency><!-- lombok --><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>${lombok.version}</version></dependency></dependencies></dependencyManagement><dependencies><!-- SpringBoot Web --><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><!--SpringBoot Actuator--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></dependency><!--请求参数校验--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-validation</artifactId></dependency><!--lombok--><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>${lombok.version}</version><optional>true</optional></dependency></dependencies><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>3.8.0</version><configuration><source>${java.version}</source><target>${java.version}</target><encoding>${project.build.sourceEncoding}</encoding></configuration></plugin></plugins></build></project>

EvaluationProcess 接口

package org.example.process;public interface EvaluationProcess {void process(Object object);boolean supports(Integer type);}

ConsultingEvaluationProcess 类

package org.example.process.impl;import org.example.process.EvaluationProcess;
import org.springframework.stereotype.Service;@Service
public class ConsultingEvaluationProcess implements EvaluationProcess {@Overridepublic void process(Object object) {System.out.println("ConsultingEvaluationProcess");}@Overridepublic boolean supports(Integer type) {return type == 1;}
}

DiagnoseEvaluationProcess类

package org.example.process.impl;import org.example.process.EvaluationProcess;
import org.springframework.stereotype.Service;@Service
public class DiagnoseEvaluationProcess implements EvaluationProcess {@Overridepublic void process(Object object) {System.out.println("DiagnoseEvaluationProcess");}@Overridepublic boolean supports(Integer type) {return type == 2;}
}

EvaluationService  业务类

package org.example.process;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;import java.util.List;
import java.util.Optional;@Service
public class EvaluationService {//集合注入
    @Autowiredprivate List<EvaluationProcess> evaluationProcesses;private Optional<EvaluationProcess> getProcess(Integer type) {if (this.evaluationProcesses != null) {return this.evaluationProcesses.stream().filter(a -> a.supports(type)).findFirst();}return Optional.empty();}public void save() {getProcess(1).ifPresent(origin -> origin.process(null));}
}

ScanConfig 配置

package org.example.config;import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;@Configuration
@ComponentScan("org.example.process")
public class ScanConfig {}

测试类  Test

package org.example.process;import org.example.config.ScanConfig;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;public class Test {public static void main(String[] args) {//纯注解ApplicationContext c1 = new AnnotationConfigApplicationContext(ScanConfig.class);EvaluationService bean = c1.getBean(EvaluationService.class);bean.save();}
}

源码分析：

org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#createBean(java.lang.String, org.springframework.beans.factory.support.RootBeanDefinition, java.lang.Object[])
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#doCreateBean
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#populateBean
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor#postProcessProperties
org.springframework.beans.factory.annotation.InjectionMetadata#inject
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.AutowiredFieldElement#inject
org.springframework.context.annotation.ContextAnnotationAutowireCandidateResolver#getLazyResolutionProxyIfNecessary
org.springframework.beans.factory.support.DefaultListableBeanFactory#resolveMultipleBeans