SpringBoot之旅-启动原理及自定义starter

public static ConfigurableApplicationContext run(Class<?>[] primarySources,
String[] args) {
return new SpringApplication(primarySources).run(args);
}

public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
this.resourceLoader = resourceLoader;
    Assert.notNull(primarySources, "PrimarySources must not be null");
//保存主配置类 
this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));
//确定web应用类型
this.webApplicationType = WebApplicationType.deduceFromClasspath();
//从类路径下找到META-INF/spring.factories配置的所有ApplicationContextInitializer；然后保存起来
    setInitializers((Collection) getSpringFactoriesInstances(
          ApplicationContextInitializer.class));
//从类路径下找到ETA-INF/spring.factories配置的所有ApplicationListener
    setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
//从多个配置类中找到有main方法的主配置类
this.main

public ConfigurableApplicationContext run(String... args) {
   StopWatch stopWatch = new StopWatch();
   stopWatch.start();
   ConfigurableApplicationContext context = null;
   Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
   configureHeadlessProperty();
//从类路径下META-INF/spring.factories获取SpringApplicationRunListeners
   SpringApplicationRunListeners listeners = getRunListeners(args);
//回调所有的获取SpringApplicationRunListener.starting()方法
   listeners.starting();
try {
//封装命令行参数
      ApplicationArguments applicationArguments = new DefaultApplicationArguments(
            args);
//准备环境 
      ConfigurableEnvironment environment = prepareEnvironment(listeners,
            applicationArguments);//创建环境完成后回调SpringApplicationRunListener.environmentPrepared()；表示环境准备完成
      configureIgnoreBeanInfo(environment);
//打印Banner图
      Banner printedBanner = printBanner(environment);
//创建ApplicationContext,决定创建web的ioc还是普通的ioc  
      context = createApplicationContext();
//异常分析报告
      exceptionReporters = getSpringFactoriesInstances(
            SpringBootExceptionReporter.class,
new Class[] { ConfigurableApplicationContext.class }, context);
//准备上下文环境，将environment保存到ioc中
//applyInitializers()：回调之前保存的所有的ApplicationContextInitializer的initialize方法 
//listeners.contextPrepared(context) 
//prepareContext运行完成以后回调所有的SpringApplicationRunListener的contextLoaded（）
      prepareContext(context, environment, listeners, applicationArguments,
            printedBanner);
//刷新容器,ioc容器初始化（如果是web应用还会创建嵌入式的Tomcat）
//扫描，创建，加载所有组件的地方,（配置类，组件，自动配置）
      refreshContext(context);       
      afterRefresh(context, applicationArguments);
      stopWatch.stop();
if (this.logStartupInfo) {
new StartupInfoLogger(this.mainApplicationClass)
               .logStarted(getApplicationLog(), stopWatch);
      }
//所有的SpringApplicationRunListener回调started方法
      listeners.started(context);
//从ioc容器中获取所有的ApplicationRunner和CommandLineRunner进行回调，
//ApplicationRunner先回调，CommandLineRunner再回调
      callRunners(context, applicationArguments);
   }
catch (Throwable ex) {
      handleRunFailure(context, ex, exceptionReporters, listeners);
throw new IllegalStateException(ex);
   }

try {
//所有的SpringApplicationRunListener回调running方法
      listeners.running(context);
   }
catch (Throwable ex) {
      handleRunFailure(context, ex, exceptionReporters, null);
throw new IllegalStateException(ex);
   }
//整个SpringBoot应用启动完成以后返回启动的ioc容器
return context;
}

<dependencies>
<!--引入自动配置模块-->
<dependency>
<groupId>com.yuanqinnan-starter</groupId>
<artifactId>yuanqinnan-springboot-starter-autoconfigurer</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
</dependencies>

<?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>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.4.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.yuanqinnan-starter</groupId>
<artifactId>yuanqinnan-springboot-starter-autoconfigurer</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<properties>
<java.version>1.8</java.version>
</properties>

<dependencies>
<!--引入spring-boot-starter；所有starter的基本配置-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
</dependencies>
</project>

@ConfigurationProperties(prefix = "yuanqinnan.hello")
public class HelloProperties {
//前缀
private String prefix;
//后缀
private String suffix;

public String getPrefix() {
return prefix;
    }

public void setPrefix(String prefix) {
this.prefix = prefix;
    }

public String getSuffix() {
return suffix;
    }

public void setSuffix(String suffix) {
this.suffix = suffix;
    }
}

public class HelloService {

    HelloProperties helloProperties;

public HelloProperties getHelloProperties() {
return helloProperties;
    }

public void setHelloProperties(HelloProperties helloProperties) {
this.helloProperties = helloProperties;
    }

public String sayHello(String name) {
return helloProperties.getPrefix() + "-" + name + helloProperties.getSuffix();
    }
}

@Configuration
@ConditionalOnWebApplication //web应用才生效
@EnableConfigurationProperties(HelloProperties.class)
public class HelloServiceAutoConfiguration {

@Autowired
    HelloProperties helloProperties;
@Bean
public HelloService helloService(){
        HelloService service = new HelloService();
        service.setHelloProperties(helloProperties);
return service;
    }
}

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
  com.yuanqinnan.starter.HelloServiceAutoConfiguration

<!--引入自定义starter-->
<dependency>
<groupId>com.yuanqinnan.starter</groupId>
<artifactId>yuanqinnan-springboot-starter</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>

yuanqinnan.hello.prefix=早安
yuanqinnan.hello.suffix=晚安

@Autowired
HelloService helloService;

@Test
public void contextLoads() {
System.out.println(helloService.sayHello("世界"));
}