springapplication注解_java导入外部jar包

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发布于 2022-09-30 19:00:23

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发布于 2022-09-30 19:00:23

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SpringApplication

定义：Spring应用引导类，提供便利的自定义行为方法场景：嵌入式Web应用和非Web应用

准备阶段

配置：Spring Bean来源
- Java配置Class：Spring注解驱动中Java配置类，大多是情况下是Spring 模式注解锁标注的类，如被@configuration标注的类
- XML上下文配置文件：用于Spring 传统配置驱动中的xml文件

BeanDefinitionLoader(BeanDefinitionRegistry registry, Object... sources) {
        Assert.notNull(registry, "Registry must not be null");
        Assert.notEmpty(sources, "Sources must not be empty");
        this.sources = sources;
        // 使用AnnotatedBeanDefinitionReader进行配置
        this.annotatedReader = new AnnotatedBeanDefinitionReader(registry);
        // 使用XmlBeanDefinitionReader进行配置
        this.xmlReader = XML_ENABLED ? new XmlBeanDefinitionReader(registry) : null;
        this.groovyReader = this.isGroovyPresent() ? new GroovyBeanDefinitionReader(registry) : null;
        this.scanner = new ClassPathBeanDefinitionScanner(registry);
        this.scanner.addExcludeFilter(new BeanDefinitionLoader.ClassExcludeFilter(sources));
    }

推断：Web应用类型和主引导类(Main Class)
- Web Reactive：webApplicaitonType.REACTIVE
- Web Servlet：webApplicaitonType.SERVLET

static WebApplicationType deduceFromClasspath() {
        // WEBFLUX_INDICATOR_CLASS = "org.springframework.web.reactive.DispatcherHandler";
        // WEBMVC_INDICATOR_CLASS = "org.springframework.web.servlet.DispatcherServlet";
        // JERSEY_INDICATOR_CLASS = "org.glassfish.jersey.servlet.ServletContainer";
        // 如果没有上面的方式，默认使用Servlet_indicator_classes，如果共存的情况下优先使用Servlet_indicator_classes
		if (ClassUtils.isPresent(WEBFLUX_INDICATOR_CLASS, null) && !ClassUtils.isPresent(WEBMVC_INDICATOR_CLASS, null)
				&& !ClassUtils.isPresent(JERSEY_INDICATOR_CLASS, null)) {
			return WebApplicationType.REACTIVE;
		}
		for (String className : SERVLET_INDICATOR_CLASSES) {
			if (!ClassUtils.isPresent(className, null)) {
				return WebApplicationType.NONE;
			}
		}
		return WebApplicationType.SERVLET;
	}

可以在引导类中指定引导的具体类型

/**
 * {@link SpringApplication} 引导类
 */

public class SpringApplicationBootstrap {
    public static void main(String[] args) {
        // 交给其运行的类只要上面有@SpringBootApplicat ion注解就行，不一定是主类名
        // SpringApplication.run(ApplicationConfiguration.class, args);
        HashSet<String> set = new HashSet<>();
        set.add(ApplicationConfiguration.class.getName());
        SpringApplication springApplication = new SpringApplication();
        springApplication.setSources(set);
        // 默认为Servlet类型，此处对它进行强制关闭，变成普通类型--主线程会中断[非web容器], web容器主线程会阻塞等待请求
        springApplication.setWebApplicationType(WebApplicationType.NONE);
        ConfigurableApplicationContext context = springApplication.run(args);
        // 反射EnhancerBySpringCGLIB
        // com.SpringBoot.study.SpringApplicationBootstrap$ApplicationConfiguration$$EnhancerBySpringCGLIB$$ea8d68dc@400d912a
        System.out.println(context.getBean(ApplicationConfiguration.class));
    }
    
    @SpringBootApplication
    public static class ApplicationConfiguration{
    }
}

加载：应用上下文初始化器和应用事件监听器

public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
		this.resourceLoader = resourceLoader;
		Assert.notNull(primarySources, "PrimarySources must not be null");
		this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));
		this.webApplicationType = WebApplicationType.deduceFromClasspath();
		this.bootstrappers = new ArrayList<>(getSpringFactoriesInstances(Bootstrapper.class));
        // 上下文初始化器
		setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
        // 监听器
		setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
		this.mainApplicationClass = deduceMainApplicationClass();
	}