10-SpringBoot主启动类运行解析

package com.studymyself;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;

import javax.sound.midi.Soundbank;

@SpringBootApplication
public class BSpringbootAnnotationApplication {

	public static void main(String[] args) {
		//获取容器对象,即返回一个ConfigurableApplicationContext对象
ConfigurableApplicationContext run = SpringApplication.run(BSpringbootAnnotationApplication.class, args);//参数1：应用入口的类	参数2：命令行参数

	}

}

SpringApplication.run()方法解析

分析该方法主要分两部分：一是SpringApplication的实例化，二是run方法的执行

SpringApplication这个类主要做了下面四个事情：

• 推断这个应用类型是普通的项目还是Web项目
• 查找并加载所有可使用的初始化器，设置到Initializers属性中
• 找出所有的应用程序监听器，设置到listeners属性中
• 推断并设置main方法的定义类，找到运行的主类（这里就是为什么运行run方法需要当前主类的Class对象作为参数的原因）

SpringApplication类的一个构造器如下：

 public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
        this.sources = new LinkedHashSet();
        this.bannerMode = Mode.CONSOLE;
        this.logStartupInfo = true;
        this.addCommandLineProperties = true;
        this.addConversionService = true;
        this.headless = true;
        this.registerShutdownHook = true;
        this.additionalProfiles = Collections.emptySet();
        this.isCustomEnvironment = false;
        this.lazyInitialization = false;
        this.applicationContextFactory = ApplicationContextFactory.DEFAULT;
        this.applicationStartup = ApplicationStartup.DEFAULT;
        this.resourceLoader = resourceLoader;
        Assert.notNull(primarySources, "PrimarySources must not be null");
        this.primarySources = new LinkedHashSet(Arrays.asList(primarySources));
        this.webApplicationType = WebApplicationType.deduceFromClasspath();//判断类型
        this.bootstrappers = new ArrayList(this.getSpringFactoriesInstances(Bootstrapper.class));
        this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class));//初始化器
        this.setListeners(this.getSpringFactoriesInstances(ApplicationListener.class));//监听器
        this.mainApplicationClass = this.deduceMainApplicationClass();//运行的主类	
    }