7_1.springboot2.x启动配置原理_1.创建SpringApplication对象

柔情只为你懂 2023-06-04 07:54 5阅读 0赞

### 环境准备 ###

**springboot2.1.9、idea2019、**

**pom.xml**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2phdHBlbg_size_16_color_FFFFFF_t_70][]

### 解析 ###

**几个重要的事件回调机制  
配置在META-INF/spring.factories  
ApplicationContextInitializer  
SpringApplicationRunListener**

**只需要放在ioc容器中  
ApplicationRunner  
CommandLineRunner**

在主配置类打断点进行调试

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2phdHBlbg_size_16_color_FFFFFF_t_70 1][]

可见springboot应用程序分为两步：1、创建SpringApplication对象；2、运行run方法

### ![20191007173438737.png][] ###

**创建SpringApplication对象**

public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
    		this.resourceLoader = resourceLoader;
            //判断主配置类不能为空
    		Assert.notNull(primarySources, "PrimarySources must not be null");
            //保存主配置类
    		this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));
            //判断当前是否一个web应用
    		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
    		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.mainApplicationClass = deduceMainApplicationClass();
    	}

setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2phdHBlbg_size_16_color_FFFFFF_t_70 2][]

setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2phdHBlbg_size_16_color_FFFFFF_t_70 3][]

查看已创建的SpringApplication对象：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2phdHBlbg_size_16_color_FFFFFF_t_70 4][]

之后运行run方法。。

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[20191007173438737.png]: /images/20230601/49994d47b2724dd0ada3141544679cd2.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2phdHBlbg_size_16_color_FFFFFF_t_70 2]: /images/20230601/83be8f78ed2749a4ae8fbb50d0672771.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2phdHBlbg_size_16_color_FFFFFF_t_70 3]: /images/20230601/97fd9eabb7564cf4aec1d150ff391d76.png
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