SpringBoot启动跟踪-白红宇

SpringBoot启动跟踪

阅读量：5263 次

发布时间：2019-06-14

本文共 2829 字，大约阅读时间需要 9 分钟。

程序启动入口

@SpringBootApplicationpublic class Chapter001Application {    public static void main(String[] args) {        SpringApplication.run(Chapter001Application.class, args);    }}

调试跟踪

执行初始化方法

/**     * Create a new {
    @link SpringApplication} instance. The application context will load     * beans from the specified sources (see {
    @link SpringApplication class-level}     * documentation for details. The instance can be customized before calling     * {
    @link #run(String...)}.     * @param sources the bean sources     * @see #run(Object, String[])     * @see #SpringApplication(ResourceLoader, Object...)     */    public SpringApplication(Object... sources) {        initialize(sources);    }

初始化方法

applicationContext和applicationListener方法详情

/**     * Sets the {
    @link ApplicationContextInitializer} that will be applied to the Spring     * {
    @link ApplicationContext}.     * @param initializers the initializers to set     */    public void setInitializers(            Collection
     > initializers) {        this.initializers = new ArrayList
     
      >();        this.initializers.addAll(initializers);    }

ApplicationContextInitializer初始化applicationContext

/**     * Sets the {
    @link ApplicationListener}s that will be applied to the SpringApplication     * and registered with the {
    @link ApplicationContext}.     * @param listeners the listeners to set     */    public void setListeners(Collection
     > listeners) {        this.listeners = new ArrayList
     
      >();        this.listeners.addAll(listeners);    }

注册listener到apllicationContext

applicationContext和applicationlistener初始化都是通过getSpringFactoriesInstances实现的，我们一探究竟

private 
     
       Collection
       getSpringFactoriesInstances(Class
      
        type) {        return getSpringFactoriesInstances(type, new Class
       [] {});    }    private 
       
         Collection
         getSpringFactoriesInstances(Class
        
          type,            Class
         [] parameterTypes, Object... args) {        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();        // Use names and ensure unique to protect against duplicates        Set
         
           names = new LinkedHashSet
          
           ( SpringFactoriesLoader.loadFactoryNames(type, classLoader)); List
           
             instances = createSpringFactoriesInstances(type, parameterTypes, classLoader, args, names); AnnotationAwareOrderComparator.sort(instances); return instances; }