大家好，又见面了，我是你们的朋友全栈君。
最近在项目中运用了Springboot，简单的学习了简单的使用，于是想去看看源码是如何实现的。
自己也是第一次尝试看源码，结合了网上的东西和自己的理解，在博客里写点东西，做做积累, 如果其中哪些地方解释有问题，
欢迎老司机指出
参考文章：
1.https://my.oschina.net/u/3081965/blog/916126
2.http://www.cfanz.cn/index.php?c=article&a=read&id=307782
首先不知道从哪里入手，于是我从项目的启动入口开始。
以下就是项目入口代码，很简单，由于是在慕课网上学习的，这里的报名就直接写imooc了（这个为对应springboot的学习地址：http://www.imooc.com/learn/767）
这边的spring-boot版本为1.4.7
package com.imooc;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class GirlApplication {
public static void main(String[] args) {
SpringApplication.run(GirlApplication.class, args);
}
}
@SpringBootApplication 注解暂时不讲，先从下面这个方法开始讲起SpringApplication.run(GirlApplication.class, args);点击进去可以看到
/** * Static helper that can be used to run a {@link SpringApplication} from the * specified source using default settings. * @param source the source to load * @param args the application arguments (usually passed from a Java main method) * @return the running {@link ApplicationContext} */ public static ConfigurableApplicationContext run(Object source, String... args) {//第一次进入到达这里 return run(new Object[] { source }, args); } /** * Static helper that can be used to run a {@link SpringApplication} from the * specified sources using default settings and user supplied arguments. * @param sources the sources to load * @param args the application arguments (usually passed from a Java main method) * @return the running {@link ApplicationContext} */ public static ConfigurableApplicationContext run(Object[] sources, String[] args) {//上面方法后进入这里 return new SpringApplication(sources).run(args); }首先为第一步，第一步调用第二部的方法，这里主要看下第二步。
第二步这边分为两个步骤去看，第一个步骤为调用SpringApplication类的构造方法创建对象，第二步为调用创建对象的run方法，这里以这两个步骤进行解读。构建对象：/** * 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) {//调用初始化方法 initialize(sources); }@SuppressWarnings({ "unchecked", "rawtypes" }) private void initialize(Object[] sources) {//将对象资源存放到sources这个linkedSet下，这里的sources就是上诉的com.imooc.GirlController对象 if (sources != null && sources.length > 0) { this.sources.addAll(Arrays.asList(sources)); }//这里暂时没有看懂，从字面上来看，是判断是否有web环境 this.webEnvironment = deduceWebEnvironment();//实例化Initializer，initializers成员变量，是一个ApplicationContextInitializer类型对象的集合。//顾名思义，ApplicationContextInitializer是一个可以用来初始化ApplicationContext的接口。//初始化ApplicationContext的Initializer程序 //boot包下的META-INF/spring.factories 0 = "org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer" 1 = "org.springframework.boot.context.ContextIdApplicationContextInitializer" 2 = "org.springframework.boot.context.config.DelegatingApplicationContextInitializer" 3 = "org.springframework.boot.context.web.ServerPortInfoApplicationContextInitializer" //autoconfigure下的META-INF/spring.factories 4 = "org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer" 5 = "org.springframework.boot.autoconfigure.logging.AutoConfigurationReportLoggingInitializer" setInitializers((Collection) getSpringFactoriesInstances( ApplicationContextInitializer.class));//实例化监听器//初始化 ApplicationListener boot下9个，autoconfigure一个//0 = "org.springframework.boot.ClearCachesApplicationListener"//1 = "org.springframework.boot.builder.ParentContextCloserApplicationListener"//2 = "org.springframework.boot.context.FileEncodingApplicationListener"
//3 = "org.springframework.boot.context.config.AnsiOutputApplicationListener"
//4 = "org.springframework.boot.context.config.ConfigFileApplicationListener"
//5 = "org.springframework.boot.context.config.DelegatingApplicationListener"
//6 = "org.springframework.boot.liquibase.LiquibaseServiceLocatorApplicationListener"
//7 = "org.springframework.boot.logging.ClasspathLoggingApplicationListener"
//8 = "org.springframework.boot.logging.LoggingApplicationListener"
//9 = "org.springframework.boot.autoconfigure.BackgroundPreinitializer"setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));//找出main方法的全类名并返回其实例并设置到SpringApplication的this.mainApplicationClass完成初始化this.mainApplicationClass = deduceMainApplicationClass(); }这里附上deduceWebEnvironment()方法的实现，其中WEB_ENVIRONMENT_CLASSES的值为
private static final String[] WEB_ENVIRONMENT_CLASSES = { "javax.servlet.Servlet", "org.springframework.web.context.ConfigurableWebApplicationContext" };private boolean deduceWebEnvironment() { for (String className : WEB_ENVIRONMENT_CLASSES) { if (!ClassUtils.isPresent(className, null)) { return false; } } return true; }上面SpringApplication的初始化动作已经做完了，然后看下run方法里做了哪些操作。public ConfigurableApplicationContext run(String... args) {//StopWatch是一个监视器，主要是用来记录程序的运行时间，这里是用来记录程序启动所需要的时间 StopWatch stopWatch = new StopWatch(); stopWatch.start(); ConfigurableApplicationContext context = null; FailureAnalyzers analyzers = null; configureHeadlessProperty(); SpringApplicationRunListeners listeners = getRunListeners(args); listeners.started(); try { ApplicationArguments applicationArguments = new DefaultApplicationArguments( args); ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments); Banner printedBanner = printBanner(environment); context = createApplicationContext(); analyzers = new FailureAnalyzers(context); prepareContext(context, environment, listeners, applicationArguments, printedBanner); refreshContext(context); afterRefresh(context, applicationArguments); listeners.finished(context, null); stopWatch.stop(); if (this.logStartupInfo) { new StartupInfoLogger(this.mainApplicationClass) .logStarted(getApplicationLog(), stopWatch); } return context; } catch (Throwable ex) { handleRunFailure(context, listeners, analyzers, ex); throw new IllegalStateException(ex); } }版权声明：本文内容由互联网用户自发贡献，该文观点仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容， 请联系我们举报，一经查实，本站将立刻删除。发布者：全栈程序员-站长，转载请注明出处：https://javaforall.net/132201.html原文链接：https://javaforall.net
