手寫簡化版SpringBoot

Springboot項目全部依賴注解的，web工程是如何啟動的

1 首先引入了Tomcat依賴，然后用java代碼啟動Tomcat容器，默認Tomcat版本是8.5版本

2 Tomcat是實現了servlet3.0規范，在servlet加載類的過程中會尋找實現了ServletContainerInitializer接口的類，spring為我們實現了這個接口的類是SpringServletContainerInitializer，最后又會去調用實現了WebApplicationInitializer接口的類，最后真正是實現WebApplicationInitializer接口的是這個AbstractAnnotationConfigDispatcherServletInitializer，然后在該類中去初始化spring容器和springmvc容器和servlet攔截的url

public class AppTomcat {

    public static void main(String[] args) throws ServletException, LifecycleException {
        start();
    }

    public static void start() throws ServletException, LifecycleException {
        //創建Tomcat容器和設置端口
        Tomcat tomcatServer = new Tomcat();
        tomcatServer.setPort(9090);
        
        StandardContext ctx = (StandardContext) tomcatServer.addWebapp("/", new File("src/main").getAbsolutePath());
        ctx.setReloadable(false);
        WebResourceRoot resources = new StandardRoot(ctx);
        
        File additionWebInfClasses = new File("target/classes");
        //告訴Tomcat項目的class目錄，根目錄
        resources.addPreResources(
                new DirResourceSet(resources, "/WEB-INF/classes", additionWebInfClasses.getAbsolutePath(), "/"));
        //啟動容器
        tomcatServer.start();
        tomcatServer.getServer().await();
        
    }
    
}

項目結構：

github下載地址：https://github.com/jake1263/MySpringBoot