Spring Boot项目的真实程序入口

最新推荐文章于 2025-11-04 22:46:06 发布

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最新推荐文章于 2025-11-04 22:46:06 发布 · 8.1k 阅读

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#Spring Boot #程序入口 #main函数 #JarLauncher

Spring Boot项目的实际启动入口并非自定义的main函数，而是由Spring Boot的JarLauncher负责。当使用spring-boot-starter开发时，启动类查找依赖于MANIFEST.MF文件中的Start-Class。进一步深入，JarLauncher继承ExecutableArchiveLauncher，后者再继承Launcher，最终通过MainMethodRunner反射调用我们定义的main方法。

基于 spring-boot-start开发的项目，其程序入口并不是我们开发的业务代码中定义了 main 函数的类，而是 Spring Boot 定义的 JarLauncher 类（下文源码反编译自 spring-boot-loader-1.5.8.RELEASE.jar）。

通常使用 spring boot 进行开发时，会定义类似以下程序入口

@SpringBootApplication
/**
 * This @SpringBootApplication is a convenience annotation that adds all of the following:
 * @Configuration tags the class as a source of bean definitions for the application context.
 * @EnableAutoConfiguration tells Spring Boot to start adding beans based on classpath settings, other beans, and various property settings.
 * @EnableWebMvc Normally you would add @EnableWebMvc for a Spring MVC app, but Spring Boot adds it automatically when it sees spring-webmvc on the classpath. This flags the application as a web application and activates key behaviors such as setting up a DispatcherServlet.
 * @ComponentScan tells Spring to look for other components, configurations, and services in the hello package, allowing it to find the cont