SpringBoot应用能直接运行java -jar的原因分析

<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
</plugin>

Manifest-Version: 1.0
Spring-Boot-Classpath-Index: BOOT-INF/classpath.idx
Archiver-Version: Plexus Archiver
Built-By: yimin
Spring-Boot-Layers-Index: BOOT-INF/layers.idx
Start-Class: com.example.k8sdemo.K8sDemoApplication
Spring-Boot-Classes: BOOT-INF/classes/
Spring-Boot-Lib: BOOT-INF/lib/
Spring-Boot-Version: 2.6.13
Created-By: Apache Maven 3.8.8
Build-Jdk: 1.8.0_392
Main-Class: org.springframework.boot.loader.JarLauncher

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-loader</artifactId>
</dependency>

public static void main(String[] args) throws Exception {
	new JarLauncher().launch(args);
}

protected void launch(String[] args) throws Exception {
	if (!isExploded()) {
		JarFile.registerUrlProtocolHandler();
	}
	ClassLoader classLoader = createClassLoader(getClassPathArchivesIterator());
	String jarMode = System.getProperty("jarmode");
	String launchClass = (jarMode != null && !jarMode.isEmpty()) ? JAR_MODE_LAUNCHER : getMainClass();
	launch(args, launchClass, classLoader);
}


@Override
protected String getMainClass() throws Exception {
	String mainClass = getProperty(MAIN, "Start-Class");
	if (mainClass == null) {
		throw new IllegalStateException("No '" + MAIN + "' or 'Start-Class' specified");
	}
	return mainClass;
}


protected void launch(String[] args, String launchClass, ClassLoader classLoader) throws Exception {
	Thread.currentThread().setContextClassLoader(classLoader);
	createMainMethodRunner(launchClass, args, classLoader).run();
}


protected MainMethodRunner createMainMethodRunner(String mainClass, String[] args, ClassLoader classLoader) {
	return new MainMethodRunner(mainClass, args);
}

public void run() throws Exception {
	Class<?> mainClass = Class.forName(this.mainClassName, false, Thread.currentThread().getContextClassLoader());
	Method mainMethod = mainClass.getDeclaredMethod("main", String[].class);
	mainMethod.setAccessible(true);
	mainMethod.invoke(null, new Object[] { this.args });
}