SpringBoot自定义servlet容器配置后,启动报错以及不生效的问题

最近在学习springboot,看到定制servlet容器配置这里.当通过编码方式去设置server的属性时

1.
此种情况是继承了WebMvcConfigurationSupport,直接报错起不来,

报错信息:org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'resourceHandlerMapping' defined in class path resource [com/practice/springbootweb/config/MyMvcConfig.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.web.servlet.HandlerMapping]: Factory method 'resourceHandlerMapping' threw exception; nested exception is java.lang.IllegalStateException: No ServletContext set

	at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:656) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:636) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:882) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:878) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

	at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

	at com.practice.springbootweb.SpringbootWebApplication.main(SpringbootWebApplication.java:10) [classes/:na]

Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.web.servlet.HandlerMapping]: Factory method 'resourceHandlerMapping' threw exception; nested exception is java.lang.IllegalStateException: No ServletContext set

	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:651) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	... 19 common frames omitted

Caused by: java.lang.IllegalStateException: No ServletContext set

	at org.springframework.util.Assert.state(Assert.java:73) ~[spring-core-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport.resourceHandlerMapping(WebMvcConfigurationSupport.java:534) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at com.practice.springbootweb.config.MyMvcConfig$$EnhancerBySpringCGLIB$$dac75723.CGLIB$resourceHandlerMapping$9(<generated>) ~[classes/:na]

	at com.practice.springbootweb.config.MyMvcConfig$$EnhancerBySpringCGLIB$$dac75723$$FastClassBySpringCGLIB$$ca627b0a.invoke(<generated>) ~[classes/:na]

	at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244) ~[spring-core-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:331) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	at com.practice.springbootweb.config.MyMvcConfig$$EnhancerBySpringCGLIB$$dac75723.resourceHandlerMapping(<generated>) ~[classes/:na]

	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_144]

	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_144]

	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_144]

	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_144]

	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

	... 20 common frames omitted



Disconnected from the target VM, address: '127.0.0.1:50412', transport: 'socket'



Process finished with exit code 1

2.以上为题一直没有解决,后来发现添加注解@EnableWebMVC全面接管后,错误解决,但是不知道是啥原理,而且修改的配置未生效.


3.网上搜索后https://blog.csdn.net/l1336037686/article/details/81047312,按照大佬的方法,去掉继承WebMvcConfigurationSupport后,启动不报错,但是修改的配置未生效.


以上有没有大佬知道是啥原因的?解答下,谢谢了.
下面是测试代码,springBoot版本2.2.6.RELEASE:

/**

 * MVC配置类

 */

@Configuration

//@EnableWebMvc

public class MyMvcConfig extends WebMvcConfigurationSupport {



    @Bean

    public ConfigurableServletWebServerFactory configurableServletWebServerFactory() {

        TomcatServletWebServerFactory factory = new TomcatServletWebServerFactory();

        factory.setPort(8081);

        return factory;

    }

}