eureka The method‘s class, javax.servlet.ServletContext, is available from the following locations

做一个项目，整合springboot，spring-cloud-dependencies，eureka

springboot版本是
2.3.5.RELEASE

spring-cloud-dependencies版本为:
Hoxton.SR9

eureka版本为:
2.2.6.RELEASE

启动总是报错：
The method's class, javax.servlet.ServletContext, is available from the following locations
查了百度说是jar包冲突，开始以为是tomcat，于是在spring-boot-starter-web中exclusion了tomcat，使用了undertow

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
<!--                 exclude tomcat-->
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.slf4j</groupId>
                    <artifactId>slf4j-log4j12</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

可是启动还是报错，后来查到是
Description:

An attempt was made to call a method that does not exist. The attempt was made from the following location:

org.apache.catalina.authenticator.AuthenticatorBase.startInternal(AuthenticatorBase.java:1178)

The following method did not exist:

javax.servlet.ServletContext.getVirtualServerName()Ljava/lang/String;

The method’s class, javax.servlet.ServletContext, is available from the following locations:

jar:file:/G:/mavenRepo/javax/servlet/servlet-api/2.5/servlet-api-2.5.jar!/javax/servlet/ServletContext.class
jar:file:/G:/mavenRepo/org/apache/tomcat/embed/tomcat-embed-core/9.0.17/tomcat-embed-core-9.0.17.jar!/javax/servlet/ServletContext.class

It was loaded from the following location:

file:/G:/mavenRepo/javax/servlet/servlet-api/2.5/servlet-api-2.5.jar

Action:

Correct the classpath of your application so that it contains a single, compatible version of javax.servlet.ServletContext

经过判断，原因是jar包冲突，从错误信息看出，在tomcat-embed-core-9.0.17.jar和servlet-api-2.5.jar里面都有javax.servlet.ServletContext, 而这个类在eureka中使用默认用了servlet-api-2.5.jar进行。经过查看发现，servlet-api-2.5.jar是eureka里面引进来的，

于是就告诉

spring-cloud-starter-netflix-eureka-server 不要把servlet-api引进来。
即在pom中修改成:

 <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
            <version>2.2.6.RELEASE</version>
            <exclusions>
                <exclusion>
                    <artifactId>servlet-api</artifactId>
                    <groupId>javax.servlet</groupId>
                </exclusion>
            </exclusions>
        </dependency>

主要参考这篇文章：
https://blog.csdn/kingzhaoc/article/details/102883112