java -- 异常 The class hierarchy was loaded from the following locations:

背景：

        最近做一个项目，代码是maven 多模块的，新增了一个模块，代码新增完启动发现报错。

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APPLICATION FAILED TO START
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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:1319)

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:/I:/apache-maven-3.5.0/repo/javax/servlet/servlet-api/2.5/servlet-api-2.5.jar!/javax/servlet/ServletContext.class
    jar:file:/I:/apache-maven-3.5.0/repo/javax/servlet/javax.servlet-api/4.0.1/javax.servlet-api-4.0.1.jar!/javax/servlet/ServletContext.class
    jar:file:/I:/apache-maven-3.5.0/repo/org/apache/tomcat/embed/tomcat-embed-core/9.0.63/tomcat-embed-core-9.0.63.jar!/javax/servlet/ServletContext.class

The class hierarchy was loaded from the following locations:

    javax.servlet.ServletContext: file:/I:/apache-maven-3.5.0/repo/javax/servlet/servlet-api/2.5/servlet-api-2.5.jar

一开始我以为是缺了servlet-api-2.5.jar 这个jar包，后面发现本地目录下是有这个包的

原因：

         原来是因为在主模块中启动类已经有个启动类，springboot有内置的tomcat，我新增模块的时候导入了web基础依赖，导致两者的servlet冲突了

解决：

        删除上述多余依赖

        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-core</artifactId>
        </dependency>

        重新加载项目，再启动，结果正常启动