Caused by: java.lang.ClassNotFoundException: javax.servlet.Filter报错解决

Caused by: java.lang.NoClassDefFoundError: javax/servlet/Filter

Caused by: java.lang.NoClassDefFoundError: javax/servlet/Filter
    at java.lang.Class.getDeclaredMethods0(Native Method) ~[na:1.8.0_191]
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2701) ~[na:1.8.0_191]
    at java.lang.Class.getDeclaredMethods(Class.java:1975) ~[na:1.8.0_191]
    at org.springframework.core.type.StandardAnnotationmetadata.getAnnotatedMethods(StandardAnnotationmetadata.java:158) ~[spring-core-5.0.12.RELEASE.jar:5.0.12.RELEASE]
    ... 23 common frames omitted
Caused by: java.lang.ClassNotFoundException: javax.servlet.Filter
    at java.net.URLClassLoader.findClass(URLClassLoader.java:382) ~[na:1.8.0_191]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_191]
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:349) ~[na:1.8.0_191]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_191]
    ... 27 common frames omitted

有两个原因：（1）在maven中的作用域，不能是provided，需要是compile就是默认的scope（2）spring-boot-starter-tomcat的版本bug，换个新的或旧的版本试试

修改POM文件

注释掉< scope>provided< /scope>

    org.springframework.boot
    spring-boot-starter-tomcat
    

注释掉之后再运行就可以了。