在使用tomcat的时候，tomcat 能够正常访问，index.html也能正常访问。报错界面：

但是只有@WebServlet的资源无法访问，原因是：servlet的版本太高。

改正后的maven:

<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.example</groupId><artifactId>demo</artifactId><version>1.0-SNAPSHOT</version><name>demo</name><packaging>war</packaging><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><maven.compiler.target>11</maven.compiler.target><maven.compiler.source>11</maven.compiler.source><junit.version>5.9.1</junit.version></properties><dependencies><!--    <dependency>--><!--      <groupId>jakarta.servlet</groupId>--><!--      <artifactId>jakarta.servlet-api</artifactId>--><!--      <version>5.0.0</version>--><!--      <scope>provided</scope>--><!--    </dependency>       --><!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api --><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>3.1.0</version><scope>provided</scope></dependency><!--    <dependency>--><!--      <groupId>jakarta.websocket</groupId>--><!--      <artifactId>jakarta.websocket-api</artifactId>--><!--      <version>2.0.0</version>--><!--      <scope>provided</scope>--><!--    </dependency>                                        --><!--    &lt;!&ndash; https://mvnrepository.com/artifact/javax.websocket/javax.websocket-api &ndash;&gt;--><!--    <dependency>--><!--      <groupId>javax.websocket</groupId>--><!--      <artifactId>javax.websocket-api</artifactId>--><!--      <version>1.1</version>--><!--      <scope>provided</scope>--><!--    </dependency>--><dependency><groupId>org.junit.jupiter</groupId><artifactId>junit-jupiter-api</artifactId><version>${junit.version}</version><scope>test</scope></dependency><dependency><groupId>org.junit.jupiter</groupId><artifactId>junit-jupiter-engine</artifactId><version>${junit.version}</version><scope>test</scope></dependency></dependencies><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-war-plugin</artifactId><version>3.3.2</version></plugin></plugins></build>
</project>