Fix javax.servlet.filter Not Found in Spring Boot

In Spring Boot, if the javax.servlet.filter class cannot be found, it is usually because the relevant dependencies have not been properly imported. You can resolve this issue by following these steps:

1. Make sure to add the correct dependencies in the pom.xml or build.gradle file. When using a Servlet Filter in Spring Boot, you need to include dependencies for servlet-api or javax.servlet. For example, add the following dependency in the pom.xml file:

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>4.0.1</version>
    <scope>provided</scope>
</dependency>

Please note that you can choose the corresponding version based on the Servlet specification you are using.

1. Make sure that the project’s dependencies have been successfully downloaded and installed. You can rebuild the project by running mvn clean install (for Maven projects) or ./gradlew build (for Gradle projects) to ensure that the dependencies are properly loaded.
2. If you are using an IDE like Eclipse or IntelliJ IDEA, try reimporting the project or restarting the IDE to ensure that the IDE correctly recognizes and loads the dependencies.

If none of the above steps have resolved the issue, try deleting the relevant dependency cache in the local Maven repository and rebuild the project.

If the issue persists, it is advised to provide more relevant error messages and code in order to be able to more accurately help solve the problem.