Struts2启动报错：org.apache.struts2.dispatcher.FilterDispatcher未找到求助

Hey there, let's break down how to fix this frustrating error and point you to better learning resources!

First, Resolving the ClassNotFoundException #

This error almost always boils down to one of a few common issues—let's go through them one by one:

• You're using an outdated Struts2 version (or outdated configuration)
  FilterDispatcher was deprecated years ago (removed entirely in Struts2 2.5+). If you're working with a modern Struts2 version (which you absolutely should be!), replace it with org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter in your web.xml file. Here's the correct configuration snippet:

  <filter>
      <filter-name>struts2</filter-name>
      <filter-class>org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter</filter-class>
  </filter>
  <filter-mapping>
      <filter-name>struts2</filter-name>
      <url-pattern>/*</url-pattern>
  </filter-mapping>
  

• Missing or mismatched Struts2 dependencies
  Double-check that your project has all required core jars. If using Maven/Gradle, ensure your pom.xml or build.gradle includes the latest stable struts2-core dependency (build tools will handle transitive dependencies automatically). If adding jars manually, confirm you haven't missed key files like struts2-core.jar, ognl.jar, freemarker.jar, and commons-lang3.jar—and that all versions match (no mixing old and new jars!).

• IDE deployment oversights
  Sometimes your IDE fails to deploy Struts2 jars to the server's WEB-INF/lib directory. Verify in your project's deployment assembly (Eclipse/IntelliJ settings) that Struts2 dependencies are marked for inclusion in the deployed artifact. For Tomcat, you can also check the webapps/[your-project]/WEB-INF/lib folder directly to confirm the jars are present.

Recommended Struts2 Tutorials #

As a beginner, focusing on up-to-date, authoritative resources will save you from more version-related headaches:

• Struts2 Official User Guide
  This is the gold standard—updated for every stable release, it covers everything from basic setup to advanced features like interceptors, validation, and REST support. It’s written clearly and includes practical examples you can follow along with.

• Struts2 Official Sample Projects
  The official blank and showcase projects are perfect for hands-on learning. Clone them from the Apache Struts repo, import into your IDE, and run directly. Examining working code will help you understand how configurations tie together far better than just reading text.

• Modern Step-by-Step Beginners' Tutorials
  Look for tutorials explicitly using Struts2 2.5.x or 6.x (the latest stable versions). Start with a simple HelloWorld project, then move on to actions, results, form handling, and validation. Avoid any tutorials still referencing FilterDispatcher—they’re outdated and will lead to issues like the one you’re facing now.

内容的提问来源于stack exchange，提问作者Bruno Vignola