Spring基于注解的Java配置无效，请求404问题求助

问题现象 #

学习Spring基于注解的Java配置时，配置始终不生效。提交表单后请求/SpringTesting/add返回404错误，无明确报错信息，仅收到Tomcat状态报告：

HTTP Status 404 – Not Found
Type Status Report

Message The requested resource [/SpringTesting/add] is not available

Description The origin server did not find a current representation for the target resource or is not willing to disclose that one exists.

Apache Tomcat/9.0.95

使用Apache Tomcat 9.0.95作为服务器，相关代码与项目结构如下：

相关代码 #

AppConfig.java #

package com.test.Configuration;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;

@Configuration
@ComponentScan("com.test")
@EnableWebMvc
public class AppConfig extends WebMvcConfigurationSupport {
    
     public AppConfig() {
            System.out.println("AppConfig has been initialized!");
        }

}

AppInitializer.java #

package com.test.Configuration;

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

public class AppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[] { AppConfig.class };
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        return null;
    }

    @Override
    protected String[] getServletMappings() {
        return new String[] { "/" };
    }

}

FirstController.java #

package com.test.Controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;

@Controller
public class FirstController {

    @RequestMapping("/add")
    public void addNumbers(@RequestParam("val1") int val1, @RequestParam("val2") int val2) {
        System.out.println("Reached");//Debug Breakpoint here
    }

}

index.jsp #

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Web MVC Testing</title>
</head>
<body>
    <form action="add">
        <input type="number" name="val1"><br> 
        <input type="number" name="val2"><br> 
        <input type="submit"><br>
    </form>
</body>
</html>

pom.xml #

<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>SpringTesting</groupId>
    <artifactId>SpringTesting</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>
    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.13.0</version>
                <configuration>
                    <release>21</release>
                </configuration>
            </plugin>
            <plugin>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.2.3</version>
            </plugin>
        </plugins>
    </build>
    <dependencies>
        <!-- Spring Dependency -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>6.2.0</version>
        </dependency>
        <!-- Lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.36</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
</project>

项目结构 #

src
 └── main
      └── java
           └── com
                └── test
                     ├── Configuration
                     │     ├── AppConfig.java
                     │     ├── AppInitializer.java
                     ├── Controller
                     │     └── FirstController.java
      └── webapp
           └── index.jsp

问题原因与解决方案 #

1. Spring与Tomcat版本不兼容 #

Spring Web MVC 6.2.0要求Servlet 6.0规范，但Tomcat 9.0.x仅支持Servlet 4.0，版本不匹配会导致Spring容器无法正常初始化，这是核心问题。

• 修复方案：
  • 降级Spring Web MVC到5.3.x系列（完全兼容Tomcat 9）；
  • 升级Tomcat到10.1.x或更高版本（支持Servlet 6.0）。

2. Controller方法返回值错误 #

addNumbers方法返回void，Spring MVC默认会寻找与方法名同名的视图（如addNumbers.jsp），但项目中不存在该视图，会引发异常。

• 修复方案：
  • 若无需返回视图，添加@ResponseBody注解直接返回响应内容：

    @RequestMapping("/add")
    @ResponseBody
    public String addNumbers(@RequestParam("val1") int val1, @RequestParam("val2") int val2) {
        System.out.println("Reached");
        return "计算结果：" + (val1 + val2);
    }
    

  • 若需要跳转视图，确保项目中存在对应jsp页面并指定返回路径。

3. 验证容器初始化状态 #

启动服务器后查看控制台，若未输出AppConfig has been initialized!，说明Spring容器未正常启动，需优先解决版本兼容问题。

4. 表单路径验证 #

表单action="add"为相对路径，确保访问index.jsp的路径是http://localhost:8080/SpringTesting/index.jsp，提交后会自动拼接为http://localhost:8080/SpringTesting/add，与Controller的@RequestMapping("/add")匹配，此部分逻辑无问题。

内容的提问来源于stack exchange，提问作者Jeet Siyall