如何解决IntelliJ IDEA中Spring项目Tomcat访问/home报404错误

两个月前刚入职，很久没碰Spring框架了。现在在IntelliJ IDEA里启动Tomcat服务器，访问/home路径时弹出HTTP Status 404 – Not Found错误。鼠标悬停代码里的"home"，IDEA能找到对应的home.html文件，但访问就是不行。就连之前能正常跑的旧项目现在也出同样问题，谷歌搜了方案没解决，求帮忙。

错误信息 #

HTTP Status 404 – Not Found
Type Status Report
Message The requested resource [/home] 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/9.0.65

相关代码 #

HomeController.java #

package com.example.demo;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class HomeController {

    @RequestMapping("/home")
    public String landingPage() {
        return ("home");
    }
}

home.html #

<!DOCTYPE html>
<html lang="en"
      xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<h1>Landing page</h1>

</body>
</html>

pom.xml #

<?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>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.3</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>demo</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

排查方向 #

• 检查html文件路径：Spring Boot + Thymeleaf默认要求html文件放在src/main/resources/templates目录下，确认home.html的存放位置是否符合要求。
• 切换启动方式：Spring Boot自带内置Tomcat，直接启动带@SpringBootApplication注解的主类试试，避免外部Tomcat配置错误（比如部署路径、上下文路径设置不当）。
• 核对访问路径：如果用外部Tomcat，查看部署配置的上下文路径，若设置了/demo这类前缀，访问路径需改为http://localhost:8080/[上下文路径]/home。
• 清理缓存重建：执行IDEA的Build -> Clean Project和Build -> Rebuild Project，清除缓存后重启服务器。
• 检查主类位置：Spring Boot主类需放在根包（如com.example.demo）下，确保能扫描到HomeController所在的包，否则控制器不会被注册。
• 查看控制台日志：启动时留意控制台，若没有Mapped "{[/home]}" onto public java.lang.String com.example.demo.HomeController.landingPage()这类日志，说明控制器未被Spring扫描到。

内容的提问来源于stack exchange，提问作者jonas