Spring Boot Controller映射失败（Whitelabel Error Page 404）求助

在IntelliJ和STS 4中运行Spring Boot 3.0.3项目时，均出现Whitelabel Error Page 404错误，仅将@RestController放在主应用类内部时可正常运行，因此推测是包结构问题。

已尝试以下方案但均无效：

• 添加/不添加@ComponentScan注解
• 将Controller放在主类同一包或子包下
• 使用@Controller配合/不配合@ResponseBody
• 仅使用@RequestMapping或@GetMapping定义请求路径
• 配置不同的@ComponentScan扫描路径
• 更换浏览器测试

访问地址为：http://localhost:8080/hello

项目代码 #

主类IfredApplication.java（包路径：com.ifred.app） #

package com.ifred.app;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
@ComponentScan(basePackages={"com.ifred.app"})

public class IfredApplication {
    
    public static void main(String[] args) {
        SpringApplication.run(IfredApplication.class, args);
    }

}

Controller类hello.java（包路径：com.ifred.app.controller） #

package com.ifred.app.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/hello")
public class hello {
    
    @GetMapping
    public String hi() {
        return"Hello world";
    }

}

POM文件内容 #

<?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>3.0.3</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.ifred</groupId>
    <artifactId>ifred</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>ifred</name>
    <description>projeto ifood</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

控制台输出 #

[2m2023-02-26T10:43:59.509-03:00[0;39m [32m INFO[0;39m [35m5492[0;39m [2m---[0;39m [2m[           main][0;39m [36mcom.ifred.app.IfredApplication          [0;39m [2m:[0;39m Starting IfredApplication using Java 17.0.6 with PID 5492 (D:\Frederico\Softwares\Projetos Spring Tools Suite\ifred\target\classes started by Pichau in D:\Frederico\Softwares\Projetos Spring Tools Suite\ifred)
[2m2023-02-26T10:43:59.513-03:00[0;39m [32m INFO[0;39m [35m5492[0;39m [2m---[0;39m [2m[           main][0;39m [36mcom.ifred.app.IfredApplication          [0;39m [2m:[0;39m No active profile set, falling back to 1 default profile: "default"
[2m2023-02-26T10:44:00.280-03:00[0;39m [32m INFO[0;39m [35m5492[0;39m [2m---[0;39m [2m[           main][0;39m [36mo.s.b.w.embedded.tomcat.TomcatWebServer [0;39m [2m:[0;39m Tomcat initialized with port(s): 8080 (http)
[2m2023-02-26T10:44:00.290-03:00[0;39m [32m INFO[0;39m [35m5492[0;39m [2m---[0;39m [2m[           main][0;39m [36mo.apache.catalina.core.StandardService  [0;39m [2m:[0;39m Starting service [Tomcat]
[2m2023-02-26T10:44:00.291-03:00[0;39m [32m INFO[0;39m [35m5492[0;39m [2m---[0;39m [2m[           main][0;39m [36mo.apache.catalina.core.StandardEngine   [0;39m [2m:[0;39m Starting Servlet engine: [Apache Tomcat/10.1.5]
[2m2023-02-26T10:44:00.391-03:00[0;39m [32m INFO[0;39m [35m5492[0;39m [2m---[0;39m [2m[           main][0;39m [36mo.a.c.c.C.[Tomcat].[localhost].[/]      [0;39m [2m:[0;39m Initializing Spring embedded WebApplicationContext
[2m2023-02-26T10:44:00.391-03:00[0;39m [32m INFO[0;39m [35m5492[0;39m [2m---[0;39m [2m[           main][0;39m [36mw.s.c.ServletWebServerApplicationContext[0;39m [2m:[0;39m Root WebApplicationContext: initialization completed in 830 ms
[2m2023-02-26T10:44:00.710-03:00[0;39m [32m INFO[0;39m [35m5492[0;39m [2m---[0;39m [2m[           main][0;39m [36mo.s.b.w.embedded.tomcat.TomcatWebServer [0;39m [2m:[0;39m Tomcat started on port(s): 8080 (http) with context path ''
[2m2023-02-26T10:44:00.721-03:00[0;39m [32m INFO[0;39m [35m5492[0;39m [2m---[0;39m [2m[           main][0;39m [36mcom.ifred.app.IfredApplication          [0;39m [2m:[0;39m Started IfredApplication in 1.597 seconds (process running for 2.4)
[2m2023-02-26T10:44:09.601-03:00[0;39m [32m INFO[0;39m [35m5492[0;39m [2m---[0;39m [2m[nio-8080-exec-1][0;39m [36mo.a.c.c.C.[Tomcat].[localhost].[/]      [0;39m [2m:[0;39m Initializing Spring DispatcherServlet 'dispatcherServlet'
[2m2023-02-26T10:44:09.602-03:00[0;39m [32m INFO[0;39m [35m5492[0;39m [2m---[0;39m [2m[nio-8080-exec-1][0;39m [36mo.s.web.servlet.DispatcherServlet       [0;39m [2m:[0;39m Initializing Servlet 'dispatcherServlet'
[2m2023-02-26T10:44:09.602-03:00[0;39m [32m INFO[0;39m [35m5492[0;39m [2m---[0;39m [2m[nio-8080-exec-1][0;39m [36mo.s.web.servlet.DispatcherServlet       [0;39m [2m:[0;39m Completed initialization in 0 ms

补充信息 #

问题似乎出在首次启动项目时的结构上：

• 将项目文件发给朋友，他的电脑无法运行；
• 朋友用Spring Initializr按相同方式创建项目并首次运行后，该项目在所有电脑上都能正常运行；
• 朋友发给我的项目文件，在我的电脑上首次运行也无法正常工作。

内容的提问来源于stack exchange，提问作者f.e.7777