Spring Boot中GetMapping接口调用出现404 Not Found问题求助

我是Spring Boot新手，尝试用RestController创建API端点，但调用localhost:8080/api/v1/guides时出现404 Not Found错误，浏览器显示白标错误页面。相关代码如下：

应用类 #

package com.guider.guiderfinder;

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

@SpringBootApplication
@EnableAutoConfiguration
@ComponentScan("com.guider")
public class GuiderFinderApplication {

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

}

控制器类 #

package com.guider.guiderfinder.controller;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import com.guider.guiderfinder.model.Guide;
import com.guider.guiderfinder.repository.GuideRepository;

@RestController
@RequestMapping("/api/v1/") //Standard url endpoint defined
public class GuideController {
    
    @Autowired
    private GuideRepository guideRepository;
    
    @GetMapping("/guides") //this api endpoint is called from url = localhost:8080/api/v1/guides
    public List<Guide> getAllGuides() {
        System.out.println("API was hit");
        return guideRepository.findAll();
    }

}

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.guider</groupId>
    <artifactId>guider-finder</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>guider-finder</name>
    <description>Backend of guide finder</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        
        <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>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        
        <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-devtools -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            </dependency>
        
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-web -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            </dependency>
        
        <!-- https://mvnrepository.com/artifact/org.springframework.data/spring-data-jpa -->
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-jpa</artifactId>
            </dependency>
        
        <!-- https://mvnrepository.com/artifact/net.sourceforge.javydreamercsw/MySQL-Driver -->
        <dependency>
            <groupId>net.sourceforge.javydreamercsw</groupId>
            <artifactId>MySQL-Driver</artifactId>
            <version>0.1</version>
        </dependency>
    </dependencies>

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

</project>

排查与解决步骤 #

1. 简化应用类注解
   @SpringBootApplication已经包含@EnableAutoConfiguration和@ComponentScan（默认扫描主类所在包及其子包），额外添加的@ComponentScan("com.guider")虽范围更大，但可简化代码避免冲突。修改后应用类：

   package com.guider.guiderfinder;
   
   import org.springframework.boot.SpringApplication;
   import org.springframework.boot.autoconfigure.SpringBootApplication;
   
   @SpringBootApplication
   public class GuiderFinderApplication {
   
       public static void main(String[] args) {
           SpringApplication.run(GuiderFinderApplication.class, args);
       }
   
   }
   

   这样Spring仍能扫描到com.guider.guiderfinder.controller下的控制器。

2. 修正控制器路径配置
   类上@RequestMapping("/api/v1/")末尾带斜杠，方法上@GetMapping("/guides")开头也带斜杠，拼接后会出现重复斜杠（虽Spring会自动处理，但规范写法需统一）。推荐调整为：

   @RestController
   @RequestMapping("/api/v1")
   public class GuideController {
       
       @Autowired
       private GuideRepository guideRepository;
       
       @GetMapping("/guides")
       public List<Guide> getAllGuides() {
           System.out.println("API was hit");
           return guideRepository.findAll();
       }
   }
   

3. 清理冗余依赖并替换MySQL驱动

   • spring-boot-starter-web已包含spring-web，删除pom.xml中单独的spring-web依赖；
   • spring-boot-starter-data-jpa已包含spring-data-jpa，删除单独的spring-data-jpa依赖；
   • 替换非官方MySQL驱动为官方版本：

     <dependency>
         <groupId>mysql</groupId>
         <artifactId>mysql-connector-java</artifactId>
         <scope>runtime</scope>
     </dependency>
     

   冗余依赖可能引发类加载冲突，非官方驱动易导致数据库连接问题，影响组件初始化。

4. 验证启动日志
   启动应用后查看控制台日志，确认是否有Mapping GET "/api/v1/guides"类输出。有则说明控制器映射成功，无则需检查组件扫描或控制器注解。

5. 补充数据库配置
   若GuideRepository是JPA仓库，需在application.properties中添加数据库连接信息：

   spring.datasource.url=jdbc:mysql://localhost:3306/your_db_name
   spring.datasource.username=your_username
   spring.datasource.password=your_password
   spring.jpa.hibernate.ddl-auto=update
   spring.jpa.show-sql=true
   

   缺少配置会导致JPA初始化失败，影响控制器正常加载。

按以上步骤调整后重启应用，再访问localhost:8080/api/v1/guides即可正常调用。

内容的提问来源于stack exchange，提问作者Rudra Kakadia