Spring Boot中IUserRepository Bean找不到问题求助

正在学习Java Spring Boot并编写基础REST API，此前一切正常。连接VPN后应用无法运行，报错提示：

com.example.demo.Registration构造器的第0个参数需要类型为com.example.demo.IUserRepository的Bean，但未找到。

排查情况：

• 认为并非VPN导致，但不清楚问题所在
• 所有文件均在同一包com.example.demo下（除POM.xml）
• Eclipse中无编译错误
• 尝试过Stack Overflow上的旧解决方案（为Repository添加@Autowired、@Repository注解，主类添加@EnableJpaRepositories），但均无效
• 同包下的文件似乎无法互相识别，点击Eclipse的导入提示无反应

相关代码 #

1. User实体类 #

package com.example.demo;

import java.util.UUID;

import org.springframework.data.annotation.Id;

import jakarta.persistence.Entity;

@Entity
public class User {
    @Id
    private String id;
    private String prename;
    private String lastname;
    private String password;
    private String email;
    private int age;
    
    public User() { }
    
    public User(String prename, String lastname, int age, String password, String email) {
        this.id = UUID.randomUUID().toString();
        this.prename = prename;
        this.lastname = lastname;
        this.password = password;
        this.email = email;
        this.age = age;
    }
    
    //getter
    public String getID() {return id;}
    public String getPrename() { return prename;}
    public String getLastname() {return lastname;}
    public int getAge() {return age;}
    public String getEmail() {return email;}
    public String getPassword() {return password;}
    
    //setter
    public void setID(String id) {this.id = id;}
    public void setPrename(String prename) {this.prename = prename;}
    public void setLastname(String lastname) {this.lastname = lastname;}
    public void setAge(int age) {this.age = age;}
    public void setEmail(String email) {this.email = email;}
    public void setPassword(String password) {this.password = password;}
}

2. IUserRepository接口 #

package com.example.demo;

import org.springframework.data.repository.CrudRepository;

public interface IUserRepository extends CrudRepository<User, String>
{

}

3. Registration控制器 #

package com.example.demo;

import java.util.Map;
import java.util.Optional;

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

//import denniscompany.websitemodels.*;
//import denniscompany.websiterepositories.*;

@RestController
public class Registration {
    
    private IUserRepository userRepository;

    public Registration(IUserRepository p_oUserRepository ) {
        userRepository = p_oUserRepository;
        userRepository.save(new User("Test", "User", 28, "test@gmx.de", "1234"));
        
    }

    @GetMapping("/")
    public Iterable<User> getUsers() { return userRepository.findAll(); }
    
}

4. POM.xml配置 #

<?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>3.2.4</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 project for Spring Boot</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
    <dependency>
        <groupId>jakarta.persistence</groupId>
        <artifactId>jakarta.persistence-api</artifactId>
        <version>3.2.0-B01</version>
    </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-rest</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>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <version>2.2.224</version>
            <scope>test</scope>
        </dependency>

    </dependencies>

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

问题排查与解决方案 #

1. 确保Spring Boot主类配置正确 #

Spring Boot主类必须在根包（com.example.demo）下，并且带有@SpringBootApplication注解。如果主类不在根包，需要手动指定扫描范围：

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

2. 修正POM依赖问题 #

当前POM存在三个关键问题，修改后的依赖部分如下：

<dependencies>
    <!-- 添加JPA starter，自动生成Repository代理实现 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-rest</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>
    <!-- 移除test scope，让运行时能加载H2驱动 -->
    <dependency>
        <groupId>com.h2database</groupId>
        <artifactId>h2</artifactId>
        <version>2.2.224</version>
    </dependency>
</dependencies>

3. 为Repository添加@Repository注解 #

显式添加注解确保Spring正确识别Repository：

package com.example.demo;

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface IUserRepository extends CrudRepository<User, String>
{

}

4. 修正控制器初始化逻辑 #

不要在构造器中直接调用Repository方法，改用@PostConstruct执行初始化：

package com.example.demo;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import jakarta.annotation.PostConstruct;

@RestController
public class Registration {
    
    private final IUserRepository userRepository;

    public Registration(IUserRepository userRepository ) {
        this.userRepository = userRepository;
    }

    @PostConstruct
    public void init() {
        userRepository.save(new User("Test", "User", 28, "test@gmx.de", "1234"));
    }

    @GetMapping("/")
    public Iterable<User> getUsers() { 
        return userRepository.findAll(); 
    }
}

5. 清理Eclipse项目缓存 #

执行以下步骤解决Eclipse识别问题：

• 点击Project -> Clean清理编译缓存
• 右键项目选择Maven -> Update Project，勾选Force Update of Snapshots/Releases
• 重启Eclipse

内容的提问来源于stack exchange，提问作者Razielruss