java - 创建名称为 'mainController' : Unsatisfied dependency expressed through field 'userRepository' 的 bean 时出错

Question

我已经遇到这个错误几个星期了，但我不知道如何修复它。 Stack Overflow 上的类似解决方案不适合我的项目。

我目前使用的是mysql数据库，但是每当尝试启动服务器时都会遇到这个问题:StackTrace

[ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:1.5.6.RELEASE:run (default-cli) on project iPbackend: An exception occurred while running. null: InvocationTargetException: Error creating bean with name 'mainController': Unsatisfied dependency expressed through field 'userRepository'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.resource.iPbackend.UserRepository' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)

我正在使用这个主 Controller :MainController.java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;

import com.resource.iPbackend.UserRepository;
import com.resource.iPbackend.User;

@Controller
@RequestMapping(path = "/main")
public class MainController {

    @Autowired
    private UserRepository userRepository;

    @RequestMapping(path = "/reg", method = RequestMethod.POST)
    public @ResponseBody String regNewUser (@RequestParam String firstName,      @RequestParam String lastName, @RequestParam String email, @RequestParam String password, @RequestParam String username) {
        User n = new User();
        n.setFirstName(firstName);
        n.setLastName(lastName);
        n.setEmail(email);
        n.setPassword(password);
        n.setUsername(username);
        userRepository.save(n);
        return "User is stored in database: " + n;
    }

    @GetMapping(path = "/all")
    public @ResponseBody Iterable<User> getAllUsers() {
        return userRepository.findAll();
    }
}

与此存储库一起:UserRepository.java

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
import com.resource.iPbackend.User;


@Repository
public interface UserRepository extends CrudRepository<User, Long> {

}

这个实体:User.java

import org.springframework.data.annotation.Id;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
@Entity
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;
    private String firstName;
    private String lastName;
    private String email;
    private String password;
    private String username;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }
}

Answer 1

您需要在基本配置类中包含注释@EnableJpaRepositories，以便 Spring Data 将扩展 CrudRepository 的接口(interface)注册为 spring bean。

此外，注释 @Repository 在接口(interface)上不执行任何操作，因此不需要这样做，但它也不会因为存在而破坏任何内容。

编辑:

您还可以尝试通过告诉 @EnableJpaRepositories 注释您的存储库的确切位置来更加具体。即:

@EnableJpaRepositories("com.resource.iPbackened")