沒有可用類型的合格 bean - 預計至少有 1 個 bean 有資格作為自動裝配候選

Question

我大致遵循 Spring In Action，第 5 版中的代碼。 目前在自動裝配 bean 時遇到問題，我似乎無法弄清楚為什么 bean 在運行上下文中不可用。 以下是一些相關的類：

需要UserRepository bean 的控制器：

package tacos.web;

import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import tacos.data.jpa.UserRepository;
import tacos.security.RegistrationForm;

@Controller
@RequestMapping("/register")
public class RegistrationController {

    private final UserRepository userRepo;
    private final PasswordEncoder passwordEncoder;

    public RegistrationController(
            UserRepository userRepo, PasswordEncoder passwordEncoder) {
        this.userRepo = userRepo;
        this.passwordEncoder = passwordEncoder;
    }

    @GetMapping
    public String registerForm() {
        return "registration";
    }

    @PostMapping
    public String processRegistration(RegistrationForm form) {
        userRepo.save(form.toUser(passwordEncoder));
        return "redirect:/login";
    }

}

UserRepository JPA 接口：

package tacos.data.jpa;

import org.springframework.data.repository.CrudRepository;
import tacos.security.User;

public interface UserRepository extends CrudRepository<User, Long> {
}

User類：

package tacos.security;

import java.util.Arrays;
import java.util.Collection;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.userdetails.UserDetails;
import lombok.AccessLevel;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.RequiredArgsConstructor;

@Entity
@Data
@NoArgsConstructor(access=AccessLevel.PRIVATE, force=true)
@RequiredArgsConstructor
public class User implements UserDetails {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Long id;

    private final String username;
    private final String password;
    private final String fullname;
    private final String street;
    private final String city;
    private final String state;
    private final String zip;
    private final String phoneNumber;

    @Override
    public Collection<? extends GrantedAuthority> getAuthorities() {
        return Arrays.asList(new SimpleGrantedAuthority("USER"));
    }

    @Override
    public boolean isAccountNonExpired() {
        return true;
    }

    @Override
    public boolean isAccountNonLocked() {
        return true;
    }

    @Override
    public boolean isCredentialsNonExpired() {
        return true;
    }

    @Override
    public boolean isEnabled() {
        return true;
    }

}

主要類：

package tacos;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@SpringBootApplication
public class TacoCloudApplication implements WebMvcConfigurer {

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

    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("home");
    }
}

錯誤本身：

Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'registrationController' defined in file: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'tacos.data.jpa.UserRepository' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}

不太確定為什么UserRepository bean 沒有正確連接。 我的項目中有其他類，其中 bean 接線正確發生。

很高興包含理解為什么我看到此錯誤所需的任何其他類。

Answer 1

嘗試以下幾點

1. 請檢查 spring boot 是否能夠掃描您的存儲庫類的包結構。
2. 還要檢查您的 User 類是否應該用@Entity 進行注釋。