自动连线导致Spring Boot应用程序出现异常

Question

I am having trouble getting the Autowired annotation to work in my spring boot application.

The error that I am receiving is "Could not autowire field. No qualifying bean of type"

I have verified that the code from the Controller on down are not POJO and have Spring annotations.

I am also unable to run my main method outside of a package. Any suggestions?

package com.xxx.controller;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.context.web.SpringBootServletInitializer;

@SpringBootApplication
public class SampleWebJspApplication extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(SampleWebJspApplication.class);
    }

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

}

UserService class

package com.xxx.service;

    import java.util.List;

    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;

    import com.xxx.entity.User;
    import com.xxx.repository.UserRepository;

    @Service
    public class UserService {

        @Autowired
        private UserRepository userRepository;

        public List<User> findAll() {
            return userRepository.findAll();
        }

    }

UserRepository class

package com.xxx.repository;

import org.springframework.data.jpa.repository.JpaRepository;

import com.xxx.entity.User;

public interface UserRepository extends JpaRepository<User, Integer> {

}

Answer 1

There could be two possible reasons for this:

• Package of component is not included in @ComponentScan packages.
• Package of repository is not included in @EnableJPARepositories packages.

Answer 2

Your @SpringBootApplication annotation is in the package "com.xxx.controller", so Spring will be able to scan components from this package to packages inside it.

Docs: If specific packages are not defined, scanning will occur from the package of the class that declares this annotation.

Try:

• Add @ComponentScan({"com.xxx"}) under @SpringBootApplication or modify to @SpringBootApplication(scanBasePackages = {"com.xxx"}).

or

• Just move your class "SampleWebJspApplication" to the package "com.xxx". This is probably the best solution, once this class of yours doesn't look like a controller.