Spring 启动 controller 未能命中错误 404

Question

I am building this Spring Boot application with Hibernate and MySQL. I know this is pretty basic and the same question is asked multiple times but I can't figure out why my controller isn't hitting and gives 404 error. As I see, the problem is with ComponentScan where my @SpringBootApplication and @RestController reside within one package while my @Repository and @Entity lie in another package. When I include the package as @ComponentScan(basePackages = "com.sample.user") , the project builds and runs successfully but does not hit the GET method getUser() and no console output of an error as well. The GET method hits only when I omit the @Autowired private UserRepository userRepository; from the controller class along with @ComponentScan in application class.

Controller

package com.sample.rest.controller;

import com.sample.user.entity.User;
import com.sample.user.repository.UserRepository;
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.RestController;

@RestController
@RequestMapping ("user")
public class UserController {

    @Autowired
    private UserRepository userRepository;

    @GetMapping("/")
    public User getUser() {
        User user  = new User();
        user.setFirstName("Lady");
        user.setLastName("Gaga");
        user.setEmail("l.gaga@ymail.com");
        userRepository.save(user);
        return user;
    }
}

Application

package com.sample.rest;

import com.sample.rest.controller.UserController;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
@ComponentScan(basePackages = "com.sample.user")
public class RestServicesApplication {

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

}

Repository Interface

package com.sample.user.repository;

import com.sample.user.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.stereotype.Repository;

@EnableJpaRepositories
@Repository
public interface UserRepository extends JpaRepository<User, Long> {}

Entity

package com.sample.user.entity;

import org.springframework.data.jpa.domain.support.AuditingEntityListener;

import javax.persistence.*;

@Entity
@Table(name = "user")
@EntityListeners(AuditingEntityListener.class)
public class User {

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

    @Column(name = "first_name", nullable = false)
    private String firstName;

    @Column(name = "last_name", nullable = false)
    private String lastName;

    @Column(name = "email_address", nullable = false)
    private String email;

    public long getId() {
        return id;
    }

    public void setId(long 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;
    }
}

Browser Page https://ibb.co/KDsqLn3

Answer 1

With @ComponentScan(basePackages = "com.sample.user") you are overwriting the default behavior.

So either remove this and put the packages below the package where you have @SpringBootApplication or add all packages to @ComponentScan .

I recommend not to use the default Spring Boot behavior.

So remove ComponentScan an move RestServicesApplication to the com.sample package

Answer 2

Use this it will resolve your Issue.

@ComponentScan(basePackages = "com.sample")

or use multiple package sacn somthing like

@ComponentScan({ "com.sample", "com.sample.user" })