User Service

User Bean

Create a new bean class

package me.chairat.spring.boot.workshop.user;

import java.util.Date;

public class User {

    private Integer id;
    private String name;
    private Date birthDate;

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Date getBirthDate() {
        return birthDate;
    }

    public void setBirthDate(Date birthDate) {
        this.birthDate = birthDate;
    }

    public User(Integer id, String name, Date birthDate) {
        this.id = id;
        this.name = name;
        this.birthDate = birthDate;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", birthDate=" + birthDate +
                '}';
    }
}

User DAO

Create a new DAO class

package me.chairat.spring.boot.workshop.user;

import org.springframework.stereotype.Component;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

@Component
public class UserDaoService {

    private static List<User> users = new ArrayList<>();
    private static int userCount = 3;

    static {
        users.add(new User(1, "Adam", new Date()));
        users.add(new User(2, "Eve", new Date()));
        users.add(new User(3, "Jack", new Date()));
    }

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

    public User save(User user) {
        if (user.getId()==null) {
            user.setId(++userCount);
        }
        users.add(user);
        return user;
    }

    public User findOne(int id) {
        for (User user:users) {
            if (user.getId() == id) {
                return user;
            }
        }
        return null;
    }

}

User Resource

Create a new resource class

package me.chairat.spring.boot.workshop.user;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
public class UserResource {

    @Autowired
    private UserDaoService service;

    @GetMapping("/users")
    public List<User> retrieveAllUsers() {
        return service.findAll();
    }

}

If the date is displayed as timestamp, try appending spring.jackson.serialization.write-dates-as-timestamps=false to the application.properties

Add a new method

    @GetMapping("/users/{id}")
    public User retrieveUser(@PathVariable int id) {
        return service.findOne(id);
    }

Create User

Add a new method

    @PostMapping("/users")
    public void createUser(@RequestBody User user) {
        User savedUser = service.save(user);
    }

You also need to add the default constructor to the class User. Otherwise, you will get 500 Internal Server Error.

Test create a new user

Get all users

Response Entity

Enhance the createUser method

    @PostMapping("/users")
    public ResponseEntity<Object> createUser(@RequestBody User user) {
        User savedUser = service.save(user);

        URI location = ServletUriComponentsBuilder
                .fromCurrentRequest()
                .path("/{id}")
                .buildAndExpand(savedUser.getId())
                .toUri();

        return ResponseEntity.created(location).build();
    }

Delete User

Add a new method deleteById in UserDaoService

    public User deleteById(int id) {
        Iterator<User> iterator = users.iterator();
        while (iterator.hasNext()) {
            User user = iterator.next();
            if (user.getId() == id) {
                iterator.remove();
                return user;
            }
        }
        return null;
    }

And add a new REST method

    @DeleteMapping("/users/{id}")
    public void deleteUser(@PathVariable int id) {
        User user = service.deleteById(id);
        if (user==null) {
            throw new UserNotFoundException("id-" + id);
        }
    }

Exception handling is explained on the next page