---
title: 'SpringBoot crud restful api (使用資料庫還有postman)'
disqus: hackmd
---
###### tags: `SpringBoot`
SpringBoot crud restful api (使用資料庫還有postman)
===

[TOC]

## 筆記目的

> 讓你了解怎麼樣使用mysql還有spring boot 實現restful api 讓你可以前後端分離，本筆記只有後端部分，所以使用postman來當作客戶端來測試

本筆記的架構大概如下:


> 介面層(Controller) 接收前端請求(處理網址)
業務邏輯層（Service）：根據請求做資料處理或是處理從DAO回來的資料。
資料訪問層（Dao）：對資料庫做增修查改等操作。

開發的順序很簡單:

1. 先完成applications的設定
2. 完成model
3. 完成dao也就是repository
4. 完成service
5. 完成controller
6. 完成exception

[引用自Day 17 - Spring Boot Todo List RESTful API 實作](https://ithelp.ithome.com.tw/articles/10244715)

具體請參考:

* [Spring Boot Hibernate MySQL CRUD REST API Tutorial | Full Course](https://www.youtube.com/watch?v=4Ico2HjRTCE)
* [application.properties (ithome)](https://ithelp.ithome.com.tw/articles/10217667)
* [完整的設定application(ithome)](https://ithelp.ithome.com.tw/articles/10223745)

## 先備條件

1. 請安裝mysql 並設定好root的密碼
2. 請在spring boot 啟用時對以下的東西打勾

Spring Web
Spring data jpa
mysql driver
lombok


## 程式碼部分

### 專案架構


### application.properties

spring.jpa.hibernate.ddl-auto=update
spring.datasource.url=jdbc:mysql://localhost:3306/helloworld?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC
###helloworld is database name資料庫名稱，不是資料表名稱喔
spring.datasource.username=root
spring.datasource.password=yourpassword
###下面的都照抄，不懂去翻ithome的連結
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.jpa.database-platform=org.hibernate.dialect.MySQL8Dialect
spring.jpa.properties.hibernate.dialect.storage_engine=innodb

### pom.xml

在此省略，因為只要你有在先備條件裡面打勾，便會自動生成

### Model

package com.example.demo.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="employees")
public class Employee {
	
	
	
	public Employee() {
		super();
		// TODO Auto-generated constructor stub
	}

	public Employee(long id, String firstName, String lastName, String email) {
		super();
		this.id = id;
		this.firstName = firstName;
		this.lastName = lastName;
		this.email = email;
	}

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private long id;
	
	@Column(name = "first_name", nullable = false)
	private String firstName;
	
	@Column(name = "last_name")
	private String lastName;
	
	@Column(name = "email")
	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;
	}
	
	
}

### Dao

package com.example.demo.dao;

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

import com.example.demo.model.Employee;
@Repository
public interface EmployeeRepository extends JpaRepository<Employee, Long>{

}

> 繼承JpaRepository讓我不需要去實作方法，只是要記住他的語法，所以重點都會擺在
> service impl

### Service

package com.example.demo.service;

import java.util.List;

import org.springframework.stereotype.Service;

import com.example.demo.model.Employee;
@Service
public interface EmployeeService {
	Employee saveEmployee(Employee employee);
	List<Employee> getAllEmployees();
	Employee getEmployeeById(long id);
	Employee updateEmployee(Employee employee, long id);
	void deleteEmployee(long id);
}

> service的介面，重點是回傳的資料型態，還有方法名稱要取的好，參數當然也是

### Service impl

package com.example.demo.service.impl;

import java.util.List;

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

import com.example.demo.dao.EmployeeRepository;
import com.example.demo.model.Employee;
import com.example.demo.service.EmployeeService;

import exception.ResourceNotFoundException;

@Service
public class EmployeeServiceImpl implements EmployeeService {
	@Autowired
	EmployeeRepository employeeRepository;

	public EmployeeServiceImpl(EmployeeRepository employeeRepository) {
		super();
		this.employeeRepository = employeeRepository;
	}

	@Override
	public Employee saveEmployee(Employee employee) {
		return employeeRepository.save(employee);
	}

	@Override
	public List<Employee> getAllEmployees() {
		return employeeRepository.findAll();
	}

	@Override
	public Employee getEmployeeById(long id) {
//		Optional<Employee> employee = employeeRepository.findById(id);
//		if(employee.isPresent()) {
//			return employee.get();
//		}else {
//			throw new ResourceNotFoundException("Employee", "Id", id);
//		}
		return employeeRepository.findById(id).orElseThrow(() -> new ResourceNotFoundException("Employee", "Id", id));

	}

	@Override
	public Employee updateEmployee(Employee employee, long id) {

		// we need to check whether employee with given id is exist in DB or not
		Employee existingEmployee = employeeRepository.findById(id)
				.orElseThrow(() -> new ResourceNotFoundException("Employee", "Id", id));

		existingEmployee.setFirstName(employee.getFirstName());
		existingEmployee.setLastName(employee.getLastName());
		existingEmployee.setEmail(employee.getEmail());
		// save existing employee to DB
		employeeRepository.save(existingEmployee);
		return existingEmployee;
	}

	@Override
	public void deleteEmployee(long id) {

		// check whether a employee exist in a DB or not
		employeeRepository.findById(id).orElseThrow(() -> new ResourceNotFoundException("Employee", "Id", id));
		employeeRepository.deleteById(id);
	}

}

> 千萬要記住要`Autowired EmployeeRepository employeeRepository`
> 基本上就是宣告一個類別型態為EmployeeRepository的實體，而employeeRepository是變數名稱，所以都要使用employeeRepository來call 內建的方法
put的邏輯比較難，務必要看懂她的巧妙思考方式
### Controller

package com.example.demo.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.example.demo.model.Employee;
import com.example.demo.service.EmployeeService;

@RestController
@RequestMapping("/api/employees")
public class EmployeeController {
	
	@Autowired
	EmployeeService employeeService;

//	public EmployeeController(EmployeeService employeeService) {
//		super();
//		this.employeeService = employeeService;
//	}

	// build create employee REST API
	@PostMapping()
	public ResponseEntity<Employee> saveEmployee(@RequestBody Employee employee) {
		return new ResponseEntity<Employee>(employeeService.saveEmployee(employee), HttpStatus.CREATED);
	}

	// build get all employees REST API
	@GetMapping
	public List<Employee> getAllEmployees() {
		return employeeService.getAllEmployees();
	}

	// build get employee by id REST API
	// http://localhost:8080/api/employees/1
	@GetMapping("{id}")
	public ResponseEntity<Employee> getEmployeeById(@PathVariable("id") long employeeId) {
		return new ResponseEntity<Employee>(employeeService.getEmployeeById(employeeId), HttpStatus.OK);
	}

	// build update employee REST API
	// http://localhost:8080/api/employees/1
	@PutMapping("{id}")
	public ResponseEntity<Employee> updateEmployee(@PathVariable("id") long id, @RequestBody Employee employee) {
		return new ResponseEntity<Employee>(employeeService.updateEmployee(employee, id), HttpStatus.OK);
	}

	// build delete employee REST API
	// http://localhost:8080/api/employees/1
	@DeleteMapping("{id}")
	public ResponseEntity<String> deleteEmployee(@PathVariable("id") long id) {

		// delete employee from DB
		employeeService.deleteEmployee(id);

		return new ResponseEntity<String>("Employee deleted successfully!.", HttpStatus.OK);
	}

}

### Exception

package exception;

import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.http.HttpStatus;

@ResponseStatus(value = HttpStatus.NOT_FOUND)
public class ResourceNotFoundException extends RuntimeException{
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	private String resourceName;
	private String fieldName;
	private Object fieldValue;
	
	public ResourceNotFoundException(String resourceName, String fieldName, Object fieldValue) {
		super(String.format("%s not found with %s : '%s'", resourceName, fieldName, fieldValue));
		this.resourceName = resourceName;
		this.fieldName = fieldName;
		this.fieldValue = fieldValue;
	}
	
	public String getResourceName() {
		return resourceName;
	}
	
	public String getFieldName() {
		return fieldName;
	}
	
	public Object getFieldValue() {
		return fieldValue;
	}
	
}

## 測試

基本上這裡測試的邏輯都是使用postman，基本的操作是所謂的crud
就是大家說的增刪改查就對了

| 資料庫操作 | 對應的postman request |
| ---------- | --------------------- |
| create | Post |
| read | Get |
| update | Put |
| delete | Delete |

所以我的測試邏輯很簡單，你想要新增員工就使用Post請求，然會去看看我們的controller是
怎麼寫url的

@RequestMapping("/api/employees")

所以你可以知道你要適用的url就會是`http://localhost:8080`+`/api/employees`

=`http://localhost:8080/api/employees`

然後再加上一些變化。以下會詳細給出例子

### 新增員工


http://localhost:8080/api/employees

put the block code into body

{
    "firstName":"mike",
    "lastName":"sandy",
    "email":"[e-mail]"
}

> 因為我這裡是新增員工，所以我不需要給定員工id，這個程式碼會自動幫我加上

### 查詢員工

http://localhost:8080/api/employees/5


### 更改員工

http://localhost:8080/api/employees/5

{
    "id": 5,
    "firstName": "Terry",
    "lastName": "sandy",
    "email": "[e-mail]"
}

> 更改員工便需要在body的地方加上id，不然你不知道你是要更改誰而且要傳回完整的你想要更改的，不然他會變成null，舉例而言，如果你把lastname刪掉，他就會變成


### 刪除員工

http://localhost:8080/api/employees/5


打開資料庫後會發現5號員工確實被刪除了