Spring Boot and REST API

1. {} Coding Saint .
http://codingsaint.com | http://codingsaint.in

2. Spring Boot - Introduction

3. Overview
Spring Boot
● An easy , robust ,faster way to create
production ready spring application
● It is a very opinionated approach of
Spring boot library and third party
application with a motive of starting
an application without much
configuration.

4. Primary Goals of Spring Boot
● A faster way for developers to create
spring application
● Out of the box opinions to provide
defaults for spring and third party
configurations.
● Providing range of non functional
features like health checks, metrics,
embedded servers, security etc
● No code generation and no
requirement of XML configuration

5. Requirements and Prerequisites
As an application
Java Version 8
Maven 3.2 + or Gradle 4
Servlet Container as Tomcat 8.5 /Jetty 9.4
/Undertow 1.3
While proceeding further we do expect that
you have Java version 8, Maven 3.2 or Gradle
As a developer
Knowledge of Java
Good to have prior knowledge of Spring
Framework

6. Bootstrapping the first Spring Boot
Project

7. Spring Initializr Spring Initializr
● https://start.spring.io

8. First Hello World !!!
Handling a URL
Url :
http://localhost:8080/greetings
http://localhost:8080/greetings
Hello ,World

9. First Hello World !!!
Handling a URL
Url :
http://localhost:8080/greetings
http://localhost:8080/greetings
@RestController
public class UserController {
@RequestMapping(path="greetings",
method=RequestMethod.GET)
protected String greetings() {
return "Hello, World";
}
}
Hello ,World

10. @SpringBootApplication
1. @SpringBootConfiguration
2. @EnableAutoConfiguration
3. @ComponentScan

11. @RestController
1. Denotes that the class contains request mappings.
2. Automatically serialize and deserialize java object response to Json /XML or any format
whatever is intended.

12. RequestMapping in Detail
@RequestMapping(path="greetings", method=RequestMethod.GET) @RequestMapping("greetings") @GetMapping("greetings")

13. Configuring Database
http://localhost:8080/users
List of users
query to database

14. Connecting to database
Creating dataSource
Just tell Spring boot app about which database to connect.
# H2
spring.h2.console.enabled=true
spring.h2.console.path=/h2
# Datasource
spring.datasource.url=jdbc:h2:file:~/user
spring.datasource.username=sa
spring.datasource.password=
spring.datasource.driver-class-name=org.h2.Driver
application.properties

15. HTTP POST
● HTTP POST request : Used to create a resource on server.
● Most of the time it’s like creating INSERT(s) at database.
● POST should be used for non-idempotent request, which changes the state of
server.

16. HTTP POST
● HTTP POST request : Used to create a resource on server.
● Most of the time it’s like creating INSERT(s) at database.
● POST should be used for non-idempotent request, which changes the state of
server.

17. HTTP POST
Model
public class User {
private Long id;
private String
firstName;
private String
lastName;
private String email;
//getters and setters
}
Controller
@RequestMapping(path={"/user"}, method=RequestMethod.POST)
public ResponseEntity<Void> add(@RequestBody User
user){
//logic
}
http://localhost:8080/user
{
"firstName":"Ray",
"lastName":"McFallen",
"email":"Ray@codingsaint.com"
}
Request Body in JSON

18. HTTP GET
HTTP GET request : Used to get the information already present on
server/database.
GET request doesn’t change state of server but only fetch the data.
http://localhost:8080/user/1

19. HTTP GET
Model
public class User {
private Long id;
private String
firstName;
private String
lastName;
private String email;
//getters and setters
}
Controller
@RequestMapping(path={"/user/{id}"}, method=RequestMethod.GET)
public ResponseEntity<User> get(@PathVariable ("id")
String id){
//logic
}
http://localhost:8080/user/1
{
"id": 1,
"firstName": "Ray",
"lastName": "McFallen",
"email": "Ray@codingsaint.com"
}
Response Body in JSON
Response as User (JSON) with id

20. HTTP PUT
HTTP PUT request : Used to update an existing resource on server.
PUT should be used for non-idempotent request, which changes the state of
server.

21. HTTP PUT
Controller
@RequestMapping(path={"/user"}, method=RequestMethod.PUT)
public ResponseEntity<Void> update(@RequestBody
User user){
//logic
}
http://localhost:8080/user
{
"id": 1,
"firstName": "Tim",
"lastName": "McFallen",
"email": "Ray@codingsaint.com"
}
Request Body in JSON

22. HTTP DELETE
HTTP DELETE request : Used to remove/purge an existing resource on server.
DELETE should be used for non-idempotent request, which changes the state of
server.

23. HTTP DELETE
Controller
@RequestMapping(path={"/user/{id}"}, method=RequestMethod.DELETE)
public ResponseEntity<Void> delete(@PathVariable ("id") String id){
//logic
}
http://localhost:8080/user/1

24. User Information API - Introduction
{
"id": 1,
"firstName": "Ray",
"lastName": "McFallen",
"email": "Ray@codingsaint.com"
}
public class User {
private Long id;
private String firstName;
private String lastName;
private String email;
//getters and setters
}

25. HTTP Status Codes
Status Code Range Description
1XX Informational
2XX Success
3XX Redirect
4XX Client error
5XX Server Error

26. Famous HTTP Codes
200 OK
201 Created
204 No content
301 Moved permanently
400 Bad Request
401 Unauthorized
405 Method not allowed
403 Forbidden access
415 Unsupported Media Type
500 Internal server error

27. Learn Spring Boot REST API and Microservices:
Spring Cloud
Join us in learning Spring Boot REST API and Microservices
● More than 7000 students
● Learn Step by step Spring Boot , Microservices and Spring Cloud
● 90 % Discount and price not more than 2 cups of coffee and 1 month money back
guarantee
● Follow the link and unveil the new learning
● Spring Boot REST API and Microservices: : Spring Cloud