Spring-Boot-Introduction

Agenda

0. Spring Boot Basics
1. Hibernate ORM Basics
2. Set Up
3. Build a Spring boot applicaton with MySQL database together!

0. Spring Boot Basics

0.0 Why Java?

0.1 Comparision between Spring and Spring boot

	Spring	Spring boot
Definition	huge Enterprise Java Framework	bootstrap a standalone, producation-grade Spring application that can be easily run
Features	- POJOs - MVC Dependency Injection - Testing - Dependency Injection - Security ...	- Convention over configuration. - Embedded Tomcat server ...

0.2 When will you use Spring boot?

• Develop web application.

• Send data to Front-end via RESTful API.

  • RESTful API: An application program interface (API) that uses HTTP requests to GET, PUT, POST and DELETE data.

• Security solution to web application.

• Communicate with database.

• Integrate with external resources.

0.3 Important Concept

• POJO: Plain Old Java Object. For more information.

POJO	Java Bean
No extends No implements No prespecified annotation
Not all POJOs are Java Beans	All Java Beans are POJOS

POJO example:

@Component
public class ExampleListener {

    @JmsListener(destination = "myDestination")
    public void processOrder(String message) {
        System.out.println(message);
    }
}

Java Bean example:

public class ExampleListener implements MessageListener {

    public void onMessage(Message message) {
        ...
    }

}

• MVC: Model-View-Controller architecture(MVC).

• Dependency Injection: Details will be talked with the hands-on coding part.

• Tomcat: A Java-capable HTTP Server

• HTTP Server: A piece of software that understands URLs and HTTP protocol.

1. Hibernate ORM Basics

1.0 Hibernate

Hibernate is a high-performance object/relational persistence and query service.

1.1 ORM

A way to leverage SQL in other programming languages.

Example:

SQL	Hibernate ORM
CREATE TABLE product	@Entity @Table(name = "product") public class Cart { … }

1.2 What is Hibernate ORM? (http://hibernate.org/orm/what-is-an-orm/)

An object-relational mapping tool for the Java programming language.

Using Hibernate ORM will help your application to achieve Data Persistence.

2.Set Up

2.0 Environment Requirement

• Java 8 SDK
• A Java IDE that you are comfortable to work with.
• Postman

2.1 Create Spring Boot Application (Enable Maven Auto-import)

Suggested Method 1: Use IntelliJ IDE

• Instead of downloading the Community Edition from above, it is recommended that students get the IntelliJ IDEA Ultimate for free by signing up using their university email address here.

• If you do not see Spring Initializr in IntelliJ, (you are probably using the Community Edition which doesn't support this and thus) you can download the Spring Assistant plug-in by going to File > Settings > Plugins > Marketplace > Search for "Spring Assistant". Click "Install", then "Restart". Now when you create a new project under File > New > Project, you should be able to see Spring Assistant (an alternative to Spring Initializr).

Method 2: Use Eclipse IDE

Add the following codes to your pom.xml under the first hierarchy

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
</parent>

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
 </dependencies>

Method 3: Download from Spring Boot Website

2.2 Set Up MySQL database

• For Windows

  • Download MySQL Community Server. Please download the zip file.

  

  

  • Unzip the mysql-X.X.X-winxXX.zip to a directory. E.g. C:\Users\%USERNAME%\Downloads

  • Open command prompt. Type in the following:

  $ cd C:\Users\%USERNAME%\Downloads\mysql-X.X.XX-winxXX\mysql-X.X.XX-winxXX\bin
  
  # Initialize the database. Create a root user with random password. Show the messages on console
  $ mysqld --initialize --console
  ...
  ...A temporary password is generated for root@localhost: xxxxxxxx // take note of this password, if forget, delete and unzipped folder, unzip it, and repeat the above steps
  

  • To start the server:

  $ mysqld --console
  

  • To shut down the server: Ctrl+C (but don't do it now, we need to keep the connection alive to connect to MySQL)

  • Open another Command Prompt. To start a 'Client':

  $ mysql -u root -p
  Enter password: XXXXXXX  // Enter temporary password which was generated just now
  Welcome to the MySQL monitor.  Commands end with ; or \g.
  Your MySQL connection id is 1
  Server version: 8.0.xx
  Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
  
  mysql>
  

• For MacOS

  • Download MySQL Community Server. Please download the dmg file.

  

  

  • Follow this. Basically just open the dmg and follow the instruction. Take note of the password!!

  • It will be installed in /usr/local/mysql

  • To start and shutdown the server:

  

  

  • To start a 'Client':

  $ cd /usr/local/mysql/bin
  ./mysql -u root -p
  Enter password:   // Enter the root's password given during installation. You will NOT any * for maximum security
  Welcome to the MySQL monitor.  Commands end with ; or \g.
  ......
  mysql>
  

• For Ubuntu.

2.3 Connect MySQL Database to Spring Boot project via Hibernate

• Step 1: Open File/Project Structure in IntelliJ

• Step 2: Open Database on the right-hand side tool bar

We are good to go!

3. Build a Spring boot applicaton with MySQL database together!

3.0 Goals

• (GET) Retreive products according to catagory

• (GET) Retreive products that a merchant has

• (POST) Add new products

• (PUT) Update product information

• (DELETE) Delete products

3.1 Database Design

3.2 File Structure (Good Software Engineering Practice Suggestion)

3.3 Coding

• Step 0: Create Database in MySQL and configuration ini application.properties

Windows:

cd \SpringBootIntroduction\mysql\bin
mysql -u root -p
...
mysql> CREATE DATABASE inventory;

MacOS:

cd /usr/local/mysql/bin
./mysql -u root -p
...
mysql> CREATE DATABASE inventory;

Insert some data:

insert into Product (productID, category,description,merchantID,name,price) VALUES (110,"book","extrodinary book that deserves your reading",200,"Black Swan Green", 37.9);
insert into Product (productID, category,description,merchantID,name,price) VALUES (111,"pen","hand made wood pen that is specially for you",200,"Burgendy Pen",26.8);
insert into Product (productID, category,description,merchantID,name,price) VALUES (112,"mouse","hold this mouse, you will feel you own the whole world",201,"Good Mouse", 67);
insert into Product (productID, category,description,merchantID,name,price) VALUES (113,"book","heartbreaking. The portrait of Afghan culture broadly painted",202,"The Kite Runner",37);
insert into Product (productID, category,description,merchantID,name,price) VALUES (114,"book","When a man is found murdered in an abandoned building, unflappable detective Sasagaki is assigned to the case.", 202,"Journey Under the Midnight Sun", 37);

Application.properties:

server:
  port: 8080

spring:
  jpa:
    generate-ddl: true
    show-sql: true
    hibernate:
      show-sql: true
      ddl-auto: update
      naming.physical-strategy: org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl
    properties:
      hibernate:
        default_schema: app
        id.new_generator_mappings: true
        dialect: org.hibernate.dialect.MySQL5Dialect
  datasource:
    url: jdbc:mysql://localhost:3306/inventory?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
    username: root
    password: 

• Step 1: Write Entities

@Entity: name an entity

@Table(name="product"): name a table in database

@Id: primary key

@Column: name a column in database

• Step 2: Create Repo

extends JpaRepository<T,D>: JpaRepository = CrudRepository + PageAndSortingRepository

• Step 3: Write Service

ProductService: ProductServiceImpl, ProductServiceCacheImpl,...

@Service: sterotype annotation

@Autowire: dependency injection

• Step 4: Write Controller

@RestController: = @Controller + @RequestBody

@RequestMapping: annotation

Reference:

1. https://www.quora.com/What-is-Spring-Framework-used-for
2. https://www.ntu.edu.sg/home/ehchua/programming/sql/MySQL_HowTo.html
3. Java Brains Youtube Tutorial Series
4. Telusko Youtube Tutorial Series