Getting started with SpringBoot!

Before starting SpringBoot, Let me tell you, How did I find Spring Boot.

I have started my career with Play Framework. Play is popular for its simplicity. Play almost required no configuration. It does not need to write any XML, yes, I repeat No XML.

Play by default provides below things:

1. DataSource - Hikaricp
2. Logger - SLF4J with LogBack
3. Dependency Injection -  Google Juice
4. Build tool - SBT (Simple Build Tool)

The play comes with Scala and Java. It supports Non-blocking IO.

After exploring play enough, I have started working on Spring rest (Jersy) with Angular. For play developer, it's difficult to write boiler code for Spring. Spring required a lot of boiler code.
I have started exploring seed projects for Spring, I found few useful (To avoid writing boiler code).
While watching one of the Devoxx videos, I came to know about SpringBoot. I started Exploring Spring Boot example. I was very Happy With SpringBoot. It required almost Zero Boiler code.

1. No Need of Tomcat.
2. No Need to write XMLs

Within a few minutes, I was able to create a simple SpringBoot application with HelloWorld rest API. It's almost like working with Play framework again.

SpringBoot comes with Maven, Gradle. I choose Gradle, as, I was already familiar with Maven.

To understand SpringBoot, I have developed the REST API for the retail manager.

The problem statement is as Below:

A basic Spring Boot Application for the retail manager. Shops are stored in the Java in the memory map. Nearby shops can be retrieved by providing latitude and longitude of a customer. The distance between customer and shop is calculated by Haversine formula! The latitude and longitude of a shop are calculated using Google map API.


I have pushed all the code to Github: https://github.com/prashant7090/retail-manager

Let's understand springBoot. SoringBoot provides annotations to specify controller, model, service layer.

@SpringBootApplication
@ComponentScan("com.retailmanager")
public class BootRetailManager {
    public static void main(String[] args) {
        SpringApplication.run(BootRetailManager.class, args);
    }
} 

This is the starting point of SpringBoot.  @SpringBootApplication annotation loads components required for springBoot. @ComponentScan("com.retailmanager") - annotation by default scans spring components in child package, or, we can specify package.

@Controller
@RequestMapping("/shop")

@Controller annotation to specify controller.   @RequestMapping("/shop")   used to create route for the request.

@Autowired
GoogleApiUrlBuilder googleApiUrlBuilder;

@Autowired annotation to do dependency injection.

@Component
public class ShopDaoImpl implements ShopDao

 @Component annotation to indicate this is the class is an auto scan component. @ComponentScan  find out the bean (annotated with @Component) and register it in Spring container.

We have different annotations like @Service, @RestController etc, I have not used those. Rest of code is preety simple. (DAO layer).

Happy Learning!

DataSource - Connection Cook

Datasource:  Datasource is connection cook which provides us the connection through the Connection pool. It's up to us to order n number of connections.

Why DataSource:

Without Datasource, we left with a driver manager. we face following problem with driver manager:

• Take care of open & close the connection.
• Can not create a connection pool
• Hard to balance connection load.

Datasource provides us n number of connection, Connections are a reserve in the pool, so whenever someone required, it takes from the pool. When it close the connection is returned to the pool. We can externalize the properties of a Datasource. It help us If we want to keep different configuration depending upon a server. The Database vendor provides the implementation for Datasource. i.e Mysql, Oracle database provides the classes required build a Datasource. 

The most know DataSource in apache DBCP.

Below is the Spring configuration in for DBCP.

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">

<property name="driverClassName" value="com.mysql.jdbc.Driver" />

<property name="url" value="jdbc:mysql://localhost:3306/databaseName" />

<property name="username" value="databaseUserName" />

<property name="password" value="databasePassword" />

<property name="defaultAutoCommit" value="true" />

</bean>

Below is the maven dependency for DBCP:

<dependency>

<groupId>commons-dbcp</groupId>

<artifactId>commons-dbcp</artifactId>

<version>1.2.2</version>

</dependency>

Play Framework internally use Hikaricp DataSource: 

Hikaricp is faster than DBCP: Below is the performance statistics from HikariCp GitHub page:

Below is the Spring Configuration of Hikaricp for Mysql:

  

<bean id="HikariCpConfig" class="com.zaxxer.hikari.HikariConfig">

    <property name="dataSourceClassName"                     value="com.mysql.jdbc.jdbc2.optional.MysqlDataSource"/>

    

 <property name="dataSourceProperties">

      <props>

        <prop key="serverName"> localhost </prop>

        <prop key="port">3306</prop>

        <prop key="databaseName">databasename</prop>

        <prop key="user">databaseUserName</prop>

        <prop key="password">databaseUserPasswod</prop>

      </props>

    </property>

  </bean>

Below is the maven dependency required for HikariCp:

    <dependency>

      <groupId>com.zaxxer</groupId>

      <artifactId>HikariCP</artifactId>

      <version>2.5.1</version>

    </dependency>

You Can choose latest from search.maven.org.