tags	projects

Table of Contents

• What you’ll build
• What you’ll need
• Create the database
• Create the Spring Application
• Create the application.properties file
• Create the @Entity model
• Create the repository
• Create a new controller for your Spring application
• Make the application executable
• Test the application
• Summary

This guide walks you through the process of creating a Spring application connected with a MySQL Database.

What you’ll build

You’ll create a MySQL database, build a Spring application and connect it with the newly created database.

Note	MySQL is `GPL’d, so ANY PROGRAM USING IT MUST BE GPL’d too

What you’ll need

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MySQL version 5.6

Create the database

Go to the terminal (Command Prompt (cmd) in Microsoft Windows). Open MySQL Client with a user that can create new users.

For example: On a Linux, use the command

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$ sudo mysql --password
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Note	This connects to MySQL as a root, this is NOT THE RECOMMENDED WAY.

Create a new database

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mysql> create database db_example; -- Create the new database
mysql> create user 'springuser'@'localhost' identified by 'ThePassword'; -- Creates the user
mysql> grant all on db_example.* to 'springuser'@'localhost'; -- Gives all the privileges to the new user on the newly created database
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Create the Spring Application

Add pom.xml dependencies

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<!-- JPA Data (We are going to use Repositories, Entities, Hibernate, etc...) -->

<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> <version>1.4.3.RELEASE</version> </dependency>

<!-- Use MySQL Connector-J -→

<dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.40</version> </dependency> ---

or in Gradle build.gradle:

---
// JPA Data (We are going to use Repositories, Entities, Hibernate, etc...)
compile group: 'org.springframework.boot', name: 'spring-boot-starter-data-jpa', version: '1.4.3.RELEASE'

compile group: 'mysql', name: 'mysql-connector-java', version: '5.1.40' ---

Spring Boot gives you defaults on all things, the default in database is H2SQLDB, so when you want to change this and use any other database you must define the connection attributes in the application.properties file

Create the application.properties file

In the sources folder, you create a resource file src/main/resources/application.properties

src/main/resources/application.properties

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link:complete/src/main/resources/application.properties[role=include]
---

Here, spring.jpa.hibernate.ddl-auto can be update, create, create-drop, refer to the Hibernate documentation for details.

Create the @Entity model

src/main/java/mysqlapp/models/User.java

link:complete/src/main/java/mysqlapp/models/User.java[role=include]

This is the entity class which Hibernate will automatically translate into a table

Create the repository

src/main/java/mysqlapp/repositories/UsersRepository.java

link:complete/src/main/java/mysqlapp/repositories/UsersRepository.java[role=include]

This is the repository interface, this will be automatically implemented by Spring in a bean with the same name with changing case The bean name will be usersRepository

Note	If you want to make the interface an inner one, use the @EnableJpaRepository annotation on the controller with the parameter considerNestedRepositories = true

Create a new controller for your Spring application

src/main/java/mysqlapp/controllers/MainController.java

link:complete/src/main/java/mysqlapp/controllers/MainController.java[role=include]

Note	The above example does not specify GET vs. PUT, POST, and so forth, because @RequestMapping maps all HTTP operations by default. Use @RequestMapping(method=GET) to narrow this mapping.

Make the application executable

Although it is possible to package this service as a traditional WAR file for deployment to an external application server, the simpler approach demonstrated below creates a standalone application. You package everything in a single, executable JAR file, driven by a good old Java main() method. Along the way, you use Spring’s support for embedding the Tomcat servlet container as the HTTP runtime, instead of deploying to an external instance.

src/main/java/mysqlapp/Application.java

link:complete/src/main/java/mysqlapp/Application.java[role=include]

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Logging output is displayed. The service should be up and running within a few seconds.

Test the application

Now that the application is running, you can test it.

Use curl for example. Now you have 2 REST Web Services you can test

localhost:8080/demo/getAll This gets all data localhost:8080/demo/add This adds one user to the data

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$ curl 'localhost:8080/demo/add?name=First&[email protected]'
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The reply should be

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Saved
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$ curl 'localhost:8080/demo/getAll'
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The reply should be

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[{"id":1,"name":"First","email":"[email protected]"}]
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Summary

Congratulations! You’ve just developed a Spring application!

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