How to get streaming results with Spring JPA, Java 8 Stream and PostgreSQL | Spring Boot
Tags: springboot, springjpa, java8, postgres
Published: 2021-04-22 11:54:35

https://grokonez.com/spring-framework/spring-boot/how-to-get-streaming-results-with-spring-jpa-java-8-stream-and-postgresql-spring-boot

How to get streaming results with Spring JPA, Java 8 Stream and PostgreSQL | Spring Boot

In tradition approach, implementing Data Access Layer makes lots of boilerplate code. Spring Data provides us <strong>Spring JPA</strong> which supports the ways to write interface for repositories and custom finder methods. The implementation will be done automatically by Spring Framework.

The tutorial shows you how to make <strong>streaming results</strong> with <strong>Spring JPA</strong>, <strong>Java 8 Stream</strong> and <strong>PostgreSQL</strong> using Spring Boot.

Related articles:
- <a href="https://grokonez.com/java/java-8-streams">Java 8 Streams</a>
- <a href="https://grokonez.com/spring-framework/spring-boot/use-spring-jpa-mysql-spring-boot" target="_blank">How to use Spring JPA MySQL | Spring Boot</a>
- <a href="https://grokonez.com/spring-framework/spring-boot/use-spring-jpa-postgresql-spring-boot">How to use Spring JPA with PostgreSQL | Spring Boot</a>
- <a href="https://grokonez.com/spring-framework/spring-boot/datajpatest-with-spring-boot">@DataJPATest with Spring Boot</a>

<!--more-->
<div id="tuttoc" class="jsa-toc"></div>

<div id="tutcontents">
<h2>I. Technology</h2>
- Java 1.8
- Maven 3.3.9
- Spring Tool Suite – Version 3.8.1.RELEASE
- Spring Boot: 1.5.1.RELEASE
<h2>II. Overview</h2>
<h3>1. Project Structure</h3>
<img src="https://grokonez.com/wp-content/uploads/2017/02/jpastream-structure.png" alt="" width="700" height="344" class="alignnone size-full wp-image-2830" />
- Class <strong>Customer</strong> corresponds to entity and table <strong>customer</strong>, it should be implemented <strong>Serializable</strong>.
- <strong>CustomerRepository</strong> is an interface extends <strong>CrudRepository</strong>, will be autowired in <strong>WebController</strong> for implementing repository methods and custom finder methods.
- <strong>WebController</strong> is a REST Controller which has request mapping methods for RESTful requests such as: save, findall, findalllastname, findbylastname.
- Configuration for Spring Datasource and Spring JPA properties in <strong>application.properties</strong>
- <strong>Dependencies</strong> for <strong>Spring Boot</strong> and <strong>PostgreSQL</strong> in <strong>pom.xml</strong>
<h3>2. Step to do</h3>
- Create Spring Boot project &amp; add Dependencies
- Configure Spring JPA
- Create DataModel Class
- Create Spring JPA Repository Interface
- Create Web Controller
- Create PostGreSQL table
- Run Spring Boot Application &amp; Enjoy Result
<h2>III. Practice</h2>
<h3>1. Create Spring Boot project &amp; add Dependencies</h3>
Open <strong>Spring Tool Suite</strong>, on <strong>Menu</strong>, choose <strong>File</strong> -&gt; <strong>New </strong>-&gt; Spring Starter Project, then fill each fields.
Click <strong>Next</strong>, in <strong>SQL</strong>: choose <strong>JPA</strong> and <strong>PostgreSQL</strong>, in <strong>Web</strong>: choose <strong>Web</strong>.
<img class="alignnone size-full wp-image-1009" src="https://grokonez.com/wp-content/uploads/2016/09/springjpa-postgresql-configdependencystarter.jpg" alt="springjpa-postgresql-configdependencystarter" width="650" height="259" />
Click <strong>Finish</strong>, then our project will be created successfully.

Open <strong>pom.xml</strong> and check Dependencies:

More at:

https://grokonez.com/spring-framework/spring-boot/how-to-get-streaming-results-with-spring-jpa-java-8-stream-and-postgresql-spring-boot

How to get streaming results with Spring JPA, Java 8 Stream and PostgreSQL | Spring Boot