Book Image

Spring Data

By : Petri Kainulainen
Book Image

Spring Data

By: Petri Kainulainen

Overview of this book

Spring Framework has always had a good support for different data access technologies. However, developers had to use technology-specific APIs, which often led to a situation where a lot of boilerplate code had to be written in order to implement even the simplest operations. Spring Data changed all this. Spring Data makes it easier to implement Spring-powered applications that use cloud-based storage services, NoSQL databases, map-reduce frameworks or relational databases. "Spring Data" is a practical guide that is full of step-by-step instructions and examples which ensure that you can start using the Java Persistence API and Redis in your applications without extra hassle. This book provides a brief introduction to the underlying data storage technologies, gives step-by-step instructions that will help you utilize the discussed technologies in your applications, and provides a solid foundation for expanding your knowledge beyond the concepts described in this book. You will learn an easier way to manage your entities and to create database queries with Spring Data JPA. This book also demonstrates how you can add custom functions to your repositories. You will also learn how to use the Redis key-value store as data storage and to use its other features for enhancing your applications. "Spring Data" includes all the practical instructions and examples that provide you with all the information you need to create JPA repositories with Spring Data JPA and to utilize the performance of Redis in your applications by using Spring Data Redis.
Table of Contents (13 chapters)

Paginating query results

Paginating query results is a very common requirement for practically every application that presents some kind of data. The key component of the pagination support of Spring Data JPA is the Pageable interface that declares the following methods:



int getPageNumber()

Returns the number of the requested page. The page numbers are zero indexed. Thus, the number of the first page is zero.

int getPageSize()

Returns the number of elements shown on a single page. The page size must always be larger than zero.

int getOffset()

Returns the selected offset according to the given page number and page size.

Sort getSort()

Returns the sorting parameters used to sort the query results.

We can use this interface to paginate the query results with Spring Data JPA by:

  1. Creating a new PageRequest object. We can use the PageRequest class because it implements the Pageable interface.

  2. Passing the created object to a repository method as a parameter.