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This article shows you how to use SpringBoot HATEOAS, the content is concise and easy to understand, it will definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

A brief introduction to REST style

Before introducing HATEOAS, let's briefly introduce that REST,REST is the abbreviation of Representational state transfer, which translates to expressive state transition. REST is an architectural style

Richardson Maturity Model

Richardson proposed a maturity model of REST, which we call Richardson Maturity Model, which divides REST into four levels according to maturity.

Level0: using HTTP as the transport of WEB services, exposing SOAP Web services Level1 in REST style: exposing resources using appropriate URI (using nouns), this approach puts forward the concept of resources Level2: resources use the correct URI + HTTP method, such as put for updating users, get for query Level3: use HATEOAS (hypermedia as application state engine), link information is included in the expression of resources The client can find actions that can be performed in the link information

What is HATEOAS?

HATEOAS stands for "Hypermedia is the engine of application state"

We can clearly know from the preface that using HATEOAS constraints is the most mature and officially recommended way in the REST style. For projects that do not use HATEOAS, the server and the client are coupled, and the client can only know what modifications the server has made through the relevant documents. After using the REST service with HATEOAS constraints, the server modifies the interface information. The client can intelligently discover the operations that can be performed through the expression of the resources provided by the server, and the client does not need to make any changes, because the resource information will change dynamically.

Documentation for the project is already available on Spring's website, link: https://spring.io/projects/spring-hateoas

SpringBoot HATEOAS

There is also an integrated HATEOAS in SpringBoot. This blog describes how to use the

Tool preparation:

JDK8.0 Maven 3.0 + build tool Eclipse or IntelliJ IDEA git&gitlab

Maven related configuration

Add hateoas configuration to pom.xml

Org.springframework.boot spring-boot-starter-hateoas

Because it is to write a simple curd example of web, other needs are also added.

Org.springframework.boot spring-boot-starter-data-jpa org.springframework.boot spring-boot-starter-hateoas org.springframework.boot spring-boot-starter-web com.alibaba druid 1.0.25 mysql mysql-connector-java 5.1.40 org.springframework.boot spring-boot-starter-test test org.junit.vintage junit-vintage-engine

Entity classes implement ResourceSupport

The Model class implements the ResourceSuppor provided by hateoas

Import com.fasterxml.jackson.annotation.JsonCreator;import com.fasterxml.jackson.annotation.JsonProperty;import org.springframework.hateoas.ResourceSupport;import javax.persistence.*;import java.io.Serializable;@Entity@Table (name= "sys_user") public class SysUserInfo extends ResourceSupport implements Serializable {@ Id @ GeneratedValue private Long userId; @ Column (unique=true,length=20,nullable=false) private String username; @ Column (length=2,nullable=true) private String sex; @ Column (length=10,nullable=true) private String password Public SysUserInfo () {} @ JsonCreator public SysUserInfo (@ JsonProperty ("userId") Long userId,@JsonProperty ("username") String username, @ JsonProperty ("sex") String sex,@JsonProperty ("password") String password) {this.userId = userId; this.username = username; this.sex = sex; this.password = password;}}.

Interface call, based on HATEOAS mode

@ GetMapping ("/ findBySysUserId/ {userId}") public SysUserInfo findBySysUserId (@ PathVariable ("userId") long userId) {if (LOG.isInfoEnabled ()) {LOG.info ("request parameter userId: {}", userId);} Optional sysUserInfo = Optional.ofNullable (sysUserRepository.findByUserId (userId)); if (! sysUserInfo.isPresent ()) {throw new NotFoundException ("user information not found! UserId: "+ userId);} / / Resource resource = new Resource (sysUserInfo.get ()); ControllerLinkBuilder linkBuilder = linkTo (methodOn (this.getClass ()) .findBySysUserId (userId)); sysUserInfo.get () .add (linkBuilder.withRel (" findBySysUserId ")); return sysUserInfo.get ();}

The above is how to use SpringBoot HATEOAS. Have you learned any knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.

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