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This article to share with you is about SpringBoot HATEOAS principle is what, Xiaobian think quite practical, so share to everyone to learn, I hope you can read this article after some harvest, not much to say, follow Xiaobian to see it.

REST Style Introduction

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

Richardson Maturity Model

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

Level0： Using HTTP as the transport method of Web services, SOAP Web services are exposed in REST style Level1: resources are exposed with appropriate URIs (nouns), which introduces the concept of resources Level 2: resources are used with correct URIs + HTTP methods, such as put for updating users and get for querying Level3: HATEOAS(hypermedia as application state engine), link information is included in the expression of resources, and clients can find operations that can be performed in the link information

What is HATEOAS?

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

From the preface, we can clearly know that using HATEOAS constraint is the most mature in REST style and is also an officially recommended way. For projects that do not use HATEOAS, the server and client are coupled, and the client can only know what modifications the server has made through relevant documents. After using HATEOAS constrained REST service, the client can intelligently discover the operations that can be executed through the expression of resources provided by the server. The client does not need to make any changes because the resource information changes dynamically.

On Spring's official website, there is already a document related to this project, link: spring.io/projects/spring-hateoas

SpringBoot HATEOAS

HATEOAS is also integrated with SpringBoot, and this blog explains how to use it.

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 web curd example, 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 class implements ResourceSupport

Model class implements 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 invocation, based on HATEOAS pattern

@GetMapping("/findBySysUserId/{userId}") public SysUserInfo findBySysUserId(@PathVariable("userId") long userId) { if (LOG.isInfoEnabled()) {LOG.info ("Please seek parameters userId : {}" , userId); } Optional sysUserInfo = Optional.ofNullable(sysRepository.findByUserId(userId)); if (! sysUserInfo.isPresent()) { throw new NotFoundException("No user information 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 what the principle of SpringBoot HATEOAS is. Xiaobian believes that some knowledge points may be seen or used in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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