Spring boot - 102

Overview

This Article explains step by step how to create a restful spring-boot application

Use case

We are build an application that allows users to store api specifications.

POST url: <host>/api/api-spec POST request:

• API = <host>/api
• METHOD = GET, POST, PUT, DELETE
• HEADERS = {Authorization: "", hash: ""}
• QUERY_PARAMS = {userdata: {a: 1, b: 2}}

POST response:

• Saved object

GET url: <host>/api/api-spec/<id> GET request:

• ID = object id

GET response:

• Saved specified by the id

Technology:

• Gradle
• Spring Boot
• Spring Data

Steps followed:

• create the application structure (on *nix machines)

mkdir -p ~/Documents/projects/spring-boot-102/src/main/java/apispec
mkdir -p ~/Documents/projects/spring-boot-102/src/main/resources
mkdir -p ~/Documents/projects/spring-boot-102/src/test

• Add a project management tool

cd ~/Documents/projects/spring-boot-102
gradle init

gradle init creates the build.gradle. After this, we add the project dependencies and other information needed to identify the current projet.

Final build.gradle looks like this.

buildscript {
     repositories {
         mavenCentral()
     }
     dependencies {
         classpath("org.springframework.boot:spring-boot-gradle-plugin:1.2.6.RELEASE")
     }
 }
apply plugin: 'java'
apply plugin: 'idea'
apply plugin: 'spring-boot'

springBoot {
  mainClass = 'apispec.ApiSpecController'
}
jar {
    baseName = 'spring-boot-102'
    version =  '0.0.1'
}

repositories {
    mavenCentral()
}

sourceCompatibility = 1.8
targetCompatibility = 1.8

dependencies {
    compile 'org.springframework.boot:spring-boot-starter-data-rest'
    compile 'org.springframework.boot:spring-boot-starter-data-jpa'
    compile 'com.h2database:h2'

    compile 'org.slf4j:slf4j-api:1.7.12'
    testCompile 'junit:junit:4.12'
}

task wrapper(type: Wrapper) {
    gradleVersion = '2.7'
}

• Add data related library dependancies

org.springframework.boot:spring-boot-starter-data-rest
org.springframework.boot:spring-boot-starter-data-jpa

• Add a model object (this is basically a java class)

cd ~/Documents/projects/spring-boot-102
touch src/main/java/apispec/ApiSpec.java

// ApiSpec.java - model object definition

package apispec;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class ApiSpec {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;
    public long getId() { return id;}

    private String api;
    private String method;
    private String headers;
    private String queryParams;

    public String getApi() { return api;}
    public void setApi(String api) {  this.api = api;}

    public String getMethod() { return method;}
    public void setMethod(String method) { this.method = method;}

    public String getHeaders() {return headers;}
    public void setHeaders(String headers) { this.headers = headers;}

    public String getQueryParams() {return queryParams;}
    public void setQueryParams(String queryParams) {  this.queryParams = queryParams;}

    public ApiSpec(){}
    public ApiSpec(String api, String method, String headers, String queryParams) {
            this.api = api;
            this.method = method;
            this.headers = headers;
            this.queryParams = queryParams;
    }
}

• Add a controller class (it is in charge of serving 2 restful API's)

cd ~/Documents/projects/spring-boot-102
touch src/main/java/apispec/ApiSpecController.java

// ApiSpecController.java - controller and application starter/entry point
package apispec;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class ApiSpecController {

  public static void main(String [] arguments){
    SpringApplication.run(ApiSpecController.class, arguments);
  }
}

• Add a repository class (it is in charge of data storage)

cd ~/Documents/projects/spring-boot-102
touch src/main/java/ApiSpecRepository.java

// ApiSpecRepository.java - repository for data storage
package apispec;

import java.util.List;

import org.springframework.data.repository.PagingAndSortingRepository;
import org.springframework.data.repository.query.Param;
import org.springframework.data.rest.core.annotation.RepositoryRestResource;

@RepositoryRestResource(collectionResourceRel = "apispec", path = "apispec")
public interface ApiSpecRepository extends PagingAndSortingRepository<ApiSpec, Long> {

    List<ApiSpec> findByApi(@Param("api") String api);

}

• Build the application

gradle build

• Run the application

gradle bootRun

• Access the application from a web browser

http://localhost:8080/apispec

Resources:

• https://docs.gradle.org/current/userguide/build_init_plugin.html
• http://spring.io/guides/gs/accessing-data-rest

Tags: spring boot general architecture,