Lesson 5: Giving Your Microservice a REST

livelessons-rest/README.adoc

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+:compat-mode:
+= Lesson 5: Giving Your Microservice a REST
+
+_Why the web is a existence proof of the HTTP architecture and how to build
+services that exploit that._
+
+- link:livelessons-rest-basic[Basic]
+- link:livelessons-rest-sync[Sync]

livelessons-rest/livelessons-rest-basic/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>livelessons</groupId>
+		<artifactId>livelessons-rest</artifactId>
+		<version>1.0.0-SNAPSHOT</version>
+	</parent>
+	<artifactId>livelessons-rest-basic</artifactId>
+	<properties>
+		<main.basedir>../..</main.basedir>
+	</properties>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-web</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-data-rest</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-data-jpa</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>com.h2database</groupId>
+			<artifactId>h2</artifactId>
+		</dependency>
+	</dependencies>
+</project>

livelessons-rest/livelessons-rest-basic/src/main/java/demo/Application.java

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+package demo;
+
+import java.util.Arrays;
+
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+
+@SpringBootApplication
+public class Application {
+
+	@Bean
+	CommandLineRunner commandLineRunner(PersonRepository personRepository) {
+		return args -> {
+			Arrays.asList("Phil", "Josh").forEach(name -> personRepository
+					.save(new Person(name, (name + "@email.com").toLowerCase())));
+			personRepository.findAll().forEach(System.out::println);
+		};
+	}
+
+	public static void main(String[] args) {
+		SpringApplication.run(Application.class, args);
+	}
+
+}

livelessons-rest/livelessons-rest-basic/src/main/java/demo/Person.java

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+package demo;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+
+@Entity
+public class Person {
+
+	@Id
+	@GeneratedValue
+	private Long id;
+
+	private String name;
+
+	private String email;
+
+	Person() {
+	}
+
+	public Person(String name, String email) {
+		this.name = name;
+		this.email = email;
+	}
+
+	public Long getId() {
+		return this.id;
+	}
+
+	public String getName() {
+		return this.name;
+	}
+
+	public String getEmail() {
+		return this.email;
+	}
+
+	@Override
+	public String toString() {
+		return "Person{" + "id=" + id + ", name='" + name + '\'' + ", email='" + email
+				+ '\'' + '}';
+	}
+
+}

livelessons-rest/livelessons-rest-basic/src/main/java/demo/PersonPhotoRestController.java

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+package demo;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.net.URI;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.core.io.FileSystemResource;
+import org.springframework.core.io.Resource;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.util.Assert;
+import org.springframework.util.FileCopyUtils;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.multipart.MultipartFile;
+import org.springframework.web.servlet.support.ServletUriComponentsBuilder;
+
+@RestController
+@RequestMapping("/people/{id}/photo")
+public class PersonPhotoRestController {
+
+	private File root;
+
+	@Autowired
+	private PersonRepository personRepository;
+
+	@Value("${user.home}")
+	public void setUserHome(String home) {
+		this.root = new File(home, "Desktop/images");
+		Assert.isTrue(this.root.exists() || this.root.mkdirs(),
+				"The path '" + this.root.getAbsolutePath() + "' must exist.");
+	}
+
+	@RequestMapping(method = RequestMethod.GET)
+	public ResponseEntity<Resource> read(@PathVariable Long id) throws Exception {
+		Person person = this.personRepository.findOne(id);
+		File file = fileFor(person);
+		if (!file.exists()) {
+			throw new FileNotFoundException(file.getAbsolutePath());
+		}
+		HttpHeaders httpHeaders = new HttpHeaders();
+		httpHeaders.setContentType(MediaType.IMAGE_JPEG);
+		Resource resource = new FileSystemResource(file);
+		return new ResponseEntity<>(resource, httpHeaders, HttpStatus.OK);
+	}
+
+	@RequestMapping(method = { RequestMethod.POST, RequestMethod.PUT })
+	public ResponseEntity<?> write(@PathVariable Long id,
+			@RequestParam MultipartFile file) throws Exception {
+		Person person = this.personRepository.findOne(id);
+		FileCopyUtils.copy(file.getInputStream(), new FileOutputStream(fileFor(person)));
+		URI location = ServletUriComponentsBuilder.fromCurrentRequest().buildAndExpand(id)
+				.toUri();
+		return ResponseEntity.created(location).build();
+	}
+
+	private File fileFor(Person person) {
+		return new File(this.root, Long.toString(person.getId()));
+	}
+
+}

livelessons-rest/livelessons-rest-basic/src/main/java/demo/PersonRepository.java

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+package demo;
+
+import java.util.Collection;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.repository.query.Param;
+import org.springframework.data.rest.core.annotation.RepositoryRestResource;
+
+@RepositoryRestResource(path = "people")
+interface PersonRepository extends JpaRepository<Person, Long> {
+
+	Collection<Person> findByEmail(@Param("email") String e);
+
+}

livelessons-rest/livelessons-rest-basic/src/main/java/demo/PersonResourceProcessor.java

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+package demo;
+
+import org.springframework.hateoas.Link;
+import org.springframework.hateoas.Resource;
+import org.springframework.hateoas.ResourceProcessor;
+import org.springframework.stereotype.Component;
+import org.springframework.web.servlet.support.ServletUriComponentsBuilder;
+import org.springframework.web.util.UriComponents;
+
+@Component
+public class PersonResourceProcessor implements ResourceProcessor<Resource<Person>> {
+
+	@Override
+	public Resource<Person> process(Resource<Person> resource) {
+		String id = Long.toString(resource.getContent().getId());
+		UriComponents uriComponents = ServletUriComponentsBuilder.fromCurrentContextPath()
+				.path("/people/{id}/photo").buildAndExpand(id);
+		String uri = uriComponents.toUriString();
+		resource.add(new Link(uri, "photo"));
+		return resource;
+	}
+
+}

livelessons-rest/livelessons-rest-basic/src/main/java/demo/SimpleRepositoryRestMvcConfiguration.java

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+package demo;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.rest.core.config.RepositoryRestConfiguration;
+import org.springframework.data.rest.webmvc.config.RepositoryRestMvcConfiguration;
+
+@Configuration
+public class SimpleRepositoryRestMvcConfiguration extends RepositoryRestMvcConfiguration {
+
+	@Override
+	protected void configureRepositoryRestConfiguration(
+			RepositoryRestConfiguration config) {
+		config.exposeIdsFor(Person.class);
+	}
+
+}

livelessons-rest/livelessons-rest-basic/src/main/resources/data.sql

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+insert into person( name, email) values ( 'josh', 'josh@email.com');
+insert into person( name, email) values ( 'john', 'john@email.com');
+insert into person( name, email) values ( 'yoana', 'yoana@email.com');
+insert into person( name, email) values ( 'emo', 'emo@email.com');

livelessons-rest/livelessons-rest-errors/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>livelessons</groupId>
+		<artifactId>livelessons-rest</artifactId>
+		<version>1.0.0-SNAPSHOT</version>
+	</parent>
+	<artifactId>livelessons-rest-errors</artifactId>
+	<properties>
+		<main.basedir>../..</main.basedir>
+	</properties>
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-web</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-data-rest</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.hateoas</groupId>
+			<artifactId>spring-hateoas</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.plugin</groupId>
+			<artifactId>spring-plugin-core</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-data-jpa</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>com.h2database</groupId>
+			<artifactId>h2</artifactId>
+		</dependency>
+	</dependencies>
+</project>

livelessons-rest/livelessons-rest-errors/src/main/java/demo/Application.java

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+package demo;
+
+import java.util.Arrays;
+
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+
+@SpringBootApplication
+public class Application {
+
+	@Bean
+	public CommandLineRunner commandLineRunner(PersonRepository personRepository) {
+		return args -> {
+			Arrays.asList("Phil", "Josh").forEach(name -> personRepository
+					.save(new Person(name, (name + "@email.com").toLowerCase())));
+			personRepository.findAll().forEach(System.out::println);
+		};
+	}
+
+	public static void main(String[] args) {
+		SpringApplication.run(Application.class, args);
+	}
+
+}

livelessons-rest/livelessons-rest-errors/src/main/java/demo/Person.java

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+package demo;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+
+@Entity
+public class Person {
+
+	@Id
+	@GeneratedValue
+	private Long id;
+
+	private String name;
+
+	private String email;
+
+	Person() {
+	}
+
+	public Person(String name, String email) {
+		this.name = name;
+		this.email = email;
+	}
+
+	public Long getId() {
+		return id;
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	public String getEmail() {
+		return email;
+	}
+
+	@Override
+	public String toString() {
+		return "Person{" + "id=" + id + ", name='" + name + '\'' + ", email='" + email
+				+ '\'' + '}';
+	}
+
+}

livelessons-rest/livelessons-rest-errors/src/main/java/demo/PersonControllerAdvice.java

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+package demo;
+
+import java.io.FileNotFoundException;
+import java.util.Optional;
+
+import org.springframework.hateoas.VndErrors;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+@ControllerAdvice
+@RequestMapping(produces = "application/vnd.error")
+@ResponseBody
+public class PersonControllerAdvice {
+
+	@ResponseStatus(value = HttpStatus.NOT_FOUND)
+	@ExceptionHandler(FileNotFoundException.class)
+	public VndErrors fileNotFoundException(FileNotFoundException ex) {
+		return this.error(ex, ex.getLocalizedMessage());
+	}
+
+	@ResponseStatus(value = HttpStatus.NOT_FOUND)
+	@ExceptionHandler(PersonNotFoundException.class)
+	public VndErrors personNotFoundException(PersonNotFoundException e) {
+		return this.error(e, e.getPersonId() + "");
+	}
+
+	private <E extends Exception> VndErrors error(E e, String logref) {
+		String msg = Optional.of(e.getMessage()).orElse(e.getClass().getSimpleName());
+		return new VndErrors(logref, msg);
+	}
+
+}