Example for hexagonal architecture in java

patterns/hexagonal-architecture/.gitignore

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+target/
+.mvn/
+mvnw
+mvnw.cmd
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**
+!**/src/test/**
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+
+### VS Code ###
+.vscode/

patterns/hexagonal-architecture/README.md

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+# HEXAGONAL ARCHITECTURE - EXAMPLE IN JAVA
+
+A Spring Boot base web application for address book has been built as part of this project based on the hexagonal architecture guidelines, which allows the user to add a contact ad list all the contacts that are available. 
+
+### Running the application
+
+The application can be run using maven spring-boot run command 
+
+```
+mvn spring-boot:run
+
+```
+
+New contact can be added through a POST request on http://loalhost:8080/contacts  with the body as 
+
+```
+{
+	"name": "ABC",
+	"address": "Address",
+	"contactNumber": 1234567890
+}
+
+```
+Existing contacts can be listed using a GET request on the same url http://loalhost:8080/contacts

patterns/hexagonal-architecture/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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>2.2.0.RELEASE</version>
+		<relativePath/> <!-- lookup parent from repository -->
+	</parent>
+	<groupId>com.baeldung.hexagonal.arch</groupId>
+	<artifactId>hexagonal-architecture</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<name>hexagonal-architecture</name>
+	<description>Demo project for Spring Boot</description>
+
+	<properties>
+		<java.version>1.8</java.version>
+	</properties>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-data-jpa</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-web</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
+			<scope>test</scope>
+			<exclusions>
+				<exclusion>
+					<groupId>org.junit.vintage</groupId>
+					<artifactId>junit-vintage-engine</artifactId>
+				</exclusion>
+			</exclusions>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.boot</groupId>
+				<artifactId>spring-boot-maven-plugin</artifactId>
+			</plugin>
+		</plugins>
+	</build>
+
+</project>

patterns/hexagonal-architecture/src/main/java/com/baeldung/hexagonal/arch/AddressBookApplication.java

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+package com.baeldung.hexagonal.arch;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
+
+@SpringBootApplication
+@EnableAutoConfiguration(exclude = { DataSourceAutoConfiguration.class })
+public class AddressBookApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(AddressBookApplication.class, args);
+    }
+
+}

patterns/hexagonal-architecture/src/main/java/com/baeldung/hexagonal/arch/adapter/controller/AddressBookController.java

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+package com.baeldung.hexagonal.arch.adapter.controller;
+
+import java.util.List;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.baeldung.hexagonal.arch.core.domain.Contact;
+import com.baeldung.hexagonal.arch.port.service.AddressBookService;
+
+@RestController
+@RequestMapping("/contacts")
+public class AddressBookController {
+
+    @Autowired
+    private AddressBookService addressBookService;
+
+    @PostMapping
+    public void addContact(@RequestBody Contact contact) {
+        addressBookService.createContact(contact);
+    }
+
+    @GetMapping
+    public List<Contact> getAllContacts() {
+        return addressBookService.getAllContacts();
+    }
+
+}

patterns/hexagonal-architecture/src/main/java/com/baeldung/hexagonal/arch/adapter/repository/ContactRepositoryImpl.java

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+package com.baeldung.hexagonal.arch.adapter.repository;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import org.springframework.stereotype.Repository;
+
+import com.baeldung.hexagonal.arch.core.domain.Contact;
+import com.baeldung.hexagonal.arch.port.repo.ContactRepository;
+
+@Repository
+public class ContactRepositoryImpl implements ContactRepository {
+
+    private Map<String, Contact> contactsRepo = new HashMap<String, Contact>();
+
+    @Override
+    public void createContact(Contact contact) {
+        contactsRepo.put(contact.getName(), contact);
+    }
+
+    @Override
+    public List<Contact> getAllContacts() {
+        return contactsRepo.values()
+            .stream()
+            .collect(Collectors.toList());
+    }
+
+}

patterns/hexagonal-architecture/src/main/java/com/baeldung/hexagonal/arch/core/domain/Contact.java

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+package com.baeldung.hexagonal.arch.core.domain;
+
+public class Contact {
+
+    private String name;
+    private String address;
+    private int contactNumber;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getAddress() {
+        return address;
+    }
+
+    public void setAddress(String address) {
+        this.address = address;
+    }
+
+    public int getContactNumber() {
+        return contactNumber;
+    }
+
+    public void setContactNumber(int contactNumber) {
+        this.contactNumber = contactNumber;
+    }
+
+}

patterns/hexagonal-architecture/src/main/java/com/baeldung/hexagonal/arch/core/service/AddressBookServiceImpl.java

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+package com.baeldung.hexagonal.arch.core.service;
+
+import java.util.List;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+import com.baeldung.hexagonal.arch.core.domain.Contact;
+import com.baeldung.hexagonal.arch.port.repo.ContactRepository;
+import com.baeldung.hexagonal.arch.port.service.AddressBookService;
+
+@Service
+public class AddressBookServiceImpl implements AddressBookService {
+
+    @Autowired
+    ContactRepository contactRepository;
+
+    @Override
+    public void createContact(Contact contact) {
+        contactRepository.createContact(contact);
+    }
+
+    @Override
+    public List<Contact> getAllContacts() {
+        return contactRepository.getAllContacts();
+    }
+
+}

patterns/hexagonal-architecture/src/main/java/com/baeldung/hexagonal/arch/port/repo/ContactRepository.java

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+package com.baeldung.hexagonal.arch.port.repo;
+
+import java.util.List;
+
+import com.baeldung.hexagonal.arch.core.domain.Contact;
+
+public interface ContactRepository {
+
+    void createContact(Contact contact);
+
+    List<Contact> getAllContacts();
+
+}

patterns/hexagonal-architecture/src/main/java/com/baeldung/hexagonal/arch/port/service/AddressBookService.java

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+package com.baeldung.hexagonal.arch.port.service;
+
+import java.util.List;
+
+import com.baeldung.hexagonal.arch.core.domain.Contact;
+
+public interface AddressBookService {
+
+    public void createContact(Contact contact);
+
+    public List<Contact> getAllContacts();
+
+}

patterns/hexagonal-architecture/src/main/resources/application.properties

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+