Convert JSON schema to Java classes using maven plugin

Introduction

We often need to convert JSON schema’s to Java classes, there is a jsonschema2pojo-maven-plugin which helps in generating POJO(plain old java objects) from JSON or JSON schema.

To use it all we need is add this plugin, update dependencies and run mvn generate

Add jsonschema2pojo-maven-plugin in POM.XML

Add this plugin to your POM.XML under plugin section

<plugin>
				<groupId>org.jsonschema2pojo</groupId>
				<artifactId>jsonschema2pojo-maven-plugin</artifactId>
				<version>0.4.34</version>
				<configuration>
					<sourceDirectory>${basedir}/src/main/resources/schema</sourceDirectory>
					<targetPackage>com.test.gen</targetPackage>
					<useCommonsLang3>true</useCommonsLang3>
				</configuration>
				<executions>
					<execution>
						<goals>
							<goal>generate</goal>
						</goals>
					</execution>
				</executions>
			</plugin>

Add Maven dependencies

The generated types depend on Commons Lang library for equals, hashCode and toString. Also, you need to add Jackson-databind which contains the data-binding functionality and tree-model for Jackson Data Processor, this jar has a transitive dependency on jackson-core and jackson-annotations so they will be downloaded automatically.

<dependency>
			<groupId>org.apache.commons</groupId>
			<artifactId>commons-lang3</artifactId>
			<version>3.0</version>
		</dependency>
		
		<dependency>
			<groupId>com.fasterxml.jackson.core</groupId>
			<artifactId>jackson-databind</artifactId>
		</dependency>

Run the Maven Goal

You can run

mvn generate-sources

${basedir}/src/main/gen

Make sure that generated folder is added as a source folder in your IDE (Properties ->Java build Path -> Add source folder in eclipse).

Generating classes from JSON and not from schema

If you want to generate Java classes from JSON rather than JSON schema add

<sourceType>json</sourceType>

inside the configuration tag as default source type is JSON Schema.

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Push a Docker image to DockerHub using docker maven plugin fabric8.io

Introduction

If you want to push a docker image to Docker Hub repository, it can be achieved using docker maven plugin from fabric8.io. This plugin lets you build images, start and stop containers and push it to Docker repositories

&nsbp;

1. For the below example, I have used Spring Boot Rest service project which is connected to MongoDB. See below link for reference.
2. Using io.fabric8 plugin, under the plugin section add the io.fabric8 plugin
   

   <plugin>
   	<groupId>io.fabric8</groupId>
   	<artifactId>docker-maven-plugin</artifactId>
   	<version>0.20.0</version>....

   
   
3. We need to first build the image from Dockerfile, this plugin supports all the command which are in Dockerfile and you can directly create a docker image by giving arguments in pom.xml but In my view making docker images from Docker file is much easier and simpler. So we will ask maven plugin in below step to look for Dockerfile in root( project base directory)
   

   <name>springboot-mongo-dockerimage:${project.version}</name>
       <alias>springboot-mongo-dockerimage</alias>
   <build>
       <dockerFileDir>${project.basedir}</dockerFileDir>
   </build>

4. Next we specify the docker registry address
   

   <registry>registry.hub.docker.com/YOUR_DOCKER_HUB_USERNAME</registry>

5. Now we need to add authentication credentials in <authconfig> tag
   

   <authConfig>
   	<username>ENTER YOUR DOCKER HUB USERNAME LIKE abhishek</username>
   	<password>ENTER YOUR DOCKER HUB PASSWORD</password>
   </authConfig>

6. We will add execution phases, where we will push the image
   

   <execution>
   	<id>push</id>
   	<phase>post-integration-test</phase>
   	<goals>
   		<goal>push</goal>
   	</goals>
   </execution>

7. Now run the pom.xml using mvn clean install and check your docker hub repo after some time to see if image has been pushed. If you are pushing the image for first time its gonna take some time  depending on the size of image.

Here is the complete build section from the plugin, hope this help.

<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
			<plugin>
				<groupId>io.fabric8</groupId>
				<artifactId>docker-maven-plugin</artifactId>
				<version>0.20.0</version>
				<configuration>
					<registry>registry.hub.docker.com/YOUR_DOCKER_HUB_USERNAME</registry>

					<images>
						<image>
							<name>springboot-mongo-dockerhub:${project.version}</name>
							<alias>springboot-mongo-dockerhub</alias>
							<build>
								<dockerFileDir>${project.basedir}</dockerFileDir>

							</build>
							<run>
								<namingStrategy>alias</namingStrategy>
								<dependsOn>
									<container>mongo</container>
								</dependsOn>

								<links>
									<link>mongo</link>
								</links>
								<ports>
									<port>9876:8080</port>
								</ports>
								<log>
									<prefix>TC</prefix>
									<date>default</date>
									<color>cyan</color>
								</log>
							</run>
						</image>
					</images>
					<authConfig>
						<username>ENTER YOUR DOCKER HUB USERNAME LIKE abhishek</username>
						<password>ENTER YOUR DOCKER HUB PASSWORD</password>
					</authConfig>
				</configuration>

				<executions>
					<execution>
						<id>start</id>
						<phase>pre-integration-test</phase>
						<goals>
							<goal>stop</goal>
							<goal>build</goal>
							<goal>start</goal>
						</goals>
					</execution>
					<execution>
						<id>push</id>
						<phase>post-integration-test</phase>
						<goals>
							<goal>stop</goal>
							<goal>push</goal>
						</goals>
					</execution>
				</executions>
			</plugin>
		</plugins>
	</build>

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Add Maven Remote catalogue in eclipse

Maven remote catalogues are very useful in starting a project quickly and neatly. The project structure including src, test directory are created along with pom dependencies.

Follow below steps to add remote archetype catalogue

1. Go to Windows -> Preferences -> Maven ->Archetype
2. Click on Add Remote Catalog
   
3. Add catalogue file as
   • http://repo1.maven.org/maven2/archetype-catalog.xml
4. Description as
   • Remote Archetype catalogue
5. Click on Verify, you should see a message like Found XXX archetype’s

If you are behind a proxy you might need to go to Windows -> Preference-> Network and add the proxy details

Why not use this remote archetype to create your first Spring Boot Project

Follow this Video for more details

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