[java] [maven] [dropwizard] DropWizard HelloWorld API from scratch

[0] Preparation.

• java jdk 11(set JAVA_HOME path e.g. C:\Program Files\Java\jdk-11)
• maven
• curl
• IntelliJ IDE(optional)

[1] Make project directory

mkdir mydrophello cd mydrophello

[2] Create pom file

notepad pom.xml <project> <modelVersion>4.0.0</modelVersion> <groupId>com.mycompany.helloworld</groupId> <artifactId>helloworld</artifactId> <version>0.0.0</version> </project>

[3] Create source directory

mkdir -p src\main\java\com\mycompany\helloworld mkdir -p src\test\java\com\mycompany\helloworld

[4] Complete the pom file

The full pom file would be as follows:

<?xml version="1.0" encoding="UTF-8"?> <project> <modelVersion>4.0.0</modelVersion> <groupId>com.mycompany.helloworld</groupId> <artifactId>helloworld</artifactId> <version>0.0.0</version> <name>HelloWorld DropWizard</name> <properties> <dropwizard.version>2.0.0</dropwizard.version> <maven.compiler.source>1.8</maven.compiler.source> <maven.compiler.target>1.8</maven.compiler.target> <mainClass>com.mycompany.helloworld.HelloWorldApplication</mainClass> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <dependency> <groupId>io.dropwizard</groupId> <artifactId>dropwizard-core</artifactId> <version>${dropwizard.version}</version> </dependency> <dependency> <groupId>io.dropwizard</groupId> <artifactId>dropwizard-testing</artifactId> <version>${dropwizard.version}</version> </dependency> <dependency> <groupId>org.assertj</groupId> <artifactId>assertj-core</artifactId> <version>3.6.2</version> <scope>test</scope> </dependency> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-api</artifactId> <version>5.4.2</version> <scope>test</scope> </dependency> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-engine</artifactId> <version>5.4.2</version> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-shade-plugin</artifactId> <version>3.1.1</version> <executions> <execution> <phase>package</phase> <goals> <goal>shade</goal> </goals> <configuration> <createDependencyReducedPom>true</createDependencyReducedPom> <transformers> <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer"> <mainClass>com.mycompany.helloworld.HelloWorldApplication</mainClass> </transformer> </transformers> </configuration> </execution> </executions> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <version>3.0.0-M5</version> </plugin> </plugins> </build> </project>

[5] Add Dropwizard files

• Configuration Class File
• Application Class File
• Representation Class File
• Resource Class File
• Health Check Class File (optional)
• Config File

[5.1] Configuration

Location:src\main\java\com\mycompany\helloworld\HelloWorldConfiguration.java

notepad src\main\java\com\mycompany\helloworld\HelloWorldConfiguration.java package com.mycompany.helloworld; import io.dropwizard.Configuration; import com.fasterxml.jackson.annotation.JsonProperty; import javax.validation.constraints.NotEmpty; public class HelloWorldConfiguration extends Configuration { @NotEmpty private String defaultMessage = "Hello World!"; @JsonProperty public String getDefaultMessage() { return defaultMessage; } @JsonProperty public void setDefaultMessage(String message) { this.defaultMessage = message; } }

[5.2] Application

Location:src\main\java\com\mycompany\helloworld\HelloWorldApplication.java

notepad src\main\java\com\mycompany\helloworld\HelloWorldApplication.java package com.mycompany.helloworld; import com.mycompany.helloworld.health.ConfigHealthCheck; import com.mycompany.helloworld.resources.HelloWorldResource; import io.dropwizard.Application; import io.dropwizard.setup.Environment; public class HelloWorldApplication extends Application<HelloWorldConfiguration> { public static void main(String[] args) throws Exception { new HelloWorldApplication().run(args); } @Override public String getName() { return "helloworld"; } @Override public void run(HelloWorldConfiguration configuration, Environment environment) { final HelloWorldResource resource = new HelloWorldResource( configuration.getDefaultMessage() ); final ConfigHealthCheck healthCheck; healthCheck = new ConfigHealthCheck(configuration.getDefaultMessage()); environment.healthChecks().register("defaultMessage", healthCheck); environment.jersey().register(resource); } }

[5.3] Representation

Location:src\main\java\com\mycompany\helloworld\api\HelloWorld.java

mkdir src\main\java\com\mycompany\helloworld\api notepad src\main\java\com\mycompany\helloworld\api\HelloWorld.java package com.mycompany.helloworld.api; import com.fasterxml.jackson.annotation.JsonProperty; public class HelloWorld { private long id; private String content; public HelloWorld(long id, String content) { this.id = id; this.content = content; } @JsonProperty public long getId() { return id; } @JsonProperty public String getContent() { return content; } }

[5.4] Resource

Location:src\main\java\com\mycompany\helloworld\resources\HelloWorldResource.java

mkdir src\main\java\com\mycompany\helloworld\resources notepad src\main\java\com\mycompany\helloworld\resources\HelloWorldResource.java package com.mycompany.helloworld.resources; import com.mycompany.helloworld.api.HelloWorld; import javax.ws.rs.GET; import javax.ws.rs.Path; import javax.ws.rs.Produces; import javax.ws.rs.core.MediaType; import java.util.concurrent.atomic.AtomicLong; @Path("/") @Produces(MediaType.APPLICATION_JSON) public class HelloWorldResource { private final String defaultMessage; private final AtomicLong counter; public HelloWorldResource(String defaultMessage) { this.counter = new AtomicLong(); this.defaultMessage = defaultMessage; } @GET public HelloWorld sayHello() { return new HelloWorld(counter.incrementAndGet(), defaultMessage); } }

[5.5] HealthCheck

Location:src\main\java\com\mycompany\helloworld\health\HelloWorldResource.java

mkdir src\main\java\com\mycompany\helloworld\health notepad src\main\java\com\mycompany\helloworld\health\ConfigHealthCheck.java package com.mycompany.helloworld.health; import com.codahale.metrics.health.HealthCheck; public class ConfigHealthCheck extends HealthCheck { private final String defaultMessage; public ConfigHealthCheck(String defaultMessage) { this.defaultMessage = defaultMessage; } @Override protected Result check() throws Exception { if (this.defaultMessage == null) { return Result.unhealthy("Config file doesn't contain key - defaultMessage"); } return Result.healthy(); } }

[5.6] Config

Location:config.yml

notepad config.yml defaultMessage: "Hello World!"

[6] Compile and run

mvn package java -jar target/helloworld-0.0.0.jar server config.yml

REF:https://geekyshacklebolt.wordpress.com/2021/01/06/dropwizard-helloworld-api-from-scratch/
https://github.com/GeekyShacklebolt/dropwizard-helloworld

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[java] [maven] [dropwizard] Running a Dropwizard application in IntelliJ IDEA, Eclipse and NetBeans

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Dropwizard is a framework for building RESTful web services in Java. Similar to Spring Boot, Dropwizard applications are packaged into an executable fat JAR file. In addition to executing a Dropwizard application from the command line, you can increase your productivity by configuring your IDE to do that for you. I’m going to be looking at how to run a Dropwizard application in IntelliJ IDEA, Eclipse and NetBeans.

To execute a Dropwizard application, its main method needs to be called with the correct arguments. When you execute a JAR file from the command line, the JVM reads the entry point to your application from the MANIFEST.MF file. It contains key-value pairs and the key we’re interested in is Main-Class. In a Dropwizard application, this is set to your Applicaiton class.

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https://blog.indrek.io/articles/running-a-dropwizard-application-in-intellij-eclipse-and-netbeans/

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[java] [maven] [dropwizard] Dropwizard with JDBI

[0] Preparation.

• git
• java jdk 11(set JAVA_HOME path e.g. C:\Program Files\Java\jdk-11)
• maven
• curl
• IntelliJ IDE(optional)
• DBeaver(optional)

[1] Clone project

git clone https://github.com/Appdynamics/dropwizard-sample-app.git

[2] Compile Maven project

mvn package

Note: you may get error like "Blocked mirror for repositories". This is due to the use of unsecured http. Open pom.xml file and replace "http://" with "https://"

[3] Run migration (h2 database)

java -jar target/dropwizard-example-0.7.0-SNAPSHOT.jar db migrate example.yml

Note: you may get error like "Exception in thread "main" java.lang.NoClassDefFoundError: javax/xml/bind/JAXBException". This is due to the JAXB APIs considered to be Java EE APIs and therefore are no longer contained on the default classpath in Java SE 9. In Java 11, they are completely removed from the JDK.

Add the following codes to the dependency section of pom.xml file

<!-- API, java.xml.bind module --> <dependency> <groupId>jakarta.xml.bind</groupId> <artifactId>jakarta.xml.bind-api</artifactId> <version>2.3.2</version> </dependency> <!-- Runtime, com.sun.xml.bind module --> <dependency> <groupId>org.glassfish.jaxb</groupId> <artifactId>jaxb-runtime</artifactId> <version>2.3.2</version> </dependency>

[4] Run application

java -jar target/dropwizard-example-0.7.0-SNAPSHOT.jar server example.yml

The application will be opened at port 8082 (refer below console output)

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[java] [maven] [dropwizard] [mysql] Dropwizard on host with MySQL on docker

[0] Preparation.

• git
• java jdk 11(set JAVA_HOME path e.g. C:\Program Files\Java\jdk-11)
• maven
• curl
• IntelliJ IDE(optional)
• DBeaver(optional)

[1] Clone project

git clone https://github.com/joebew42/dropwizard-sample-app.git

[2] Change directory to the project root

cd dropwizard-sample-app

[3] Compile Maven project

mvn package

If you get error invalid target release 11, it could be that your java sdk is not 11. Install JDK 11 first and then set JAVA_HOME path for the JDK 11.

[4] Setup MySQL to run in Docker

docker-compose up -d docker exec -it dropwizard-sample-app-db-1 mysql -u root -proot -e "create database db_notes;"

Note:you may need to check the name of the container by running docker console command first.

docker ps
  

[5] Run migration

mvn package java -jar target/sample-app-1.0-SNAPSHOT.jar db migrate configuration.yml

[6] Run application

mvn package java -jar target/sample-app-1.0-SNAPSHOT.jar server configuration.yml

[7] Test

curl -X POST http://localhost:8080/notes --data "Hello world" curl -X POST http://localhost:8080/notes --data "This is a sample application" curl http://127.0.0.1:8080/notes/ curl http://127.0.0.1:8080/notes/1 curl http://127.0.0.1:8080/notes/2

[8] Check MySQL Database using container terminal

mysql -u root -p db_notes mysql> show tables; mysql> select * from notes;

[9] Check MySQL Database using DBeaver on host

host=localhost port=3306 username=root password=root

REF:

https://github.com/joebew42/dropwizard-sample-app

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[java] [maven] [intellij] How to Write Unit Tests in Java

[0] preparation.

• git
• java jdk 17
• maven
• IntelliJ IDE

[1] Git clone project.

git clone https://github.com/KunalN25/junit-testing-tutorial.git

[2] Change directory to the project root.

cd junit-testing-tutorial

[3] Open project using IntelliJ IDE.

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follow the next steps at https://www.freecodecamp.org/news/java-unit-testing/

REF:

• https://www.freecodecamp.org/news/java-unit-testing/ 
• cache: https://web.archive.org/web/20230403174101/https://www.freecodecamp.org/news/java-unit-testing/
• https://github.com/KunalN25/junit-testing-tutorial/tree/master
• cache: https://web.archive.org/web/20230410174822/https://github.com/KunalN25/junit-testing-tutorial

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[docker] [dockerhub] Create a new Docker Image, Run as Container

Start working in a new project directory.

mkdir demo1 cd demo1

Create demo index.html file.

<!DOCTYPE html> <html> <body style="background-color:lightgoldenrodyellow;"> <h1>Welcome to Stack Simplify</h1> <p>Docker for Beginners Demo</p> <p>Application Version: V1</p> </body> </html>

Create Dockerfile and copy the index.html into the container. (save as .Dockerfile)

FROM nginx COPY index.html /usr/share/nginx/html

Build image.

docker build -f .Dockerfile -t stacksimplify/mynginx_image1:v1 .

Run container from image.

docker run --name mynginx1 -p 80:80 -d stacksimplify/mynginx_image1:v1

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[docker] [dockerhub] Pull Docker Image from Docker Hub and Run it

Pull Image from Docker Hub.

docker pull stacksimplify/dockerintro-springboot-helloworld-rest-api:1.0.0-RELEASE

Run the downloaded Docker Image & Access the Application.

docker run --name app1 -p 80:8080 -d stacksimplify/dockerintro-springboot-helloworld-rest-api:1.0.0-RELEASE

Browse the application at http://localhost/hello.

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REF: https://www.stacksimplify.com/aws-eks/docker-basics/get-docker-image-from-docker-hub-and-run-/

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