Demo AWS lambda function as Java

This demonstration shows:

• AWS Lambda
• Java programming langauage
• Maven package tool

Contents:

• Create a project
• Add AWS lamba
• Source

Create a project

Create a Maven project:

sh mvn -B archetype:generate \ -DarchetypeGroupId=org.apache.maven.archetypes \ -DgroupId=com.joelparkerhenderson \ -DartifactId=demo-aws-lamba-function-hello-world-java cd demo-aws-lamba-function-hello-world-java mvn compile

If you get this error:

sh [ERROR] Source option 6 is no longer supported. Use 7 or later. [ERROR] Target option 6 is no longer supported. Use 7 or later.

Then edit pom.xml to upgrade the Java version to the highest available on AWS Lamba, which is currently Java 11, by adding these lines:

xml <project …> … <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.source>11</maven.compiler.source> <maven.compiler.target>11</maven.compiler.target> </properties> …

Then retry:

sh mvn compile

Output:

sh … [INFO] Building demo-aws-lamba-function-hello-world-java 1.0-SNAPSHOT … [INFO] BUILD SUCCESS

Add AWS lamba

Add AWS dependency to pom.xml:

xml <dependency> <groupId>com.amazonaws</groupId> <artifactId>aws-lambda-java-core</artifactId> <version>1.2.0</version> </dependency>

Add build with maven-shade-plugin. The plugin provides the capability to package the artifact in an uber-jar, including its dependencies and to shade - i.e. rename - the packages of some of the dependencies.

xml <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-shade-plugin</artifactId> <version>3.2.1</version> <configuration> <createDependencyReducedPom>false</createDependencyReducedPom> </configuration> <executions> <execution> <phase>package</phase> <goals> <goal>shade</goal> </goals> </execution> </executions> </plugin> </plugins> </build>

Source

Create a main class such as Hello.java to handle each request:

```java package com.joelparkerhenderson;

import com.amazonaws.services.lambda.runtime.Context; import com.amazonaws.services.lambda.runtime.LambdaLogger; import com.amazonaws.services.lambda.runtime.RequestHandler;

public class Hello implements RequestHandler {

public ResponseClass handleRequest(RequestClass request, Context context){
    String greeting = String.format("Hello %s", request.name);
    return new ResponseClass(greeting);
}

} ```

Create a AWS Lamba RequestClass to serialize input from JSON:

```java package com.joelparkerhenderson;

public class RequestClass { String name;

public String gettName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}


public RequestClass(String name) {
    this.name = name;
}

public RequestClass() {
}

} ```

Create a AWS Lamba ResponseClass to serialize output to JSON:

```java package com.joelparkerhenderson;

public class ResponseClass { String greeting;

public String getGreeting() {
    return greeting;
}

public void setGreeting(String greeting) {
    this.greeting = greeting;
}

public ResponseClass(String greeting) {
    this.greeting = greeting;
}

public ResponseClass() {
}

} ```