Creating a simple application using the AWS SDK for Java 2.x (original) (raw)

This tutorial shows you how to use Apache Maven to define dependencies for the SDK for Java 2.x and then write code that connects to Amazon S3 to upload a file.

Follow these steps to complete this tutorial:

Step 1: Set up for this tutorial

Before you begin this tutorial, you need the following:

Use the instructions in Setup overview to get set up for this tutorial. After you have configured your development environment with single sign-on access for the Java SDK and you have an active AWS access portal session, continue with Step 2 of this tutorial.

Step 2: Create the project

To create the project for this tutorial, you run a Maven command that prompts you for input on how to configure the project. After all input is entered and confirmed, Maven finishes building out the project by creating a pom.xml and creates stub Java files.

  1. Open a terminal or command prompt window and navigate to a directory of your choice, for example, your Desktop or Home folder.
  2. Enter the following command at the terminal and press Enter.
mvn archetype:generate \  
  -DarchetypeGroupId=software.amazon.awssdk \  
  -DarchetypeArtifactId=archetype-app-quickstart \  
  -DarchetypeVersion=2.27.21
  1. Enter the value listed in the second column for each prompt.
    Prompt Value to enter
    Define value for property 'service': s3
    Define value for property 'httpClient': apache-client
    Define value for property 'nativeImage': false
    Define value for property 'credentialProvider' identity-center
    Define value for property 'groupId': org.example
    Define value for property 'artifactId': getstarted
    Define value for property 'version' 1.0-SNAPSHOT:
    Define value for property 'package' org.example:
  2. After the last value is entered, Maven lists the choices you made. Confirm by entering_Y_ or re-enter values by entering_N_.

Maven creates the project folder named getstarted based on theartifactId value that you entered. Inside the getstarted folder, find a README.md file that you can review, a pom.xml file, and asrc directory.

Maven builds the following directory tree.

getstarted
├── README.md
├── pom.xml
└── src
    ├── main
    │   ├── java
    │   │   └── org
    │   │       └── example
    │   │           ├── App.java
    │   │           ├── DependencyFactory.java
    │   │           └── Handler.java
    │   └── resources
    │       └── simplelogger.properties
    └── test
        └── java
            └── org
                └── example
                    └── HandlerTest.java

10 directories, 7 files

The following shows the contents of the pom.xml project file.

The dependencyManagement section contains a dependency to the AWS SDK for Java 2.x and the dependencies section has a dependency for Amazon S3. The project uses Java 1.8 because of the 1.8 value in the maven.compiler.source andmaven.compiler.target properties.

<?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>

    <groupId>org.example</groupId>
    <artifactId>getstarted</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <maven.shade.plugin.version>3.2.1</maven.shade.plugin.version>
        <maven.compiler.plugin.version>3.6.1</maven.compiler.plugin.version>
        <exec-maven-plugin.version>1.6.0</exec-maven-plugin.version>
        <aws.java.sdk.version>2.27.21</aws.java.sdk.version> <-------- SDK version picked up from archetype version.
        <slf4j.version>1.7.28</slf4j.version>
        <junit5.version>5.8.1</junit5.version>
    </properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>software.amazon.awssdk</groupId>
                <artifactId>bom</artifactId>
                <version>${aws.java.sdk.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>software.amazon.awssdk</groupId>
            <artifactId>s3</artifactId>  <-------- S3 dependency
            <exclusions>
                <exclusion>
                    <groupId>software.amazon.awssdk</groupId>
                    <artifactId>netty-nio-client</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>software.amazon.awssdk</groupId>
                    <artifactId>apache-client</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>software.amazon.awssdk</groupId>
            <artifactId>sso</artifactId> <-------- Required for identity center authentication.
        </dependency>

        <dependency>
            <groupId>software.amazon.awssdk</groupId>
            <artifactId>ssooidc</artifactId> <-------- Required for identity center authentication.
        </dependency>

        <dependency>
            <groupId>software.amazon.awssdk</groupId>
            <artifactId>apache-client</artifactId> <-------- HTTP client specified.
            <exclusions>
                <exclusion>
                    <groupId>commons-logging</groupId>
                    <artifactId>commons-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${slf4j.version}</version>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-simple</artifactId>
            <version>${slf4j.version}</version>
        </dependency>

        <!-- Needed to adapt Apache Commons Logging used by Apache HTTP Client to Slf4j to avoid
        ClassNotFoundException: org.apache.commons.logging.impl.LogFactoryImpl during runtime -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>jcl-over-slf4j</artifactId>
            <version>${slf4j.version}</version>
        </dependency>

        <!-- Test Dependencies -->
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter</artifactId>
            <version>${junit5.version}</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>${maven.compiler.plugin.version}</version>
            </plugin>
        </plugins>
    </build>

</project>

Step 3: Write the code

The following code shows the App class created by Maven. The main method is the entry point into the application, which creates an instance of theHandler class and then calls its sendRequest method.

package org.example;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class App {
    private static final Logger logger = LoggerFactory.getLogger(App.class);

    public static void main(String... args) {
        logger.info("Application starts");

        Handler handler = new Handler();
        handler.sendRequest();

        logger.info("Application ends");
    }
}

The DependencyFactory class created by Maven contains the s3Client factory method that builds and returns an S3Client instance. The S3Client instance uses an instance of the Apache-based HTTP client. This is because you specified apache-client when Maven prompted you for which HTTP client to use.

The DependencyFactory is shown in the following code.

package org.example;

import software.amazon.awssdk.http.apache.ApacheHttpClient;
import software.amazon.awssdk.services.s3.S3Client;

/**
 * The module containing all dependencies required by the {@link Handler}.
 */
public class DependencyFactory {

    private DependencyFactory() {}

    /**
     * @return an instance of S3Client
     */
    public static S3Client s3Client() {
        return S3Client.builder()
                       .httpClientBuilder(ApacheHttpClient.builder())
                       .build();
    }
}

The Handler class contains the main logic of your program. When an instance ofHandler is created in the App class, theDependencyFactory furnishes the S3Client service client. Your code uses the S3Client instance to call the Amazon S3 service.

Maven generates the following Handler class with a_TODO_ comment. The next step in the tutorial replaces the_TODO_ with code.

package org.example;

import software.amazon.awssdk.services.s3.S3Client;


public class Handler {
    private final S3Client s3Client;

    public Handler() {
        s3Client = DependencyFactory.s3Client();
    }

    public void sendRequest() {
        // TODO: invoking the api calls using s3Client.
    }
}

To fill in the logic, replace the entire contents of the Handler class with the following code. The sendRequest method is filled in and the necessary imports are added.

The code first creates a new S3 bucket with the last part of the name generated usingSystem.currentTimeMillis() in order to make the bucket name unique.

After creating the bucket in the createBucket() method, the program uploads an object using the putObject method of S3Client. The contents of the object is a simple string created with the RequestBody.fromString method.

Finally, the program deletes the object followed by the bucket in the cleanUp method.

package org.example;

import software.amazon.awssdk.core.sync.RequestBody;
import software.amazon.awssdk.services.s3.S3Client;
import software.amazon.awssdk.services.s3.model.CreateBucketRequest;
import software.amazon.awssdk.services.s3.model.DeleteBucketRequest;
import software.amazon.awssdk.services.s3.model.DeleteObjectRequest;
import software.amazon.awssdk.services.s3.model.HeadBucketRequest;
import software.amazon.awssdk.services.s3.model.PutObjectRequest;
import software.amazon.awssdk.services.s3.model.S3Exception;


public class Handler {
    private final S3Client s3Client;

    public Handler() {
        s3Client = DependencyFactory.s3Client();
    }

    public void sendRequest() {
        String bucket = "bucket" + System.currentTimeMillis();
        String key = "key";

        createBucket(s3Client, bucket);

        System.out.println("Uploading object...");

        s3Client.putObject(PutObjectRequest.builder().bucket(bucket).key(key)
                        .build(),
                RequestBody.fromString("Testing with the {sdk-java}"));

        System.out.println("Upload complete");
        System.out.printf("%n");

        cleanUp(s3Client, bucket, key);

        System.out.println("Closing the connection to {S3}");
        s3Client.close();
        System.out.println("Connection closed");
        System.out.println("Exiting...");
    }

    public static void createBucket(S3Client s3Client, String bucketName) {
        try {
            s3Client.createBucket(CreateBucketRequest
                    .builder()
                    .bucket(bucketName)
                    .build());
            System.out.println("Creating bucket: " + bucketName);
            s3Client.waiter().waitUntilBucketExists(HeadBucketRequest.builder()
                    .bucket(bucketName)
                    .build());
            System.out.println(bucketName + " is ready.");
            System.out.printf("%n");
        } catch (S3Exception e) {
            System.err.println(e.awsErrorDetails().errorMessage());
            System.exit(1);
        }
    }

    public static void cleanUp(S3Client s3Client, String bucketName, String keyName) {
        System.out.println("Cleaning up...");
        try {
            System.out.println("Deleting object: " + keyName);
            DeleteObjectRequest deleteObjectRequest = DeleteObjectRequest.builder().bucket(bucketName).key(keyName).build();
            s3Client.deleteObject(deleteObjectRequest);
            System.out.println(keyName + " has been deleted.");
            System.out.println("Deleting bucket: " + bucketName);
            DeleteBucketRequest deleteBucketRequest = DeleteBucketRequest.builder().bucket(bucketName).build();
            s3Client.deleteBucket(deleteBucketRequest);
            System.out.println(bucketName + " has been deleted.");
            System.out.printf("%n");
        } catch (S3Exception e) {
            System.err.println(e.awsErrorDetails().errorMessage());
            System.exit(1);
        }
        System.out.println("Cleanup complete");
        System.out.printf("%n");
    }
}

Step 4: Build and run the application

After the project is created and contains the complete Handler class, build and run the application.

  1. Make sure that you have an active IAM Identity Center session. To do so, run the AWS Command Line Interface commandaws sts get-caller-identity and check the response. If you don't have an active session, see this section for instructions.
  2. Open a terminal or command prompt window and navigate to your project directorygetstarted.
  3. Use the following command to build your project:
mvn clean package
  1. Use the following command to run the application.
mvn exec:java -Dexec.mainClass="org.example.App"

To view the new bucket and object that the program creates, perform the following steps.

  1. In Handler.java, comment out the line cleanUp(s3Client, bucket, key) in the sendRequest method and save the file.
  2. Rebuild the project by running mvn clean package.
  3. Rerun mvn exec:java -Dexec.mainClass="org.example.App" to upload the text object once more.
  4. Sign in to the S3 console to view the new object in the newly created bucket.

After you view the file, delete the object, and then delete the bucket.

Success

If your Maven project built and ran without error, then congratulations! You have successfully built your first Java application using the SDK for Java 2.x.

Cleanup

To clean up the resources you created during this tutorial, do the following:

Next steps

Now that you have the basics down, you can learn about the following: