# Creating a simple application using the AWS SDK for Java 2.x
<a name="get-started-tutorial"></a>

This tutorial shows you how to use [Apache Maven](https://maven.apache.org/) 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](#get-started-setup) 
+  [Step 2: Create the project](#get-started-projectsetup) 
+  [Step 3: Write the code](#get-started-code) 
+  [Step 4: Build and run the application](#get-started-run) 

## Step 1: Set up for this tutorial
<a name="get-started-setup"></a>

Before you begin this tutorial, you need the following:
+ Permission to access Amazon S3
+ A Java development environment that is configured to access AWS services using single sign-on to the AWS IAM Identity Center

Use the instructions in [Setup overview](setup.md#setup-overview) to get set up for this tutorial. After you have [configured your development environment with single sign-on access](get-started-auth.md#setup-credentials) for the Java SDK and you have an [active AWS access portal session](get-started-auth.md#setup-login-sso), continue with Step 2 of this tutorial.

## Step 2: Create the project
<a name="get-started-projectsetup"></a>

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.

1. 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.    
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started-tutorial.html)

1. 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 the `artifactId` value that you entered. Inside the `getstarted` folder, find a `README.md` file that you can review, a `pom.xml` file, and a `src` 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.

### `pom.xml`
<a name="projectsetup-collapse2"></a>

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` and `maven.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
<a name="get-started-code"></a>

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 the `Handler` class and then calls its `sendRequest` method.

### `App` class
<a name="projectsetup-collapse2"></a>

```
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 [https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/s3/S3Client.html](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/s3/S3Client.html) 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.

### `DependencyFactory` class
<a name="code-collapse2"></a>

```
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 of `Handler` is created in the `App` class, the `DependencyFactory` 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.

### `Handler` class, Maven-generated
<a name="code-collapsible3"></a>

```
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.

### `Handler` class, implemented
<a name="code-collapse4"></a>

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

After creating the bucket in the `createBucket()` method, the program uploads an object using the [https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/s3/S3Client.html#putObject(software.amazon.awssdk.services.s3.model.PutObjectRequest,software.amazon.awssdk.core.sync.RequestBody)](https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/s3/S3Client.html#putObject(software.amazon.awssdk.services.s3.model.PutObjectRequest,software.amazon.awssdk.core.sync.RequestBody)) 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
<a name="get-started-run"></a>

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 command `aws sts get-caller-identity` and check the response. If you don't have an active session, see [this section](get-started-auth.md#setup-login-sso) for instructions.

1. Open a terminal or command prompt window and navigate to your project directory `getstarted`.

1. 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.

1. Rebuild the project by running `mvn clean package`.

1. Rerun `mvn exec:java -Dexec.mainClass="org.example.App"` to upload the text object once more.

1. Sign in to [the S3 console](https://console.aws.amazon.com/s3/) to view the new object in the newly created bucket.

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

### Success
<a name="get-started-success"></a>

If your Maven project built and ran without error, then congratulations\$1 You have successfully built your first Java application using the SDK for Java 2.x.

### Cleanup
<a name="cleanup"></a>

To clean up the resources you created during this tutorial, do the following:
+ If you haven't done so already, in [the S3 console](https://console.aws.amazon.com/s3/), delete any objects and any buckets created when you ran the application.
+ Delete the project folder (`getstarted`).

## Next steps
<a name="get-started-next"></a>

Now that you have the basics down, you can learn about the following:
+  [Working with Amazon S3](examples-s3.md) 
+  [Working with other Amazon Web Services](work-with-services.md), such as [DynamoDB](examples-dynamodb.md), [Amazon EC2](examples-ec2.md), and [various database services](examples-databases.md) 
+  [Use the SDK](using.md) 
+  [Security for the AWS SDK for Java](security.md) **