Build Java apps with Microsoft Graph

This tutorial teaches you how to build a Java console app that uses the Microsoft Graph API to access data on behalf of a user.

In this tutorial, you will:

• Get the signed-in user
• List the user's inbox messages
• Send an email

Prerequisites

Before you start this tutorial, you should have the Java SE Development Kit (JDK) and Gradle installed on your development machine.

You should also have a Microsoft work or school account with an Exchange Online mailbox. If you don't have a Microsoft 365 tenant, you might qualify for one through the Microsoft 365 Developer Program; for details, see the FAQ. Alternatively, you can sign up for a one-month free trial or purchase a Microsoft 365 plan.

Register an application for user authentication

Register an application that supports user authentication using device code flow. You can register an application using the Microsoft Entra admin center, or by using the Microsoft Graph PowerShell SDK.

Create a Java console app

Create a basic Java console app.

1. Open your command-line interface (CLI) in a directory where you want to create the project. Run the following command to create a new Gradle project.

   gradle init --dsl groovy --test-framework junit --type java-application --project-name graphtutorial --package graphtutorial
   

2. Once the project is created, verify that it works by running the following command to run the app in your CLI.

   ./gradlew --console plain run
   

   If it works, the app should output Hello World..

Install dependencies

Before moving on, add dependencies that you use later.

• Azure Identity client library for Java to authenticate the user and acquire access tokens.
• Microsoft Graph SDK for Java to make calls to the Microsoft Graph.

1. Open ./app/build.gradle. Update the dependencies section to add those dependencies.

   dependencies {
       // Use JUnit test framework.
       testImplementation 'junit:junit:4.13.2'
   
       // This dependency is used by the application.
       implementation 'com.google.guava:guava:33.4.6-jre'
       implementation 'com.azure:azure-identity:1.15.4'
       implementation 'com.microsoft.graph:microsoft-graph:6.33.0'
   }
   

2. Add the following to the end of ./app/build.gradle.

   run {
       standardInput = System.in
   }
   

   The next time you build the project, Gradle will download those dependencies.

Load application settings

Next, add the details of your app registration to the project.

1. Create a new directory named graphtutorial in the ./app/src/main/resources directory.

2. Create a new file in the ./app/src/main/resources/graphtutorial directory named oAuth.properties, and add the following text in that file.

   app.clientId=YOUR_CLIENT_ID_HERE
   app.tenantId=common
   app.graphUserScopes=user.read,mail.read,mail.send
   

3. Update the values according to the following table.

   Setting	Value
   app.clientId	The client ID of your app registration
   app.tenantId	If you chose the option to only allow users in your organization to sign in, change this value to your tenant ID. Otherwise leave as common.

   Important

   If you're using source control such as git, now would be a good time to exclude the oAuth.properties file from source control to avoid inadvertently leaking your app ID.

Design the app

Continue by creating a simple console-based menu.

1. Open ./app/src/main/java/graphtutorial/App.java and add the following import statements.

   package graphtutorial;
   
   import java.io.IOException;
   import java.time.ZoneId;
   import java.time.format.DateTimeFormatter;
   import java.time.format.FormatStyle;
   import java.util.InputMismatchException;
   import java.util.Properties;
   import java.util.Scanner;
   
   import com.microsoft.graph.models.Message;
   import com.microsoft.graph.models.MessageCollectionResponse;
   import com.microsoft.graph.models.User;
   

2. Replace the existing main function with the following.

   public static void main(String[] args) {
       System.out.println("Java Graph Tutorial");
       System.out.println();
   
       final Properties oAuthProperties = new Properties();
       try {
           oAuthProperties.load(App.class.getResourceAsStream("oAuth.properties"));
       } catch (IOException e) {
           System.out.println("Unable to read OAuth configuration. Make sure you have a properly formatted oAuth.properties file. See README for details.");
           return;
       }
   
       initializeGraph(oAuthProperties);
   
       greetUser();
   
       Scanner input = new Scanner(System.in);
   
       int choice = -1;
   
       while (choice != 0) {
           System.out.println("Please choose one of the following options:");
           System.out.println("0. Exit");
           System.out.println("1. Display access token");
           System.out.println("2. List my inbox");
           System.out.println("3. Send mail");
           System.out.println("4. Make a Graph call");
   
           try {
               choice = input.nextInt();
           } catch (InputMismatchException ex) {
               // Skip over non-integer input
           }
   
           input.nextLine();
   
           // Process user choice
           switch(choice) {
               case 0:
                   // Exit the program
                   System.out.println("Goodbye...");
                   break;
               case 1:
                   // Display access token
                   displayAccessToken();
                   break;
               case 2:
                   // List emails from user's inbox
                   listInbox();
                   break;
               case 3:
                   // Send an email message
                   sendMail();
                   break;
               case 4:
                   // Run any Graph code
                   makeGraphCall();
                   break;
               default:
                   System.out.println("Invalid choice");
           }
       }
   
       input.close();
   }
   

3. Add the following placeholder methods at the end of the file. You implement them in later steps.

   private static void initializeGraph(Properties properties) {
       // TODO
   }
   
   private static void greetUser() {
       // TODO
   }
   
   private static void displayAccessToken() {
       // TODO
   }
   
   private static void listInbox() {
       // TODO
   }
   
   private static void sendMail() {
       // TODO
   }
   
   private static void makeGraphCall() {
       // TODO
   }
   

This implements a basic menu and reads the user's choice from the command line.

1. Delete ./app/src/test/java/graphtutorial/AppTest.java.

Next step