Setting up a Java project for GitHub Codespaces

Introduction

This guide shows you how to set up an example Java project in Codespaces, entweder mithilfe der Visual Studio Code-Desktopanwendung oder mithilfe des VS Code-Webclients. Anhand eines Beispiels wird erklärt, wie du dein Projekt in einem Codespace öffnen und eine vordefinierte Entwicklungscontainerkonfiguration hinzufügen und bearbeiten kannst.

Step 1: Open the project in a codespace

1. Go to https://github.com/microsoft/vscode-remote-try-java.

2. Click Use this template, then click Open in a codespace.

   

When you create a codespace, your project is created on a remote virtual machine that is dedicated to you. By default, the container for your codespace has many languages and runtimes, including Java. It also includes a set of commonly used tools such as Gradle, Maven, git, wget, rsync, openssh, and nano.

Du kannst deinen Codespace anpassen, indem du die Anzahl der vCPUs und den RAM anpassst, Dotfiles zum Personalisieren deiner Umgebung hinzufügst oder die installierten Tools und Skripts bearbeitest.

Codespaces verwendet eine Datei namens devcontainer.json, um den Entwicklungscontainer zu konfigurieren, mit dem du in einem Codespace arbeitest. Jedes Repository kann eine oder mehrere devcontainer.json-Dateien enthalten, sodass du genau die Entwicklungsumgebung erhältst, die du zum Arbeiten an deinem Code in einem Codespace benötigst.

Beim Starten verwendet Codespaces eine devcontainer.json-Datei sowie alle davon abhängigen Dateien, aus denen die Entwicklungscontainerkonfiguration besteht, um Tools und Runtimes zu installieren und weitere Einrichtungsaufgaben auszuführen, die für das Projekt benötigt werden. Weitere Informationen findest du unter Einführung in Entwicklungscontainer.

Step 2: Add a dev container configuration

The default development container, or "dev container," for GitHub Codespaces will allow you to work successfully on a Java project like vscode-remote-try-java. However, we recommend that you configure your own dev container to include all of the tools and scripts your project needs. This will ensure a fully reproducible environment for all GitHub Codespaces users in your repository.

Wenn du dein Repository so einrichten möchtest, dass ein benutzerdefinierter Entwicklungscontainer verwendet wird, musst du eine oder mehrere devcontainer.json-Datei(en) erstellen. Du kannst diese entweder aus einer vordefinierten Konfigurationsvorlage in Visual Studio Code hinzufügen oder selbst schreiben. Weitere Informationen zur Konfiguration von Entwicklungscontainern findest du unter Einführung in Entwicklungscontainer.

1. Greife auf die Visual Studio Code Command Palette zu (UMSCHALT+COMMAND+P (Mac)/STRG+UMSCHALT+P (Windows/Linux)) zu, und beginne dann mit der Eingabe „dev container“. Wähle Codespaces: Konfigurationsdateien für Entwicklungscontainer hinzufügen... aus.

   

2. Type java and click the Java option. Other options are available if your project uses particular tools. For example, Java & PostgreSQL.

   

3. Click the latest version of Java.

   

4. Select the option to Install Maven and click OK.

   

5. A list of additional features you can install is displayed. We'll install Ant, the Java library and command-line tool for building applications. To install this feature, type ant, select Ant (via SDKMAN), then click OK.

   

6. A message is displayed telling you that the dev container configuration file already exists. Click Overwrite.

   A devcontainer.json file is created and is opened in the editor.

Details of your custom dev container configuration

If you look in the Visual Studio Code Explorer you'll see that a .devcontainer directory has been added to the root of your project's repository containing the devcontainer.json file. This is the main configuration file for codespaces created from this repository.

devcontainer.json

The devcontainer.json file that you have added will contain values for the name, image, and features properties. Some additional properties that you may find useful are included but are commented out.

The file will look similar to this, depending on which image you chose:

// For format details, see https://aka.ms/devcontainer.json. For config options, see the
// README at: https://github.com/devcontainers/templates/tree/main/src/java
{
  "name": "Java",
  // Or use a Dockerfile or Docker Compose file. More info: https://containers.dev/guide/dockerfile
  "image": "mcr.microsoft.com/devcontainers/java:0-17",

  "features": {
    "ghcr.io/devcontainers/features/java:1": {
      "version": "none",
      "installMaven": "true",
      "installGradle": "false"
    },
    "ghcr.io/devcontainers-contrib/features/ant-sdkman:2": {}
  }

  // Use 'forwardPorts' to make a list of ports inside the container available locally.
  // "forwardPorts": [],

  // Use 'postCreateCommand' to run commands after the container is created.
  // "postCreateCommand": "java -version",

  // Configure tool-specific properties.
  // "customizations": {},

  // Uncomment to connect as root instead. More info: https://aka.ms/dev-containers-non-root.
  // "remoteUser": "root"
}

• name: You can name your dev container anything you want. A default value is supplied.
• image: The name of an image in a container registry (DockerHub, GitHub Container registry, or Azure Container Registry) that will be used to create the dev container for the codespace.
• features: A list of one or more objects, each of which references one of the available dev container features. Features are self-contained, shareable units of installation code and development container configuration. They provide an easy way to add more tooling, runtime, or library features to your development container. For more information, see "Available Dev Container Features" on the Development Containers website. You can add features by going to the VS Code Command Palette and typing features.
• forwardPorts: Any ports listed here will be forwarded automatically. For more information, see "Forwarding ports in your codespace."
• postCreateCommand: Use this property to run commands after your codespace is created.
• customizations: This property allows you to customize a specific tool or service when it is used for working in a codespace. For example, you can configure specific settings and extensions for VS Code. For more information, see "Supporting tools and services" on the Development Containers website.
• remoteUser: By default, you’re running as the vscode user, but you can optionally set this to root.

For a complete list of available properties, see the dev containers specification on the Development Containers website.

Additional dev container configuration files

If you are familiar with Docker, you may want to use a Dockerfile, or Docker Compose, to configure your codespace environment, in addition to the devcontainer.json file. You can do this by adding your Dockerfile or docker-compose.yml files alongside the devcontainer.json file. For more information, see "Using Images, Dockerfiles, and Docker Compose" on the Development Containers website.

Step 3: Modify your devcontainer.json file

With your dev container configuration added and a basic understanding of what everything does, you can now make changes to customize your environment further. In this example, you'll add properties that will:

• Run a command, after the dev container is created, to create a new file.
• Automatically install two VS Code extensions in this codespace.

1. In the devcontainer.json file, add a comma after the features property.

   JSON

   "features": {
     "ghcr.io/devcontainers/features/java:1": {
       "version": "none",
       "installMaven": "true",
       "installGradle": "false"
     },
     "ghcr.io/devcontainers-contrib/features/ant-sdkman:2": {}
   },

2. Uncomment the postCreateCommand property and change its value to echo \"This file was added by the postCreateCommand.\" > TEMP.md.

   JSON

   // Use 'postCreateCommand' to run commands after the container is created.
   "postCreateCommand": "echo \"This file was added by the postCreateCommand.\" > TEMP.md",

3. Uncomment the customizations property and edit it as follows to install the "Code Spell Checker" extension and the "Extension Pack for Java."

   JSON

   // Configure tool-specific properties.
   "customizations": {
     // Configure properties specific to VS Code.
     "vscode": {
       // Add the IDs of extensions you want installed when the container is created.
       "extensions": [
         "streetsidesoftware.code-spell-checker",
         "vscjava.vscode-java-pack"
       ]
     }
   }

   The devcontainer.json file should now look similar to this, depending on which image you chose:

   // For format details, see https://aka.ms/devcontainer.json. For config options, see the
   // README at: https://github.com/devcontainers/templates/tree/main/src/java
   {
     "name": "Java",
     // Or use a Dockerfile or Docker Compose file. More info: https://containers.dev/guide/dockerfile
     "image": "mcr.microsoft.com/devcontainers/java:0-17",
   
     "features": {
       "ghcr.io/devcontainers/features/java:1": {
         "version": "none",
         "installMaven": "true",
         "installGradle": "false"
       },
       "ghcr.io/devcontainers-contrib/features/ant-sdkman:2": {}
     },
   
     // Use 'forwardPorts' to make a list of ports inside the container available locally.
     // "forwardPorts": [],
   
     // Use 'postCreateCommand' to run commands after the container is created.
     "postCreateCommand": "echo \"This file was added by the postCreateCommand.\" > TEMP.md",
   
     // Configure tool-specific properties.
     "customizations": {
       // Configure properties specific to VS Code.
       "vscode": {
         // Add the IDs of extensions you want installed when the container is created.
         "extensions": [
           "streetsidesoftware.code-spell-checker",
           "vscjava.vscode-java-pack"
         ]
       }
     }
   
     // Uncomment to connect as root instead. More info: https://aka.ms/dev-containers-non-root.
     // "remoteUser": "root"
   }
   

4. Save your changes.

5. Greife auf die VS Code Command Palette zu (UMSCHALT+BEFEHL+P (Mac)/STRG+UMSCHALT+P (Windows/Linux)), und beginne dann mit der Eingabe „rebuild“. Wähle Codespaces: Container neu erstellen aus.

   

   Tipp: Führe gelegentlich eine vollständige Neuerstellung durchführen, um deinen Cache zu löschen und deinen Container mit neuen Images neu zu erstellen. Weitere Informationen findest du unter Durchführen einer vollständigen Neuerstellung eines Containers.

   Durch das Neuerstellen innerhalb deines Codespace wird sichergestellt, dass die Änderungen wie erwartet funktionieren, bevor du einen Commit für die Änderungen im Repository ausführst. Wenn etwas zu einem Fehler führt, wirst du in einem Codespace mit einem Wiederherstellungscontainer platziert, den du neu erstellen kannst, um deinen Container weiter anzupassen.

   After the dev container is rebuilt, and your codespace becomes available again, the postCreateCommand will have been run, creating a TEMP.md file, and the two extensions will be available for use.

Step 4: Run your application

1. Run the application by pressing F5.

2. If a "toast" notification message is displayed at the bottom right corner of VS Code, asking whether you want to switch to standard mode, click Yes.

   

3. When the project files have been imported, click the Debug Console tab to see the program output.

   

Step 5: Commit your changes

Nachdem du Änderungen an deinem Codespace vorgenommen hast (neuer Code oder Konfigurationsänderungen), möchtest du deine Änderungen committen. Durch das Committen von Änderungen an dein Repository wird sichergestellt, dass jeder Benutzer, der einen Codespace aus diesem Repository erstellt, die gleiche Konfiguration verwendet. Dies bedeutet auch, dass alle von dir ausgeführten Anpassungen, z. B. das Hinzufügen von VS Code-Erweiterungen, für alle Benutzer angezeigt werden.

Weitere Informationen findest du unter Verwenden der Quellcodeverwaltung in deinem Codespace.

Next steps

You should now be able to add a custom dev container configuration to your own Java project.

• Verwalten verschlüsselter Schlüssel für Codespaces
• Verwalten der GDP-Überprüfung für Codespaces
• Weiterleiten von Ports in Ihrem Codespace