Developing and deploying a basic Java application on SAP Cloud Platform

The first step in building your application is to create a new Dynamic Web Project. Open your Eclipse IDE with the installed SAP Cloud Platform Tools. Make sure the Java EE perspective is open by choosing Window > Open Perspective > Other.

Then choose the perspective Java EE (Default) and confirm by clicking OK.

The J2EE perspective is now open.

In the Eclipse main menu choose File > New > Dynamic Web Project to open the respective wizard.

In the New Dynamic Web Project Wizard define the Project name to be helloworld. Make sure the Target Runtime is set to Java Web, the Server Runtime Environment that has been created in the tutorial Configuring Eclipse with SAP Cloud Platform Tools for Java. Leave all other settings untouched and click Finish to create the project.

The helloworld project is now ready for your code.

In Java EE, web applications are implemented as Servlets. On the newly created helloworld project node, open the context menu with a right-click and choose New > Servlet to open the Create Servlet wizard.

In the Create Servlet wizard enter helloworld as Java package and HelloWorldServlet as Class name. This will create Java classes with the respective package and name. Choose Next.

You will want this Servlet to be accessible via the URL <servername>/helloworld, for example http://localhost:8080/helloworld. For this we will set the URL mapping to \. For this select /HelloWorldServlet in the URL mappings field and choose Edit.

In the Pattern field, replace the current value with just /. Confirm with OK.

Click Finish to generate the servlet.

The Java Editor will open the corresponding HelloWorldServlet class in the editor pane. You will also find the Servlet under the helloworld project node > Java Resources > src > helloworld > HelloWorldServlet.java

Next, you will edit the Servlet to output the classical “Hello World”. For this you will modify the doGet() method and add the following code and save your changes.

/**
 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
 */
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.getWriter().println("Hello World!");
}

The application is now ready to run.

To test your application before deploying it to the SAP Cloud Platform you can run it on a local runtime. To do this, do the following:

Navigate to your HelloWorldServlet.java via the helloworld project node > Java Resources > src > helloworld > HelloWorldServlet.java. Open the context menu on the Servlet with a right-click and choose the Run on Server option.

Make sure that Manually define a new server is selected and choose SAP > Java Web Server as server type. Leave all other settings unchanged and click Finish.

A local server will start with your helloworld application deployed. After the server is ready your application will be opened in a browser within Eclipse and greet you with “Hello World!”. In the Servers view you can also see the running server with your application deployed.

To run your application on the SAP Cloud Platform you will choose a different server to run it. Again, navigate to your HelloWorldServlet.java via the helloworld project node > Java Resources > src > helloworld > HelloWorldServlet.java. Open the context menu on the Servlet with a right-click and choose the Run on Server option.

As before, make sure that Manually define a new server is selected. This time choose SAP > SAP Cloud Platform as server type. Make sure to set the Landscape host to hanatrial.ondemand.com. Leave all other settings unchanged and choose Next.

Note: The used Landscape host hanatrial.ondemand.com is only valid if you are using a free Developer Account. Please change the landscape host if you want to use a productive account. The respective landscape hosts can be found in the official documentation.

On the next wizard page specify the Application name to be helloworld, provide the login information for your SAP Cloud Platform account and click Finish:

A Cloud server will start that has your helloworld application deployed. After the server is ready your application will be opened in a browser in Eclipse and greet you with Hello World!. In the Servers view you can also see the running server with your application deployed

Congratulations: You have your first application running on the SAP Cloud Platform!