One of the main challenges when integrating the Author Component applet in your SharePoint site is to avoid authenticating twice when opening a document resource stored in your SharePoint repository.
You have already signed in when you started the SharePoint session, but the applet is not aware of your current session. In this case every time the applet is accessing a document it will ask you to input your credentials again.
As a possible solution, do not execute HTTP requests directly from the Java code, but forward them to the web browser that hosts the applet, because it is aware of the current user session (authentication cookies).
To open documents stored on your SharePoint repository, register your own protocol handler to the JVM. We implemented a handler for both http and https protocols that forwards the HTTP requests to a JavaScript XMLHttpRequest object. This way, the browser that executes the JavaScript code is responsible for handling the authentication to the SharePoint site.
URL.setURLStreamHandlerFactory(new ro.sync.net.protocol.http.handlers.CustomURLStreamHandlerFactory(this));
<applet width="100%" height="600" code="ro.sync.ecss.samples.AuthorComponentSampleApplet" name="authorComponentAppletName" id="authorComponentApplet" MAYSCRIPT="true"> ..... </applet>