Servlet retrieves XML from URL and returns XML response

Question

On a project I am doing I have been forced into developing a server side part due to restrictions of the "Same Origin Policy" in browsers, that prevents the AJAX making requests to anything outside of the domain of the page.

Therefore I am building a Java Servlet that will act as the handler for the page and will retrieve XML's from external sites and return it back to the client page using AJAX

I will use GET parameters to instruct the servlet what URL to fetch XMLs from.

I am a beginner with Java, I could easily do this in PHP but sadly there are no environments availale to host PHP or Apache

Skeleton Code

public void doGet(HttpServletRequest agentRequest, HttpServletResponse agentResponse) 
throws ServletException, IOException
{

    agentResponse.setContentType("text/xml");


    //determine if agentRequest is for templateList or templateDetails


        //build URL for specific request

    //if no parameters sent or invalid send error response


    //fetch XML from URL 


    //output response XML to client  

}

I do not want a full code solution, just references and ideas to get me in the right direction!

e.g. what java features to use for this, etc.

Thanks

score 1 · Accepted Answer · edited May 23 '17 at 10:25

As requested, some high-level ideas to get you started: Firstly, get the external URL from the request parameter:

//equivalent of PHP $_GET["url"]
String externalUrl = agentRequest.getParameter("url");

Then you need to retrieve the response from the external URL. There are already various Q'a and A's on that topic, including How do I do a HTTP GET in Java?

Finally, you need to write the response into your response using the OutputStream supplied:

agentResponse.getOutputStream();

Servlet retrieves XML from URL and returns XML response

1 Answers1