call a servlet from a JSP ?

[18Harry]

Hi EveryOne ,

I have a servlet that uses some request parameters and based on that sets a JSON Response.

Is it possible to use this in my JSP (I do not have a form) .

I want to invoke the servlet by passing the parameters and obtain the JSON Response and display this content on my JSP. I dont want to copy the same code to my JSP because this servlet is already being used by several classes and hence would like re-use the same.

Thanks in  Advance

Harish

[JohnFait]

You can use SlingRequestProcessor.

http://sling.apache.org/apidocs/sling6/org/apache/sling/engine/SlingRequestProcessor.html

You can try something like the following;

private RequestResponseFactory requestResponseFactory;

private SlingRequestProcessor requestProcessor;

 private ResourceResolver resourceResolver;

 private JSONObject getResourceJSON(Resource resource, Map<String, Object> anyOtherRequestParams) {
        JSONObject jsonObject = null;
        String requestURL = null;
        try {
                requestURL = resource.getPath() + ".json";
                HttpServletRequest request = this.requestResponseFactory.createRequest("GET", requestURL, anyOtherRequestParams);
                ByteArrayOutputStream out = new ByteArrayOutputStream();
                HttpServletResponse response = requestResponseFactory.createResponse(out);
                this.requestProcessor.processRequest(request, response, this.resourceResolver);
                jsonObject = new JSONObject(new String(out.toByteArray(), STRING_ENCODING));           
        } catch (Exception ex) {
            LOGGER.warn("Failed to export resource as JSON " + resource + "," + requestURL, ex);
        }
        return jsonObject;
    }

[smacdonald2008 · Accepted solution]

You can invoke AEM servlets from an AEM JSP. We have community articles on this subject. See this one:

http://helpx.adobe.com/experience-manager/using/custom-sling-servlets.html

This servlet also encodes posted data as JSON as well. 

Here is a more advanced article that talks about invoking a Servlet from a CQ widget that you drag from the CQ sidekick:

http://helpx.adobe.com/experience-manager/using/creating-custom-cq-tree.html

[Krishna_C]

We can achieve it using an ajax call to the servlet as well .I would prefer something like this 

function myFunction(){
        var urlBulder='/myservletpath?param1=xxx&param2=yyy';
        $.ajax({
                type: 'POST',
                url: urlBulder,
                dataType: 'json',
                error : function() {
                    alert('Error in getting the response from server');
                },
                success: function(data) {
                  // logic here
                }
             }); 
      } 

You can call this javascript ajax function and perform the logic on the received json to display/modify any elements on the jsp .

Regards,

Krishna