How enable JSONP in RESTEasy?

Question

Title say about my issue. I need wrap DTO in to a javascript method callback. Currently I return on request JSON. But problem with using this in Ajax because I send GET to other domain. and of course security police.

I have idea to create addition provide. Have you any example, links or suggestion how can do this.

Answer 1

There's no explicit support for JSONP in RESTEasy, however one easy way to enable JSONP in your application is to write a Servlet Filter.

Here's a few links that can help you write a filter:

• jsonp-java: server side filter wraps any response into a jsonp callback

• Serving up JSONP from your JAX-RS Web Services

• Implementing a Servlet Filter for JSONP callback with Spring’s DelegatingFilterProxy (if you're using Spring)

When I had this requirement I ended up writing my own since none of the examples I found seemed to quite nail it. Here's my advice for writing your own filter:

• only wrap the response if a callback parameter is specified (obviously)

• only wrap the response if the response content type is application/json (or if you want to support a wider selection of variants, only wrap if the response content type is application/json or application/*+json)

• use an HttpServletResponseWrapper so that you can invoke the forward chain (chain.doFilter) without writing any data to the real response. Once the forward chain is complete you can then check the content type, make sure you want to wrap the response as JSONP, then write the captured data into the real response, along with the JSONP prefix and suffix.

• when you do decide to wrap the response as JSONP, make sure you change the response content type to text/javascript

If you haven't done much with Java EE Filters before, you may want to read the relevant section of the Java EE tutorial first: Filtering Requests and Responses.