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== response



=== Purpose


The `response` object is an instance of the Servlet API's {jakartaee}jakarta/servlet/http/HttpServletResponse.html[HttpServletResponse] class


=== Examples


[source,groovy]
----
class BookController {
    def downloadFile() {
        byte[] bytes = // read bytes
        response.outputStream << bytes
    }
}
----


=== Description


The Servlet API's `HttpServletResponse` class can be used within Grails to perform all typical activities such as writing out binary data, writing directly to the response and sending error response codes to name but a few. Refer to the documentation on the {jakartaee}jakarta/servlet/http/HttpServletResponse.html[HttpServletResponse] class in the Servlet API for more information. Grails provides the following additional methods and/or properties on the `response` object

* `format` - The request format, used for link:{guidePath}theWebLayer.html#contentNegotiation[Content Negotiation].
* `withFormat(Closure)` - The withFormat method, used for link:{guidePath}theWebLayer.html#contentNegotiation[Content Negotiation].

Grails also overrides the left shift operator on the `response` object making it easier to write to the response writer:

[source,groovy]
----
response << "Hello World"
----
