15 August 2014
It's been quite awhile since I last posted but my wife and I had a kid in November and, despite my very vocal protestations, diapers trump TDD. Today's article is a short one, but I've found it useful ever since switching away from servlet definitions in web.xml to inline @WebServlet annotations. It's applicable to any type of annotations, I suppose, but for me the @WebServlet annotation comes up quite a bit in my day-to-day development.
First, here's our servlet class definition:
@WebServlet(
name="Pleb Control",
description="This servlet is for keeping the plebs in check",
loadOnStartup=1,
asyncSupported=true,
urlPatterns={
"/stupidplebs/subjugateBrutually",
"/stupidplebs/governFairly"
},
initParams = {
@WebInitParam(name="enforcementMethod1", value="the stink eye"),
@WebInitParam(name="enforcementMethod2", value="propaganda")
}
)
public class StupidPlebServlet extends HttpServlet {
@Override
public void doGet(HttpServletRequest request, HttpServletResponse response) {
// do some stuff
}
}
Back in the day when all your servlet and filter definitions were listed in web.xml, it was a bit cumbersome but quite possible to load web.xml in a test and verify settings using an XML parser. Inlining your servlet and filter configurations using @WebServlet and @WebFilter annotations doesn't work with this method but fortunately Java makes it pretty easy to iterate the declared annotations for a class and perform verifications. Here's a test in JUnit:
@Test
public void webServletAnnotationShouldBeConstructedWithExpectedConfigurationSettings() {
// Given the first annotation (assumed to be WebServlet)
WebServlet annotation = (WebServlet)StupidPlebServlet.class.getDeclaredAnnotations()[0];
// Expect
assertThat(annotation.name(), is("Pleb Control"));
// And
assertThat(annotation.description(), is(
"This servlet is for keeping the plebs in check"));
// And the servlet should be loaded when the container starts
assertThat(annotation.loadOnStartup(), is(1));
// And asynchronous processing should be supported
assertThat(annotation.asyncSupported(), is(true));
// And the servlet should be mapped to 2 url patterns
assertThat(annotation.urlPatterns(), is(new String[]{
"/stupidplebs/subjugateBrutually",
"/stupidplebs/governFairly"
}));
// And there should be 2 initialization parameters
assertThat(annotation.initParams().length, is(2));
assertThat(annotation.initParams()[0].name(), is("enforcementMethod1"));
assertThat(annotation.initParams()[0].value(), is("the stink eye"));
assertThat(annotation.initParams()[1].name(), is("enforcementMethod2"));
assertThat(annotation.initParams()[1].value(), is("propaganda"));
}
Here's the same test in Spock:
def "@WebServlet annotation should be constructed with expected configuration settings"() {
given: "groovy makes it easier to find the annotation we're interested"
def annotation = StupidPlebServlet.class.declaredAnnotations.find { it ->
it instanceof WebServlet
}
expect:
annotation.name() == "Pleb Control"
and:
annotation.description() ==
"This servlet is for keeping the plebs in check"
and: "the servlet should be loaded when the container starts"
annotation.loadOnStartup() == 1
and: "asynchronous processing should be supported"
annotation.asyncSupported()
and: "the servlet should be mapped to 2 url patterns"
annotation.urlPatterns() == [
"/stupidplebs/subjugateBrutually",
"/stupidplebs/governFairly"
]
and: "there should be 2 initialization parameters"
annotation.initParams().length == 2
annotation.initParams()[0].name() == "enforcementMethod1"
annotation.initParams()[0].value() == "the stink eye"
annotation.initParams()[1].name() == "enforcementMethod2"
annotation.initParams()[1].value() == "propaganda"
}