Spring 3.1 WebApplicationInitializer & Embedded Jetty 8 AnnotationConfiguration
I'm trying to create a simple webapp without any XML configuration using Spring 3.1 and an embedded Jetty 8 server.
However, I'm struggling to get Jetty to recognise my implementaton of the Spring WebApplicationInitializer interface.
Project structure:
src
+- main
+- java
| +- JettyServer.java
| +- Initializer.java
|
+- webapp
+- web.xml (objective is to remove this - see below).
The Initializer class above is a simple implementation of WebApplicationInitializer:
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import org.springframework.web.WebApplicationInitializer;
public class Initializer implements WebApplicationInitializer {
@Override
public void onStartup(ServletContext servletContext) throws ServletException {
System.out.println("onStartup");
}
}
Likewise JettyServer is a simple implementation of an embedded Jetty server:
import org.eclipse.jetty.annotations.AnnotationConfiguration;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.webapp.Configuration;
import org.eclipse.jetty.webapp.WebAppContext;
public class JettyServer {
public static void main(String[] args) throws Exception {
Server server = new Server(8080);
WebAppContext webAppContext = new WebAppContext();
webAppContext.setResourceBase("src/main/webapp");
webAppContext.setContextPath("/");
webAppContext.setConfigurations(new Configuration[] { new AnnotationConfiguration() });
webAppContext.setParentLoaderPriority(true);
server.setHandler(webAppContext);
server.start();
server.join();
}
}
My understanding is that on startup Jetty will use AnnotationConfiguration to scan for annotated implementations of ServletContainerInitializer; it should find Initializer and wire it in...
However, when I start the Jetty server (from within Eclipse) I see the following on the command-line:
2012-11-04 16:59:04.552:INFO:oejs.Server:jetty-8.1.7.v20120910
2012-11-04 16:59:05.046:INFO:/:No Spring WebApplicationInitializer types detected on classpath
2012-11-04 16:59:05.046:INFO:oejsh.ContextHandler:started o.e.j.w.WebAppContext{/,file:/Users/duncan/Coding/spring-mvc-embedded-jetty-test/src/main/webapp/}
2012-11-04 16:59:05.117:INFO:oejs.AbstractConnector:Started [email protected]:8080
The important bit is this:
No Spring WebApplicationInitializer types detected on classpath
Note that src/main/java is defined as a source folder in Eclipse, so should be on the classpath. Also note that the Dynamic Web Module Facet is set to 3.0.
I'm sure there's a simple explanation, but I'm struggling to see the wood for the trees! I suspect the key is with the following line:
...
webAppContext.setResourceBase("src/main/webapp");
...
This makes sense with a 2.5 servlet using web.xml (see below), but what should it be when using AnnotationConfiguration?
NB: Everything fires up correctly if I change the Configurations to the following:
...
webAppContext.setConfigurations(new Configuration[] { new WebXmlConfiguration() });
...
In this case it finds the web.xml under src/main/webapp and uses it to wire the servlet using DispatcherServlet and AnnotationConfigWebApplicationContext in the usual way (completely bypassing the WebApplicationInitializer implementation above).
This feels very much like a classpath problem, but I'm struggling to understand quite how Jetty associates itself with implementations of WebApplicationInitializer - any suggestions would be most appreciated!
For info, I'm using the following:
Spring 3.1.1 Jetty 8.1.7 STS 3.1.0
Answer
The problem is that Jetty's AnnotationConfiguration class does not scan non-jar resources on the classpath (except under WEB-INF/classes).
It finds my WebApplicationInitializer's if I register a subclass of AnnotationConfiguration which overrides configure(WebAppContext) to scan the host classpath in addition to the container and web-inf locations.
Most of the sub-class is (sadly) copy-paste from the parent. It includes:
- an extra parse call (
parseHostClassPath) at the end of the configure method; - the
parseHostClassPathmethod which is largely copy-paste fromAnnotationConfiguration'sparseWebInfClasses; - the
getHostClassPathResourcemethod which grabs the first non-jar URL from the classloader (which, for me at least, is the file url to my classpath in eclipse).
I am using slightly different versions of Jetty (8.1.7.v20120910) and Spring (3.1.2_RELEASE), but I imagine the same solution will work.
Edit: I created a working sample project in github with some modifications (the code below works fine from Eclipse but not when running in a shaded jar) - https://github.com/steveliles/jetty-embedded-spring-mvc-noxml
In the OP's JettyServer class the necessary change would replace line 15 with:
webAppContext.setConfigurations (new Configuration []
{
new AnnotationConfiguration()
{
@Override
public void configure(WebAppContext context) throws Exception
{
boolean metadataComplete = context.getMetaData().isMetaDataComplete();
context.addDecorator(new AnnotationDecorator(context));
AnnotationParser parser = null;
if (!metadataComplete)
{
if (context.getServletContext().getEffectiveMajorVersion() >= 3 || context.isConfigurationDiscovered())
{
parser = createAnnotationParser();
parser.registerAnnotationHandler("javax.servlet.annotation.WebServlet", new WebServletAnnotationHandler(context));
parser.registerAnnotationHandler("javax.servlet.annotation.WebFilter", new WebFilterAnnotationHandler(context));
parser.registerAnnotationHandler("javax.servlet.annotation.WebListener", new WebListenerAnnotationHandler(context));
}
}
List<ServletContainerInitializer> nonExcludedInitializers = getNonExcludedInitializers(context);
parser = registerServletContainerInitializerAnnotationHandlers(context, parser, nonExcludedInitializers);
if (parser != null)
{
parseContainerPath(context, parser);
parseWebInfClasses(context, parser);
parseWebInfLib (context, parser);
parseHostClassPath(context, parser);
}
}
private void parseHostClassPath(final WebAppContext context, AnnotationParser parser) throws Exception
{
clearAnnotationList(parser.getAnnotationHandlers());
Resource resource = getHostClassPathResource(getClass().getClassLoader());
if (resource == null)
return;
parser.parse(resource, new ClassNameResolver()
{
public boolean isExcluded (String name)
{
if (context.isSystemClass(name)) return true;
if (context.isServerClass(name)) return false;
return false;
}
public boolean shouldOverride (String name)
{
//looking at webapp classpath, found already-parsed class of same name - did it come from system or duplicate in webapp?
if (context.isParentLoaderPriority())
return false;
return true;
}
});
//TODO - where to set the annotations discovered from WEB-INF/classes?
List<DiscoveredAnnotation> annotations = new ArrayList<DiscoveredAnnotation>();
gatherAnnotations(annotations, parser.getAnnotationHandlers());
context.getMetaData().addDiscoveredAnnotations (annotations);
}
private Resource getHostClassPathResource(ClassLoader loader) throws IOException
{
if (loader instanceof URLClassLoader)
{
URL[] urls = ((URLClassLoader)loader).getURLs();
for (URL url : urls)
if (url.getProtocol().startsWith("file"))
return Resource.newResource(url);
}
return null;
}
},
});
Update: Jetty 8.1.8 introduces internal changes that are incompatible with the code above. For 8.1.8 the following seems to work:
webAppContext.setConfigurations (new Configuration []
{
// This is necessary because Jetty out-of-the-box does not scan
// the classpath of your project in Eclipse, so it doesn't find
// your WebAppInitializer.
new AnnotationConfiguration()
{
@Override
public void configure(WebAppContext context) throws Exception {
boolean metadataComplete = context.getMetaData().isMetaDataComplete();
context.addDecorator(new AnnotationDecorator(context));
//Even if metadata is complete, we still need to scan for ServletContainerInitializers - if there are any
AnnotationParser parser = null;
if (!metadataComplete)
{
//If metadata isn't complete, if this is a servlet 3 webapp or isConfigDiscovered is true, we need to search for annotations
if (context.getServletContext().getEffectiveMajorVersion() >= 3 || context.isConfigurationDiscovered())
{
_discoverableAnnotationHandlers.add(new WebServletAnnotationHandler(context));
_discoverableAnnotationHandlers.add(new WebFilterAnnotationHandler(context));
_discoverableAnnotationHandlers.add(new WebListenerAnnotationHandler(context));
}
}
//Regardless of metadata, if there are any ServletContainerInitializers with @HandlesTypes, then we need to scan all the
//classes so we can call their onStartup() methods correctly
createServletContainerInitializerAnnotationHandlers(context, getNonExcludedInitializers(context));
if (!_discoverableAnnotationHandlers.isEmpty() || _classInheritanceHandler != null || !_containerInitializerAnnotationHandlers.isEmpty())
{
parser = createAnnotationParser();
parse(context, parser);
for (DiscoverableAnnotationHandler h:_discoverableAnnotationHandlers)
context.getMetaData().addDiscoveredAnnotations(((AbstractDiscoverableAnnotationHandler)h).getAnnotationList());
}
}
private void parse(final WebAppContext context, AnnotationParser parser) throws Exception
{
List<Resource> _resources = getResources(getClass().getClassLoader());
for (Resource _resource : _resources)
{
if (_resource == null)
return;
parser.clearHandlers();
for (DiscoverableAnnotationHandler h:_discoverableAnnotationHandlers)
{
if (h instanceof AbstractDiscoverableAnnotationHandler)
((AbstractDiscoverableAnnotationHandler)h).setResource(null); //
}
parser.registerHandlers(_discoverableAnnotationHandlers);
parser.registerHandler(_classInheritanceHandler);
parser.registerHandlers(_containerInitializerAnnotationHandlers);
parser.parse(_resource,
new ClassNameResolver()
{
public boolean isExcluded (String name)
{
if (context.isSystemClass(name)) return true;
if (context.isServerClass(name)) return false;
return false;
}
public boolean shouldOverride (String name)
{
//looking at webapp classpath, found already-parsed class of same name - did it come from system or duplicate in webapp?
if (context.isParentLoaderPriority())
return false;
return true;
}
});
}
}
private List<Resource> getResources(ClassLoader aLoader) throws IOException
{
if (aLoader instanceof URLClassLoader)
{
List<Resource> _result = new ArrayList<Resource>();
URL[] _urls = ((URLClassLoader)aLoader).getURLs();
for (URL _url : _urls)
_result.add(Resource.newResource(_url));
return _result;
}
return Collections.emptyList();
}
}
});