REST with Jersey and Jetty part 2

REST with Jersey and Jetty part 2

Getting Jersey into play

In this part, we will introduce Jetty as serving with rest. We will att a class serving a @GET request.

We will need an extra dependency for Jersey to work, and after getting a strange error under startup I ended up changing the dependency on Jetty from the previous post [http://ironicprogrammer.blogspot.se/2015/04/rest-with-jersey-and-jetty-part-1.html]. I got the following error:

2015-05-01 11:37:38.214:INFO:oejs.Server:main: jetty-9.1.1.v20140108 2015-05-01 11:37:38.224:WARN:oejuc.AbstractLifeCycle:main: FAILED org.eclipse.jetty.server.Server@7637f22: java.lang.NoSuchMethodError: org.eclipse.jetty.util.DateCache.setTimeZone(Ljava/util/TimeZone;)V java.lang.NoSuchMethodError: org.eclipse.jetty.util.DateCache.setTimeZone(Ljava/util/TimeZone;)V
When adding the dependency for Jersey 2.17 after th Jetty dependency. Actually I got it to work by moving the Jetty dependency to after the Jersey dependency. But reading the log you can see that 2.17 if Jersey used Jetty 9.1.1 so, updating Jetty dependency to 9.1.1.v20140108, the order does not matter.
This is the dependencies for this part.

<dependencies> <dependency> <groupid>org.glassfish.jersey.containers</groupId> <artifactid>jersey-container-jetty-servlet</artifactId> <version>2.17</version> </dependency> <dependency> <groupid>org.eclipse.jetty</groupId> <artifactid>jetty-servlet</artifactId> <version>9.1.1.v20140108</version> </dependency> </dependencies>

We will also create a new statup-class, It will not be much more code than the one in the previous part, but some extra stuff is needed to get Jersey into play.

package app; import java.util.logging.Level; import java.util.logging.Logger; import org.eclipse.jetty.server.Server; import org.eclipse.jetty.servlet.ServletContextHandler; import org.eclipse.jetty.servlet.ServletHolder; public class JerseyServer { public static void main(String[] args) { int port = 2001; if(args.length == 1) { port = Integer.parseInt(args[0]); } Server server = new Server(port); ServletHolder servletHolder = new ServletHolder(org.glassfish.jersey.servlet.ServletContainer.class); servletHolder.setInitParameter("com.sun.jersey.config.property.resourceConfigClass", "com.sun.jersey.api.core.PackagesResourceConfig"); servletHolder.setInitParameter("jersey.config.server.provider.packages", "rest");//Set the package where the services reside servletHolder.setInitParameter("com.sun.jersey.api.json.POJOMappingFeature", "true"); ServletContextHandler contextHandler = new ServletContextHandler(ServletContextHandler.SESSIONS); server.setHandler(contextHandler); contextHandler.addServlet(servletHolder, "/api/*"); try { server.start(); server.join(); } catch (Exception ex) { Logger.getLogger(JerseyServer.class.getName()).log(Level.SEVERE, null, ex); System.exit(1); } } }
The difference here is that we use a ServletHolder with some init parameters to set Jersey up. We also set the path to serve to "/api/*" instead of plain root "/".
That brings us to REST, we need something to show that it works. To do this we have a class under "rest" package called HelloResource.
package rest; import javax.ws.rs.GET; import javax.ws.rs.Path; import javax.ws.rs.Produces; @Path("hello") public class HelloResource { @GET @Produces("text/plain") public String sayHello() { return "Hello from HelloResource!"; } }

So now the only thing you have to do is to start upp JerseyServer and surf into [http://localhost:2001/api/hello] and you should see the hello message. And there you have your first little Microservice ;)

In future post will explore how to use more than @GET and also how to add JSON support to this.