I have a basic JAXRS service that I can provide easily, but this time I want to use the dependency injection API, and I suspect Google Guice will be one of the best. With that in mind, I tried to integrate it, but the documentation is a bit heavy, and I had to hunt to try and find the right combination
- web.xml
- Context Listener (should I use ServletContainer or GuiceContainer)
- Service
- Whether to comment on the service using @Singleton or @Request or nothing (I should annotate using @Singleton - docs say what I should, but then says that it requests scope by default)
- Should annotate constructor parameters using @InjectParam
But I'm currently getting errors from Google Guice, and they change depending on whether I use the @InjectParam annotation or not.
If I comment on @InjectParam then I get
Mar 29, 2013 9:52:04 PM com.sun.jersey.spi.inject.Errors processErrorMessages SEVERE: The following errors and warnings have been detected with resource and/or provider classes: SEVERE: The class com.hillingar.server.dao.interfaces.UserDao is an interface and cannot be instantiated. SEVERE: Missing dependency for constructor public com.hillingar.server.SessionUtility(com.hillingar.server.dao.interfaces.UserDao) at parameter index 0
If I do not comment, I get
Mar 29, 2013 9:54:59 PM com.sun.jersey.spi.inject.Errors processErrorMessages SEVERE: The following errors and warnings have been detected with resource and/or provider classes: SEVERE: Missing dependency for constructor public com.hillingar.server.rest.UserService(com.hillingar.server.dao.interfaces.UserDao,com.hillingar.server.SessionUtility) at parameter index 0 SEVERE: Missing dependency for constructor public com.hillingar.server.rest.UserService(com.hillingar.server.dao.interfaces.UserDao,com.hillingar.server.SessionUtility) at parameter index 1
This is my web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <filter> <filter-name>guiceFilter</filter-name> <filter-class>com.google.inject.servlet.GuiceFilter</filter-class> </filter> <filter-mapping> <filter-name>guiceFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <listener> <listener-class>com.hillingar.server.ServletContextListener</listener-class> </listener> <session-config> <session-timeout> 30 </session-timeout> </session-config> </web-app>
This is my ServletContextListener
package com.hillingar.server; import java.util.logging.Logger; import javax.servlet.ServletContextEvent; import com.google.inject.Guice; import com.google.inject.Singleton; import com.hillingar.server.dao.jdbcImpl.UserJdbc; import com.hillingar.server.dao.interfaces.UserDao; import com.sun.jersey.guice.JerseyServletModule; import com.sun.jersey.guice.spi.container.servlet.GuiceContainer; import com.sun.jersey.spi.container.servlet.ServletContainer; public class ServletContextListener implements javax.servlet.ServletContextListener { Logger logger = Logger.getLogger(this.getClass().getName()); @Override public void contextDestroyed(ServletContextEvent arg0) { } /* * Covered in URL * https://code.google.com/p/google-guice/wiki/ServletModule */ @Override public void contextInitialized(ServletContextEvent arg0) { // Note the user of JerseyServletModule instead of ServletModule // otherwise the expected constructor injection doesn't happen // (just the default constructor is called) Guice.createInjector(new JerseyServletModule() { @Override protected void configureServlets() { /* * Note: Every servlet (or filter) is required to be a * @Singleton. If you cannot annotate the class directly, * you must bind it using bind(..).in(Singleton.class), * separate to the filter() or servlet() rules. * Mapping under any other scope is an error. This is to * maintain consistency with the Servlet specification. * Guice Servlet does not support the * deprecated SingleThreadModel. */ bind(SecurityFilter.class).in(Singleton.class); bind(ServletContainer.class).in(Singleton.class); /* * Filter Mapping * * This will route every incoming request through MyFilter, * and then continue to any other matching filters before * finally being dispatched to a servlet for processing. * */ // SECURITY - currently disabled // filter("/*").through(SecurityFilter.class); /* * Registering Servlets * * This registers a servlet (subclass of HttpServlet) called * ServletContainer, the same one that I would have used in * the web.xml file, to serve any web requests with the * path /rest/* ie ... * <servlet> <servlet-name>ServletAdaptor</servlet-name> <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>ServletAdaptor</servlet-name> <url-pattern>/rest/*</url-pattern> </servlet-mapping> */ serve("/rest/*").with(ServletContainer.class); // JAX-RS // Using this and it starts bitching about // com.sun.jersey.api.container.ContainerException: The ResourceConfig instance does not contain any root resource classes. // So presumably wants an Application class that enumerates // all my services? //serve("/rest/*").with(GuiceContainer.class); /* * Bindings */ bind(UserDao.class).to(UserJdbc.class); bind(SessionUtility.class); } }); } }
This is my UserService
package com.hillingar.server.rest; import com.google.inject.Inject; import com.google.inject.Singleton; import java.util.List; import javax.servlet.http.HttpServletRequest; import javax.ws.rs.Consumes; import javax.ws.rs.GET; import javax.ws.rs.POST; import javax.ws.rs.Path; import javax.ws.rs.PathParam; import javax.ws.rs.Produces; import javax.ws.rs.core.Context; import javax.ws.rs.core.SecurityContext; import com.hillingar.server.SessionUtility; import com.hillingar.server.dao.interfaces.UserDao; import com.hillingar.server.model.User; import com.hillingar.server.model.dto.AuthenticationResponse; @Path("/user") @Produces("application/json") @Consumes({"application/xml","application/json"}) @Singleton // <-- Added Singleton here public class UserService { private UserDao userDao; private SessionUtility sessionManager; /* Error if I annotate with @InjectParam... Mar 29, 2013 9:52:04 PM com.sun.jersey.spi.inject.Errors processErrorMessages SEVERE: The following errors and warnings have been detected with resource and/or provider classes: SEVERE: The class com.hillingar.server.dao.interfaces.UserDao is an interface and cannot be instantiated. SEVERE: Missing dependency for constructor public com.hillingar.server.SessionUtility(com.hillingar.server.dao.interfaces.UserDao) at parameter index 0 Error If I don't annotate at all... Mar 29, 2013 9:54:59 PM com.sun.jersey.spi.inject.Errors processErrorMessages SEVERE: The following errors and warnings have been detected with resource and/or provider classes: SEVERE: Missing dependency for constructor public com.hillingar.server.rest.UserService(com.hillingar.server.dao.interfaces.UserDao,com.hillingar.server.SessionUtility) at parameter index 0 SEVERE: Missing dependency for constructor public com.hillingar.server.rest.UserService(com.hillingar.server.dao.interfaces.UserDao,com.hillingar.server.SessionUtility) at parameter index 1 (both output Initiating Jersey application, version 'Jersey: 1.13 06/29/2012 05:14 PM') */ @Inject public UserService(UserDao userDao, SessionUtility sessionManager) { this.userDao = userDao; this.sessionManager = sessionManager; } @GET public List<User> test(@Context HttpServletRequest hsr) { // USER DAO IS ALWAYS NULL - CONSTRUCTOR INJECTION NOT WORKING User loggedInUser = userDao.findBySessionId(hsr.getSession().getId()); ... return users; } }