example of filtering

dropwizard-example/src/main/java/com/example/helloworld/HelloWorldApplication.java

@@ -5,6 +5,7 @@
 import com.example.helloworld.core.Person;
 import com.example.helloworld.core.Template;
 import com.example.helloworld.db.PersonDAO;
+import com.example.helloworld.filter.DateNotSpecifiedFilterFactory;
 import com.example.helloworld.health.TemplateHealthCheck;
 import com.example.helloworld.resources.*;
 import io.dropwizard.Application;
@@ -56,6 +57,7 @@ public void run(HelloWorldConfiguration configuration,
         final Template template = configuration.buildTemplate();
 
         environment.healthChecks().register("template", new TemplateHealthCheck(template));
+        environment.jersey().getResourceConfig().getResourceFilterFactories().add(new DateNotSpecifiedFilterFactory());
 
         environment.jersey().register(new BasicAuthProvider<>(new ExampleAuthenticator(),
                                                               "SUPER SECRET STUFF"));
@@ -64,5 +66,6 @@ public void run(HelloWorldConfiguration configuration,
         environment.jersey().register(new ProtectedResource());
         environment.jersey().register(new PeopleResource(dao));
         environment.jersey().register(new PersonResource(dao));
+        environment.jersey().register(new FilteredResource());
     }
 }

dropwizard-example/src/main/java/com/example/helloworld/filter/DateNotSpecifiedFilterFactory.java

@@ -0,0 +1,55 @@
+package com.example.helloworld.filter;
+
+import com.google.common.collect.Lists;
+import com.sun.jersey.api.model.AbstractMethod;
+import com.sun.jersey.spi.container.ContainerRequest;
+import com.sun.jersey.spi.container.ContainerRequestFilter;
+import javax.ws.rs.WebApplicationException;
+import javax.ws.rs.core.HttpHeaders;
+import javax.ws.rs.core.Response;
+
+import com.sun.jersey.spi.container.ContainerResponse;
+import com.sun.jersey.spi.container.ContainerResponseFilter;
+import com.sun.jersey.spi.container.ResourceFilter;
+import com.sun.jersey.spi.container.ResourceFilterFactory;
+import java.util.List;
+
+public class DateNotSpecifiedFilterFactory implements ResourceFilterFactory {
+
+    @Override
+    public List<ResourceFilter> create(AbstractMethod am) {
+        boolean methodNeedsDateHeader = am.isAnnotationPresent(DateRequired.class);
+
+        return methodNeedsDateHeader ? Lists.<ResourceFilter>newArrayList(new DateNotSpecifiedFilter()) :
+                Lists.<ResourceFilter>newArrayList();
+    }
+
+    private static class DateNotSpecifiedFilter implements ResourceFilter {
+        @Override
+        public ContainerRequestFilter getRequestFilter() {
+            return new ContainerRequestFilter() {
+                @Override
+                public ContainerRequest filter(ContainerRequest request) {
+                    String dateHeader = request.getHeaderValue(HttpHeaders.DATE);
+
+                    if (dateHeader == null) {
+                        Exception cause = new IllegalArgumentException("Date Header was not specified");
+                        throw new WebApplicationException(cause, Response.Status.BAD_REQUEST);
+                    } else {
+                        return request;
+                    }
+                }
+            };
+        }
+
+        @Override
+        public ContainerResponseFilter getResponseFilter() {
+            return new ContainerResponseFilter() {
+                @Override
+                public ContainerResponse filter(ContainerRequest request, ContainerResponse response) {
+                    return response;
+                }
+            };
+        }
+    }
+}

dropwizard-example/src/main/java/com/example/helloworld/filter/DateRequired.java

@@ -0,0 +1,11 @@
+package com.example.helloworld.filter;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.METHOD)
+public @interface DateRequired {
+}

dropwizard-example/src/main/java/com/example/helloworld/resources/FilteredResource.java

@@ -0,0 +1,17 @@
+package com.example.helloworld.resources;
+
+import com.example.helloworld.filter.DateRequired;
+
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+
+@Path("/filtered")
+public class FilteredResource {
+
+    @GET
+    @DateRequired
+    @Path("hello")
+    public String sayHello() {
+        return "hello";
+    }
+}