Ensure that HATEOAS sample does not try to produce XML

The HATEOAS sample does not support XML responses. Previously, the
controller doesn't constrain the media types that it could produce.
This would result in a failure when handling a request that prefers
XML responses.

This commit updates the produces clauses in the controller so that
the sample will only attempt to produce JSON.

Closes gh-4343

spring-boot-samples/spring-boot-sample-hateoas/src/test/java/sample/SampleHateoasApplicationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2014 the original author or authors.
+ * Copyright 2012-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,8 @@
 
 package sample;
 
+import java.net.URI;
+
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -23,9 +25,12 @@ import org.springframework.beans.factory.annotation.Value;
 import org.springframework.boot.test.IntegrationTest;
 import org.springframework.boot.test.SpringApplicationConfiguration;
 import org.springframework.boot.test.TestRestTemplate;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.RequestEntity;
 import org.springframework.http.ResponseEntity;
-import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
 import org.springframework.test.context.web.WebAppConfiguration;
 
@@ -38,7 +43,6 @@ import static org.junit.Assert.assertThat;
 @SpringApplicationConfiguration(classes = SampleHateoasApplication.class)
 @WebAppConfiguration
 @IntegrationTest("server.port:0")
-@DirtiesContext
 public class SampleHateoasApplicationTests {
 
 	@Value("${local.server.port}")
@@ -54,4 +58,17 @@ public class SampleHateoasApplicationTests {
 		assertThat(entity.getBody(), containsString("_links\":{\"self\":{\"href\""));
 	}
 
+	@Test
+	public void producesJsonWhenXmlIsPreferred() throws Exception {
+		HttpHeaders headers = new HttpHeaders();
+		headers.set(HttpHeaders.ACCEPT, "application/xml;q=0.9,application/json;q=0.8");
+		RequestEntity<?> request = new RequestEntity<Void>(headers, HttpMethod.GET,
+				URI.create("http://localhost:" + this.port + "/customers/1"));
+		ResponseEntity<String> response = new TestRestTemplate().exchange(request,
+				String.class);
+		assertThat(response.getStatusCode(), equalTo(HttpStatus.OK));
+		assertThat(response.getHeaders().getContentType(),
+				equalTo(MediaType.parseMediaType("application/json;charset=UTF-8")));
+	}
+
 }