Add support for Spring HATEOAS hypermedia in Actuator endpoints

If spring-hateoas is on the classpath and an MvcEndpoint returns a
@ResponseBody it will be extended and wrapped into a Resource with links.
All the existing endpoints that return sensible JSON data can be extended
this way (i.e. not /logfile). The HAL browser will also be added as an
endpoint if available on the classpath. Finally, asciidocs for the
Actuator endpoints are available as a separate jar file, which if
included in an app will also generate a new (HTTP) endpoint.

Fixes gh-1390

spring-boot-samples/spring-boot-sample-hypermedia-jpa/src/main/java/demo/Book.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package demo;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+
+@Entity
+public class Book {
+	@Id
+	@GeneratedValue
+	private Long id;
+	private String title;
+	public String getTitle() {
+		return this.title;
+	}
+	public void setTitle(String title) {
+		this.title = title;
+	}
+}

spring-boot-samples/spring-boot-sample-hypermedia-jpa/src/main/java/demo/BookRepository.java

@@ -0,0 +1,22 @@
+/*
+ * Copyright 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package demo;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface BookRepository extends JpaRepository<Book, Long> {
+}

spring-boot-samples/spring-boot-sample-hypermedia-jpa/src/main/java/demo/JpaHypermediaApplication.java

@@ -0,0 +1,13 @@
+package demo;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class JpaHypermediaApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(JpaHypermediaApplication.class, args);
+	}
+
+}

spring-boot-samples/spring-boot-sample-hypermedia-jpa/src/main/resources/application.properties

@@ -0,0 +1,2 @@
+management.contextPath=/admin
+endpoints.docs.curies.enabled=true

spring-boot-samples/spring-boot-sample-hypermedia-jpa/src/test/java/demo/JpaHypermediaApplicationTests.java

@@ -0,0 +1,18 @@
+package demo;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.test.context.web.WebAppConfiguration;
+import org.springframework.boot.test.SpringApplicationConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@SpringApplicationConfiguration(classes = JpaHypermediaApplication.class)
+@WebAppConfiguration
+public class JpaHypermediaApplicationTests {
+
+	@Test
+	public void contextLoads() {
+	}
+
+}

spring-boot-samples/spring-boot-sample-hypermedia-jpa/src/test/java/demo/VanillaHypermediaIntegrationTests.java

@@ -0,0 +1,74 @@
+package demo;
+
+import static org.hamcrest.Matchers.containsString;
+import static org.junit.Assert.assertEquals;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.actuate.endpoint.mvc.MvcEndpoints;
+import org.springframework.boot.test.SpringApplicationConfiguration;
+import org.springframework.http.MediaType;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.web.WebAppConfiguration;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.MvcResult;
+import org.springframework.test.web.servlet.setup.MockMvcBuilders;
+import org.springframework.web.context.WebApplicationContext;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@SpringApplicationConfiguration(classes = JpaHypermediaApplication.class)
+@WebAppConfiguration
+@DirtiesContext
+public class VanillaHypermediaIntegrationTests {
+
+	@Autowired
+	private WebApplicationContext context;
+
+	@Autowired
+	private MvcEndpoints mvcEndpoints;
+
+	private MockMvc mockMvc;
+
+	@Before
+	public void setUp() {
+		this.mockMvc = MockMvcBuilders.webAppContextSetup(this.context).build();
+	}
+
+	@Test
+	public void links() throws Exception {
+		this.mockMvc.perform(get("/").accept(MediaType.APPLICATION_JSON))
+				.andExpect(status().isOk()).andExpect(jsonPath("$._links").exists());
+	}
+
+	@Test
+	public void health() throws Exception {
+		this.mockMvc.perform(get("/admin/health").accept(MediaType.APPLICATION_JSON))
+				.andExpect(status().isOk()).andExpect(jsonPath("$._links").exists());
+	}
+
+	@Test
+	public void adminLinks() throws Exception {
+		this.mockMvc.perform(get("/admin").accept(MediaType.APPLICATION_JSON))
+				.andExpect(status().isOk()).andExpect(jsonPath("$._links").exists());
+	}
+
+	@Test
+	public void docs() throws Exception {
+		MvcResult response = this.mockMvc.perform(get("/admin/docs/").accept(MediaType.TEXT_HTML))
+				.andExpect(status().isOk()).andReturn();
+		System.err.println(response.getResponse().getContentAsString());
+	}
+
+	@Test
+	public void browser() throws Exception {
+		MvcResult response = this.mockMvc.perform(get("/").accept(MediaType.TEXT_HTML))
+				.andExpect(status().isFound()).andReturn();
+		assertEquals("/browser/index.html#", response.getResponse().getHeaders("location").get(0));
+	}
+
+}