Extract metric export into a separate autoconfig class

This avoids a potential problems with ordering between Dropwizard and
normal repository configuration. A Dropwizard sample has been added to
verify the behaviour.

spring-boot-samples/spring-boot-sample-metrics-dropwizard/src/main/java/sample/metrics/dropwizard/HelloWorldService.java

@@ -0,0 +1,40 @@
+/*
+ * 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.
+ * 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 sample.metrics.dropwizard;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.stereotype.Component;
+
+@Component
+@ConfigurationProperties(prefix = "service", ignoreUnknownFields = false)
+public class HelloWorldService {
+
+	private String name = "World";
+
+	public String getName() {
+		return this.name;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+
+	public String getHelloMessage() {
+		return "Hello " + this.name;
+	}
+
+}

spring-boot-samples/spring-boot-sample-metrics-dropwizard/src/main/java/sample/metrics/dropwizard/SampleController.java

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+/*
+ * 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.
+ * 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 sample.metrics.dropwizard;
+
+import java.util.Collections;
+import java.util.Map;
+
+import org.hibernate.validator.constraints.NotBlank;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.actuate.metrics.GaugeService;
+import org.springframework.context.annotation.Description;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.ResponseBody;
+
+@Controller
+@Description("A controller for handling requests for hello messages")
+public class SampleController {
+
+	@Autowired
+	private HelloWorldService helloWorldService;
+
+	@Autowired
+	private GaugeService gauges;
+
+	@RequestMapping(value = "/", method = RequestMethod.GET)
+	@ResponseBody
+	public Map<String, String> hello() {
+		this.gauges.submit("timer.test.value", Math.random() * 1000 + 1000);
+		return Collections.singletonMap("message",
+				this.helloWorldService.getHelloMessage());
+	}
+
+	protected static class Message {
+
+		@NotBlank(message = "Message value cannot be empty")
+		private String value;
+
+		public String getValue() {
+			return this.value;
+		}
+
+		public void setValue(String value) {
+			this.value = value;
+		}
+	}
+
+}

spring-boot-samples/spring-boot-sample-metrics-dropwizard/src/main/java/sample/metrics/dropwizard/SampleDropwizardMetricsApplication.java

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+/*
+ * 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.
+ * 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 sample.metrics.dropwizard;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class SampleDropwizardMetricsApplication {
+
+	public static void main(String[] args) throws Exception {
+		SpringApplication.run(SampleDropwizardMetricsApplication.class, args);
+	}
+
+}