Now after starting application PID file will be created

Fixes gh-550

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/system/ApplicationPidListener.java

@@ -0,0 +1,122 @@
+/*
+ * Copyright 2010-2014 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 org.springframework.boot.actuate.system;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.context.event.ApplicationStartedEvent;
+import org.springframework.boot.util.SystemUtils;
+import org.springframework.context.ApplicationEvent;
+import org.springframework.context.event.SmartApplicationListener;
+import org.springframework.core.Ordered;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/**
+ * An {@link org.springframework.context.ApplicationListener} that saves
+ * application PID into file
+ *
+ * @author Jakub Kubrynski
+ */
+public class ApplicationPidListener implements SmartApplicationListener {
+
+	private static Class<?>[] EVENT_TYPES = {ApplicationStartedEvent.class};
+
+	private static final String DEFAULT_PID_FILE_NAME = "application.pid";
+
+	private static final AtomicBoolean pidFileCreated = new AtomicBoolean(false);
+
+	private int order = Ordered.HIGHEST_PRECEDENCE + 13;
+
+	private final Log log = LogFactory.getLog(getClass());
+
+	private String pidFileName = DEFAULT_PID_FILE_NAME;
+
+	@Override
+	public boolean supportsEventType(Class<? extends ApplicationEvent> eventType) {
+		for (Class<?> type : EVENT_TYPES) {
+			if (type.isAssignableFrom(eventType)) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+	@Override
+	public boolean supportsSourceType(Class<?> sourceType) {
+		return SpringApplication.class.isAssignableFrom(sourceType);
+	}
+
+	@Override
+	public void onApplicationEvent(ApplicationEvent applicationEvent) {
+		if (pidFileCreated.get()) {
+			return;
+		}
+
+		String applicationPid;
+		try {
+			applicationPid = SystemUtils.getApplicationPid();
+		} catch (IllegalStateException ignore) {
+			return;
+		}
+
+		if (pidFileCreated.compareAndSet(false, true)) {
+			File file = new File(pidFileName);
+			FileOutputStream fileOutputStream = null;
+			try {
+				fileOutputStream = new FileOutputStream(file);
+				fileOutputStream.write(applicationPid.getBytes());
+			} catch (FileNotFoundException e) {
+				log.warn(String.format("Cannot create pid file %s !", pidFileName));
+			} catch (IOException e) {
+				log.warn(String.format("Cannot write to pid file %s!", pidFileName));
+			} finally {
+				if (fileOutputStream != null) {
+					try {
+						fileOutputStream.close();
+					} catch (IOException e) {
+						log.warn(String.format("Cannot close pid file %s!", pidFileName));
+					}
+				}
+			}
+		}
+	}
+
+	public void setOrder(int order) {
+		this.order = order;
+	}
+
+	@Override
+	public int getOrder() {
+		return order;
+	}
+
+	/**
+	 * Sets the pid file name. This file will contains current process id.
+	 *
+	 * @param pidFileName the name of file containing pid
+	 */
+	public void setPidFileName(String pidFileName) {
+		this.pidFileName = pidFileName;
+	}
+
+}

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/system/ApplicationPidListenerTest.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2010-2014 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 org.springframework.boot.actuate.system;
+
+import org.junit.Test;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.context.event.ApplicationStartedEvent;
+
+import java.io.File;
+
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Created by jkubrynski@gmail.com / 2014-03-25
+ */
+public class ApplicationPidListenerTest {
+
+	private static final String[] NO_ARGS = {};
+
+	public static final String PID_FILE_NAME = "test.pid";
+
+	@Test
+	public void shouldCreatePidFile() {
+		//given
+		ApplicationPidListener sut = new ApplicationPidListener();
+		sut.setPidFileName(PID_FILE_NAME);
+
+		//when
+		sut.onApplicationEvent(new ApplicationStartedEvent(
+				new SpringApplication(), NO_ARGS));
+
+		//then
+		File pidFile = new File(PID_FILE_NAME);
+		assertTrue(pidFile.exists());
+		pidFile.delete();
+	}
+
+}