Polish diagnostics support

Rework a few parts of the diagnostics support:

- Move code from SpringApplication to FailureAnalyzers
- Allow AbstractFailureAnalyzer to take generic cause type
- Move own analyzers into a new package and make package private

See gh-4907

spring-boot/src/main/java/org/springframework/boot/SpringApplication.java

@@ -41,9 +41,7 @@ import org.springframework.beans.factory.groovy.GroovyBeanDefinitionReader;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.BeanNameGenerator;
 import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;
-import org.springframework.boot.diagnostics.FailureAnalysis;
-import org.springframework.boot.diagnostics.FailureAnalysisReporter;
-import org.springframework.boot.diagnostics.FailureAnalyzer;
+import org.springframework.boot.diagnostics.FailureAnalyzers;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextInitializer;
 import org.springframework.context.ApplicationListener;
@@ -835,8 +833,7 @@ public class SpringApplication {
 
 	private void reportFailure(Throwable failure) {
 		try {
-			FailureAnalysis failureAnalysis = analyzeFailure(failure);
-			if (failureAnalysis != null && reportFailureAnalysis(failureAnalysis)) {
+			if (FailureAnalyzers.analyzeAndReport(failure, getClass().getClassLoader())) {
 				registerLoggedException(failure);
 				return;
 			}
@@ -850,30 +847,6 @@ public class SpringApplication {
 		}
 	}
 
-	private FailureAnalysis analyzeFailure(Throwable failure) {
-		List<FailureAnalyzer> analyzers = SpringFactoriesLoader
-				.loadFactories(FailureAnalyzer.class, getClass().getClassLoader());
-		for (FailureAnalyzer analyzer : analyzers) {
-			FailureAnalysis analysis = analyzer.analyze(failure);
-			if (analysis != null) {
-				return analysis;
-			}
-		}
-		return null;
-	}
-
-	private boolean reportFailureAnalysis(FailureAnalysis failureAnalysis) {
-		List<FailureAnalysisReporter> reporters = SpringFactoriesLoader.loadFactories(
-				FailureAnalysisReporter.class, getClass().getClassLoader());
-		if (!reporters.isEmpty()) {
-			for (FailureAnalysisReporter reporter : reporters) {
-				reporter.report(failureAnalysis);
-			}
-			return true;
-		}
-		return false;
-	}
-
 	/**
 	 * Register that the given exception has been logged. By default, if the running in
 	 * the main thread, this method will suppress additional printing of the stacktrace.

spring-boot/src/main/java/org/springframework/boot/context/embedded/PortInUseException.java

@@ -29,7 +29,6 @@ public class PortInUseException extends EmbeddedServletContainerException {
 
 	/**
 	 * Creates a new port in use exception for the given {@code port}.
-	 *
 	 * @param port the port that was in use
 	 */
 	public PortInUseException(int port) {
@@ -39,7 +38,6 @@ public class PortInUseException extends EmbeddedServletContainerException {
 
 	/**
 	 * Returns the port that was in use.
-	 *
 	 * @return the port
 	 */
 	public int getPort() {

spring-boot/src/main/java/org/springframework/boot/context/embedded/tomcat/TomcatEmbeddedServletContainer.java

@@ -167,9 +167,7 @@ public class TomcatEmbeddedServletContainer implements EmbeddedServletContainer
 			if (connector != null && this.autoStart) {
 				startConnector(connector);
 			}
-
 			checkThatConnectorsHaveStarted();
-
 			TomcatEmbeddedServletContainer.logger
 					.info("Tomcat started on port(s): " + getPortsDescription(true));
 		}

spring-boot/src/main/java/org/springframework/boot/diagnostics/AbstractFailureAnalyzer.java

@@ -16,25 +16,57 @@
 
 package org.springframework.boot.diagnostics;
 
+import org.springframework.core.ResolvableType;
+
 /**
  * Abstract base class for most {@code FailureAnalyzer} implementations.
  *
+ * @param <T> The type of exception to analyze
  * @author Andy Wilkinson
+ * @author Phillip Webb
  * @since 1.4.0
  */
-public abstract class AbstractFailureAnalyzer implements FailureAnalyzer {
+public abstract class AbstractFailureAnalyzer<T extends Throwable>
+		implements FailureAnalyzer {
+
+	@Override
+	public FailureAnalysis analyze(Throwable failure) {
+		T cause = findCause(failure, getCauseType());
+		if (cause != null) {
+			return analyze(failure, cause);
+		}
+		return null;
+	}
+
+	/**
+	 * Returns an analysis of the given {@code failure}, or {@code null} if no analysis
+	 * was possible.
+	 * @param rootFailure the root failure passed to the analyzer
+	 * @param cause the actual found cause
+	 * @return the analysis or {@code null}
+	 */
+	protected abstract FailureAnalysis analyze(Throwable rootFailure, T cause);
+
+	/**
+	 * Return the cause type being handled by the analyzer. By default the class generic
+	 * is used.
+	 * @return the cause type
+	 */
+	@SuppressWarnings("unchecked")
+	protected Class<? extends T> getCauseType() {
+		return (Class<? extends T>) ResolvableType
+				.forClass(AbstractFailureAnalyzer.class, getClass()).resolveGeneric();
+	}
 
 	@SuppressWarnings("unchecked")
-	protected <T extends Throwable> T findFailure(Throwable failure, Class<T> type) {
-		Throwable candidate = failure;
-		T mostSpecificMatch = null;
-		while (candidate != null) {
-			if (type.isInstance(candidate)) {
-				mostSpecificMatch = (T) candidate;
+	protected final <E extends Throwable> T findCause(Throwable failure, Class<E> type) {
+		while (failure != null) {
+			if (type.isInstance(failure)) {
+				return (T) failure;
 			}
-			candidate = candidate.getCause();
+			failure = failure.getCause();
 		}
-		return mostSpecificMatch;
+		return null;
 	}
 
 }

spring-boot/src/main/java/org/springframework/boot/diagnostics/FailureAnalysis.java

@@ -34,7 +34,6 @@ public class FailureAnalysis {
 	 * Creates a new {@code FailureAnalysis} with the given {@code description} and
 	 * {@code action}, if any, that the user should take to address the problem. The
 	 * failure had the given underlying {@code cause}.
-	 *
 	 * @param description the description
 	 * @param action the action
 	 * @param cause the cause
@@ -47,7 +46,6 @@ public class FailureAnalysis {
 
 	/**
 	 * Returns a description of the failure.
-	 *
 	 * @return the description
 	 */
 	public String getDescription() {
@@ -56,7 +54,6 @@ public class FailureAnalysis {
 
 	/**
 	 * Returns the action, if any, to be taken to address the failure.
-	 *
 	 * @return the action or {@code null}
 	 */
 	public String getAction() {
@@ -65,7 +62,6 @@ public class FailureAnalysis {
 
 	/**
 	 * Returns the cause of the failure.
-	 *
 	 * @return the cause
 	 */
 	public Throwable getCause() {

spring-boot/src/main/java/org/springframework/boot/diagnostics/FailureAnalysisReporter.java

@@ -26,9 +26,8 @@ public interface FailureAnalysisReporter {
 
 	/**
 	 * Reports the given {@code failureAnalysis} to the user.
-	 *
-	 * @param failureAnalysis the analysis
+	 * @param analysis the analysis
 	 */
-	void report(FailureAnalysis failureAnalysis);
+	void report(FailureAnalysis analysis);
 
 }

spring-boot/src/main/java/org/springframework/boot/diagnostics/FailureAnalyzer.java

@@ -28,7 +28,6 @@ public interface FailureAnalyzer {
 	/**
 	 * Returns an analysis of the given {@code failure}, or {@code null} if no analysis
 	 * was possible.
-	 *
 	 * @param failure the failure
 	 * @return the analysis or {@code null}
 	 */

spring-boot/src/main/java/org/springframework/boot/diagnostics/FailureAnalyzers.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2012-2016 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.diagnostics;
+
+import java.util.List;
+
+import org.springframework.core.io.support.SpringFactoriesLoader;
+
+/**
+ * Utility to trigger {@link FailureAnalyzer} and {@link FailureAnalysisReporter}
+ * instances loaded from {@code spring.factories}.
+ *
+ * @author Andy Wilkinson
+ * @author Phillip Webb
+ * @since 1.4.0
+ */
+public final class FailureAnalyzers {
+
+	private FailureAnalyzers() {
+	}
+
+	public static boolean analyzeAndReport(Throwable failure, ClassLoader classLoader) {
+		List<FailureAnalyzer> analyzers = SpringFactoriesLoader
+				.loadFactories(FailureAnalyzer.class, classLoader);
+		List<FailureAnalysisReporter> reporters = SpringFactoriesLoader
+				.loadFactories(FailureAnalysisReporter.class, classLoader);
+		FailureAnalysis analysis = analyze(failure, analyzers);
+		return report(analysis, reporters);
+	}
+
+	private static FailureAnalysis analyze(Throwable failure,
+			List<FailureAnalyzer> analyzers) {
+		for (FailureAnalyzer analyzer : analyzers) {
+			FailureAnalysis analysis = analyzer.analyze(failure);
+			if (analysis != null) {
+				return analysis;
+			}
+		}
+		return null;
+	}
+
+	private static boolean report(FailureAnalysis analysis,
+			List<FailureAnalysisReporter> reporters) {
+		if (analysis == null || reporters.isEmpty()) {
+			return false;
+		}
+		for (FailureAnalysisReporter reporter : reporters) {
+			reporter.report(analysis);
+		}
+		return true;
+	}
+
+}

spring-boot/src/main/java/org/springframework/boot/diagnostics/analyzer/BeanCurrentlyInCreationFailureAnalyzer.java

@@ -14,62 +14,59 @@
  * limitations under the License.
  */
 
-package org.springframework.boot.diagnostics;
+package org.springframework.boot.diagnostics.analyzer;
 
 import java.util.ArrayList;
 import java.util.List;
 
 import org.springframework.beans.factory.BeanCreationException;
 import org.springframework.beans.factory.BeanCurrentlyInCreationException;
+import org.springframework.boot.diagnostics.AbstractFailureAnalyzer;
+import org.springframework.boot.diagnostics.FailureAnalysis;
 import org.springframework.util.StringUtils;
 
 /**
- * A {@link FailureAnalyzer} the performs analysis of failures caused by a
+ * A {@link AbstractFailureAnalyzer} the performs analysis of failures caused by a
  * {@link BeanCurrentlyInCreationException}.
  *
  * @author Andy Wilkinson
- * @since 1.4.0
  */
-public class BeanCurrentlyInCreationFailureAnalyzer extends AbstractFailureAnalyzer {
+class BeanCurrentlyInCreationFailureAnalyzer
+		extends AbstractFailureAnalyzer<BeanCurrentlyInCreationException> {
 
 	private static final String FIELD_AUTOWIRING_FAILURE_MESSAGE_PREFIX = "Could not autowire field: ";
 
 	@Override
-	public FailureAnalysis analyze(Throwable failure) {
-		BeanCurrentlyInCreationException inCreationEx = findFailure(failure,
-				BeanCurrentlyInCreationException.class);
-		if (inCreationEx != null) {
-			List<String> beansInCycle = new ArrayList<String>();
-			Throwable candidate = failure;
-			while (candidate != null) {
-				if (candidate instanceof BeanCreationException) {
-					BeanCreationException creationEx = (BeanCreationException) candidate;
-					if (StringUtils.hasText(creationEx.getBeanName())) {
-						beansInCycle.add(
-								creationEx.getBeanName() + getDescription(creationEx));
-					}
+	protected FailureAnalysis analyze(Throwable rootFailure,
+			BeanCurrentlyInCreationException cause) {
+		List<String> beansInCycle = new ArrayList<String>();
+		Throwable candidate = rootFailure;
+		while (candidate != null) {
+			if (candidate instanceof BeanCreationException) {
+				BeanCreationException creationEx = (BeanCreationException) candidate;
+				if (StringUtils.hasText(creationEx.getBeanName())) {
+					beansInCycle
+							.add(creationEx.getBeanName() + getDescription(creationEx));
 				}
-				candidate = candidate.getCause();
 			}
-			StringBuilder message = new StringBuilder();
-			int uniqueBeans = beansInCycle.size() - 1;
-			message.append(String
-					.format("There is a circular dependency between %s beans in the "
-							+ "application context:%n", uniqueBeans));
-			for (String bean : beansInCycle) {
-				message.append(String.format("\t- %s%n", bean));
-			}
-
-			return new FailureAnalysis(message.toString(), null, failure);
+			candidate = candidate.getCause();
+		}
+		StringBuilder message = new StringBuilder();
+		int uniqueBeans = beansInCycle.size() - 1;
+		message.append(
+				String.format("There is a circular dependency between %s beans in the "
+						+ "application context:%n", uniqueBeans));
+		for (String bean : beansInCycle) {
+			message.append(String.format("\t- %s%n", bean));
 		}
-		return null;
+		return new FailureAnalysis(message.toString(), null, cause);
 	}
 
 	private String getDescription(BeanCreationException ex) {
 		if (StringUtils.hasText(ex.getResourceDescription())) {
 			return String.format(" defined in %s", ex.getResourceDescription());
 		}
-		else if (causedByFieldAutowiringFailure(ex)) {
+		if (causedByFieldAutowiringFailure(ex)) {
 			return String.format(" (field %s)",
 					ex.getCause().getMessage().substring(
 							FIELD_AUTOWIRING_FAILURE_MESSAGE_PREFIX.length(),

spring-boot/src/main/java/org/springframework/boot/diagnostics/analyzer/PortInUseFailureAnalyzer.java

@@ -14,8 +14,9 @@
  * limitations under the License.
  */
 
-package org.springframework.boot.context.embedded;
+package org.springframework.boot.diagnostics.analyzer;
 
+import org.springframework.boot.context.embedded.PortInUseException;
 import org.springframework.boot.diagnostics.AbstractFailureAnalyzer;
 import org.springframework.boot.diagnostics.FailureAnalysis;
 
@@ -24,24 +25,18 @@ import org.springframework.boot.diagnostics.FailureAnalysis;
  * {@code PortInUseException}.
  *
  * @author Andy Wilkinson
- * @since 1.4.0
  */
-public class PortInUseFailureAnalyzer extends AbstractFailureAnalyzer {
+class PortInUseFailureAnalyzer extends AbstractFailureAnalyzer<PortInUseException> {
 
 	@Override
-	public FailureAnalysis analyze(Throwable failure) {
-		PortInUseException portInUseException = findFailure(failure,
-				PortInUseException.class);
-		if (portInUseException != null) {
-			return new FailureAnalysis(
-					"Embedded servlet container failed to start. Port "
-							+ portInUseException.getPort() + " was already in use.",
-					"Identify and stop the process that's listening on port "
-							+ portInUseException.getPort() + " or configure this "
-							+ "application to listen on another port.",
-					portInUseException);
-		}
-		return null;
+	protected FailureAnalysis analyze(Throwable rootFailure, PortInUseException cause) {
+		return new FailureAnalysis(
+				"Embedded servlet container failed to start. Port " + cause.getPort()
+						+ " was already in use.",
+				"Identify and stop the process that's listening on port "
+						+ cause.getPort() + " or configure this "
+						+ "application to listen on another port.",
+				cause);
 	}
 
 }

spring-boot/src/main/java/org/springframework/boot/diagnostics/analyzer/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012-2014 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.
+ */
+
+/**
+ * Internal {@link org.springframework.boot.diagnostics.FailureAnalyzer} implementations.
+ */
+package org.springframework.boot.diagnostics.analyzer;

spring-boot/src/main/java/org/springframework/boot/diagnostics/package-info.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2012-2014 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.
+ */
+
+/**
+ * Support for failure analysis and reporting.
+ *
+ * @see org.springframework.boot.diagnostics.FailureAnalyzer
+ * @see org.springframework.boot.diagnostics.FailureAnalysisReporter
+ */
+package org.springframework.boot.diagnostics;

spring-boot/src/main/resources/META-INF/spring.factories

@@ -33,8 +33,8 @@ org.springframework.boot.env.SpringApplicationJsonEnvironmentPostProcessor
 
 # Failure Analyzers
 org.springframework.boot.diagnostics.FailureAnalyzer=\
-org.springframework.boot.context.embedded.PortInUseFailureAnalyzer,\
-org.springframework.boot.diagnostics.BeanCurrentlyInCreationFailureAnalyzer
+org.springframework.boot.diagnostics.analyzer.PortInUseFailureAnalyzer,\
+org.springframework.boot.diagnostics.analyzer.BeanCurrentlyInCreationFailureAnalyzer
 
 # FailureAnalysisReporters
 org.springframework.boot.diagnostics.FailureAnalysisReporter=\

spring-boot/src/test/java/org/springframework/boot/diagnostics/analyzer/BeanCurrentlyInCreationFailureAnalyzerTests.java

@@ -14,11 +14,13 @@
  * limitations under the License.
  */
 
-package org.springframework.boot.diagnostics;
+package org.springframework.boot.diagnostics.analyzer;
 
 import org.junit.Test;
 
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.diagnostics.FailureAnalysis;
+import org.springframework.boot.diagnostics.FailureAnalyzer;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;