[bs-53] Aid for users debugging auto-configuration failures

Add logging to Condition implementations.

[Fixes #48389533]

spring-bootstrap/src/main/java/org/springframework/bootstrap/autoconfigure/jdbc/EmbeddedDatabaseAutoConfiguration.java

@@ -22,6 +22,8 @@ import java.util.Map;
 import javax.annotation.PostConstruct;
 import javax.sql.DataSource;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.bootstrap.context.annotation.ConditionalOnMissingBean;
 import org.springframework.bootstrap.context.annotation.EnableAutoConfiguration;
@@ -48,6 +50,9 @@ import org.springframework.util.ClassUtils;
 @ConditionalOnMissingBean(DataSource.class)
 public class EmbeddedDatabaseAutoConfiguration {
 
+	private static Log logger = LogFactory
+			.getLog(EmbeddedDatabaseAutoConfiguration.class);
+
 	private static final Map<EmbeddedDatabaseType, String> EMBEDDED_DATABASE_TYPE_CLASSES;
 	static {
 		EMBEDDED_DATABASE_TYPE_CLASSES = new LinkedHashMap<EmbeddedDatabaseType, String>();
@@ -100,8 +105,15 @@ public class EmbeddedDatabaseAutoConfiguration {
 			if (!ClassUtils.isPresent(
 					"org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseType",
 					context.getClassLoader())) {
+				if (logger.isDebugEnabled()) {
+					logger.debug("Spring JDBC not detected (EmbeddedDatabaseCondition evaluated false).");
+				}
 				return false;
 			}
+			if (logger.isDebugEnabled()) {
+				logger.debug("Spring JDBC detected (embedded database type is "
+						+ getEmbeddedDatabaseType() + ").");
+			}
 			return getEmbeddedDatabaseType() != null;
 		}
 	}

spring-bootstrap/src/main/java/org/springframework/bootstrap/context/annotation/AbstractOnBeanCondition.java

@@ -19,6 +19,8 @@ package org.springframework.bootstrap.context.annotation;
 import java.util.ArrayList;
 import java.util.List;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.factory.BeanFactoryUtils;
 import org.springframework.context.annotation.Condition;
 import org.springframework.context.annotation.ConditionContext;
@@ -34,6 +36,8 @@ import org.springframework.util.MultiValueMap;
  */
 abstract class AbstractOnBeanCondition implements Condition {
 
+	private static Log logger = LogFactory.getLog(OnBeanCondition.class);
+
 	protected abstract Class<?> annotationClass();
 
 	@Override
@@ -49,6 +53,9 @@ abstract class AbstractOnBeanCondition implements Condition {
 		List<String> beanClassesFound = new ArrayList<String>();
 		List<String> beanNamesFound = new ArrayList<String>();
 
+		if (logger.isDebugEnabled()) {
+			logger.debug("Looking for beans with class: " + beanClasses);
+		}
 		for (String beanClass : beanClasses) {
 			try {
 				// eagerInit set to false to prevent early instantiation (some
@@ -65,13 +72,20 @@ abstract class AbstractOnBeanCondition implements Condition {
 			}
 		}
 
+		if (logger.isDebugEnabled()) {
+			logger.debug("Looking for beans with names: " + beanNames);
+		}
 		for (String beanName : beanNames) {
 			if (context.getBeanFactory().containsBeanDefinition(beanName)) {
 				beanNamesFound.add(beanName);
 			}
 		}
 
-		return evaluate(beanClassesFound, beanNamesFound);
+		boolean result = evaluate(beanClassesFound, beanNamesFound);
+		if (logger.isDebugEnabled()) {
+			logger.debug("Finished matching and result is matches" + result);
+		}
+		return result;
 	}
 
 	protected boolean evaluate(List<String> beanClassesFound, List<String> beanNamesFound) {

spring-bootstrap/src/main/java/org/springframework/bootstrap/context/annotation/ExpressionCondition.java

@@ -57,7 +57,11 @@ public class ExpressionCondition implements Condition {
 		BeanExpressionResolver resolver = beanFactory.getBeanExpressionResolver();
 		BeanExpressionContext expressionContext = (beanFactory != null) ? new BeanExpressionContext(
 				beanFactory, null) : null;
-		return (Boolean) resolver.evaluate(value, expressionContext);
+		Boolean result = (Boolean) resolver.evaluate(value, expressionContext);
+		if (logger.isDebugEnabled()) {
+			logger.debug("Finished matching and result is matches=" + result);
+		}
+		return result;
 	}
 
 }

spring-bootstrap/src/main/java/org/springframework/bootstrap/context/annotation/OnClassCondition.java

@@ -19,6 +19,8 @@ package org.springframework.bootstrap.context.annotation;
 import java.util.ArrayList;
 import java.util.List;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.springframework.context.annotation.Condition;
 import org.springframework.context.annotation.ConditionContext;
 import org.springframework.core.type.AnnotatedTypeMetadata;
@@ -34,6 +36,8 @@ import org.springframework.util.MultiValueMap;
  */
 class OnClassCondition implements Condition {
 
+	private static Log logger = LogFactory.getLog(OnClassCondition.class);
+
 	@Override
 	public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
 		MultiValueMap<String, Object> attributes = metadata.getAllAnnotationAttributes(
@@ -45,7 +49,14 @@ class OnClassCondition implements Condition {
 			Assert.isTrue(classNames.size() > 0,
 					"@ConditionalOnClass annotations must specify at least one class value");
 			for (String className : classNames) {
+				if (logger.isDebugEnabled()) {
+					logger.debug("Checking for class: " + className);
+				}
 				if (!ClassUtils.isPresent(className, context.getClassLoader())) {
+					if (logger.isDebugEnabled()) {
+						logger.debug("Found class: " + className
+								+ " (search terminated with matches=false)");
+					}
 					return false;
 				}
 			}

spring-bootstrap/src/main/java/org/springframework/bootstrap/context/annotation/OnResourceCondition.java

@@ -19,6 +19,8 @@ package org.springframework.bootstrap.context.annotation;
 import java.util.ArrayList;
 import java.util.List;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.springframework.context.annotation.Condition;
 import org.springframework.context.annotation.ConditionContext;
 import org.springframework.core.io.DefaultResourceLoader;
@@ -35,6 +37,8 @@ import org.springframework.util.MultiValueMap;
  */
 class OnResourceCondition implements Condition {
 
+	private static Log logger = LogFactory.getLog(OnResourceCondition.class);
+
 	private ResourceLoader loader = new DefaultResourceLoader();
 
 	@Override
@@ -47,7 +51,14 @@ class OnResourceCondition implements Condition {
 			Assert.isTrue(locations.size() > 0,
 					"@ConditionalOnResource annotations must specify at least one resource location");
 			for (String location : locations) {
+				if (logger.isDebugEnabled()) {
+					logger.debug("Checking for resource: " + location);
+				}
 				if (!this.loader.getResource(location).exists()) {
+					if (logger.isDebugEnabled()) {
+						logger.debug("Found resource: " + location
+								+ " (search terminated with matches=false)");
+					}
 					return false;
 				}
 			}