Support for liquibase in executable jars

Create LiquibaseServiceLocatorInitializer to replace the standard
liquibase classpath scanning logic with SpringPackageScanClassResolver
which will work correctly in Spring Boot packaged executable JARs.

Issue: #55580628

spring-boot-dependencies/pom.xml

@@ -166,6 +166,11 @@
 				<artifactId>hsqldb</artifactId>
 				<version>2.2.9</version>
 			</dependency>
+			<dependency>
+				<groupId>org.liquibase</groupId>
+				<artifactId>liquibase-core</artifactId>
+				<version>3.0.2</version>
+			</dependency>
 			<dependency>
 				<groupId>org.projectreactor</groupId>
 				<artifactId>reactor-spring</artifactId>

spring-boot/pom.xml

@@ -64,6 +64,11 @@
 			<artifactId>hibernate-validator</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>org.liquibase</groupId>
+			<artifactId>liquibase-core</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>org.slf4j</groupId>
 			<artifactId>slf4j-api</artifactId>

spring-boot/src/main/java/org/springframework/boot/liquibase/LiquibaseServiceLocatorInitializer.java

@@ -0,0 +1,50 @@
+package org.springframework.boot.liquibase;
+
+import liquibase.servicelocator.CustomResolverServiceLocator;
+import liquibase.servicelocator.ServiceLocator;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.SpringApplicationInitializer;
+import org.springframework.context.ApplicationContextInitializer;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.util.ClassUtils;
+
+/**
+ * {@link SpringApplicationInitializer} that replaces the liquibase {@link ServiceLocator}
+ * with a version that works with Spring Boot executable archives.
+ * 
+ * @author Phillip Webb
+ */
+public class LiquibaseServiceLocatorInitializer implements
+		ApplicationContextInitializer<ConfigurableApplicationContext>,
+		SpringApplicationInitializer {
+
+	static final Log logger = LogFactory
+			.getLog(LiquibaseServiceLocatorInitializer.class);
+
+	@Override
+	public void initialize(SpringApplication springApplication, String[] args) {
+		if (ClassUtils.isPresent("liquibase.servicelocator.ServiceLocator", null)) {
+			new LiquibasePresent().replaceServiceLocator();
+		}
+	}
+
+	@Override
+	public void initialize(ConfigurableApplicationContext applicationContext) {
+	}
+
+	/**
+	 * Inner class to prevent class not found issues
+	 */
+	private static class LiquibasePresent {
+		
+		public void replaceServiceLocator() {
+			ServiceLocator.setInstance(new CustomResolverServiceLocator(
+					new SpringPackageScanClassResolver()));
+		}
+		
+	}
+	
+}

spring-boot/src/main/java/org/springframework/boot/liquibase/SpringPackageScanClassResolver.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2012-2013 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.liquibase;
+
+import java.io.IOException;
+import java.util.Set;
+
+import liquibase.servicelocator.DefaultPackageScanClassResolver;
+import liquibase.servicelocator.PackageScanClassResolver;
+import liquibase.servicelocator.PackageScanFilter;
+
+import org.springframework.core.io.Resource;
+import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
+import org.springframework.core.io.support.ResourcePatternResolver;
+import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
+import org.springframework.core.type.classreading.MetadataReader;
+import org.springframework.core.type.classreading.MetadataReaderFactory;
+import org.springframework.util.ClassUtils;
+
+/**
+ * Liquibase {@link PackageScanClassResolver} implementation that uses Spring's resource
+ * scanning to locate classes. This variant is safe to use with Spring Boot packaged
+ * executable JARs.
+ * 
+ * @author Phillip Webb
+ */
+public class SpringPackageScanClassResolver extends DefaultPackageScanClassResolver {
+
+	@Override
+	protected void find(PackageScanFilter test, String packageName, ClassLoader loader,
+			Set<Class<?>> classes) {
+		MetadataReaderFactory metadataReaderFactory = new CachingMetadataReaderFactory(
+				loader);
+		try {
+			Resource[] resources = scan(loader, packageName);
+			for (Resource resource : resources) {
+				Class<?> candidate = loadClass(loader, metadataReaderFactory, resource);
+				if (candidate != null && test.matches(candidate)) {
+					classes.add(candidate);
+				}
+			}
+		}
+		catch (IOException ex) {
+			throw new IllegalStateException(ex);
+		}
+	}
+
+	private Resource[] scan(ClassLoader loader, String packageName) throws IOException {
+		ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver(loader);
+		String pattern = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX
+				+ ClassUtils.convertClassNameToResourcePath(packageName) + "/**/*.class";
+		Resource[] resources = resolver.getResources(pattern);
+		return resources;
+	}
+
+	private Class<?> loadClass(ClassLoader loader, MetadataReaderFactory readerFactory,
+			Resource resource) {
+		try {
+			MetadataReader reader = readerFactory.getMetadataReader(resource);
+			return ClassUtils.forName(reader.getClassMetadata().getClassName(), loader);
+		}
+		catch (Exception ex) {
+			if (LiquibaseServiceLocatorInitializer.logger.isWarnEnabled()) {
+				LiquibaseServiceLocatorInitializer.logger.warn(
+						"Ignoring cadidate class resource " + resource, ex);
+			}
+			return null;
+		}
+	}
+
+}

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

@@ -4,4 +4,5 @@ org.springframework.boot.context.initializer.ConfigFileApplicationContextInitial
 org.springframework.boot.context.initializer.ContextIdApplicationContextInitializer,\
 org.springframework.boot.context.initializer.EnvironmentDelegateApplicationContextInitializer,\
 org.springframework.boot.context.initializer.LoggingApplicationContextInitializer,\
-org.springframework.boot.context.initializer.VcapApplicationContextInitializer
+org.springframework.boot.context.initializer.VcapApplicationContextInitializer,\
+org.springframework.boot.liquibase.LiquibaseServiceLocatorInitializer

spring-boot/src/test/java/org/springframework/boot/liquibase/LiquibaseServiceLocatorInitializerTests.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2012-2013 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.liquibase;
+
+import java.lang.reflect.Field;
+
+import liquibase.servicelocator.ServiceLocator;
+
+import org.junit.Test;
+import org.springframework.boot.SpringApplication;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.util.ReflectionUtils;
+
+import static org.hamcrest.Matchers.instanceOf;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Tests for {@link LiquibaseServiceLocatorInitializer}.
+ * 
+ * @author Phillip Webb
+ */
+public class LiquibaseServiceLocatorInitializerTests {
+
+	@Test
+	public void replacesServiceLocator() throws Exception {
+		SpringApplication application = new SpringApplication(Conf.class);
+		application.setWebEnvironment(false);
+		application.run();
+		ServiceLocator instance = ServiceLocator.getInstance();
+		Field field = ReflectionUtils.findField(ServiceLocator.class, "classResolver");
+		field.setAccessible(true);
+		Object resolver = field.get(instance);
+		assertThat(resolver, instanceOf(SpringPackageScanClassResolver.class));
+	}
+
+	@Configuration
+	public static class Conf {
+
+	}
+
+}

spring-boot/src/test/java/org/springframework/boot/liquibase/SpringPackageScanClassResolverTests.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2012-2013 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.liquibase;
+
+import java.util.Set;
+
+import liquibase.logging.Logger;
+
+import org.junit.Test;
+
+import static org.hamcrest.Matchers.greaterThan;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Tests for SpringPackageScanClassResolver.
+ * 
+ * @author Phillip Webb
+ */
+public class SpringPackageScanClassResolverTests {
+
+	@Test
+	public void testScan() {
+		SpringPackageScanClassResolver resolver = new SpringPackageScanClassResolver();
+		resolver.addClassLoader(getClass().getClassLoader());
+		Set<Class<?>> implementations = resolver.findImplementations(Logger.class,
+				"liquibase.logging.core");
+		assertThat(implementations.size(), greaterThan(0));
+	}
+
+}