Use Context CL wherever it is applicable (#2656)

* Use Context CL wherever it is applicable

* Use `ClassUtils.getDefaultClassLoader()` in the `IntegrationManagementConfigurer`
for checking a Micrometer presence from the `afterSingletonsInstantiated()`
* Use `ClassUtils.getDefaultClassLoader()` in the `ScatterGatherHandler`
to load required class
* Refactor `HeaderEnricherParserSupport` do not use CL at all.
The `TypedStringValue` will resolve a target type later by the
`BeanFactory`.
This way we honor a property placeholder behavior for the `type` XML
attribute

* * Use `ClassUtils.getDefaultClassLoader()` in the ScatterGatherHandler ctor

Author: artembilan

spring-integration-core/src/main/java/org/springframework/integration/config/IntegrationManagementConfigurer.java

@@ -225,9 +225,8 @@ public void afterSingletonsInstantiated() {
 		Assert.state(this.applicationContext != null, "'applicationContext' must not be null");
 		Assert.state(MANAGEMENT_CONFIGURER_NAME.equals(this.beanName), getClass().getSimpleName()
 				+ " bean name must be " + MANAGEMENT_CONFIGURER_NAME);
-		ClassLoader classLoader = IntegrationManagementConfigurer.class.getClassLoader();
 		if (ClassUtils.isPresent("io.micrometer.core.instrument.MeterRegistry",
-				classLoader)) {
+				this.applicationContext.getClassLoader())) {
 			this.metricsCaptor = MicrometerMetricsCaptor.loadCaptor(this.applicationContext);
 		}
 		if (this.metricsCaptor != null) {

spring-integration-core/src/main/java/org/springframework/integration/config/xml/HeaderEnricherParserSupport.java

@@ -39,7 +39,6 @@
 import org.springframework.integration.transformer.support.MessageProcessingHeaderValueMessageProcessor;
 import org.springframework.integration.transformer.support.RoutingSlipHeaderValueMessageProcessor;
 import org.springframework.integration.transformer.support.StaticHeaderValueMessageProcessor;
-import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.util.xml.DomUtils;
 
@@ -50,15 +49,16 @@
  * @author Oleg Zhurakousky
  * @author Artem Bilan
  * @author Gary Russell
+ *
  * @since 2.0
  */
 public abstract class HeaderEnricherParserSupport extends AbstractTransformerParser {
 
-	private final Map<String, String> elementToNameMap = new HashMap<String, String>();
+	private final static Map<String, String[][]> cannedHeaderElementExpressions = new HashMap<>();
 
-	private final Map<String, Class<?>> elementToTypeMap = new HashMap<String, Class<?>>();
+	private final Map<String, String> elementToNameMap = new HashMap<>();
 
-	private final static Map<String, String[][]> cannedHeaderElementExpressions = new HashMap<String, String[][]>();
+	private final Map<String, String> elementToTypeMap = new HashMap<>();
 
 	static {
 		cannedHeaderElementExpressions.put("header-channels-to-string", new String[][] {
@@ -75,10 +75,10 @@ protected final String getTransformerClassName() {
 	}
 
 	protected final void addElementToHeaderMapping(String elementName, String headerName) {
-		this.addElementToHeaderMapping(elementName, headerName, null);
+		addElementToHeaderMapping(elementName, headerName, null);
 	}
 
-	protected final void addElementToHeaderMapping(String elementName, String headerName, Class<?> headerType) {
+	protected final void addElementToHeaderMapping(String elementName, String headerName, String headerType) {
 		this.elementToNameMap.put(elementName, headerName);
 		if (headerType != null) {
 			this.elementToTypeMap.put(elementName, headerType);
@@ -104,7 +104,7 @@ protected void processHeaders(Element element, ManagedMap<String, Object> header
 				String headerName = null;
 				Element headerElement = (Element) node;
 				String elementName = node.getLocalName();
-				Class<?> headerType = null;
+				String headerType = null;
 				String expression = null;
 				String overwrite = headerElement.getAttribute("overwrite");
 				if ("header".equals(elementName)) {
@@ -116,24 +116,11 @@ protected void processHeaders(Element element, ManagedMap<String, Object> header
 					if (headerType != null && StringUtils.hasText(headerElement.getAttribute("type"))) {
 						parserContext.getReaderContext().error("The " + elementName
 								+ " header does not accept a 'type' attribute. The required type is ["
-								+ headerType.getName() + "]", element);
+								+ headerType + "]", element);
 					}
 				}
 				if (headerType == null) {
-					String headerTypeName = headerElement.getAttribute("type");
-					if (StringUtils.hasText(headerTypeName)) {
-						ClassLoader classLoader = parserContext.getReaderContext().getBeanClassLoader();
-						if (classLoader == null) {
-							classLoader = getClass().getClassLoader();
-						}
-						try {
-							headerType = ClassUtils.forName(headerTypeName, classLoader);
-						}
-						catch (Exception e) {
-							parserContext.getReaderContext().error("unable to resolve type [" +
-									headerTypeName + "] for header '" + headerName + "'", element, e);
-						}
-					}
+					headerType = headerElement.getAttribute("type");
 				}
 				if (headerName == null) {
 					String ttlExpression = headerElement.getAttribute("time-to-live-expression");
@@ -148,21 +135,20 @@ protected void processHeaders(Element element, ManagedMap<String, Object> header
 								expression = expression.replace(", ####", "");
 							}
 							overwrite = "true";
-							this.addHeader(element, headers, parserContext, headerName, headerElement, headerType,
+							addHeader(element, headers, parserContext, headerName, headerElement, headerType,
 									expression, overwrite);
 						}
 					}
 				}
 				else {
-					this.addHeader(element, headers, parserContext, headerName, headerElement, headerType, null,
-							overwrite);
+					addHeader(element, headers, parserContext, headerName, headerElement, headerType, null, overwrite);
 				}
 			}
 		}
 	}
 
 	private void addHeader(Element element, ManagedMap<String, Object> headers, ParserContext parserContext,
-			String headerName, Element headerElement, Class<?> headerType, String expression, String overwrite) {
+			String headerName, Element headerElement, String headerType, String expression, String overwrite) {
 
 		String value = headerElement.getAttribute("value");
 		String ref = headerElement.getAttribute(REF_ATTRIBUTE);
@@ -233,15 +219,20 @@ else if (isScript) {
 						"The 'method' attribute cannot be used with the 'value' attribute.", element);
 			}
 			if (IntegrationMessageHeaderAccessor.ROUTING_SLIP.equals(headerName)) {
-				List<String> routingSlipPath = new ManagedList<String>();
+				List<String> routingSlipPath = new ManagedList<>();
 				routingSlipPath.addAll(Arrays.asList(StringUtils.tokenizeToStringArray(value, ";")));
 				valueProcessorBuilder =
 						BeanDefinitionBuilder.genericBeanDefinition(RoutingSlipHeaderValueMessageProcessor.class)
 								.addConstructorArgValue(routingSlipPath);
 			}
 			else {
-				Object headerValue = (headerType != null) ?
-						new TypedStringValue(value, headerType) : value;
+				Object headerValue = value;
+
+				if (StringUtils.hasText(headerType)) {
+					TypedStringValue typedStringValue = new TypedStringValue(value);
+					typedStringValue.setTargetTypeName(headerType);
+					headerValue = typedStringValue;
+				}
 				valueProcessorBuilder =
 						BeanDefinitionBuilder.genericBeanDefinition(StaticHeaderValueMessageProcessor.class)
 						.addConstructorArgValue(headerValue);
@@ -280,8 +271,9 @@ else if (isCustomBean) {
 				}
 			}
 			else {
-				valueProcessorBuilder = BeanDefinitionBuilder.genericBeanDefinition(StaticHeaderValueMessageProcessor.class);
-				valueProcessorBuilder.addConstructorArgValue(innerComponentDefinition);
+				valueProcessorBuilder =
+						BeanDefinitionBuilder.genericBeanDefinition(StaticHeaderValueMessageProcessor.class)
+								.addConstructorArgValue(innerComponentDefinition);
 			}
 		}
 		else {
@@ -296,8 +288,9 @@ else if (isCustomBean) {
 								.addConstructorArgValue(method);
 			}
 			else {
-				valueProcessorBuilder = BeanDefinitionBuilder.genericBeanDefinition(StaticHeaderValueMessageProcessor.class)
-						.addConstructorArgReference(ref);
+				valueProcessorBuilder =
+						BeanDefinitionBuilder.genericBeanDefinition(StaticHeaderValueMessageProcessor.class)
+								.addConstructorArgReference(ref);
 			}
 		}
 		if (StringUtils.hasText(overwrite)) {
@@ -312,7 +305,8 @@ else if (isCustomBean) {
 	 * @param element The element.
 	 * @param parserContext The parser context.
 	 */
-	protected void postProcessHeaderEnricher(BeanDefinitionBuilder builder, Element element, ParserContext parserContext) {
+	protected void postProcessHeaderEnricher(BeanDefinitionBuilder builder, Element element,
+			ParserContext parserContext) {
 	}
 
 }

spring-integration-core/src/main/java/org/springframework/integration/config/xml/StandardHeaderEnricherParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -36,16 +36,18 @@
  *
  * @author Mark Fisher
  * @author Oleg Zhurakousky
+ * @author Artem Bilan
  */
 public class StandardHeaderEnricherParser extends HeaderEnricherParserSupport {
 
 	public StandardHeaderEnricherParser() {
-		this.addElementToHeaderMapping("reply-channel", MessageHeaders.REPLY_CHANNEL);
-		this.addElementToHeaderMapping("error-channel", MessageHeaders.ERROR_CHANNEL);
-		this.addElementToHeaderMapping("correlation-id", IntegrationMessageHeaderAccessor.CORRELATION_ID);
-		this.addElementToHeaderMapping("expiration-date", IntegrationMessageHeaderAccessor.EXPIRATION_DATE, Long.class);
-		this.addElementToHeaderMapping("priority", IntegrationMessageHeaderAccessor.PRIORITY, Integer.class);
-		this.addElementToHeaderMapping("routing-slip", IntegrationMessageHeaderAccessor.ROUTING_SLIP, Map.class);
+		addElementToHeaderMapping("reply-channel", MessageHeaders.REPLY_CHANNEL);
+		addElementToHeaderMapping("error-channel", MessageHeaders.ERROR_CHANNEL);
+		addElementToHeaderMapping("correlation-id", IntegrationMessageHeaderAccessor.CORRELATION_ID);
+		addElementToHeaderMapping("expiration-date", IntegrationMessageHeaderAccessor.EXPIRATION_DATE,
+				Long.class.getName());
+		addElementToHeaderMapping("priority", IntegrationMessageHeaderAccessor.PRIORITY, Integer.class.getName());
+		addElementToHeaderMapping("routing-slip", IntegrationMessageHeaderAccessor.ROUTING_SLIP, Map.class.getName());
 	}
 
 	@Override

spring-integration-core/src/main/java/org/springframework/integration/scattergather/ScatterGatherHandler.java

@@ -177,13 +177,13 @@ public boolean isRunning() {
 	}
 
 	private void checkClass(Class<?> gathererClass, String className, String type) throws LinkageError {
-		Class<?> clazz = null;
 		try {
-			clazz = ClassUtils.forName(className, getClass().getClassLoader());
+			Class<?> clazz = ClassUtils.forName(className, ClassUtils.getDefaultClassLoader());
+			Assert.isAssignable(clazz, gathererClass, "the '" + type + "' must be an " + className + " instance");
 		}
-		catch (Exception e) {
+		catch (ClassNotFoundException e) {
+			throw new IllegalStateException("The class for '" + className + "' cannot be loaded", e);
 		}
-		Assert.isAssignable(clazz, gathererClass, "the '" + type + "' must be an " + className + " instance");
 	}
 
 }