Defensively access deprecated AbstractHttpClient class from Apache HttpComponents

Issue: SPR-14422

spring-web/src/main/java/org/springframework/http/client/HttpComponentsClientHttpRequestFactory.java

 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -39,6 +39,7 @@ import org.apache.http.protocol.HttpContext;
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.http.HttpMethod;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 
 /**
  * {@link org.springframework.http.client.ClientHttpRequestFactory} implementation that
@@ -58,6 +59,20 @@ import org.springframework.util.Assert;
  */
 public class HttpComponentsClientHttpRequestFactory implements ClientHttpRequestFactory, DisposableBean {
 
+	private static Class<?> abstractHttpClientClass;
+
+	static {
+		try {
+			// Looking for AbstractHttpClient class (deprecated as of HttpComponents 4.3)
+			abstractHttpClientClass = ClassUtils.forName("org.apache.http.impl.client.AbstractHttpClient",
+					HttpComponentsClientHttpRequestFactory.class.getClassLoader());
+		}
+		catch (ClassNotFoundException ex) {
+			// Probably removed from HttpComponents in the meantime...
+		}
+	}
+
+
 	private HttpClient httpClient;
 
 	private RequestConfig requestConfig;
@@ -130,7 +145,7 @@ public class HttpComponentsClientHttpRequestFactory implements ClientHttpRequest
 	 */
 	@SuppressWarnings("deprecation")
 	private void setLegacyConnectionTimeout(HttpClient client, int timeout) {
-		if (org.apache.http.impl.client.AbstractHttpClient.class.isInstance(client)) {
+		if (abstractHttpClientClass != null && abstractHttpClientClass.isInstance(client)) {
 			client.getParams().setIntParameter(org.apache.http.params.CoreConnectionPNames.CONNECTION_TIMEOUT, timeout);
 		}
 	}
@@ -171,7 +186,7 @@ public class HttpComponentsClientHttpRequestFactory implements ClientHttpRequest
 	 */
 	@SuppressWarnings("deprecation")
 	private void setLegacySocketTimeout(HttpClient client, int timeout) {
-		if (org.apache.http.impl.client.AbstractHttpClient.class.isInstance(client)) {
+		if (abstractHttpClientClass != null && abstractHttpClientClass.isInstance(client)) {
 			client.getParams().setIntParameter(org.apache.http.params.CoreConnectionPNames.SO_TIMEOUT, timeout);
 		}
 	}

spring-web/src/main/java/org/springframework/remoting/httpinvoker/HttpComponentsHttpInvokerRequestExecutor.java

 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -43,6 +43,7 @@ import org.springframework.context.i18n.LocaleContext;
 import org.springframework.context.i18n.LocaleContextHolder;
 import org.springframework.remoting.support.RemoteInvocationResult;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
 
 /**
@@ -69,6 +70,21 @@ public class HttpComponentsHttpInvokerRequestExecutor extends AbstractHttpInvoke
 
 	private static final int DEFAULT_READ_TIMEOUT_MILLISECONDS = (60 * 1000);
 
+
+	private static Class<?> abstractHttpClientClass;
+
+	static {
+		try {
+			// Looking for AbstractHttpClient class (deprecated as of HttpComponents 4.3)
+			abstractHttpClientClass = ClassUtils.forName("org.apache.http.impl.client.AbstractHttpClient",
+					HttpComponentsHttpInvokerRequestExecutor.class.getClassLoader());
+		}
+		catch (ClassNotFoundException ex) {
+			// Probably removed from HttpComponents in the meantime...
+		}
+	}
+
+
 	private HttpClient httpClient;
 
 	private RequestConfig requestConfig;
@@ -156,7 +172,7 @@ public class HttpComponentsHttpInvokerRequestExecutor extends AbstractHttpInvoke
 	 */
 	@SuppressWarnings("deprecation")
 	private void setLegacyConnectionTimeout(HttpClient client, int timeout) {
-		if (org.apache.http.impl.client.AbstractHttpClient.class.isInstance(client)) {
+		if (abstractHttpClientClass != null && abstractHttpClientClass.isInstance(client)) {
 			client.getParams().setIntParameter(org.apache.http.params.CoreConnectionPNames.CONNECTION_TIMEOUT, timeout);
 		}
 	}
@@ -198,7 +214,7 @@ public class HttpComponentsHttpInvokerRequestExecutor extends AbstractHttpInvoke
 	 */
 	@SuppressWarnings("deprecation")
 	private void setLegacySocketTimeout(HttpClient client, int timeout) {
-		if (org.apache.http.impl.client.AbstractHttpClient.class.isInstance(client)) {
+		if (abstractHttpClientClass != null && abstractHttpClientClass.isInstance(client)) {
 			client.getParams().setIntParameter(org.apache.http.params.CoreConnectionPNames.SO_TIMEOUT, timeout);
 		}
 	}