GH-2197: Rely on the Document creation for Source

Resolves https://github.com/spring-projects/spring-integration/issues/2197

Sometime we would like to avoid some XML definition features (e.g. loading of the DTD).
The `XmlValidatingMessageSelector` doesn't allow to do that easily because it doesn't
rely on the `Document` creation via `DocumentBuilderFactory`, but directly
manipulates with `Source`

* Change `DefaultXmlPayloadConverter.convertToSource()` to fallback to the `convertToDocument()`
for non-Document payloads.
This way we can configure `DefaultXmlPayloadConverter` with custom `DocumentBuilderFactory` and
bypass DTD loading, for example
* Expose `xml-converter` option for the `<int-xml:validating-filter>`  component

spring-integration-xml/src/test/java/org/springframework/integration/xml/DefaultXmlPayloadConverterTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -41,7 +41,6 @@ import org.xml.sax.InputSource;
 
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.messaging.MessagingException;
-import org.springframework.xml.transform.StringSource;
 
 /**
  *
@@ -105,7 +104,7 @@ public class DefaultXmlPayloadConverterTests {
 	@Test
 	public void testGetSourcePassingString() throws Exception {
 		Source source = converter.convertToSource(TEST_DOCUMENT_AS_STRING);
-		assertEquals(StringSource.class, source.getClass());
+		assertEquals(DOMSource.class, source.getClass());
 	}
 
 	@Test

spring-integration-xml/src/test/java/org/springframework/integration/xml/config/XmlPayloadValidatingFilterParserTests-context.xml

@@ -1,11 +1,11 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
-	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xmlns:int="http://www.springframework.org/schema/integration"
-	xmlns:int-xml="http://www.springframework.org/schema/integration/xml"
-	xmlns:context="http://www.springframework.org/schema/context"
-	xmlns:util="http://www.springframework.org/schema/util"
-	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
+	   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	   xmlns:int="http://www.springframework.org/schema/integration"
+	   xmlns:int-xml="http://www.springframework.org/schema/integration/xml"
+	   xmlns:context="http://www.springframework.org/schema/context"
+	   xmlns:util="http://www.springframework.org/schema/util"
+	   xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
 		http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration.xsd
 		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
         http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd
@@ -15,7 +15,12 @@
 
 	<util:properties id="props">
 		<prop key="xmlSchema">xml-schema</prop>
- 	</util:properties>
+	</util:properties>
+
+	<bean id="xmlPayloadConverter" class="org.springframework.integration.xml.DefaultXmlPayloadConverter">
+		<constructor-arg
+				value="#{T (org.springframework.integration.xml.config.XmlPayloadValidatingFilterParserTests).DOCUMENT_BUILDER_FACTORY}"/>
+	</bean>
 
 	<int-xml:validating-filter id="parseOnly"
 							   order="2"
@@ -34,6 +39,7 @@
 							   input-channel="inputChannelA"
 							   output-channel="validOutputChannel"
 							   discard-channel="invalidOutputChannel"
+							   xml-converter="xmlPayloadConverter"
 							   schema-location="org/springframework/integration/xml/config/validationTestsSchema.xsd"/>
 
 	<int-xml:validating-filter id="filterB"
@@ -49,7 +55,8 @@
 							   discard-channel="invalidOutputChannel"
 							   xml-validator="xmlValidator"/>
 
-	<bean id="xmlValidator" class="org.springframework.xml.validation.XmlValidatorFactory" factory-method="createValidator">
+	<bean id="xmlValidator" class="org.springframework.xml.validation.XmlValidatorFactory"
+		  factory-method="createValidator">
 		<constructor-arg value="classpath:org/springframework/integration/xml/config/validationTestsSchema.xsd"/>
 		<constructor-arg value="http://www.w3.org/2001/XMLSchema"/>
 	</bean>

spring-integration-xml/src/test/java/org/springframework/integration/xml/config/XmlPayloadValidatingFilterParserTests.java

@@ -26,6 +26,9 @@ import static org.junit.Assert.fail;
 
 import java.util.List;
 
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+
 import org.hamcrest.Matchers;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -40,6 +43,7 @@ import org.springframework.integration.support.SmartLifecycleRoleController;
 import org.springframework.integration.test.util.TestUtils;
 import org.springframework.integration.xml.AggregatedXmlMessageValidationException;
 import org.springframework.integration.xml.util.XmlTestUtil;
+import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageChannel;
 import org.springframework.messaging.PollableChannel;
 import org.springframework.messaging.support.GenericMessage;
@@ -60,6 +64,19 @@ import org.springframework.util.MultiValueMap;
 @DirtiesContext
 public class XmlPayloadValidatingFilterParserTests {
 
+	public static final DocumentBuilderFactory DOCUMENT_BUILDER_FACTORY = DocumentBuilderFactory.newInstance();
+
+	static {
+		DOCUMENT_BUILDER_FACTORY.setNamespaceAware(true);
+		try {
+			DOCUMENT_BUILDER_FACTORY.setFeature("http://apache.org/xml/features/nonvalidating/load-dtd-grammar", false);
+			DOCUMENT_BUILDER_FACTORY.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
+		}
+		catch (ParserConfigurationException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
 	@Autowired
 	private ApplicationContext ac;
 
@@ -79,10 +96,10 @@ public class XmlPayloadValidatingFilterParserTests {
 
 	@Test
 	public void testValidMessage() throws Exception {
-		Document doc = XmlTestUtil.getDocumentForString("<greeting>hello</greeting>");
-		GenericMessage<Document> docMessage = new GenericMessage<Document>(doc);
-		PollableChannel validChannel = ac.getBean("validOutputChannel", PollableChannel.class);
-		MessageChannel inputChannel = ac.getBean("inputChannelA", MessageChannel.class);
+		Message<String> docMessage =
+				new GenericMessage<>("<!DOCTYPE greeting SYSTEM \"greeting.dtd\"><greeting>hello</greeting>");
+		PollableChannel validChannel = this.ac.getBean("validOutputChannel", PollableChannel.class);
+		MessageChannel inputChannel = this.ac.getBean("inputChannelA", MessageChannel.class);
 		inputChannel.send(docMessage);
 		assertNotNull(validChannel.receive(100));
 	}
@@ -98,6 +115,7 @@ public class XmlPayloadValidatingFilterParserTests {
 		assertNotNull(invalidChannel.receive(100));
 		assertNull(validChannel.receive(100));
 	}
+
 	@Test
 	public void testInvalidMessageWithThrowException() throws Exception {
 		Document doc = XmlTestUtil.getDocumentForString("<greeting ping=\"pong\"><other/></greeting>");
@@ -117,6 +135,7 @@ public class XmlPayloadValidatingFilterParserTests {
 					Matchers.containsString("Element 'greeting' is a simple type, so it cannot have attributes,"));
 		}
 	}
+
 	@Test
 	public void testValidMessageWithValidator() throws Exception {
 		Document doc = XmlTestUtil.getDocumentForString("<greeting>hello</greeting>");