Apply HttpMessageConverter auto-config to form part converters

Closes gh-3525

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/HttpMessageConverters.java

 /*
- * Copyright 2012-2014 the original author or authors.
+ * Copyright 2012-2015 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.
@@ -16,6 +16,7 @@
 
 package org.springframework.boot.autoconfigure.web;
 
+import java.lang.reflect.Field;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -24,9 +25,11 @@ import java.util.Iterator;
 import java.util.List;
 
 import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.http.converter.support.AllEncompassingFormHttpMessageConverter;
 import org.springframework.http.converter.xml.AbstractXmlHttpMessageConverter;
 import org.springframework.http.converter.xml.MappingJackson2XmlHttpMessageConverter;
 import org.springframework.util.ClassUtils;
+import org.springframework.util.ReflectionUtils;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;
 
@@ -45,6 +48,7 @@ import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupp
  *
  * @author Dave Syer
  * @author Phillip Webb
+ * @author Andy Wilkinson
  * @see #HttpMessageConverters(HttpMessageConverter...)
  * @see #HttpMessageConverters(Collection)
  * @see #getConverters()
@@ -97,25 +101,37 @@ public class HttpMessageConverters implements Iterable<HttpMessageConverter<?>>
 	 */
 	public HttpMessageConverters(boolean addDefaultConverters,
 			Collection<HttpMessageConverter<?>> converters) {
+		List<HttpMessageConverter<?>> combined = getCombinedConverters(converters,
+				addDefaultConverters ? getDefaultConverters()
+						: Collections.<HttpMessageConverter<?>>emptyList());
+		combined = postProcessConverters(combined);
+		this.converters = Collections.unmodifiableList(combined);
+	}
+
+	private List<HttpMessageConverter<?>> getCombinedConverters(
+			Collection<HttpMessageConverter<?>> converters,
+			List<HttpMessageConverter<?>> defaultConverters) {
 		List<HttpMessageConverter<?>> combined = new ArrayList<HttpMessageConverter<?>>();
 		List<HttpMessageConverter<?>> processing = new ArrayList<HttpMessageConverter<?>>(
 				converters);
-		if (addDefaultConverters) {
-			for (HttpMessageConverter<?> defaultConverter : getDefaultConverters()) {
-				Iterator<HttpMessageConverter<?>> iterator = processing.iterator();
-				while (iterator.hasNext()) {
-					HttpMessageConverter<?> candidate = iterator.next();
-					if (isReplacement(defaultConverter, candidate)) {
-						combined.add(candidate);
-						iterator.remove();
-					}
+		for (HttpMessageConverter<?> defaultConverter : defaultConverters) {
+			Iterator<HttpMessageConverter<?>> iterator = processing.iterator();
+			while (iterator.hasNext()) {
+				HttpMessageConverter<?> candidate = iterator.next();
+				if (isReplacement(defaultConverter, candidate)) {
+					combined.add(candidate);
+					iterator.remove();
 				}
-				combined.add(defaultConverter);
+			}
+			combined.add(defaultConverter);
+			if (defaultConverter instanceof AllEncompassingFormHttpMessageConverter) {
+				configurePartConverters(
+						(AllEncompassingFormHttpMessageConverter) defaultConverter,
+						converters);
 			}
 		}
 		combined.addAll(0, processing);
-		combined = postProcessConverters(combined);
-		this.converters = Collections.unmodifiableList(combined);
+		return combined;
 	}
 
 	private boolean isReplacement(HttpMessageConverter<?> defaultConverter,
@@ -128,6 +144,28 @@ public class HttpMessageConverters implements Iterable<HttpMessageConverter<?>>
 		return ClassUtils.isAssignableValue(defaultConverter.getClass(), candidate);
 	}
 
+	private void configurePartConverters(
+			AllEncompassingFormHttpMessageConverter formConverter,
+			Collection<HttpMessageConverter<?>> converters) {
+		List<HttpMessageConverter<?>> partConverters = extractPartConverters(
+				formConverter);
+		List<HttpMessageConverter<?>> combinedConverters = getCombinedConverters(
+				converters, partConverters);
+		combinedConverters = postProcessPartConverters(combinedConverters);
+		formConverter.setPartConverters(combinedConverters);
+	}
+
+	private List<HttpMessageConverter<?>> extractPartConverters(
+			AllEncompassingFormHttpMessageConverter formConverter) {
+		Field field = ReflectionUtils.findField(
+				AllEncompassingFormHttpMessageConverter.class, "partConverters");
+		ReflectionUtils.makeAccessible(field);
+		@SuppressWarnings("unchecked")
+		List<HttpMessageConverter<?>> partConverters = (List<HttpMessageConverter<?>>) ReflectionUtils
+				.getField(field, formConverter);
+		return partConverters;
+	}
+
 	/**
 	 * Method that can be used to post-process the {@link HttpMessageConverter} list
 	 * before it is used.
@@ -139,6 +177,19 @@ public class HttpMessageConverters implements Iterable<HttpMessageConverter<?>>
 		return converters;
 	}
 
+	/**
+	 * Method that can be used to post-process the {@link HttpMessageConverter} list
+	 * before it is used to configure the part converters of
+	 * {@link AllEncompassingFormHttpMessageConverter}.
+	 * @param converters a mutable list of the converters that will be used.
+	 * @return the final converts list to use
+	 * @since 1.3.0
+	 */
+	protected List<HttpMessageConverter<?>> postProcessPartConverters(
+			List<HttpMessageConverter<?>> converters) {
+		return converters;
+	}
+
 	private List<HttpMessageConverter<?>> getDefaultConverters() {
 		List<HttpMessageConverter<?>> converters = new ArrayList<HttpMessageConverter<?>>();
 		if (ClassUtils.isPresent("org.springframework.web.servlet.config.annotation."

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/HttpMessageConvertersTests.java

@@ -18,6 +18,7 @@ package org.springframework.boot.autoconfigure.web;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Iterator;
 import java.util.List;
 
@@ -32,6 +33,7 @@ import org.springframework.http.converter.json.MappingJackson2HttpMessageConvert
 import org.springframework.http.converter.support.AllEncompassingFormHttpMessageConverter;
 import org.springframework.http.converter.xml.MappingJackson2XmlHttpMessageConverter;
 import org.springframework.http.converter.xml.SourceHttpMessageConverter;
+import org.springframework.test.util.ReflectionTestUtils;
 
 import static org.hamcrest.Matchers.equalTo;
 import static org.junit.Assert.assertEquals;
@@ -100,6 +102,19 @@ public class HttpMessageConvertersTests {
 		assertEquals(converter2, converters.getConverters().get(1));
 	}
 
+	@Test
+	public void convertersAreAddedToFormPartConverter() {
+		HttpMessageConverter<?> converter1 = mock(HttpMessageConverter.class);
+		HttpMessageConverter<?> converter2 = mock(HttpMessageConverter.class);
+		List<HttpMessageConverter<?>> converters = new HttpMessageConverters(converter1,
+				converter2).getConverters();
+		List<HttpMessageConverter<?>> partConverters = extractFormPartConverters(
+				converters);
+		assertTrue(partConverters.contains(converter1));
+		assertEquals(converter1, partConverters.get(0));
+		assertEquals(converter2, partConverters.get(1));
+	}
+
 	@Test
 	public void postProcessConverters() throws Exception {
 		HttpMessageConverters converters = new HttpMessageConverters() {
@@ -129,4 +144,52 @@ public class HttpMessageConvertersTests {
 						MappingJackson2HttpMessageConverter.class)));
 	}
 
+	@Test
+	public void postProcessPartConverters() throws Exception {
+		HttpMessageConverters converters = new HttpMessageConverters() {
+			@Override
+			protected List<HttpMessageConverter<?>> postProcessPartConverters(
+					List<HttpMessageConverter<?>> converters) {
+				for (Iterator<HttpMessageConverter<?>> iterator = converters
+						.iterator(); iterator.hasNext();) {
+					if (iterator
+							.next() instanceof MappingJackson2XmlHttpMessageConverter) {
+						iterator.remove();
+					}
+				}
+				return converters;
+			};
+		};
+		List<Class<?>> converterClasses = new ArrayList<Class<?>>();
+		for (HttpMessageConverter<?> converter : extractFormPartConverters(
+				converters.getConverters())) {
+			converterClasses.add(converter.getClass());
+		}
+		assertThat(converterClasses,
+				equalTo(Arrays.<Class<?>>asList(ByteArrayHttpMessageConverter.class,
+						StringHttpMessageConverter.class,
+						ResourceHttpMessageConverter.class,
+						SourceHttpMessageConverter.class,
+						MappingJackson2HttpMessageConverter.class)));
+	}
+
+	@SuppressWarnings("unchecked")
+	private List<HttpMessageConverter<?>> extractFormPartConverters(
+			List<HttpMessageConverter<?>> converters) {
+		AllEncompassingFormHttpMessageConverter formConverter = findFormConverter(
+				converters);
+		return (List<HttpMessageConverter<?>>) ReflectionTestUtils.getField(formConverter,
+				"partConverters");
+	}
+
+	private AllEncompassingFormHttpMessageConverter findFormConverter(
+			Collection<HttpMessageConverter<?>> converters) {
+		for (HttpMessageConverter<?> converter : converters) {
+			if (converter instanceof AllEncompassingFormHttpMessageConverter) {
+				return (AllEncompassingFormHttpMessageConverter) converter;
+			}
+		}
+		return null;
+	}
+
 }