Override StringHttpMessageConverter with UTF-8

Override the default StringHttpMessageConverter provided by the standard
Spring MVC configuration so that is uses UTF-8 instead of the aging
default of the servlet spec (that is ISO-8859-1)

Fixes gh-1800

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

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.autoconfigure.web;
 
+import java.nio.charset.Charset;
 import java.util.Collections;
 import java.util.List;
 
@@ -28,6 +29,7 @@ import org.springframework.boot.context.properties.EnableConfigurationProperties
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.http.converter.StringHttpMessageConverter;
 import org.springframework.http.converter.json.GsonHttpMessageConverter;
 import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
 import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
@@ -47,11 +49,14 @@ import com.google.gson.Gson;
  * @author David Liu
  * @author Andy Wilkinson
  * @author Sebastien Deleuze
+ * @author Stephane Nicoll
  */
 @Configuration
 @ConditionalOnClass(HttpMessageConverter.class)
 public class HttpMessageConvertersAutoConfiguration {
 
+	private static final Charset UTF_8 = Charset.forName("UTF-8");
+
 	@Autowired(required = false)
 	private final List<HttpMessageConverter<?>> converters = Collections.emptyList();
 
@@ -118,4 +123,16 @@ public class HttpMessageConvertersAutoConfiguration {
 
 	}
 
+	@Configuration
+	@ConditionalOnClass(StringHttpMessageConverter.class)
+	protected static class StringHttpMessageConverterConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean
+		public StringHttpMessageConverter stringHttpMessageConverter() {
+			return new StringHttpMessageConverter(UTF_8);
+		}
+
+	}
+
 }

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

@@ -24,6 +24,7 @@ import org.junit.Test;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.http.converter.StringHttpMessageConverter;
 import org.springframework.http.converter.json.GsonHttpMessageConverter;
 import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
 import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
@@ -46,7 +47,7 @@ import static org.junit.Assert.assertTrue;
  */
 public class HttpMessageConvertersAutoConfigurationTests {
 
-	private AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();;
+	private AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
 
 	@After
 	public void close() {
@@ -134,6 +135,26 @@ public class HttpMessageConvertersAutoConfigurationTests {
 		assertConverterBeanRegisteredWithHttpMessageConverters(GsonHttpMessageConverter.class);
 	}
 
+	@Test
+	public void defaultStringConverter() throws Exception {
+		this.context.register(HttpMessageConvertersAutoConfiguration.class);
+		this.context.refresh();
+		assertConverterBeanExists(StringHttpMessageConverter.class,
+				"stringHttpMessageConverter");
+		assertConverterBeanRegisteredWithHttpMessageConverters(StringHttpMessageConverter.class);
+	}
+
+	@Test
+	public void customStringConverter() throws Exception {
+		this.context.register(StringConverterConfig.class,
+				HttpMessageConvertersAutoConfiguration.class);
+		this.context.refresh();
+		assertConverterBeanExists(StringHttpMessageConverter.class,
+				"customStringMessageConverter");
+
+		assertConverterBeanRegisteredWithHttpMessageConverters(StringHttpMessageConverter.class);
+	}
+
 	private void assertConverterBeanExists(Class<?> type, String beanName) {
 		assertEquals(1, this.context.getBeansOfType(type).size());
 		List<String> beanNames = Arrays.asList(this.context.getBeanDefinitionNames());
@@ -202,4 +223,13 @@ public class HttpMessageConvertersAutoConfigurationTests {
 		}
 	}
 
+	@Configuration
+	protected static class StringConverterConfig {
+
+		@Bean
+		public StringHttpMessageConverter customStringMessageConverter() {
+			return new StringHttpMessageConverter();
+		}
+	}
+
 }