Move JsonMapper to spring-cloud-function-context

...in case it is needed elsewhere (see gh-151)

spring-cloud-function-context/pom.xml

@@ -32,6 +32,16 @@
 			<artifactId>spring-boot-configuration-processor</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>com.google.code.gson</groupId>
+			<artifactId>gson</artifactId>
+			<optional>true</optional>
+		</dependency>
+		<dependency>
+			<groupId>com.fasterxml.jackson.core</groupId>
+			<artifactId>jackson-databind</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-test</artifactId>

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/config/ContextFunctionCatalogAutoConfiguration.java

@@ -39,6 +39,9 @@ import java.util.function.Supplier;
 
 import javax.annotation.PreDestroy;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.gson.Gson;
+
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.beans.factory.config.BeanDefinition;
@@ -46,7 +49,10 @@ import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.beans.factory.config.ConstructorArgumentValues.ValueHolder;
 import org.springframework.beans.factory.support.AbstractBeanDefinition;
 import org.springframework.beans.factory.support.RootBeanDefinition;
+import org.springframework.boot.autoconfigure.condition.AnyNestedCondition;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.cloud.function.context.FunctionCatalog;
 import org.springframework.cloud.function.context.FunctionRegistration;
 import org.springframework.cloud.function.context.FunctionRegistry;
@@ -62,8 +68,11 @@ import org.springframework.cloud.function.core.FunctionFactoryMetadata;
 import org.springframework.cloud.function.core.IsolatedConsumer;
 import org.springframework.cloud.function.core.IsolatedFunction;
 import org.springframework.cloud.function.core.IsolatedSupplier;
+import org.springframework.cloud.function.json.GsonMapper;
+import org.springframework.cloud.function.json.JacksonMapper;
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.annotation.AnnotatedElementUtils;
@@ -86,6 +95,8 @@ import org.springframework.util.StringUtils;
 @ConditionalOnMissingBean(FunctionCatalog.class)
 public class ContextFunctionCatalogAutoConfiguration {
 
+	static final String PREFERRED_MAPPER_PROPERTY = "spring.http.converters.preferred-json-mapper";
+
 	@Autowired(required = false)
 	private Map<String, Supplier<?>> suppliers = Collections.emptyMap();
 
@@ -169,6 +180,26 @@ public class ContextFunctionCatalogAutoConfiguration {
 
 	}
 
+	@Configuration
+	@ConditionalOnClass(Gson.class)
+	@Conditional(PreferGsonOrMissingJacksonCondition.class)
+	protected static class GsonConfiguration {
+		@Bean
+		public GsonMapper jsonMapper(Gson gson) {
+			return new GsonMapper(gson);
+		}
+	}
+
+	@Configuration
+	@ConditionalOnClass(ObjectMapper.class)
+	@ConditionalOnProperty(name = ContextFunctionCatalogAutoConfiguration.PREFERRED_MAPPER_PROPERTY, havingValue = "jackson", matchIfMissing = true)
+	protected static class JacksonConfiguration {
+		@Bean
+		public JacksonMapper jsonMapper(ObjectMapper mapper) {
+			return new JacksonMapper(mapper);
+		}
+	}
+
 	@Component
 	protected static class ContextFunctionRegistry {
 
@@ -643,4 +674,22 @@ public class ContextFunctionCatalogAutoConfiguration {
 
 	}
 
+	private static class PreferGsonOrMissingJacksonCondition extends AnyNestedCondition {
+
+		PreferGsonOrMissingJacksonCondition() {
+			super(ConfigurationPhase.REGISTER_BEAN);
+		}
+
+		@ConditionalOnProperty(name = ContextFunctionCatalogAutoConfiguration.PREFERRED_MAPPER_PROPERTY, havingValue = "gson", matchIfMissing = false)
+		static class GsonPreferred {
+
+		}
+
+		@ConditionalOnMissingBean(ObjectMapper.class)
+		static class JacksonMissing {
+
+		}
+
+	}
+
 }

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/json/GsonMapper.java

@@ -13,13 +13,14 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.springframework.cloud.function.web.util;
+package org.springframework.cloud.function.json;
 
 import java.util.ArrayList;
 import java.util.List;
 
 import com.google.gson.Gson;
 
+import org.springframework.cloud.function.json.JsonMapper;
 import org.springframework.core.ResolvableType;
 
 /**
@@ -45,4 +46,8 @@ public class GsonMapper implements JsonMapper {
 		return gson.fromJson(json, type);
 	}
 
+	@Override
+	public String toString(Object value) {
+		return gson.toJson(value);
+	}
 }

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/json/JacksonMapper.java

@@ -13,13 +13,16 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.springframework.cloud.function.web.util;
+package org.springframework.cloud.function.json;
 
 import java.util.ArrayList;
 import java.util.List;
 
+import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
+import org.springframework.cloud.function.json.JsonMapper;
+
 /**
  * @author Dave Syer
  *
@@ -53,4 +56,13 @@ public class JacksonMapper implements JsonMapper {
 		}
 	}
 
+	@Override
+	public String toString(Object value) {
+		try {
+			return mapper.writeValueAsString(value);
+		}
+		catch (JsonProcessingException e) {
+			throw new IllegalArgumentException("Cannot convert to JSON", e);
+		}
+	}
 }

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/json/JsonMapper.java

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.springframework.cloud.function.web.util;
+package org.springframework.cloud.function.json;
 
 import java.util.List;
 
@@ -27,4 +27,6 @@ public interface JsonMapper {
 
 	<T> T toSingle(String json, Class<T> type);
 
+	String toString(Object value);
+
 }

spring-cloud-function-context/src/test/java/org/springframework/cloud/function/util/JsonMapperTests.java

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.springframework.cloud.function.web.util;
+package org.springframework.cloud.function.util;
 
 import java.util.Arrays;
 import java.util.List;
@@ -26,6 +26,10 @@ import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 import org.junit.runners.Parameterized.Parameters;
 
+import org.springframework.cloud.function.json.GsonMapper;
+import org.springframework.cloud.function.json.JacksonMapper;
+import org.springframework.cloud.function.json.JsonMapper;
+
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
@@ -33,7 +37,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  */
 @RunWith(Parameterized.class)
-public class MapperTests {
+public class JsonMapperTests {
 
 	private JsonMapper mapper;
 
@@ -43,16 +47,18 @@ public class MapperTests {
 				new Object[] { new JacksonMapper(new ObjectMapper()) });
 	}
 
-	public MapperTests(JsonMapper mapper) {
+	public JsonMapperTests(JsonMapper mapper) {
 		this.mapper = mapper;
 	}
 
 	@Test
 	public void vanillaArray() {
-		List<Foo> list = mapper.toList("[{\"value\":\"foo\"}, {\"value\":\"foo\"}]",
+		String json = "[{\"value\":\"foo\"},{\"value\":\"foo\"}]";
+		List<Foo> list = mapper.toList(json,
 				Foo.class);
 		assertThat(list).hasSize(2);
 		assertThat(list.get(0).getValue()).isEqualTo("foo");
+		assertThat(mapper.toString(list)).isEqualTo(json);
 	}
 
 	@Test
@@ -70,8 +76,10 @@ public class MapperTests {
 
 	@Test
 	public void vanillaObject() {
-		Foo foo = mapper.toSingle("{\"value\":\"foo\"}", Foo.class);
+		String json = "{\"value\":\"foo\"}";
+		Foo foo = mapper.toSingle(json, Foo.class);
 		assertThat(foo.getValue()).isEqualTo("foo");
+		assertThat(mapper.toString(foo)).isEqualTo(json);
 	}
 
 	@Test

spring-cloud-function-web/src/main/java/org/springframework/cloud/function/web/flux/ReactorAutoConfiguration.java

@@ -19,32 +19,24 @@ package org.springframework.cloud.function.web.flux;
 import java.util.ArrayList;
 import java.util.List;
 
-import com.fasterxml.jackson.databind.ObjectMapper;
-import com.google.gson.Gson;
-
 import org.springframework.beans.factory.SmartInitializingSingleton;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
-import org.springframework.boot.autoconfigure.condition.AnyNestedCondition;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
 import org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration;
 import org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.HttpMessageConverters;
 import org.springframework.cloud.function.context.FunctionCatalog;
 import org.springframework.cloud.function.context.catalog.FunctionInspector;
+import org.springframework.cloud.function.json.JsonMapper;
 import org.springframework.cloud.function.web.flux.request.FluxHandlerMethodArgumentResolver;
 import org.springframework.cloud.function.web.flux.response.FluxReturnValueHandler;
-import org.springframework.cloud.function.web.util.GsonMapper;
-import org.springframework.cloud.function.web.util.JacksonMapper;
-import org.springframework.cloud.function.web.util.JsonMapper;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.core.convert.ConversionService;
@@ -71,8 +63,6 @@ public class ReactorAutoConfiguration {
 	@Autowired
 	private ApplicationContext context;
 
-	static final String PREFERRED_MAPPER_PROPERTY = "spring.http.converters.preferred-json-mapper";
-
 	@Bean
 	public FunctionHandlerMapping functionHandlerMapping(FunctionCatalog catalog,
 			FunctionController controller) {
@@ -129,44 +119,6 @@ public class ReactorAutoConfiguration {
 		};
 	}
 
-	@Configuration
-	@ConditionalOnClass(Gson.class)
-	@Conditional(PreferGsonOrMissingJacksonCondition.class)
-	protected static class GsonConfiguration {
-		@Bean
-		public GsonMapper jsonMapper(Gson gson) {
-			return new GsonMapper(gson);
-		}
-	}
-
-	@Configuration
-	@ConditionalOnClass(ObjectMapper.class)
-	@ConditionalOnProperty(name = ReactorAutoConfiguration.PREFERRED_MAPPER_PROPERTY, havingValue = "jackson", matchIfMissing = true)
-	protected static class JacksonConfiguration {
-		@Bean
-		public JacksonMapper jsonMapper(ObjectMapper mapper) {
-			return new JacksonMapper(mapper);
-		}
-	}
-
-	private static class PreferGsonOrMissingJacksonCondition extends AnyNestedCondition {
-
-		PreferGsonOrMissingJacksonCondition() {
-			super(ConfigurationPhase.REGISTER_BEAN);
-		}
-
-		@ConditionalOnProperty(name = ReactorAutoConfiguration.PREFERRED_MAPPER_PROPERTY, havingValue = "gson", matchIfMissing = false)
-		static class GsonPreferred {
-
-		}
-
-		@ConditionalOnMissingBean(ObjectMapper.class)
-		static class JacksonMissing {
-
-		}
-
-	}
-
 	private static class BasicStringConverter implements StringConverter {
 
 		private ConversionService conversionService;

spring-cloud-function-web/src/main/java/org/springframework/cloud/function/web/flux/request/FluxHandlerMethodArgumentResolver.java

@@ -28,9 +28,9 @@ import org.apache.commons.logging.LogFactory;
 
 import org.springframework.cloud.function.context.catalog.FunctionInspector;
 import org.springframework.cloud.function.context.message.MessageUtils;
+import org.springframework.cloud.function.json.JsonMapper;
 import org.springframework.cloud.function.web.flux.constants.WebRequestConstants;
 import org.springframework.cloud.function.web.util.HeaderUtils;
-import org.springframework.cloud.function.web.util.JsonMapper;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.Ordered;
 import org.springframework.http.MediaType;