Move JsonMapper to spring-cloud-function-context

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

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

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2016-2017 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+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;
+
+/**
+ * @author Dave Syer
+ *
+ */
+public class GsonMapper implements JsonMapper {
+
+	private final Gson gson;
+
+	public GsonMapper(Gson gson) {
+		this.gson = gson;
+	}
+
+	@Override
+	public <T> List<T> toList(String json, Class<T> type) {
+		return gson.fromJson(json,
+				ResolvableType.forClassWithGenerics(ArrayList.class, type).getType());
+	}
+
+	@Override
+	public <T> T toSingle(String json, Class<T> type) {
+		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

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2016-2017 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+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
+ *
+ */
+public class JacksonMapper implements JsonMapper {
+
+	private final ObjectMapper mapper;
+
+	public JacksonMapper(ObjectMapper mapper) {
+		this.mapper = mapper;
+	}
+
+	@Override
+	public <T> List<T> toList(String json, Class<T> type) {
+		try {
+			return mapper.readValue(json, mapper.getTypeFactory()
+					.constructCollectionLikeType(ArrayList.class, type));
+		}
+		catch (Exception e) {
+			throw new IllegalArgumentException("Cannot convert JSON", e);
+		}
+	}
+
+	@Override
+	public <T> T toSingle(String json, Class<T> type) {
+		try {
+			return mapper.readValue(json, type);
+		}
+		catch (Exception e) {
+			throw new IllegalArgumentException("Cannot convert JSON", e);
+		}
+	}
+
+	@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

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2016-2017 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.cloud.function.json;
+
+import java.util.List;
+
+/**
+ * @author Dave Syer
+ *
+ */
+public interface JsonMapper {
+
+	<T> List<T> toList(String json, Class<T> type);
+
+	<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

@@ -0,0 +1,109 @@
+/*
+ * Copyright 2016-2017 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.cloud.function.util;
+
+import java.util.Arrays;
+import java.util.List;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.gson.Gson;
+
+import org.junit.Test;
+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;
+
+/**
+ * @author Dave Syer
+ *
+ */
+@RunWith(Parameterized.class)
+public class JsonMapperTests {
+
+	private JsonMapper mapper;
+
+	@Parameters
+	public static List<Object[]> params() {
+		return Arrays.asList(new Object[] { new GsonMapper(new Gson()) },
+				new Object[] { new JacksonMapper(new ObjectMapper()) });
+	}
+
+	public JsonMapperTests(JsonMapper mapper) {
+		this.mapper = mapper;
+	}
+
+	@Test
+	public void vanillaArray() {
+		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
+	public void intArray() {
+		List<Integer> list = mapper.toList("[123,456]", Integer.class);
+		assertThat(list).hasSize(2);
+		assertThat(list.get(0)).isEqualTo(123);
+	}
+
+	@Test
+	public void emptyArray() {
+		List<Foo> list = mapper.toList("[]", Foo.class);
+		assertThat(list).hasSize(0);
+	}
+
+	@Test
+	public void vanillaObject() {
+		String json = "{\"value\":\"foo\"}";
+		Foo foo = mapper.toSingle(json, Foo.class);
+		assertThat(foo.getValue()).isEqualTo("foo");
+		assertThat(mapper.toString(foo)).isEqualTo(json);
+	}
+
+	@Test
+	public void intValue() {
+		int foo = mapper.toSingle("123", Integer.class);
+		assertThat(foo).isEqualTo(123);
+	}
+
+	@Test
+	public void empty() {
+		Foo foo = mapper.toSingle("{}", Foo.class);
+		assertThat(foo.getValue()).isNull();
+	}
+
+	public static class Foo {
+		private String value;
+
+		public String getValue() {
+			return value;
+		}
+
+		public void setValue(String value) {
+			this.value = value;
+		}
+
+	}
+}