Added support for input Collection param

Added support for function parameter type Collection
Updated both Jackson and Gson mappers
Defined a new toObject() operation on JsonMapper and deprecated the old

Resolves #210

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2017 the original author or authors.
+ * Copyright 2016-2018 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.
@@ -15,16 +15,13 @@
  */
 package org.springframework.cloud.function.json;
 
-import java.util.ArrayList;
-import java.util.List;
+import java.lang.reflect.Type;
 
 import com.google.gson.Gson;
 
-import org.springframework.cloud.function.json.JsonMapper;
-import org.springframework.core.ResolvableType;
-
 /**
  * @author Dave Syer
+ * @author Oleg Zhurakousky
  *
  */
 public class GsonMapper implements JsonMapper {
@@ -36,13 +33,7 @@ public class GsonMapper implements JsonMapper {
 	}
 
 	@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) {
+	public <T> T toObject(String json, Type type) {
 		return gson.fromJson(json, type);
 	}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2017 the original author or authors.
+ * Copyright 2016-2018 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.
@@ -15,17 +15,15 @@
  */
 package org.springframework.cloud.function.json;
 
-import java.util.ArrayList;
-import java.util.List;
+import java.lang.reflect.Type;
 
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
-
-import org.springframework.cloud.function.json.JsonMapper;
+import com.fasterxml.jackson.databind.type.TypeFactory;
 
 /**
  * @author Dave Syer
- *
+ * @author Oleg Zhurakousky
  */
 public class JacksonMapper implements JsonMapper {
 
@@ -36,23 +34,12 @@ public class JacksonMapper implements JsonMapper {
 	}
 
 	@Override
-	public <T> List<T> toList(String json, Class<T> type) {
+	public <T> T toObject(String json, Type type) {
 		try {
-			return mapper.readValue(json, mapper.getTypeFactory()
-					.constructCollectionLikeType(ArrayList.class, type));
+			return mapper.readValue(json, TypeFactory.defaultInstance().constructType(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);
+			throw new IllegalArgumentException("Cannot convert JSON " + json, e);
 		}
 	}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2017 the original author or authors.
+ * Copyright 2016-2018 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.
@@ -15,17 +15,41 @@
  */
 package org.springframework.cloud.function.json;
 
+import java.lang.reflect.Type;
+import java.util.ArrayList;
 import java.util.List;
 
+import org.springframework.core.ResolvableType;
+
 /**
  * @author Dave Syer
- *
+ * @author Oleg Zhurakousky
  */
 public interface JsonMapper {
 
-	<T> List<T> toList(String json, Class<T> type);
+	/**
+	 * @deprecated in favor of {@link #toObject(String, Type)}
+	 */
+	@Deprecated
+	default <T> List<T> toList(String json, Class<T> type) {
+		Type actualType = (json.startsWith("[") && !List.class.isAssignableFrom(type))
+				? ResolvableType.forClassWithGenerics(ArrayList.class, (Class<?>) type)
+						.getType()
+				: type;
+		return toObject(json, actualType);
+	}
 
-	<T> T toSingle(String json, Class<T> type);
+	/**
+	 * @since 2.0
+	 */
+	<T> T toObject(String json, Type type);
+
+	/**
+	 * @deprecated in favor of {@link #toObject(String, Type)}
+	 */
+	default <T> T toSingle(String json, Class<T> type) {
+		return toObject(json, type);
+	}
 
 	String toString(Object value);
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2017 the original author or authors.
+ * Copyright 2016-2018 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.
@@ -29,11 +29,13 @@ 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 org.springframework.core.ResolvableType;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * @author Dave Syer
+ * @author Oleg Zhurakousky
  *
  */
 @RunWith(Parameterized.class)
@@ -54,8 +56,8 @@ public class JsonMapperTests {
 	@Test
 	public void vanillaArray() {
 		String json = "[{\"value\":\"foo\"},{\"value\":\"foo\"}]";
-		List<Foo> list = mapper.toList(json,
-				Foo.class);
+		List<Foo> list = mapper.toObject(json,
+				ResolvableType.forClassWithGenerics(List.class, Foo.class).getType());
 		assertThat(list).hasSize(2);
 		assertThat(list.get(0).getValue()).isEqualTo("foo");
 		assertThat(mapper.toString(list)).isEqualTo(json);
@@ -63,34 +65,36 @@ public class JsonMapperTests {
 
 	@Test
 	public void intArray() {
-		List<Integer> list = mapper.toList("[123,456]", Integer.class);
+		List<Integer> list = mapper.toObject("[123,456]",
+				ResolvableType.forClassWithGenerics(List.class, Integer.class).getType());
 		assertThat(list).hasSize(2);
 		assertThat(list.get(0)).isEqualTo(123);
 	}
 
 	@Test
 	public void emptyArray() {
-		List<Foo> list = mapper.toList("[]", Foo.class);
+		List<Foo> list = mapper.toObject("[]",
+				ResolvableType.forClassWithGenerics(List.class, Foo.class).getType());
 		assertThat(list).hasSize(0);
 	}
 
 	@Test
 	public void vanillaObject() {
 		String json = "{\"value\":\"foo\"}";
-		Foo foo = mapper.toSingle(json, Foo.class);
+		Foo foo = mapper.toObject(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);
+		int foo = mapper.toObject("123", Integer.class);
 		assertThat(foo).isEqualTo(123);
 	}
 
 	@Test
 	public void empty() {
-		Foo foo = mapper.toSingle("{}", Foo.class);
+		Foo foo = mapper.toObject("{}", Foo.class);
 		assertThat(foo.getValue()).isNull();
 	}