Merge pull request #12428 from atelechev

* atelechev/refactor-spring-boot-json-parsers:
  Polish "refactor spring-boot JSON parser"
  Refactor spring-boot JSON parsers

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/AbstractJsonParser.java

+/*
+ * Copyright 2012-2018 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.
+ * 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.boot.json;
+
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.Callable;
+import java.util.function.Function;
+
+import org.springframework.util.ReflectionUtils;
+
+/**
+ * Base class for parsers wrapped or implemented in this package.
+ *
+ * @author Anton Telechev
+ * @author Phillip Webb
+ */
+abstract class AbstractJsonParser implements JsonParser {
+
+	protected final Map<String, Object> parseMap(String json,
+			Function<String, Map<String, Object>> parser) {
+		return trimParse(json, "{", parser);
+	}
+
+	protected final List<Object> parseList(String json,
+			Function<String, List<Object>> parser) {
+		return trimParse(json, "[", parser);
+	}
+
+	protected final <T> T trimParse(String json, String prefix,
+			Function<String, T> parser) {
+		String trimmed = (json == null ? "" : json.trim());
+		if (trimmed.startsWith(prefix)) {
+			return parser.apply(trimmed);
+		}
+		throw new JsonParseException();
+	}
+
+	protected final <T> T tryParse(Callable<T> parser, Class<? extends Exception> check) {
+		try {
+			return parser.call();
+		}
+		catch (Exception ex) {
+			if (check.isAssignableFrom(ex.getClass())) {
+				throw new JsonParseException(ex);
+			}
+			ReflectionUtils.rethrowRuntimeException(ex);
+			throw new IllegalStateException(ex);
+		}
+	}
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/BasicJsonParser.java

@@ -35,28 +35,16 @@ import org.springframework.util.StringUtils;
  * @since 1.2.0
  * @see JsonParserFactory
  */
-public class BasicJsonParser implements JsonParser {
+public class BasicJsonParser extends AbstractJsonParser {
 
 	@Override
 	public Map<String, Object> parseMap(String json) {
-		if (json != null) {
-			json = json.trim();
-			if (json.startsWith("{")) {
-				return parseMapInternal(json);
-			}
-		}
-		throw new IllegalArgumentException("Cannot parse JSON");
+		return parseMap(json, this::parseMapInternal);
 	}
 
 	@Override
 	public List<Object> parseList(String json) {
-		if (json != null) {
-			json = json.trim();
-			if (json.startsWith("[")) {
-				return parseListInternal(json);
-			}
-		}
-		throw new IllegalArgumentException("Cannot parse JSON");
+		return parseList(json, this::parseListInternal);
 	}
 
 	private List<Object> parseListInternal(String json) {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/GsonJsonParser.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -31,7 +31,7 @@ import com.google.gson.reflect.TypeToken;
  * @since 1.2.0
  * @see JsonParserFactory
  */
-public class GsonJsonParser implements JsonParser {
+public class GsonJsonParser extends AbstractJsonParser {
 
 	private static final TypeToken<?> MAP_TYPE = new MapTypeToken();
 
@@ -41,24 +41,14 @@ public class GsonJsonParser implements JsonParser {
 
 	@Override
 	public Map<String, Object> parseMap(String json) {
-		if (json != null) {
-			json = json.trim();
-			if (json.startsWith("{")) {
-				return this.gson.fromJson(json, MAP_TYPE.getType());
-			}
-		}
-		throw new IllegalArgumentException("Cannot parse JSON");
+		return parseMap(json,
+				(trimmed) -> this.gson.fromJson(trimmed, MAP_TYPE.getType()));
 	}
 
 	@Override
 	public List<Object> parseList(String json) {
-		if (json != null) {
-			json = json.trim();
-			if (json.startsWith("[")) {
-				return this.gson.fromJson(json, LIST_TYPE.getType());
-			}
-		}
-		throw new IllegalArgumentException("Cannot parse JSON");
+		return parseList(json,
+				(trimmed) -> this.gson.fromJson(trimmed, LIST_TYPE.getType()));
 	}
 
 	private static final class MapTypeToken extends TypeToken<Map<String, Object>> {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/JacksonJsonParser.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -28,7 +28,7 @@ import com.fasterxml.jackson.databind.ObjectMapper;
  * @author Dave Syer
  * @see JsonParserFactory
  */
-public class JacksonJsonParser implements JsonParser {
+public class JacksonJsonParser extends AbstractJsonParser {
 
 	private static final TypeReference<?> MAP_TYPE = new MapTypeReference();
 
@@ -38,22 +38,14 @@ public class JacksonJsonParser implements JsonParser {
 
 	@Override
 	public Map<String, Object> parseMap(String json) {
-		try {
-			return getObjectMapper().readValue(json, MAP_TYPE);
-		}
-		catch (Exception ex) {
-			throw new IllegalArgumentException("Cannot parse JSON", ex);
-		}
+		return tryParse(() -> getObjectMapper().readValue(json, MAP_TYPE),
+				Exception.class);
 	}
 
 	@Override
 	public List<Object> parseList(String json) {
-		try {
-			return getObjectMapper().readValue(json, LIST_TYPE);
-		}
-		catch (Exception ex) {
-			throw new IllegalArgumentException("Cannot parse JSON", ex);
-		}
+		return tryParse(() -> getObjectMapper().readValue(json, LIST_TYPE),
+				Exception.class);
 	}
 
 	private ObjectMapper getObjectMapper() {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/JsonParseException.java

+/*
+ * Copyright 2012-2018 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.
+ * 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.boot.json;
+
+/**
+ * {@link IllegalArgumentException} thrown when source JSON is invalid.
+ *
+ * @author Anton Telechev
+ * @author Phillip Webb
+ * @since 2.0.1
+ */
+public class JsonParseException extends IllegalArgumentException {
+
+	public JsonParseException() {
+		this(null);
+	}
+
+	public JsonParseException(Throwable cause) {
+		super("Cannot parse JSON", cause);
+	}
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/JsonParser.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -35,14 +35,16 @@ public interface JsonParser {
 	 * Parse the specified JSON string into a Map.
 	 * @param json the JSON to parse
 	 * @return the parsed JSON as a map
+	 * @throws JsonParseException if the JSON cannot be parsed
 	 */
-	Map<String, Object> parseMap(String json);
+	Map<String, Object> parseMap(String json) throws JsonParseException;
 
 	/**
 	 * Parse the specified JSON string into a List.
 	 * @param json the JSON to parse
 	 * @return the parsed JSON as a list
+	 * @throws JsonParseException if the JSON cannot be parsed
 	 */
-	List<Object> parseList(String json);
+	List<Object> parseList(String json) throws JsonParseException;
 
 }

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/JsonSimpleJsonParser.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -30,28 +30,20 @@ import org.json.simple.parser.ParseException;
  * @since 1.2.0
  * @see JsonParserFactory
  */
-public class JsonSimpleJsonParser implements JsonParser {
+public class JsonSimpleJsonParser extends AbstractJsonParser {
 
 	@Override
 	@SuppressWarnings("unchecked")
 	public Map<String, Object> parseMap(String json) {
-		try {
-			return (Map<String, Object>) new JSONParser().parse(json);
-		}
-		catch (ParseException ex) {
-			throw new IllegalArgumentException("Cannot parse JSON", ex);
-		}
+		return (Map<String, Object>) tryParse(() -> new JSONParser().parse(json),
+				ParseException.class);
 	}
 
 	@Override
 	@SuppressWarnings("unchecked")
 	public List<Object> parseList(String json) {
-		try {
-			return (List<Object>) new JSONParser().parse(json);
-		}
-		catch (ParseException ex) {
-			throw new IllegalArgumentException("Cannot parse JSON", ex);
-		}
+		return (List<Object>) tryParse(() -> new JSONParser().parse(json),
+				ParseException.class);
 	}
 
 }

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/YamlJsonParser.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -28,30 +28,18 @@ import org.yaml.snakeyaml.Yaml;
  * @author Jean de Klerk
  * @see JsonParserFactory
  */
-public class YamlJsonParser implements JsonParser {
+public class YamlJsonParser extends AbstractJsonParser {
 
 	@Override
 	@SuppressWarnings("unchecked")
 	public Map<String, Object> parseMap(String json) {
-		if (json != null) {
-			json = json.trim();
-			if (json.startsWith("{")) {
-				return new Yaml().loadAs(json, Map.class);
-			}
-		}
-		throw new IllegalArgumentException("Cannot parse JSON");
+		return parseMap(json, (trimmed) -> new Yaml().loadAs(trimmed, Map.class));
 	}
 
 	@Override
 	@SuppressWarnings("unchecked")
 	public List<Object> parseList(String json) {
-		if (json != null) {
-			json = json.trim();
-			if (json.startsWith("[")) {
-				return new Yaml().loadAs(json, List.class);
-			}
-		}
-		throw new IllegalArgumentException("Cannot parse JSON");
+		return parseList(json, (trimmed) -> new Yaml().loadAs(trimmed, List.class));
 	}
 
 }