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Polish "refactor spring-boot JSON parser"

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Polish JSON parser refactoring and remove some more duplication.

Closes gh-12428
This commit is contained in:
Phillip Webb
2018-03-14 14:50:29 -07:00
parent aa69621078
commit 90949669be
7 changed files with 84 additions and 87 deletions
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83
spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/AbstractJsonParser.java
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@@ -1,5 +1,5 @@
/*
* 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.
@@ -18,74 +18,49 @@ package org.springframework.boot.json;
import java.util.List;
import java.util.Map;
import java.util.Optional;
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 {
/** Start symbol of a JSON map. **/
private static final String START_MAP = "{";
/** Start symbol of a JSON list. **/
private static final String START_LIST = "[";
/**
* Parses the specified JSON string and returns the extracted contents as a Map of
* String to Object.
*
* @param json the JSON string to parse.
* @param parser the parser function.
* @return Map<String, Object> parsed contents
* @throws IllegalArgumentException if the json String cannot be parsed as a
* Map<String, Object>
*/
Map<String, Object> parseMap(String json,
protected final Map<String, Object> parseMap(String json,
Function<String, Map<String, Object>> parser) {
assert parser != null;
return trimIfStartsWith(json, START_MAP).map(parser::apply)
.orElseThrow(AbstractJsonParser::cannotParseJson);
return trimParse(json, "{", parser);
}
/**
* Parses the specified JSON string and returns the extracted contents as a List of Objects.
*
* @param json the JSON string to parse.
* @param parser the parser function.
* @return List&lt;Object&gt; parsed contents
* @throws IllegalArgumentException if the json String cannot be parsed as a
* List&lt;Object&gt;
*/
List<Object> parseList(String json, Function<String, List<Object>> parser) {
assert parser != null;
return trimIfStartsWith(json, START_LIST).map(parser::apply)
.orElseThrow(AbstractJsonParser::cannotParseJson);
protected final List<Object> parseList(String json,
Function<String, List<Object>> parser) {
return trimParse(json, "[", parser);
}
private static IllegalArgumentException cannotParseJson() {
return cannotParseJson(null);
}
static IllegalArgumentException cannotParseJson(Exception cause) {
return new IllegalArgumentException("Cannot parse JSON", cause);
}
private static Optional<String> trimIfStartsWith(String json, String expectedPrefix) {
assert expectedPrefix != null;
if (json != null) {
final String trimmed = json.trim();
if (trimmed.startsWith(expectedPrefix)) {
return Optional.of(trimmed);
}
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);
}
return Optional.empty();
}
}

2
spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/GsonJsonParser.java
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@@ -1,5 +1,5 @@
/*
* 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.

20
spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/JacksonJsonParser.java
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@@ -1,5 +1,5 @@
/*
* 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 AbstractJsonParser.cannotParseJson(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 AbstractJsonParser.cannotParseJson(ex);
}
return tryParse(() -> getObjectMapper().readValue(json, LIST_TYPE),
Exception.class);
}
private ObjectMapper getObjectMapper() {

36
spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/JsonParseException.java Normal file
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@@ -0,0 +1,36 @@
/*
* 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);
}
}

8
spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/JsonParser.java
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@@ -1,5 +1,5 @@
/*
* 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;
}

20
spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/JsonSimpleJsonParser.java
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@@ -1,5 +1,5 @@
/*
* 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 AbstractJsonParser.cannotParseJson(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 AbstractJsonParser.cannotParseJson(ex);
}
return (List<Object>) tryParse(() -> new JSONParser().parse(json),
ParseException.class);
}
}

2
spring-boot-project/spring-boot/src/main/java/org/springframework/boot/json/YamlJsonParser.java
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@@ -1,5 +1,5 @@
/*
* 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.