Java 17
- ObjectMapper を使用してJSONを Map に変換
- Map のキーを keyMap に基づいて変更
- ネストされた Map は再帰処理で変換
- List 内に Map があれば再帰処理
- LinkedHashMap は挿入した順序を保持するために使用
方法１. 変換表のMapを宣言＆設定(プログラム内でput)
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.core.type.TypeReference;
import java.util.*;
public class JsonKeyConverter {
public static void main(String[] args) throws Exception {
String jsonStr = """
{
"name": "taro",
"age": 23,
"sex": "man",
"hobby": {
"outdoor": {
"land": ["running", "walking"],
"sea": ["swimming", "fishing"]
},
"indoor": ["movie", "game", "card"]
}
}
""";
// 旧 → 新のキーの変換マップ
Map<String, String> keyMap = new HashMap<>();
keyMap.put("name", "full_name");
keyMap.put("age", "years_old");
keyMap.put("sex", "gender");
keyMap.put("hobby", "interests");
keyMap.put("outdoor", "outside_activities");
keyMap.put("indoor", "inside_activities");
keyMap.put("land", "on_land");
keyMap.put("sea", "in_sea");
// JSONをマップに変換
ObjectMapper objectMapper = new ObjectMapper();
Map<String, Object> jsonMap = null;
try {
jsonMap = objectMapper.readValue(jsonStr, new TypeReference<>() {});
} catch (JsonProcessingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// キーを変換
Map<String, Object> convertedMap = convertKeys(jsonMap, keyMap);
// JSONに戻す
String newJsonStr = null;
try {
newJsonStr = objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(convertedMap);
} catch (JsonProcessingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(newJsonStr);
}
// 再帰的にキーを変換
private static Map<String, Object> convertKeys(Map<String, Object> original, Map<String, String> keyMap) {
Map<String, Object> converted = new LinkedHashMap<>();
for (Map.Entry<String, Object> entry : original.entrySet()) {
String newKey = keyMap.getOrDefault(entry.getKey(), entry.getKey()); // 変換マップにある場合は新キーを使用
Object value = entry.getValue();
if (value instanceof Map) {
value = convertKeys((Map<String, Object>) value, keyMap); // 再帰処理
} else if (value instanceof List) {
value = convertList((List<Object>) value, keyMap);
}
converted.put(newKey, value);
}
return converted;
}
// List内のMapも再帰的に処理
private static List<Object> convertList(List<Object> list, Map<String, String> keyMap) {
List<Object> convertedList = new ArrayList<>();
for (Object item : list) {
if (item instanceof Map) {
convertedList.add(convertKeys((Map<String, Object>) item, keyMap));
} else {
convertedList.add(item);
}
}
return convertedList;
}
}
実行
{
"full_name" : "taro",
"years_old" : 23,
"gender" : "man",
"interests" : {
"outside_activities" : {
"on_land" : [ "running", "walking" ],
"in_sea" : [ "swimming", "fishing" ]
},
"inside_activities" : [ "movie", "game", "card" ]
}
}
方法2. 変換表のMapを宣言＆設定(プロパティファイルから読み込み)
src/main/resources/key_mapping.properties
name=full_name
age=years_old
sex=gender
hobby=interests
outdoor=outside_activities
indoor=inside_activities
land=on_land
sea=in_sea
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.core.type.TypeReference;
import java.util.*;
public class JsonKeyConverter {
public static void main(String[] args) throws Exception {
String jsonStr = """
{
"name": "taro",
"age": 23,
"sex": "man",
"hobby": {
"outdoor": {
"land": ["running", "walking"],
"sea": ["swimming", "fishing"]
},
"indoor": ["movie", "game", "card"]
}
}
""";
// 旧 → 新のキーの変換マップ
Map<String, String> keyMap = loadKeyMappings("key_mapping");
// JSONをマップに変換
ObjectMapper objectMapper = new ObjectMapper();
Map<String, Object> jsonMap = null;
try {
jsonMap = objectMapper.readValue(jsonStr, new TypeReference<>() {});
} catch (JsonProcessingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// キーを変換
Map<String, Object> convertedMap = convertKeys(jsonMap, keyMap);
// JSONに戻す
String newJsonStr = null;
try {
newJsonStr = objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(convertedMap);
} catch (JsonProcessingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(newJsonStr);
}
// 再帰的にキーを変換
private static Map<String, Object> convertKeys(Map<String, Object> original, Map<String, String> keyMap) {
Map<String, Object> converted = new LinkedHashMap<>();
for (Map.Entry<String, Object> entry : original.entrySet()) {
String newKey = keyMap.getOrDefault(entry.getKey(), entry.getKey()); // 変換マップにある場合は新キーを使用
Object value = entry.getValue();
if (value instanceof Map) {
value = convertKeys((Map<String, Object>) value, keyMap); // 再帰処理
} else if (value instanceof List) {
value = convertList((List<Object>) value, keyMap);
}
converted.put(newKey, value);
}
return converted;
}
// List内のMapも再帰的に処理
private static List<Object> convertList(List<Object> list, Map<String, String> keyMap) {
List<Object> convertedList = new ArrayList<>();
for (Object item : list) {
if (item instanceof Map) {
convertedList.add(convertKeys((Map<String, Object>) item, keyMap));
} else {
convertedList.add(item);
}
}
return convertedList;
}
private static Map<String, String> loadKeyMappings(String baseName) {
Map<String, String> keyMap = new HashMap<>();
try {
ResourceBundle bundle = ResourceBundle.getBundle(baseName);
for (String key : bundle.keySet()) {
String value = bundle.getString(key);
if (StringUtils.isEmpty(value)) {
throw new IllegalArgumentException("エラー: キー '" + key + "' の値が空です。プロパティファイルを修正してください。");
}
keyMap.put(key, value);
}
} catch (MissingResourceException e) {
System.err.println("エラー: プロパティファイル '" + baseName + ".properties' が見つかりません。");
throw e; // そのまま例外を投げて処理を中断
}
return keyMap;
}
}
実行
{
"full_name" : "taro",
"years_old" : 23,
"gender" : "man",
"interests" : {
"outside_activities" : {
"on_land" : [ "running", "walking" ],
"in_sea" : [ "swimming", "fishing" ]
},
"inside_activities" : [ "movie", "game", "card" ]
}
}