オブジェクトからmapを生成するサンプル

convertapivalue.java

package com.naosim;

import com.sun.tools.javac.util.Pair;

import java.lang.reflect.Method;
import java.util.*;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class Main {
    public static void main(String[] args) {
        System.out.println(ConvertApiValue.convert(new Person()));
        // 出力: 
        // {tagList=[aaa, aaa, aaa], score={englishScore=200, mathScore=100}, name=hoge, age=20}
    }

    public static class ConvertApiValue {
        public static Object convert(Object obj) {
            Optional<Method> getApiValueMethod = Stream.of(obj.getClass().getMethods()).filter(m -> m.getName().startsWith("getApiValue")).findFirst();
            if(getApiValueMethod.isPresent()) {
                return invokeMethod(obj, getApiValueMethod.get());
            } else if(obj instanceof java.util.Collection) {
                return ((java.util.Collection)obj).stream().map(ConvertApiValue::convert).collect(Collectors.toList());
            } else {
                Map result = new HashMap<String, Object>();
                Stream.of(obj.getClass().getMethods())
                        .filter(m -> m.getName().startsWith("get") && m.getParameterCount() == 0 && isNotObjectMethod(m))// getter抽出
                        .map(m -> new Pair<>(getPramName(m.getName()), convert(invokeMethod(obj, m))))
                        .forEach(p -> result.put(p.fst, p.snd));

                return result.size() > 0 ? result : null;
            }
        }

        public static boolean isNotObjectMethod(Method method) {
            return Stream.of(new Object().getClass().getMethods()).map(Method::getName).filter(method.getName()::equals).count() == 0;
        }

        public static String getPramName(String getterMethodName) {
            return getterMethodName.substring(3, 4).toLowerCase() + getterMethodName.substring(4);//except get
        }

        public static Object invokeMethod(Object target, Method method) {
            try {
                return method.invoke(target);
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
    }


    public static class Person {
        public Name getName() {
            return new Name();
        }

        public Age getAge() {
            return new Age();
        }

        public Score getScore() {
            return new Score();
        }

        public List<Tag> getTagList() {
            List<Tag> list = new ArrayList<>();
            list.add(new Tag());
            list.add(new Tag());
            list.add(new Tag());
            return list;
        }

        public static class Name {
            public String getApiValue() {
                return "hoge";
            }
        }

        public static class Age {
            public int getApiValue() {
                return 20;
            }
        }

        public static class Score {
            public MathScore getMathScore() {
                return new MathScore();
            }

            public EnglishScore getEnglishScore() {
                return new EnglishScore();
            }
        }

        public static class MathScore {
            public int getApiValue() {
                return 100;
            }
        }
        public static class EnglishScore {
            public int getApiValue() {
                return 200;
            }
        }

        public static class Tag {
            public String getApiValue() {
                return "aaa";
            }
        }
    }
}