Java工具类，对象List提取某个属性为List，对象List转为对象Map其中某个属性作为Key值

Java工具类

package org.common;

import lombok.extern.slf4j.Slf4j;

import java.util.*;
import java.util.stream.Collectors;

@Slf4j
public final class CollectorHelper {

    /**
     * @param element
     * @param propertyName
     * @param <E>
     * @return
     */
    public static <E> List toList(Collection<E> element, String propertyName) {
        if (element == null) {
            return Collections.emptyList();
        }
        return element.stream().map(item -> {
            return ReflectCallField.getForInstance(item, propertyName);
        }).collect(Collectors.toList());
    }

    /**
     * @param element
     * @param propertyName
     * @param <E>
     * @return
     */
    public static <E> List extractList(Collection<E> element, String propertyName) {
        if (element == null) {
            return Collections.emptyList();
        }
        List dataList = new ArrayList();
        for (E item : element) {
            Object obj = ReflectCallField.getForInstance(item, propertyName);
            if (obj != null) {
                dataList.add(obj);
            }
        }
        return dataList;
    }

    /**
     * @param element
     * @param propertyName
     * @param <K>
     * @param <V>
     * @return
     */
    public static <K, V> Map<K, V> toMap(Collection<V> element, String propertyName) {
        if (element == null) {
            return Collections.emptyMap();
        }
        try {
            return (Map<K, V>) element.stream().collect(Collectors.toMap(item -> {
                return ReflectCallField.getForInstance(item, propertyName);
            }, item -> item));
        } catch (Exception e) {
            log.error(e.getMessage());
        }
        return Collections.emptyMap();
    }

    /**
     * @param element
     * @param propertyName
     * @param <K>
     * @param <V>
     * @return
     */
    public static <K, V> Map<K, V> extractMap(Collection<V> element, String propertyName) {
        if (element == null) {
            return Collections.emptyMap();
        }
        Map<K, V> dataMap = new HashMap();
        for (V item : element) {
            Object key = ReflectCallField.getForInstance(item, propertyName);
            if (key != null) {
                dataMap.put((K) key, item);
            }
        }
        return dataMap;
    }

}

package org.common;

import java.lang.reflect.Field;

public class ReflectCallField {

    /**
     * @param entryClass
     * @param fieldName
     * @param <T>
     * @return
     */
    public static <T> T getForStatic(Class entryClass, String fieldName) {
        if (entryClass == null) {
            return null;
        }
        T result = null;
        try {
            // 反射获取
            Field callField = entryClass.getDeclaredField(fieldName);
            callField.setAccessible(true);
            return (T) callField.get(entryClass);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }

    /**
     * @param entryClass
     * @param fieldName
     * @param value
     */
    public static void setForStatic(Class entryClass, String fieldName, Object value) {
        if (entryClass == null) {
            return;
        }
        try {
            Field callField = entryClass.getDeclaredField(fieldName);
            callField.setAccessible(true);
            callField.set(fieldName, value);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * @param entryObject
     * @param fieldName
     * @param <T>
     * @return
     */
    public static <T> T getForInstance(Object entryObject, String fieldName) {
        if (entryObject == null) {
            return null;
        }
        T result = null;
        try {
            // 反射获取
            Field callField = entryObject.getClass().getDeclaredField(fieldName);
            callField.setAccessible(true);
            return (T) callField.get(entryObject);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }

    /**
     * @param entryObject
     * @param fieldName
     * @param value
     */
    public static void setForInstance(Object entryObject, String fieldName, Object value) {
        if (entryObject == null) {
            return;
        }
        try {
            Field callField = entryObject.getClass().getDeclaredField(fieldName);
            callField.setAccessible(true);
            callField.set(entryObject, value);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

测试

package org.common;

import lombok.Data;

@Data
public class Franchisee {

    private Integer id;

    private String name;

}

package org.common;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public class CollectorHelperTest {

    public static void main(String[] args) {
        List<Franchisee> dataList = new ArrayList<>();
        Franchisee franchisee1 = new Franchisee();
        franchisee1.setId(1);
        franchisee1.setName("Franchisee1");
        dataList.add(franchisee1);
        Franchisee franchisee2 = new Franchisee();
        franchisee2.setId(2);
        franchisee2.setName("Franchisee2");
        dataList.add(franchisee2);
        Franchisee franchisee3 = new Franchisee();
        franchisee3.setName("Franchisee3");
        dataList.add(franchisee3);
        Franchisee franchisee4 = new Franchisee();
        franchisee4.setName("Franchisee4");
        dataList.add(franchisee4);
        //
        Map<Integer, Franchisee> dataMap = CollectorHelper.toMap(dataList, "id");
        System.out.println("dataMap = " + dataMap);
        Map<Integer, Franchisee> dataMap2 = CollectorHelper.extractMap(dataList, "id");
        System.out.println("dataMap2 = " + dataMap2);
        //
        List<Integer> idList = CollectorHelper.toList(dataList, "id");
        System.out.println("idList = " + idList);
        idList.forEach(id -> {
            System.out.println("id = " + id);
        });
        List<Integer> idList2 = CollectorHelper.extractList(dataList, "id");
        System.out.println("idList2 = " + idList2);
        idList2.forEach(id -> {
            System.out.println("id = " + id);
        });
    }

}