Java工具類

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 {// 反射獲取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 {// 反射獲取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();}}}

測試

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);});}}