看看使用策略模式之前的代码：

//        switch (type) {
//            case 0:
//                terme.setKhdmlist(dmList);
//                List<Kehu> list = getSdList$api(terme);
//                for (Kehu kehu : list) {
//                    map = new HashMap<String, String>();
//                    map.put(kehu.getKhdm(), kehu.getKhmc());
//                    mapList.add(map);
//                }
//                break;
//            case 1:
//                terme.setGhsdmlist(dmList);
//                List<Gonghuoshang> list1 = getGhsList$api(terme);
//                for (Gonghuoshang gonghuoshang : list1) {
//                    map = new HashMap<String, String>();
//                    map.put(gonghuoshang.getGhsdm(), gonghuoshang.getGhsmc());
//                    mapList.add(map);
//                }
//                break;
//            case 2:
//                terme.setKhdmlist(dmList);
//                List<Kehu> list2 = getKehuList$api(terme);
//                for (Kehu kehu : list2) {
//                    map = new HashMap<String, String>();
//                    map.put(kehu.getKhdm(), kehu.getKhmc());
//                    mapList.add(map);
//                }
//                break;
//            case 3:
//                terme.setCkdmlist(dmList);
//                List<Cangku> list3 = getCangkuList$api(terme);
//                for (Cangku cangku : list3) {
//                    map = new HashMap<String, String>();
//                    map.put(cangku.getCkdm(), cangku.getCkmc());
//                    mapList.add(map);
//                }
//                break;
//            case 4:
//                terme.setQddmlist(dmList);
//                List<Qudao> list4 = getQudaoList$api(terme);
//                for (Qudao qudao : list4) {
//                    map = new HashMap<String, String>();
//                    map.put(qudao.getQddm(), qudao.getQdmc());
//                    mapList.add(map);
//                }
//                break;
//            case 5:
//                terme.setQydmlist(dmList);
//                List<Quyu> list5 = getQuyuList$api(terme);
//                for (Quyu quyu : list5) {
//                    map = new HashMap<String, String>();
//                    map.put(quyu.getQydm(), quyu.getQymc());
//                    mapList.add(map);
//                }
//                break;
//            case 6:
//                terme.setPpdmlist(dmList);
//                List<Pinpai> list6 = getPinpaiList$api(terme);
//                for (Pinpai pinpai : list6) {
//                    map = new HashMap<String, String>();
//                    map.put(pinpai.getPpdm(), pinpai.getPpmc());
//                    mapList.add(map);
//                }
//                break;
//            default:
//                break;
//        }
//        for (SysLimitItemGroupmx itemGroupmx : resList) {
//            boolean flag = false;
//            if (isNotEmpty(mapList)) {
//                for (Map<String, String> map1 : mapList) {
//                    if (map1.containsKey(itemGroupmx.getDxdm())) {
//                        flag = true;
//                        if (!map1.containsValue(itemGroupmx.getDxmc())) {
//                            itemGroupmx.setBz(str + "编码对应的" + str + "名称不对！");
//                        }
//                        break;
//                    }
//                }
//            }
//            if (!flag) {
//                itemGroupmx.setBz(str + "编码对应的数据不存在！");
//            }
//        }

使用 策略模式 之后的代码：

枚举类：

public enum LimitItemTypeEnum {OUTMETHOD(-1 ,"-1", "输出方法"),SHOP    (0 ,"0", "XX"),SUPPLIER(1 ,"1", "XXX"),CUSTOMER(2 ,"2", "XX"),STORE   (3 ,"3", "XX"),CHANNEL (4 ,"4", "XX"),AREA    (5, "5", "XX"),BRAND   (6, "6", "XX"),;private final Integer number;private final String code;private final String info;LimitItemTypeEnum(Integer number, String code, String info) {this.number=number;this.code = code;this.info = info;}public String getCode() {return code;}public String getInfo() {return info;}public Integer getNumber() {return number;}public String getInfoByNumber(int numberIn){String infoOut="";for(LimitItemTypeEnum typeEnum:LimitItemTypeEnum.values()){if(typeEnum.getNumber()==numberIn){infoOut=typeEnum.getInfo();break;}}return infoOut;}}

接口：

public interface CheckListItemService {void check(Long tenantId,List<SysLimitItemGroupmx> mxList) throws Exception;}

实现类：

public class CheckAreaListItemServiceImpl extends ApiFrag implements CheckListItemService {@Overridepublic void check(Long tenantId,List<SysLimitItemGroupmx> mxList) throws Exception{String typeName= LimitItemTypeEnum.AREA.getInfo();Terme term=new Terme();term.setTenantId(tenantId);term.setQydmlist(listField2StrList(mxList,"dxdm"));List<Quyu> list = getQuyuList$api(term);Map<String, String> map  = new HashMap();;for (Quyu quyu : list) {map.put(quyu.getQydm(), quyu.getQymc());}for (SysLimitItemGroupmx itemGroupmx : mxList) {String key=itemGroupmx.getDxdm();boolean flag = map.containsKey(key);if(flag)    itemGroupmx.setDxmc(map.get(key));else    itemGroupmx.setBz(typeName + "编码对应的数据不存在！");itemGroupmx.setFlag(flag);}}}

public class CheckBrandListItemServiceImpl extends ApiFrag implements CheckListItemService {@Overridepublic void check(Long tenantId,List<SysLimitItemGroupmx> mxList) throws Exception{String typeName= LimitItemTypeEnum.BRAND.getInfo();Terme term=new Terme();term.setTenantId(tenantId);term.setPpdmlist(listField2StrList(mxList,"dxdm"));List<Pinpai> list = getPinpaiList$api(term);Map<String, String> map  = new HashMap();;for (Pinpai item : list) {map.put(item.getPpdm(), item.getPpmc());}for (SysLimitItemGroupmx itemGroupmx : mxList) {String key=itemGroupmx.getDxdm();boolean flag = map.containsKey(key);if(flag)    itemGroupmx.setDxmc(map.get(key));else    itemGroupmx.setBz(typeName + "编码对应的数据不存在！");itemGroupmx.setFlag(flag);}}}

上下文类：

public class CheckLimitItemProcessor {private final Map<Integer, CheckListItemService> strategyMap;public CheckLimitItemProcessor() {strategyMap = new HashMap<>();strategyMap.put(LimitItemTypeEnum.AREA.getNumber(), new CheckAreaListItemServiceImpl());strategyMap.put(LimitItemTypeEnum.BRAND.getNumber(), new CheckBrandListItemServiceImpl());strategyMap.put(LimitItemTypeEnum.CUSTOMER.getNumber(), new CheckCustomerListItemServiceImpl());strategyMap.put(LimitItemTypeEnum.SHOP.getNumber(), new CheckShopListItemServiceImpl());strategyMap.put(LimitItemTypeEnum.STORE.getNumber(), new CheckStoreListItemServiceImpl());strategyMap.put(LimitItemTypeEnum.SUPPLIER.getNumber(), new CheckSupplierListItemServiceImpl());}public void checkItem(Integer type,Long tenantId, List<SysLimitItemGroupmx> mxList)throws Exception{CheckListItemService strategy = strategyMap.get(type);if (strategy == null) {throw new IllegalArgumentException("Unsupported LimitItem type.");}strategy.check(tenantId,mxList);}}

 使用：

      CheckLimitItemProcessor processor = new CheckLimitItemProcessor();processor.checkItem(type,tenantId,resList);

 在java 中实际开发功能时候，我想绝大多数人应该是倾向于使用case when 的，而设计模式大部分用于架构层，至于该怎么用，我觉得还是黑猫白猫都行。