设计模式之组合模式(营销差异化人群发券，决策树引擎搭建场景)

前言：
往往很多大需求都是通过增删改查堆出来的，今天要一个需求if一下，明天加个内容else扩展一下。日积月累需求也就越来越大，扩展和维护的成本也就越来越高。往往大部分研发是不具备产品思维和整体业务需求导向的，总以为写好代码完成功能即可。但这样的不考虑扩展性的实现，很难让后续的需求都快速迭代，久而久之就会被陷入恶性循环，每天都有bug要改。

从上图可以看到这有点像螺丝🔩和螺母，通过一堆的链接组织出一棵结构树。而这种通过把相似对象(也可以称作是方法)组合成一组可被调用的结构树对象的设计思路叫做组合模式。

这种设计方式可以让你的服务组节点进行自由组合对外提供服务，例如你有三个原子校验功能(A：身份证、B：银行卡、C：手机号)服务并对外提供调用使用。有些调用方需要使用AB组合，有些调用方需要使用到CBA组合，还有一些可能只使用三者中的一个。那么这个时候你就可以使用组合模式进行构建服务，对于不同类型的调用方配置不同的组织关系树，而这个树结构你可以配置到数据库中也可以不断的通过图形界面来控制树结构。
用一坨坨代码实现


公司里要都是这样的程序员绝对省下不少成本，根本不要搭建微服务，一个工程搞定所有业务！

package oom.lm.design;import org.slf4j.Logger;
import org.slf4j.LoggerFactory;public class EngineController {private Logger logger = LoggerFactory.getLogger(EngineController.class);public String process(final String userId, final String userSex, final int userAge) {logger.info("ifelse实现方式判断用户结果。userId：{} userSex：{} userAge：{}", userId, userSex, userAge);if ("man".equals(userSex)) {if (userAge < 25) {return "果实A";}if (userAge >= 25) {return "果实B";}}if ("woman".equals(userSex)) {if (userAge < 25) {return "果实C";}if (userAge >= 25) {return "果实D";}}return null;}}

除了我们说的扩展性和每次的维护以外，这样的代码实现起来是最快的。而且从样子来看也很适合新人理解。
但是我劝你别写，写这样代码不是被扣绩效就是被开除。

package oom.lm.design.test;import oom.lm.design.EngineController;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;public class ApiTest {private Logger logger = LoggerFactory.getLogger(ApiTest.class);@Testpublic void test_EngineController() {EngineController engineController = new EngineController();String process = engineController.process("Oli09pLkdjh", "man", 29);logger.info("测试结果：{}", process);}}

组合模式重构代码

组合模式模型结构

树节点逻辑过滤器接口

package oom.lm.design.domain.service.logic;import oom.lm.design.domain.model.vo.TreeNodeLink;import java.util.List;
import java.util.Map;/******/
public interface LogicFilter {/*** 逻辑决策器** @param matterValue          决策值* @param treeNodeLineInfoList 决策节点* @return 下一个节点Id*/Long filter(String matterValue, List<TreeNodeLink> treeNodeLineInfoList);/*** 获取决策值** @param decisionMatter 决策物料* @return 决策值*/String matterValue(Long treeId, String userId, Map<String, String> decisionMatter);}

决策抽象类提供基础服务

package oom.lm.design.domain.service.logic;import oom.lm.design.domain.model.vo.TreeNodeLink;import java.util.List;
import java.util.Map;/******/
public abstract class BaseLogic implements LogicFilter {@Overridepublic Long filter(String matterValue, List<TreeNodeLink> treeNodeLinkList) {for (TreeNodeLink nodeLine : treeNodeLinkList) {if (decisionLogic(matterValue, nodeLine)){return nodeLine.getNodeIdTo();}}return 0L;}@Overridepublic abstract String matterValue(Long treeId, String userId, Map<String, String> decisionMatter);private boolean decisionLogic(String matterValue, TreeNodeLink nodeLink) {switch (nodeLink.getRuleLimitType()) {case 1:return matterValue.equals(nodeLink.getRuleLimitValue());case 2:return Double.parseDouble(matterValue) > Double.parseDouble(nodeLink.getRuleLimitValue());case 3:return Double.parseDouble(matterValue) < Double.parseDouble(nodeLink.getRuleLimitValue());case 4:return Double.parseDouble(matterValue) >= Double.parseDouble(nodeLink.getRuleLimitValue());case 5:return Double.parseDouble(matterValue) <= Double.parseDouble(nodeLink.getRuleLimitValue());default:return false;}}}

树节点逻辑实现类

package oom.lm.design.domain.service.logic.impl;import oom.lm.design.domain.service.logic.BaseLogic;import java.util.Map;public class UserAgeFilter extends BaseLogic {@Overridepublic String matterValue(Long treeId, String userId, Map<String, String> decisionMatter) {return decisionMatter.get("age");}}

package oom.lm.design.domain.service.logic.impl;import oom.lm.design.domain.service.logic.BaseLogic;import java.util.Map;public class UserGenderFilter extends BaseLogic {@Overridepublic String matterValue(Long treeId, String userId, Map<String, String> decisionMatter) {return decisionMatter.get("gender");}}

以上两个决策逻辑的节点获取值的方式都非常简单，只是获取用户的入参即可。实际的业务开发可以从数据库、RPC接口、缓存运算等各种方式获取。
决策引擎接口定义

package oom.lm.design.domain.service.engine;import oom.lm.design.domain.model.aggregates.TreeRich;
import oom.lm.design.domain.model.vo.EngineResult;import java.util.Map;public interface IEngine {EngineResult process(final Long treeId, final String userId, TreeRich treeRich, final Map<String, String> decisionMatter);}

决策节点配置

package oom.lm.design.domain.service.engine;import oom.lm.design.domain.service.logic.LogicFilter;
import oom.lm.design.domain.service.logic.impl.UserAgeFilter;
import oom.lm.design.domain.service.logic.impl.UserGenderFilter;import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;public class EngineConfig {static Map<String, LogicFilter> logicFilterMap;static {logicFilterMap = new ConcurrentHashMap<>();logicFilterMap.put("userAge", new UserAgeFilter());logicFilterMap.put("userGender", new UserGenderFilter());}public Map<String, LogicFilter> getLogicFilterMap() {return logicFilterMap;}public void setLogicFilterMap(Map<String, LogicFilter> logicFilterMap) {this.logicFilterMap = logicFilterMap;}}

基础决策引擎功能

package oom.lm.design.domain.service.engine;import oom.lm.design.domain.model.aggregates.TreeRich;
import oom.lm.design.domain.model.vo.EngineResult;
import oom.lm.design.domain.model.vo.TreeNode;
import oom.lm.design.domain.model.vo.TreeRoot;
import oom.lm.design.domain.service.logic.LogicFilter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;import java.util.Map;
public abstract class EngineBase extends EngineConfig implements IEngine {private Logger logger = LoggerFactory.getLogger(EngineBase.class);@Overridepublic abstract EngineResult process(Long treeId, String userId, TreeRich treeRich, Map<String, String> decisionMatter);protected TreeNode engineDecisionMaker(TreeRich treeRich, Long treeId, String userId, Map<String, String> decisionMatter) {TreeRoot treeRoot = treeRich.getTreeRoot();Map<Long, TreeNode> treeNodeMap = treeRich.getTreeNodeMap();// 规则树根IDLong rootNodeId = treeRoot.getTreeRootNodeId();TreeNode treeNodeInfo = treeNodeMap.get(rootNodeId);//节点类型[NodeType]；1子叶、2果实while (treeNodeInfo.getNodeType().equals(1)) {String ruleKey = treeNodeInfo.getRuleKey();LogicFilter logicFilter = logicFilterMap.get(ruleKey);String matterValue = logicFilter.matterValue(treeId, userId, decisionMatter);Long nextNode = logicFilter.filter(matterValue, treeNodeInfo.getTreeNodeLinkList());treeNodeInfo = treeNodeMap.get(nextNode);logger.info("决策树引擎=>{} userId：{} treeId：{} treeNode：{} ruleKey：{} matterValue：{}", treeRoot.getTreeName(), userId, treeId, treeNodeInfo.getTreeNodeId(), ruleKey, matterValue);}return treeNodeInfo;}}

这里主要提供决策树流程的处理过程，有点像通过链路的关系(性别、年龄)在二叉树中寻找果实节点的过程。
决策引擎的实现

package oom.lm.design.domain.service.engine.impl;import oom.lm.design.domain.model.aggregates.TreeRich;
import oom.lm.design.domain.model.vo.EngineResult;
import oom.lm.design.domain.model.vo.TreeNode;
import oom.lm.design.domain.service.engine.EngineBase;import java.util.Map;public class TreeEngineHandle extends EngineBase {@Overridepublic EngineResult process(Long treeId, String userId, TreeRich treeRich, Map<String, String> decisionMatter) {// 决策流程TreeNode treeNode = engineDecisionMaker(treeRich, treeId, userId, decisionMatter);// 决策结果return new EngineResult(userId, treeId, treeNode.getTreeNodeId(), treeNode.getNodeValue());}}

测试验证

package oom.lm.design.test;import com.alibaba.fastjson.JSON;
import oom.lm.design.domain.model.aggregates.TreeRich;
import oom.lm.design.domain.model.vo.EngineResult;
import oom.lm.design.domain.model.vo.TreeNode;
import oom.lm.design.domain.model.vo.TreeNodeLink;
import oom.lm.design.domain.model.vo.TreeRoot;
import oom.lm.design.domain.service.engine.IEngine;
import oom.lm.design.domain.service.engine.impl.TreeEngineHandle;
import org.junit.Before;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;public class ApiTest {private Logger logger = LoggerFactory.getLogger(ApiTest.class);private TreeRich treeRich;@Beforepublic void init() {// 节点：1TreeNode treeNode_01 = new TreeNode();treeNode_01.setTreeId(10001L);treeNode_01.setTreeNodeId(1L);treeNode_01.setNodeType(1);treeNode_01.setNodeValue(null);treeNode_01.setRuleKey("userGender");treeNode_01.setRuleDesc("用户性别[男/女]");// 链接：1->11TreeNodeLink treeNodeLink_11 = new TreeNodeLink();treeNodeLink_11.setNodeIdFrom(1L);treeNodeLink_11.setNodeIdTo(11L);treeNodeLink_11.setRuleLimitType(1);treeNodeLink_11.setRuleLimitValue("man");// 链接：1->12TreeNodeLink treeNodeLink_12 = new TreeNodeLink();treeNodeLink_12.setNodeIdFrom(1L);treeNodeLink_12.setNodeIdTo(12L);treeNodeLink_12.setRuleLimitType(1);treeNodeLink_12.setRuleLimitValue("woman");List<TreeNodeLink> treeNodeLinkList_1 = new ArrayList<>();treeNodeLinkList_1.add(treeNodeLink_11);treeNodeLinkList_1.add(treeNodeLink_12);treeNode_01.setTreeNodeLinkList(treeNodeLinkList_1);// 节点：11TreeNode treeNode_11 = new TreeNode();treeNode_11.setTreeId(10001L);treeNode_11.setTreeNodeId(11L);treeNode_11.setNodeType(1);treeNode_11.setNodeValue(null);treeNode_11.setRuleKey("userAge");treeNode_11.setRuleDesc("用户年龄");// 链接：11->111TreeNodeLink treeNodeLink_111 = new TreeNodeLink();treeNodeLink_111.setNodeIdFrom(11L);treeNodeLink_111.setNodeIdTo(111L);treeNodeLink_111.setRuleLimitType(3);treeNodeLink_111.setRuleLimitValue("25");// 链接：11->112TreeNodeLink treeNodeLink_112 = new TreeNodeLink();treeNodeLink_112.setNodeIdFrom(11L);treeNodeLink_112.setNodeIdTo(112L);treeNodeLink_112.setRuleLimitType(4);treeNodeLink_112.setRuleLimitValue("25");List<TreeNodeLink> treeNodeLinkList_11 = new ArrayList<>();treeNodeLinkList_11.add(treeNodeLink_111);treeNodeLinkList_11.add(treeNodeLink_112);treeNode_11.setTreeNodeLinkList(treeNodeLinkList_11);// 节点：12TreeNode treeNode_12 = new TreeNode();treeNode_12.setTreeId(10001L);treeNode_12.setTreeNodeId(12L);treeNode_12.setNodeType(1);treeNode_12.setNodeValue(null);treeNode_12.setRuleKey("userAge");treeNode_12.setRuleDesc("用户年龄");// 链接：12->121TreeNodeLink treeNodeLink_121 = new TreeNodeLink();treeNodeLink_121.setNodeIdFrom(12L);treeNodeLink_121.setNodeIdTo(121L);treeNodeLink_121.setRuleLimitType(3);treeNodeLink_121.setRuleLimitValue("25");// 链接：12->122TreeNodeLink treeNodeLink_122 = new TreeNodeLink();treeNodeLink_122.setNodeIdFrom(12L);treeNodeLink_122.setNodeIdTo(122L);treeNodeLink_122.setRuleLimitType(4);treeNodeLink_122.setRuleLimitValue("25");List<TreeNodeLink> treeNodeLinkList_12 = new ArrayList<>();treeNodeLinkList_12.add(treeNodeLink_121);treeNodeLinkList_12.add(treeNodeLink_122);treeNode_12.setTreeNodeLinkList(treeNodeLinkList_12);// 节点：111TreeNode treeNode_111 = new TreeNode();treeNode_111.setTreeId(10001L);treeNode_111.setTreeNodeId(111L);treeNode_111.setNodeType(2);treeNode_111.setNodeValue("果实A");// 节点：112TreeNode treeNode_112 = new TreeNode();treeNode_112.setTreeId(10001L);treeNode_112.setTreeNodeId(112L);treeNode_112.setNodeType(2);treeNode_112.setNodeValue("果实B");// 节点：121TreeNode treeNode_121 = new TreeNode();treeNode_121.setTreeId(10001L);treeNode_121.setTreeNodeId(121L);treeNode_121.setNodeType(2);treeNode_121.setNodeValue("果实C");// 节点：122TreeNode treeNode_122 = new TreeNode();treeNode_122.setTreeId(10001L);treeNode_122.setTreeNodeId(122L);treeNode_122.setNodeType(2);treeNode_122.setNodeValue("果实D");// 树根TreeRoot treeRoot = new TreeRoot();treeRoot.setTreeId(10001L);treeRoot.setTreeRootNodeId(1L);treeRoot.setTreeName("规则决策树");Map<Long, TreeNode> treeNodeMap = new HashMap<>();treeNodeMap.put(1L, treeNode_01);treeNodeMap.put(11L, treeNode_11);treeNodeMap.put(12L, treeNode_12);treeNodeMap.put(111L, treeNode_111);treeNodeMap.put(112L, treeNode_112);treeNodeMap.put(121L, treeNode_121);treeNodeMap.put(122L, treeNode_122);treeRich = new TreeRich(treeRoot, treeNodeMap);}@Testpublic void test_tree() {logger.info("决策树组合结构信息：\r\n" + JSON.toJSONString(treeRich));IEngine treeEngineHandle = new TreeEngineHandle();Map<String, String> decisionMatter = new HashMap<>();decisionMatter.put("gender", "man");decisionMatter.put("age", "29");EngineResult result = treeEngineHandle.process(10001L, "Oli09pLkdjh", treeRich, decisionMatter);logger.info("测试结果：{}", JSON.toJSONString(result));}
}

总结
1：从以上的决策树场景来看，组合模式主要解决的是一系列简单逻辑节点或者扩展的复杂逻辑节点在不同结构的组织下，对于外部的调用是仍然可以非常简单的。
2：这部分设计模式保证了开闭原则，无需更改模型结构你就可以提供新的逻辑节点的使用并配合组织出新的关系树。但如果是一些功能差异化非常大的接口进行包装就会变得比较困难，但也不是不能很好的处理，只不过需要做一些适配和特定化的开发。

好了 至此 设计模式之组合模式(营销差异化人群发券，决策树引擎搭建场景) 学习结束了 友友们 点点关注不迷路 老铁们！！！！！