流程引擎实现（二）—排他网关

背景

在流程图中，时常会涉及到分支的判断，进入判断逻辑后，我们一般只会从分支的一个出口出来，然后往下继续执行，这在流程引擎中，称之为排他网关（Exclusive Gateway)，排他网关用于在流程执行过程中做出决策，基于流程中的条件来选择一个唯一的路径继续执行。

下面我们以登录为例，在登录流程中，会依次执行下列流程：

• 账号定位：根据入参定位账号信息
• 密码检查：根据获取的账号信息，以及输入的密码，比对密码信息是否正确
• 状态检查：检查用户状态，判断是否被盗、冻结等
• 登录核身判断：
  1. 状态检查通过，颁发登录token
  2. 状态检查不通过，设置核身相关信息，如核身类型等
• 创建token：状态检查通过，则下发登录态token，若不通过，下发核身token

具体的流程图如下所示：

设计思路

原先的执行方式

• 根据流程id，解析流程配置文件，获取ActivitiFlow
• 遍历ActivitiFlow的所有节点，依次执行节点活动

修改后的执行方式

• 根据流程id，解析流程配置文件，获取ActivitiFlow
• 执行流程节点活动
  • 对于ServiceTask，转为IServiceTask执行execute方法
  • 对于排他网关，转为IExeclusiveGateway执行parseCredential方法
• 节点执行完毕后，根据sequenceFlow连线信息，获取下一个节点（对于网关，会加上凭证credential的判断，来决策下一个节点）

实现

首先，我们根据上述流程图，定义流程文件内容如下：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<activiti id="register_flow">
    <!--节点定义-->
    <startEvent id="startEvent"/>
    <serviceTask id="userLocate" name="userLocate" description="账号定位" class="com.yang.business.activiti.login.UserLocateActivity"/>
    <serviceTask id="passwordCheck" name="passwordCheck" description="密码检查" class="com.yang.business.activiti.login.PasswordCheckActivity"/>
    <serviceTask id="userAccountStatusCheck" name="userAccountStatusCheck" description="账号状态检查" class="com.yang.business.activiti.login.UserAccountStatusCheckActivity"/>
    <exclusiveGateway id="needBuildIdentityAction" name="needBuildIdentityAction" description="是否需要转核身" class="com.yang.business.activiti.login.NeedTransfer2IdentityExclusiveGateway"/>
    <serviceTask id="buildIdentityAction" name="buildIdentityAction" description="核身行为构建" class="com.yang.business.activiti.login.BuildIdentityActionActivity"/>
    <serviceTask id="buildUserToken" name="buildUserToken" description="创建用户token" class="com.yang.business.activiti.common.BuildUserTokenActivity"/>
    <endEvent id="endEvent"/>

    <!--节点执行顺序编排-->
    <sequenceFlow source="startEvent" target="userLocate"/>
    <sequenceFlow source="userLocate" target="passwordCheck"/>
    <sequenceFlow source="passwordCheck" target="userAccountStatusCheck"/>
    <sequenceFlow source="userAccountStatusCheck" target="needBuildIdentityAction"/>
    <sequenceFlow source="needBuildIdentityAction" target="buildIdentityAction" credential="identity"/>
    <sequenceFlow source="needBuildIdentityAction" target="buildUserToken" credential="login"/>
    <sequenceFlow source="buildIdentityAction" target="buildUserToken"/>
    <sequenceFlow source="buildUserToken" target="endEvent"/>
</activiti>

对于节点与节点之间的联系，是通过sequenceFlow来实现的，而目前我们的sequenceFlow只有source和target这两个信息，前者表示来源，后者表示去处，此时的sequenceFlow是没有阻塞条件的，当出现一个source有多个target时，我们可以在sequenceFlow加上阻塞条件，用于根据上下文信息，决策需要走哪一条路径。修改后的sequenceFlow如下，我们新增一个crendential字段，用于表示当上下文中凭证信息为相关值时，才可以走这条连线。

package com.yang.core.infrastructure.flow.activiti.model;

import lombok.Data;

import java.io.Serializable;

@Data
public class SequenceFlowNode implements Serializable {

    private String source;

    private String target;

    private String credential;

}

在上一节中，我们定义的activitiFlow流程模型结构如下，此时的activitiFlow对sequenceFlow不感知，因为之前涉及的时候，不存在一个来源对应多个去处的连线，所以获取节点顺序，依次执行即可。

package com.yang.core.infrastructure.flow.activiti.model;

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

public class ActivitiFlow {
    private String id;

    private List<FlowNode> flowNodeList = new ArrayList<>();

    public void addFlowNode(FlowNode flowNode) {
        this.flowNodeList.add(flowNode);
    }

    public List<FlowNode> getFlowNodeList() {
        return this.flowNodeList;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }
}

当前模型显然无法支持我们的排他网关，因为排他网关的入口是一个，但是出口可以是多个的，而List结构，只能支持一对一的顺序串联，所以我们对ActivitiFlow模型进行改造，使其能支持我们的一对多逻辑，同时，对模型进行充血，将一些决策逻辑收敛到模型中。

package com.yang.core.infrastructure.flow.activiti.model;

import lombok.Data;
import org.apache.commons.lang3.StringUtils;

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

@Data
public class ActivitiFlow {
    private String id;

    private FlowNode startNode;

    private FlowNode endNode;

    private List<SequenceFlowNode> sequenceFlowNodeList;

    private Map<String, FlowNode> nodeId2FlowNodeMap;

    public FlowNode chooseNextNode(FlowNode curNode, String credential) {
        String sourceNodeId = curNode.getId();
        String targetNodeId = null;
        for (SequenceFlowNode sequenceFlowNode : sequenceFlowNodeList) {
            if (!sequenceFlowNode.getSource().equals(sourceNodeId)) {
                continue;
            }
            if (StringUtils.isEmpty(sequenceFlowNode.getCredential())) {
                continue;
            }
            if (sequenceFlowNode.getCredential().equals(credential)) {
                targetNodeId = sequenceFlowNode.getTarget();
                break;
            }
        }
        return nodeId2FlowNodeMap.get(targetNodeId);
    }

    public FlowNode getNextNode(FlowNode curNode) {
        String sourceNodeId = curNode.getId();
        String targetNodeId = null;
        for (SequenceFlowNode sequenceFlowNode : sequenceFlowNodeList) {
            if (sequenceFlowNode.getSource().equals(sourceNodeId)) {
                targetNodeId = sequenceFlowNode.getTarget();
                break;
            }
        }
        return nodeId2FlowNodeMap.get(targetNodeId);
    }
}

因为ActivitiFlow的模型结构有所变更，因此，我们需要修改对应的解析器，以适应当前结构。首先修改XmlActivitiFileParser的parseSequenceFlowNode方法，增加对credential字段的解析：

/**
    * 解析流程执行顺序节点
    * @param attributes
    * @return
    */
   private SequenceFlowNode parseSequenceFlowNode(NamedNodeMap attributes) {
       Node sourceNode = attributes.getNamedItem("source");
       Node targetNode = attributes.getNamedItem("target");
       if (sourceNode != null && targetNode != null) {
           SequenceFlowNode sequenceFlowNode = new SequenceFlowNode();
           sequenceFlowNode.setSource(sourceNode.getNodeValue());
           sequenceFlowNode.setTarget(targetNode.getNodeValue());

           Node credentialNode = attributes.getNamedItem("credential");
           if (credentialNode != null) {
               sequenceFlowNode.setCredential(credentialNode.getNodeValue());
           }
           return sequenceFlowNode;
       }
       return null;
   }

其次，修改AbstractActivitiParser，使其能正确解析ActivitiFlow

package com.yang.core.infrastructure.flow.activiti.parser;


import com.yang.api.common.ErrorCode;
import com.yang.api.common.exception.UicException;
import com.yang.core.infrastructure.flow.activiti.enums.FlowNodeType;
import com.yang.core.infrastructure.flow.activiti.model.ActivitiFlow;
import com.yang.core.infrastructure.flow.activiti.model.FlowNode;
import com.yang.core.infrastructure.flow.activiti.model.SequenceFlowNode;
import com.yang.core.infrastructure.utils.SpringContextUtil;

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

public abstract class AbstractActivitiFileParser implements IActivitiFileParser{

    /**
     * 填充流程节点内容
     * @param flowNode
     * @param flowNodeType
     */
    protected void richFlowNode(FlowNode flowNode, FlowNodeType flowNodeType) {
        if (flowNodeType != FlowNodeType.SERVICE_TASK && flowNodeType != FlowNodeType.EXCLUSIVE_GATEWAY) {
            return;
        }
        try {
            // 填充target对象
            Class<?> aClass = Class.forName(flowNode.getClassPath());
            Object target = SpringContextUtil.getBeanByType(aClass);
            flowNode.setTarget(target);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    /**
     * 根据连线顺序，对流程节点进行排序，构建相应的流程flow
     * @param fileName
     * @param flowNodeList
     * @param sequenceFlowNodeList
     * @return
     */
    protected ActivitiFlow buildActivitiFlow(String fileName,
                                             List<FlowNode> flowNodeList,
                                             List<SequenceFlowNode> sequenceFlowNodeList) {
        String startNodeId = getStartNodeId(sequenceFlowNodeList);
        String endNodeId = getEndNodeId(sequenceFlowNodeList);
        Map<String, FlowNode> nodeId2FlowNodeMap = flowNodeList.stream()
                .collect(Collectors.toMap(FlowNode::getId, Function.identity()));

        ActivitiFlow activitiFlow = new ActivitiFlow();
        activitiFlow.setId(fileName);
        activitiFlow.setStartNode(nodeId2FlowNodeMap.get(startNodeId));
        activitiFlow.setEndNode(nodeId2FlowNodeMap.get(endNodeId));
        activitiFlow.setNodeId2FlowNodeMap(nodeId2FlowNodeMap);
        activitiFlow.setSequenceFlowNodeList(sequenceFlowNodeList);
        return activitiFlow;
    }

    /**
     * 获取结束节点id
     * @param sequenceFlowNodeList
     * @return
     */
    private String getEndNodeId(List<SequenceFlowNode> sequenceFlowNodeList) {
        List<String> oneNodeIds = filterCountOneNodeId(sequenceFlowNodeList);
        Set<String> oneNodeIdSet = new HashSet<>(oneNodeIds);
        String endNodeId = null;
        for (SequenceFlowNode sequenceFlowNode : sequenceFlowNodeList) {
            String target = sequenceFlowNode.getTarget();
            if (oneNodeIdSet.contains(target)) {
                endNodeId = target;
                break;
            }
        }
        return endNodeId;
    }

    /**
     * 获取开始节点id
     * @param sequenceFlowNodeList
     * @return
     */
    private String getStartNodeId(List<SequenceFlowNode> sequenceFlowNodeList) {
        List<String> oneNodeIds = filterCountOneNodeId(sequenceFlowNodeList);
        Set<String> oneNodeIdSet = new HashSet<>(oneNodeIds);
        String startNodeId = null;
        for (SequenceFlowNode sequenceFlowNode : sequenceFlowNodeList) {
            String source = sequenceFlowNode.getSource();
            if (oneNodeIdSet.contains(source)) {
                startNodeId = source;
                break;
            }
        }
        return startNodeId;
    }


    /**
     * 过滤计数次数只有1次的nodeId，只有startEvent和endEvent会计数1次，其他都是两次，如果是网关，那么次数会更多
     * @param sequenceFlowNodeList
     * @return
     */
    private List<String> filterCountOneNodeId(List<SequenceFlowNode> sequenceFlowNodeList) {
        Map<String, Integer> countNodeIdMap = new HashMap<>();
        for (SequenceFlowNode sequenceFlowNode : sequenceFlowNodeList) {
            Integer sourceCount = countNodeIdMap.getOrDefault(sequenceFlowNode.getSource(), 0);
            countNodeIdMap.put(sequenceFlowNode.getSource(), sourceCount + 1);

            Integer targetCount = countNodeIdMap.getOrDefault(sequenceFlowNode.getTarget(), 0);
            countNodeIdMap.put(sequenceFlowNode.getTarget(), targetCount + 1);
        }
        List<String> countOneNodeIds = new ArrayList<>();
        countNodeIdMap.forEach((nodeId, count) -> {
            if (count == 1) {
                countOneNodeIds.add(nodeId);
            }
        });
        if (countOneNodeIds.size() > 2) {
            throw new UicException(ErrorCode.ACTIVITI_PARSER_ERROR);
        }
        return countOneNodeIds;
    }

}

最后，修改ActivitiManager类，对排他网关做定制处理，根据网关返回的凭证值，决策出下一个节点是哪一个。

package com.yang.core.infrastructure.flow.activiti;


import com.yang.api.common.ErrorCode;
import com.yang.api.common.exception.UicException;
import com.yang.core.infrastructure.flow.activiti.enums.FlowNodeType;
import com.yang.core.infrastructure.flow.activiti.function.IExclusiveGateway;
import com.yang.core.infrastructure.flow.activiti.function.IServiceTask;
import com.yang.core.infrastructure.flow.activiti.model.ActivitiFlow;
import com.yang.core.infrastructure.flow.activiti.model.FlowNode;
import com.yang.core.infrastructure.flow.activiti.parser.IActivitiFileParser;
import com.yang.core.infrastructure.flow.activiti.request.ActivitiEngineRequest;
import com.yang.core.infrastructure.flow.activiti.response.ActivitiEngineResponse;
import com.yang.core.infrastructure.utils.SpringContextUtil;

import java.util.HashMap;
import java.util.Map;

public class ActivitiFlowManager {
    private static Map<String, ActivitiFlow> id2ActivitiFlowCache = new HashMap<>();

    public static ActivitiFlow getActivitiFlow(String flowName) {
        ActivitiFlow activitiFlow = id2ActivitiFlowCache.get(flowName);
        if (activitiFlow != null) {
            return activitiFlow;
        }
        IActivitiFileParser iActivitiFileParser = SpringContextUtil.getBeanByType(IActivitiFileParser.class);
        synchronized (flowName.intern()) {
            activitiFlow = id2ActivitiFlowCache.get(flowName);
            if (activitiFlow != null) {
                return activitiFlow;
            }
            activitiFlow = iActivitiFileParser.parseActivitiFlow(flowName);
            if (activitiFlow == null) {
                throw new UicException(ErrorCode.ACTIVITI_NOT_FOUND_ERROR);
            }
            id2ActivitiFlowCache.put(flowName, activitiFlow);
        }
        return activitiFlow;
    }

    /**
     * 流程引擎执行方法
     * @param flowName
     * @param activitiEngineRequest
     * @return
     * @param <Request>
     * @param <Response>
     */
    public static <Request, Response> ActivitiEngineResponse<Response> startEngine(String flowName,
                                                                                   ActivitiEngineRequest<Request> activitiEngineRequest) {
        ActivitiFlow activitiFlow = getActivitiFlow(flowName);
        ActivitiEngineResponse<Response> activitiEngineResponse = new ActivitiEngineResponse<>();
        FlowNode curNode = activitiFlow.getStartNode();
        while (curNode != null) {
            FlowNodeType flowNodeType = curNode.getFlowNodeType();
            FlowNode nextFlow = null;
            switch (flowNodeType) {
                case START_EVENT:
                    break;
                case END_EVENT:
                    break;
                case SERVICE_TASK:
                    executeServiceTask(activitiEngineRequest, activitiEngineResponse, curNode);
                    break;
                case EXCLUSIVE_GATEWAY:
                    nextFlow = executeExclusiveGateway(activitiEngineRequest, activitiEngineResponse, curNode, activitiFlow);
                    break;
            }
            if (nextFlow != null) {
                curNode = nextFlow;
            } else {
                curNode = activitiFlow.getNextNode(curNode);
            }
        }
        return activitiEngineResponse;
    }

    private static <Request, Response> FlowNode executeExclusiveGateway(ActivitiEngineRequest<Request> activitiEngineRequest,
                                                                    ActivitiEngineResponse<Response> activitiEngineResponse,
                                                                    FlowNode curNode,
                                                                    ActivitiFlow activitiFlow) {
        IExclusiveGateway iExclusiveGateway = (IExclusiveGateway) curNode.getTarget();
        String credential = iExclusiveGateway.chooseNextNode(activitiEngineRequest, activitiEngineResponse);
        return activitiFlow.chooseNextNode(curNode, credential);
    }

    private static <Request, Response> void executeServiceTask(ActivitiEngineRequest<Request> activitiEngineRequest,
                                                               ActivitiEngineResponse<Response> activitiEngineResponse, FlowNode flowNode) {
        IServiceTask iServiceTask = (IServiceTask) flowNode.getTarget();
        iServiceTask.execute(activitiEngineRequest, activitiEngineResponse);
    }
}

这里的IExclusiveGateway类定义如下：

package com.yang.core.infrastructure.flow.activiti.function;

import com.yang.core.infrastructure.flow.activiti.request.ActivitiEngineRequest;
import com.yang.core.infrastructure.flow.activiti.response.ActivitiEngineResponse;

public interface IExclusiveGateway extends IActivitiService {
    public static final String CREDENTIAL = "credential";

    default void execute(ActivitiEngineRequest request, ActivitiEngineResponse response) {
        String credential = chooseNextNode(request, response);
        request.getContext().put(CREDENTIAL, credential);
    }

    String chooseNextNode(ActivitiEngineRequest request, ActivitiEngineResponse response);

}

其具体实现示例如下：

package com.yang.business.activiti.login;

import com.yang.api.common.ErrorCode;
import com.yang.api.common.exception.UicException;
import com.yang.core.infrastructure.flow.activiti.function.IExclusiveGateway;
import com.yang.core.infrastructure.flow.activiti.request.ActivitiEngineRequest;
import com.yang.core.infrastructure.flow.activiti.response.ActivitiEngineResponse;
import org.springframework.stereotype.Component;

@Component
public class NeedTransfer2IdentityExclusiveGateway implements IExclusiveGateway {
    @Override
    public String chooseNextNode(ActivitiEngineRequest request, ActivitiEngineResponse response) {
        Object needIdentityObj = response.getContext().get("needIdentity");
        if (needIdentityObj != null) {
            boolean needIdentity = (Boolean) needIdentityObj;
            if (needIdentity) {
                return "identity";
            }
            return "login";
        }
        throw new UicException(ErrorCode.ACTIVITI_EXECUTE_ERROR);
    }
}

测试

这里准备两个账号，一个普通账号，一个被盗账号，被盗账号会进入登录转核身节点，在该节点中，会打印控制台信息——“登录转核身======”，依次登录普通账号和被盗账号，结果如下：

规则引擎决策

上述实现方式，有一个问题在于，我们的判断条件是一个隐式的判断条件，即sequenceFlow线条上指定的credential值和IExclusiveGateway网关产出的值相同时，可以进入该sequenceFlow线条指引的分支连线。这其实就是一个等于的判断，但是这种判断方式不够灵活，如果我们后续的需求是某个值大于、小于或不等于时，才能进行分支，那么显然现在这种方式是不能满足的，因此，我们需要引入规则引擎，通过执行规则引擎的方式，来进行决策。

整体的思路如下：

• 网关节点，根据业务流程需要进行判断，并设置流程上下文值
• 网关节点执行完毕后，根据sequenceFlow条件，和流程上下文信息，调用规则引擎，判断是否符合条件，符合条件则走到sequenceFlow对应分支

流程上下文参数简化

之前定义的ActivitiRequest和ActivitiResponse类的内容如下：

@Data
public class ActivitiEngineRequest <T> implements Serializable {

    /**
     * 场景code
     */
    private String scenarioCode;

    private T baseRequest;

    private Map<String, Object> context = new HashMap<>();
}



@Data
public class ActivitiEngineResponse <T> implements Serializable {
    /**
     * 场景code
     */
    private String scenarioCode;

    private T response;

    private Map<String, Object> context = new HashMap<>();
}

这两个类的字段有些重复，包括场景code和流程上下文context字段，特别是流程上下文字段，当我们需要塞值到上下文中时，有时候不好判断要放request的上下文还是response的上下文，其实感觉这里放request和放response都可以，为了减少歧义，这里将这两个类进行聚合，收敛到一个类中，即ActivitiExecuteContext类，其内容如下：

package com.yang.core.infrastructure.flow.activiti.context;

import lombok.Data;

import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;

@Data
public class ActivitiExecuteContext<Request, Response> implements Serializable {
    /**
     * 场景code
     */
    private String scenarioCode;

    private Request baseRequest;
    
    private Response baseResponse;

    private Map<String, Object> context = new HashMap<>();
}

通过ActivitiExecuteContext来替换原先的ActivitiEngineRequest和ActivitiEngineResponse, 所以要修改之前用到过那两个类的接口和实现：

package com.yang.core.infrastructure.flow.activiti.function;


import com.yang.core.infrastructure.flow.activiti.context.ActivitiExecuteContext;

public interface IActivitiService {
    void execute(ActivitiExecuteContext activitiExecuteContext);
}


package com.yang.core.infrastructure.flow.activiti.function;

import com.yang.core.infrastructure.flow.activiti.context.ActivitiExecuteContext;

public interface IExclusiveGateway extends IActivitiService {
    default void execute(ActivitiExecuteContext activitiExecuteContext) {
        parseCredential(activitiExecuteContext);
    }

    void parseCredential(ActivitiExecuteContext activitiExecuteContext);

}


package com.yang.core.infrastructure.flow.activiti.function;

import com.yang.core.infrastructure.flow.activiti.context.ActivitiExecuteContext;
public interface IServiceTask<DomainRequest, DomainResponse> extends IActivitiService {
    default void execute(ActivitiExecuteContext activitiExecuteContext) {
        DomainRequest domainRequest = buildDomainRequest(activitiExecuteContext);
        if (domainRequest != null) {
            DomainResponse domainResponse = apply(domainRequest);
            attachment(domainResponse, activitiExecuteContext);
            return;
        }
        doElse(activitiExecuteContext);
    }

    /**
     * 默认不实现，一般先转为domain Request，然后调用领域层方法，进行转化，doElse适用于目前领域层无法支持相关实现，顾需要在activity层进行适配的逻辑
     */
    default void doElse(ActivitiExecuteContext activitiExecuteContext) {}

    /**
     * 入参转化
     * @param activitiExecuteContext
     * @return
     */
    DomainRequest buildDomainRequest(ActivitiExecuteContext activitiExecuteContext);

    /**
     * 领域服务调用
     * @param domainRequest
     * @return
     */
    DomainResponse apply(DomainRequest domainRequest);

    /**
     * 领域服务调用结果填充
     * @param domainResponse
     * @param activitiExecuteContext
     */
    void attachment(DomainResponse domainResponse, ActivitiExecuteContext activitiExecuteContext);
}

引入规则引擎

市面上常见的开源规则引擎有easy-rules、 Drools、Aviator，这里使用Aviator来作为规则引擎进行决策，首先引入相关的依赖：

<dependency>
           <groupId>com.googlecode.aviator</groupId>
           <artifactId>aviator</artifactId>
           <version>5.1.4</version>
       </dependency>

然后创建相关的工具类

package com.yang.core.infrastructure.rule;

import com.googlecode.aviator.AviatorEvaluator;

import java.util.HashMap;
import java.util.Map;

public class AviatorUtil {
    public static Object execute(String condition, Map<String, Object> env) {
        return AviatorEvaluator.execute(condition, env);
    }

    public static boolean match(String condition, Map<String, Object> env) {
        return (Boolean) execute(condition, env);
    }

    public static void main(String[] args) {
        Map<String, Object> env = new HashMap<>();
        env.put("flow", "identity");
        String condition = "flow == 'identity'";
        System.out.println(match(condition, env));
    }
}

修改流程配置

原先的网关连线，通过credential来拦截是否符合条件，现在我们引入规则引擎后，可以在sequenceFlow上，通过表达式来进行拦截判断，首先修改sequenceFlow，添加condition条件字段

package com.yang.core.infrastructure.flow.activiti.model;

import lombok.Data;

import java.io.Serializable;

@Data
public class SequenceFlowNode implements Serializable {

    private String source;

    private String target;

    private String condition;

}

然后修改流程配置文件

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<activiti id="register_flow">
    <!--节点定义-->
    <startEvent id="startEvent"/>
    <serviceTask id="userLocate" name="userLocate" description="账号定位" class="com.yang.business.activiti.login.UserLocateActivity"/>
    <serviceTask id="passwordCheck" name="passwordCheck" description="密码检查" class="com.yang.business.activiti.login.PasswordCheckActivity"/>
    <serviceTask id="userAccountStatusCheck" name="userAccountStatusCheck" description="账号状态检查" class="com.yang.business.activiti.login.UserAccountStatusCheckActivity"/>
    <exclusiveGateway id="needBuildIdentityAction" name="needBuildIdentityAction" description="是否需要转核身" class="com.yang.business.activiti.login.NeedTransfer2IdentityExclusiveGateway"/>
    <serviceTask id="buildIdentityAction" name="buildIdentityAction" description="核身行为构建" class="com.yang.business.activiti.login.BuildIdentityActionActivity"/>
    <serviceTask id="buildUserToken" name="buildUserToken" description="创建用户token" class="com.yang.business.activiti.common.BuildUserTokenActivity"/>
    <endEvent id="endEvent"/>

    <!--节点执行顺序编排-->
    <sequenceFlow source="startEvent" target="userLocate"/>
    <sequenceFlow source="userLocate" target="passwordCheck"/>
    <sequenceFlow source="passwordCheck" target="userAccountStatusCheck"/>
    <sequenceFlow source="userAccountStatusCheck" target="needBuildIdentityAction"/>
    <sequenceFlow source="needBuildIdentityAction" target="buildIdentityAction" condition="flow == 'identity'"/>
    <sequenceFlow source="needBuildIdentityAction" target="buildUserToken" condition="flow == 'login'"/>
    <sequenceFlow source="buildIdentityAction" target="buildUserToken"/>
    <sequenceFlow source="buildUserToken" target="endEvent"/>
</activiti>

从上面的配置文件中，我们可以看出，当上下文的flow值为identity时，走buildIdentityAction节点，当上下文的flow值为login时，走buildUserToken节点，那么，在网关节点needBuildIdentityAction中，它的作用就是根据流程当前执行内容，对流程上下文的flow进行赋值，其具体实现如下：

package com.yang.business.activiti.login;

import com.yang.api.common.ErrorCode;
import com.yang.api.common.exception.UicException;
import com.yang.core.infrastructure.flow.activiti.context.ActivitiExecuteContext;
import com.yang.core.infrastructure.flow.activiti.function.IExclusiveGateway;
import org.springframework.stereotype.Component;

@Component
public class NeedTransfer2IdentityExclusiveGateway implements IExclusiveGateway {
    @Override
    public void parseCredential(ActivitiExecuteContext activitiExecuteContext) {
        Object needIdentityObj = activitiExecuteContext.getContext().get("needIdentity");
        if (needIdentityObj != null) {
            boolean needIdentity = (Boolean) needIdentityObj;
            if (needIdentity) {
                activitiExecuteContext.getContext().put("flow", "identity");
                return;
            }
            activitiExecuteContext.getContext().put("flow", "login");
            return;
        }
        throw new UicException(ErrorCode.ACTIVITI_EXECUTE_ERROR);
    }
}

然后，因为我们之前将决策的逻辑放到activitiFlow类中，所以这里需要对activitiFlow的决策方法进行修改，修改内容如下：

package com.yang.core.infrastructure.flow.activiti.model;

import com.yang.core.infrastructure.rule.AviatorUtil;
import lombok.Data;

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

@Data
public class ActivitiFlow {
    private String id;

    private FlowNode startNode;

    private FlowNode endNode;

    private List<SequenceFlowNode> sequenceFlowNodeList;

    private Map<String, FlowNode> nodeId2FlowNodeMap;

    public FlowNode chooseNextNode(FlowNode curNode, Map<String, Object> flowContext) {
        String sourceNodeId = curNode.getId();
        String targetNodeId = null;
        List<SequenceFlowNode> sequenceFlowNodes = new ArrayList<>();
        for (SequenceFlowNode sequenceFlowNode : sequenceFlowNodeList) {
            if (sequenceFlowNode.getSource().equals(sourceNodeId)) {
                sequenceFlowNodes.add(sequenceFlowNode);
            }
        }
        if (sequenceFlowNodes.size() == 1) {
            targetNodeId = sequenceFlowNodes.get(0).getTarget();
        } else {
            // 网关判断
            for (SequenceFlowNode sequenceFlowNode : sequenceFlowNodes) {
                String condition = sequenceFlowNode.getCondition();
                if (AviatorUtil.match(condition, flowContext)) {
                    targetNodeId = sequenceFlowNode.getTarget();
                    break;
                }
            }
        }
        return nodeId2FlowNodeMap.get(targetNodeId);
    }

}

测试

启动项目，分别测试普通账号和被盗账号，结果如下：