Getting Started with Flowable Workflow Engine in Spring Boot – Part 4

1. Environment Preparation

Required stack: JDK 11+, Spring Boot 2.7.x, Flowable 6.8.0, MySQL 8.0.

2. Dependency Configuration

<dependencies>
    <!-- Spring Boot Web -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- Flowable Starter -->
    <dependency>
        <groupId>org.flowable</groupId>
        <artifactId>flowable-spring-boot-starter</artifactId>
        <version>6.8.0</version>
    </dependency>
    <!-- MySQL Driver -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.27</version>
    </dependency>
</dependencies>

3. Database Configuration

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/flowable?useSSL=false&serverTimezone=UTC
    username: root
    password: 123456
    driver-class-name: com.mysql.cj.jdbc.Driver
flowable:
  # Auto‑update DB schema
  database-schema-update: true
  # Full history level
  history-level: full
  # Disable async executor during development
  async-executor-activate: false

4. Process Definition and Deployment

Design a leave‑request BPMN file (e.g., leave-request.bpmn20.xml) with the following structure:

<definitions xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL">
    <process id="leaveProcess" name="请假流程">
        <startEvent id="start"/>
        <userTask id="applyTask" name="提交申请"/>
        <exclusiveGateway id="decision"/>
        <userTask id="managerApproval" name="经理审批"/>
        <endEvent id="end"/>
        <sequenceFlow sourceRef="start" targetRef="applyTask"/>
        <sequenceFlow sourceRef="applyTask" targetRef="decision"/>
        <sequenceFlow sourceRef="decision" targetRef="managerApproval" conditionExpression="${days <= 3}"/>
        <sequenceFlow sourceRef="managerApproval" targetRef="end"/>
    </process>
</definitions>

Place the BPMN file under src/main/resources/processes/ so that Spring Boot deploys it automatically, or deploy programmatically:

@Autowired
private RepositoryService repositoryService;

public void deployProcess() throws Exception {
    InputStream bpmnStream = new FileInputStream("path/to/leave-request.bpmn20.xml");
    repositoryService.createDeployment()
        .addInputStream("leave-request.bpmn20.xml", bpmnStream)
        .deploy();
}

5. Process Instance Operations

Start a process instance with variables:

@Autowired
private RuntimeService runtimeService;

public String startProcess() {
    Map<String, Object> variables = new HashMap<>();
    variables.put("days", 3); // process variable
    ProcessInstance instance = runtimeService.startProcessInstanceByKey("leaveProcess", variables);
    return instance.getId();
}

Query and complete tasks:

@Autowired
private TaskService taskService;

public void completeTask(String taskId) {
    Map<String, Object> variables = new HashMap<>();
    variables.put("approved", true);
    taskService.complete(taskId, variables);
}

public List<Task> getTasks(String assignee) {
    return taskService.createTaskQuery()
        .taskAssignee(assignee)
        .list();
}

6. Dynamic Task Assignment

Static assignment in BPMN:

<userTask id="managerApproval" name="经理审批" flowable:assignee="manager1"/>

Dynamic assignment using a process variable:

// Set variable when starting the process
variables.put("nextApprover", "user123");

// BPMN expression
<userTask id="task" name="动态任务" flowable:assignee="${nextApprover}"/>

7. History Data Query

@Autowired
private HistoryService historyService;

public List<HistoricProcessInstance> getHistoryInstances() {
    return historyService.createHistoricProcessInstanceQuery()
        .finished()
        .list();
}

public List<HistoricTaskInstance> getHistoryTasks(String processInstanceId) {
    return historyService.createHistoricTaskInstanceQuery()
        .processInstanceId(processInstanceId)
        .list();
}

8. Extension Features

Multi‑instance (countersign) task using flowable:candidateUsers or flowable:candidateGroups:

<userTask id="ccApproval" name="会签审批">
    <documentation>需所有成员审批通过</documentation>
    <multiInstanceLoopCharacteristics isSequential="false" flowable:collection="ccList" flowable:elementVariable="ccUser">
        <completionCondition>${nrOfCompletedInstances/nrOfInstances >= 1}</completionCondition>
    </multiInstanceLoopCharacteristics>
</userTask>

Email notification integrated with Spring Mail:

@Autowired
private JavaMailSender mailSender;

public void sendNotification(String to, String taskId) {
    mailSender.send(new SimpleMailMessage() {{
        setTo(to);
        setSubject("新任务待处理");
        setText("您有新任务，ID: " + taskId);
    }});
}

9. Docker Deployment

Package the application: mvn clean package Create a Docker image (Dockerfile):

FROM openjdk:11-jre
COPY target/flowable-demo.jar /app.jar
EXPOSE 8080
ENTRYPOINT ["java", "-jar", "/app.jar"]

Build and run the container:

docker build -t flowable-demo .
 docker run -d -p 8080:8080 --name flowable-app flowable-demo