How to Implement Service Tasks in Activiti 7 with Spring Boot

Environment: Spring Boot 2.3.12.RELEASE + Activiti 7.1.0.M6

Introduction

In Activiti, a ServiceTask is a node that can execute custom service logic after the previous task completes, such as recording logs automatically before moving to the next task.

After the previous task finishes, the process can automatically perform operations like logging, then proceed to the next task.

Process Design

Write Service Class

public class LogService implements JavaDelegate {
    @Override
    public void execute(DelegateExecution execution) {
        System.out.println("开始记录日志");
    }
}

The service class must implement the JavaDelegate interface.

Configure ServiceTask Node

Method 1: Directly specify the service class.

Method 2: Use a delegate expression.

Method 3: Call a method on a custom Spring bean.

All three methods allow execution of local service logic.

Process Definition (BPMN XML)

<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
    xmlns:activiti="http://activiti.org/bpmn"
    xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI"
    xmlns:omgdc="http://www.omg.org/spec/DD/20100524/DC"
    xmlns:omgdi="http://www.omg.org/spec/DD/20100524/DI"
    typeLanguage="http://www.w3.org/2001/XMLSchema"
    expressionLanguage="http://www.w3.org/1999/XPath"
    targetNamespace="http://www.st.org">
  <process id="st" name="st" isExecutable="true">
    <startEvent id="startevent1" name="Start"/>
    <userTask id="usertask1" name="办公用品申请" activiti:assignee="${userId}"/>
    <serviceTask id="servicetask1" name="生成申请日志" activiti:expression="${customService.log(execution)}"/>
    <sequenceFlow id="flow1" sourceRef="startevent1" targetRef="usertask1"/>
    <sequenceFlow id="flow2" sourceRef="usertask1" targetRef="servicetask1"/>
    <endEvent id="endevent1" name="End"/>
    <userTask id="usertask2" name="部门经理" activiti:assignee="${jl}"/>
    <sequenceFlow id="flow3" sourceRef="usertask2" targetRef="endevent1"/>
    <sequenceFlow id="flow4" sourceRef="servicetask1" targetRef="usertask2"/>
  </process>
  <!-- ... -->
</definitions>

Start Process

@GetMapping("/start")
public R startProcess(String processDefinitionId, String userId) {
    Map<String, Object> variables = new HashMap<>();
    variables.put("userId", userId);
    // Start process instance (also starts the first task)
    ProcessInstance instance = ps.startProcessInstanceAssignVariables(processDefinitionId, variables);
    // Set the next executor
    variables.put("jl", "20000");
    ps.executionTask(variables, instance.getId());
    return R.success();
}

The execution result shows the ServiceTask executed successfully and the process moved to the department manager node.

Runtime task table (act_ru_task) confirms the transition.

ServiceTask execution completes the workflow.