Master Activiti: Build a Multi‑Level Approval Workflow with Spring Boot

Workflow approval is a core capability of office OA systems, and implementing it with Activiti eliminates the need for custom code to drive process flow and branch decisions.

First draw a process diagram

Use the ActiBPM plugin in IntelliJ to create a BPMN diagram (apply.mpmn) that models a leave request with two‑level supervisor approval.

Level‑1 supervisor approval

If the leave exceeds three days, trigger level‑2 supervisor approval

Deploy the process diagram

Deploy the BPMN file to the Activiti engine using the RepositoryService.

<code>ProcessEngine engine = ProcessEngines.getDefaultProcessEngine();
RepositoryService repositoryService = engine.getRepositoryService();
repositoryService.createDeployment().addClasspathResource("processes/apply.bpmn").deploy();</code>

Start a process instance

Provide variables for the applicant and supervisors, then start the process by its key.

<code>Map<String, Object> variableMap = new HashMap<>();
variableMap.put("applyUser", "zhang3");
variableMap.put("supervisor", "li4");
variableMap.put("upperSupervisor", "wang5");
ProcessInstance instance = engine.getRuntimeService()
    .startProcessInstanceByKey("apply_processor_1", variableMap);</code>

Handle tasks

Query and complete tasks for each participant, setting result variables that the exclusive gateways later evaluate.

<code>// Applicant completes the request and sets the leave days
Task firstTask = engine.getTaskService().createTaskQuery().taskAssignee("zhang3").singleResult();
engine.getTaskService().complete(firstTask.getId(), Maps.newHashMap("day", 4));

// Level‑1 supervisor approves
Task secondTask = engine.getTaskService().createTaskQuery().taskAssignee("li4").singleResult();
engine.getTaskService().setVariable(secondTask.getId(), "result1", true);
engine.getTaskService().complete(secondTask.getId());

// Level‑2 supervisor (if needed) approves
Task thirdTask = engine.getTaskService().createTaskQuery().taskAssignee("wang5").singleResult();
if (thirdTask != null) {
    engine.getTaskService().setVariable(thirdTask.getId(), "result2", true);
    engine.getTaskService().complete(thirdTask.getId());
}
</code>

Exclusive gateways drive branch logic

The engine checks the conditions on the gateways. For example, the first gateway uses

#{result1==true}

to decide whether to continue to the second‑level approval, and the second uses

#{day>3}

to decide if the second‑level path is taken.

Workflow engine API overview

ProcessEngine

: entry point to obtain all services.

RepositoryService

: deploy and manage process definitions.

RuntimeService

: start, suspend, or delete process instances.

TaskService

: query, claim, and complete user tasks.

HistoryService

: query completed tasks, variables, and execution history.

Database tables used by Activiti

Activiti stores definitions, runtime data, history, and identity information in tables prefixed with

ACT_RE_

,

ACT_RU_

,

ACT_HI_

, and

ACT_ID_

respectively.

What is BPMN?

BPMN (Business Process Modeling Notation) is a standard visual language for describing business processes, enabling clear communication across departments.

Project basic configuration

Add Activiti dependency

<code>&lt;dependency&gt;
    &lt;groupId&gt;org.activiti&lt;/groupId&gt;
    &lt;artifactId&gt;activiti-spring-boot-starter-basic&lt;/artifactId&gt;
    &lt;version&gt;5.23.0&lt;/version&gt;
&lt;/dependency&gt;</code>

Configure datasource (H2 for learning)

<code>&lt;bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"&gt;
    &lt;property name="driverClassName" value="org.h2.Driver"/&gt;
    &lt;property name="url" value="jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1;mode=MySQL;"/&gt;
&lt;/bean&gt;

&lt;bean id="processEngineConfiguration" class="org.activiti.engine.impl.cfg.StandaloneProcessEngineConfiguration"&gt;
    &lt;property name="dataSource" ref="dataSource"/&gt;
    &lt;property name="databaseSchemaUpdate" value="true"/&gt;
&lt;/bean&gt;</code>

Further learning directions

Event types and listeners

Task types: user, service, script

Form management

Parallel gateways and other flow controls

Performance, ID generation, sharding

Conclusion

Activiti is ideal for multi‑user approval processes.

Workflow development consists of designing the BPMN diagram, deploying it, and driving instances via code.

Adding new process templates requires no additional engine code—only front‑end pages and simple back‑end interfaces.