Activiti Workflow Engine: Concepts, Configuration, and Hands‑On Java Examples

1. What is a workflow – A workflow automates business processes by passing documents, information, or tasks among participants according to predefined rules to achieve a business goal.

2. Activiti 7 Overview – Activiti is an open‑source BPMN 2.0 workflow engine that externalizes process management from business code, reducing upgrade effort and improving robustness.

3. Environment configuration – Create a MySQL database, add Maven dependencies (activiti‑engine, activiti‑spring, MySQL driver, Log4j, SLF4J, MyBatis, Commons‑DBCP, JUnit), and define activiti.cfg.xml and Spring beans for the data source and StandaloneProcessEngineConfiguration . The configuration sets databaseSchemaUpdate="true" to auto‑create the required tables.

4. Initializing Activiti tables

public class ActivitiInit {
    @Test
    public void GenActivitiTables() {
        ProcessEngineConfiguration cfg = ProcessEngineConfiguration.createProcessEngineConfigurationFromResource(
                "activiti.cfg.xml", "processEngineConfiguration");
        ProcessEngine engine = cfg.buildProcessEngine();
        System.out.println(engine);
    }

    @Test
    public void GenActivitiTables2() {
        ProcessEngine engine = ProcessEngines.getDefaultProcessEngine();
        System.out.println(engine);
    }
}

5. Deploying a process definition

@Test
public void activitiDeploymentTest() {
    ProcessEngine engine = ProcessEngines.getDefaultProcessEngine();
    RepositoryService repo = engine.getRepositoryService();
    Deployment deployment = repo.createDeployment()
        .addClasspathResource("diagram/holiday.bpmn")
        .addClasspathResource("diagram/holiday.png")
        .name("请假申请单流程")
        .deploy();
    System.out.println(deployment.getName());
    System.out.println(deployment.getId());
}

@Test
public void activitiDeploymentTest2() {
    ProcessEngine engine = ProcessEngines.getDefaultProcessEngine();
    RepositoryService repo = engine.getRepositoryService();
    InputStream is = ActivitiDeployment.class.getClassLoader()
        .getResourceAsStream("diagram/holidayBPMN.zip");
    ZipInputStream zip = new ZipInputStream(is);
    Deployment deployment = repo.createDeployment()
        .addZipInputStream(zip)
        .name("请假申请单流程")
        .deploy();
    System.out.println(deployment.getName());
    System.out.println(deployment.getId());
}

6. Starting a process instance

public static void main(String[] args) {
    ProcessEngine engine = ProcessEngines.getDefaultProcessEngine();
    RuntimeService runtime = engine.getRuntimeService();
    ProcessInstance instance = runtime.startProcessInstanceByKey("holiday");
    System.out.println("部署ID" + instance.getDeploymentId());
    System.out.println("定义ID" + instance.getProcessDefinitionId());
    System.out.println("实例ID" + instance.getId());
    System.out.println("活动ID" + instance.getActivityId());
}

7. Querying process definitions

@Test
public void queryProceccDefinition() {
    String key = "holiday";
    ProcessEngine engine = ProcessEngines.getDefaultProcessEngine();
    RepositoryService repo = engine.getRepositoryService();
    List
list = repo.createProcessDefinitionQuery()
        .processDefinitionKey(key)
        .orderByProcessDefinitionVersion().desc()
        .list();
    for (ProcessDefinition pd : list) {
        System.out.println("------------------------");
        System.out.println("部署ID: " + pd.getDeploymentId());
        System.out.println("定义ID: " + pd.getId());
        System.out.println("名称: " + pd.getName());
        System.out.println("Key: " + pd.getKey());
        System.out.println("版本: " + pd.getVersion());
    }
}

8. Deleting a deployment

public void deleteDeployment() {
    String deploymentId = "8801";
    ProcessEngine engine = ProcessEngines.getDefaultProcessEngine();
    RepositoryService repo = engine.getRepositoryService();
    // Simple delete (fails if instances exist)
    repo.deleteDeployment(deploymentId);
    // Cascade delete (removes related instances)
    repo.deleteDeployment(deploymentId, true);
}

9. Retrieving BPMN and PNG resources

@Test
public void getProcessResources() throws IOException {
    String procDefId = ""; // fill with actual ID
    ProcessEngine engine = ProcessEngines.getDefaultProcessEngine();
    RepositoryService repo = engine.getRepositoryService();
    ProcessDefinition pd = repo.createProcessDefinitionQuery()
        .processDefinitionId(procDefId).singleResult();
    String bpmn = pd.getResourceName();
    String png = pd.getDiagramResourceName();
    System.out.println("bpmn: " + bpmn);
    System.out.println("png: " + png);
    // Write BPMN to file
    try (InputStream in = repo.getResourceAsStream(pd.getDeploymentId(), bpmn);
         FileOutputStream out = new FileOutputStream("d:/process.bpmn")) {
        byte[] buf = new byte[1024];
        int len;
        while ((len = in.read(buf)) != -1) {
            out.write(buf, 0, len);
        }
    }
    // Write PNG to file (similar code)
}

The article also includes SQL snippets for inspecting Activiti tables (ACT_RE_DEPLOYMENT, ACT_RE_PROCDEF, ACT_GE_BYTEARRAY, etc.) and tips for generating BPMN diagram PNGs in IDEA/Eclipse.