操作指南：在 Java SDK 中编写和管理 Dapr 工作流

git clone https://github.com/dapr/java-sdk.git
cd java-sdk

mvn clean install

cd examples

public class DemoWorkflowWorker {

  public static void main(String[] args) throws Exception {
    // 在运行时中注册工作流。
    WorkflowRuntime.getInstance().registerWorkflow(DemoWorkflow.class);
    System.out.println("Start workflow runtime");
    WorkflowRuntime.getInstance().startAndBlock();
    System.exit(0);
  }
}

dapr run --app-id demoworkflowworker --resources-path ./components/workflows --dapr-grpc-port 50001 -- java -jar target/dapr-java-sdk-examples-exec.jar io.dapr.examples.workflows.DemoWorkflowWorker

public class DemoWorkflowClient {

  // ...
  public static void main(String[] args) throws InterruptedException {
    DaprWorkflowClient client = new DaprWorkflowClient();

    try (client) {
      String separatorStr = "*******";
      System.out.println(separatorStr);
      String instanceId = client.scheduleNewWorkflow(DemoWorkflow.class, "input data");
      System.out.printf("Started new workflow instance with random ID: %s%n", instanceId);

      System.out.println(separatorStr);
      System.out.println("**GetInstanceMetadata:Running Workflow**");
      WorkflowState workflowMetadata = client.getWorkflowState(instanceId, true);
      System.out.printf("Result: %s%n", workflowMetadata);

      System.out.println(separatorStr);
      System.out.println("**WaitForWorkflowStart**");
      try {
        WorkflowState waitForWorkflowStartResult =
            client.waitForWorkflowStart(instanceId, Duration.ofSeconds(60), true);
        System.out.printf("Result: %s%n", waitForWorkflowStartResult);
      } catch (TimeoutException ex) {
        System.out.printf("waitForWorkflowStart has an exception:%s%n", ex);
      }

      System.out.println(separatorStr);
      System.out.println("**SendExternalMessage**");
      client.raiseEvent(instanceId, "TestEvent", "TestEventPayload");

      System.out.println(separatorStr);
      System.out.println("** Registering parallel Events to be captured by allOf(t1,t2,t3) **");
      client.raiseEvent(instanceId, "event1", "TestEvent 1 Payload");
      client.raiseEvent(instanceId, "event2", "TestEvent 2 Payload");
      client.raiseEvent(instanceId, "event3", "TestEvent 3 Payload");
      System.out.printf("Events raised for workflow with instanceId: %s\n", instanceId);

      System.out.println(separatorStr);
      System.out.println("** Registering Event to be captured by anyOf(t1,t2,t3) **");
      client.raiseEvent(instanceId, "e2", "event 2 Payload");
      System.out.printf("Event raised for workflow with instanceId: %s\n", instanceId);


      System.out.println(separatorStr);
      System.out.println("**waitForWorkflowCompletion**");
      try {
        WorkflowState waitForWorkflowCompletionResult =
            client.waitForWorkflowCompletion(instanceId, Duration.ofSeconds(60), true);
        System.out.printf("Result: %s%n", waitForWorkflowCompletionResult);
      } catch (TimeoutException ex) {
        System.out.printf("waitForWorkflowCompletion has an exception:%s%n", ex);
      }

      System.out.println(separatorStr);
      System.out.println("**purgeWorkflow**");
      boolean purgeResult = client.purgeWorkflow(instanceId);
      System.out.printf("purgeResult: %s%n", purgeResult);

      System.out.println(separatorStr);
      System.out.println("**raiseEvent**");

      String eventInstanceId = client.scheduleNewWorkflow(DemoWorkflow.class);
      System.out.printf("Started new workflow instance with random ID: %s%n", eventInstanceId);
      client.raiseEvent(eventInstanceId, "TestException", null);
      System.out.printf("Event raised for workflow with instanceId: %s\n", eventInstanceId);

      System.out.println(separatorStr);
      String instanceToTerminateId = "terminateMe";
      client.scheduleNewWorkflow(DemoWorkflow.class, null, instanceToTerminateId);
      System.out.printf("Started new workflow instance with specified ID: %s%n", instanceToTerminateId);

      TimeUnit.SECONDS.sleep(5);
      System.out.println("Terminate this workflow instance manually before the timeout is reached");
      client.terminateWorkflow(instanceToTerminateId, null);
      System.out.println(separatorStr);

      String restartingInstanceId = "restarting";
      client.scheduleNewWorkflow(DemoWorkflow.class, null, restartingInstanceId);
      System.out.printf("Started new  workflow instance with ID: %s%n", restartingInstanceId);
      System.out.println("Sleeping 30 seconds to restart the workflow");
      TimeUnit.SECONDS.sleep(30);

      System.out.println("**SendExternalMessage: RestartEvent**");
      client.raiseEvent(restartingInstanceId, "RestartEvent", "RestartEventPayload");

      System.out.println("Sleeping 30 seconds to terminate the eternal workflow");
      TimeUnit.SECONDS.sleep(30);
      client.terminateWorkflow(restartingInstanceId, null);
    }

    System.out.println("Exiting DemoWorkflowClient.");
    System.exit(0);
  }
}

java -jar target/dapr-java-sdk-examples-exec.jar io.dapr.examples.workflows.DemoWorkflowClient

public class TaskExecutionKeyActivity implements WorkflowActivity {
  @Override
  public Object run(WorkflowActivityContext ctx) {
    // 获取此活动的任务执行键
    String taskExecutionKey = ctx.getTaskExecutionKey();
    
    // 使用该键来实现幂等性或状态管理
    // 例如，检查此任务是否已执行
    if (isTaskAlreadyExecuted(taskExecutionKey)) {
      return getPreviousResult(taskExecutionKey);
    }
    
    // 执行活动逻辑
    Object result = executeActivityLogic();
    
    // 使用任务执行键存储结果
    storeResult(taskExecutionKey, result);
    
    return result;
  }
}