flowable启动流程实例源码分析

1 流程实例助手类初始化源码

public void initHelpers() {
        if (processInstanceHelper == null) {
            processInstanceHelper = new ProcessInstanceHelper();
        }
        if (listenerNotificationHelper == null) {
            listenerNotificationHelper = new ListenerNotificationHelper();
        }
        if (formHandlerHelper == null) {
            formHandlerHelper = new FormHandlerHelper();
        }
}

2 执行startProcessInstanceByKey方法,调用命令类StartProcessInstanceCmd

public ProcessInstance startProcessInstanceByKey(String processDefinitionKey) {
        return commandExecutor.execute(new StartProcessInstanceCmd(processDefinitionKey, null, null, null));
}

3 重点执行execute方法

public ProcessInstance execute(CommandContext commandContext) {
        DeploymentManager deploymentCache = CommandContextUtil.getProcessEngineConfiguration(commandContext).getDeploymentManager();

        // Find the process definition
        ProcessDefinition processDefinition = null;
        if (processDefinitionId != null) {

            processDefinition = deploymentCache.findDeployedProcessDefinitionById(processDefinitionId);
            if (processDefinition == null) {
                throw new FlowableObjectNotFoundException("No process definition found for id = '" + processDefinitionId + "'", ProcessDefinition.class);
            }

        } else if (processDefinitionKey != null && (tenantId == null || ProcessEngineConfiguration.NO_TENANT_ID.equals(tenantId))) {

            processDefinition = deploymentCache.findDeployedLatestProcessDefinitionByKey(processDefinitionKey);
            if (processDefinition == null) {
                throw new FlowableObjectNotFoundException("No process definition found for key '" + processDefinitionKey + "'", ProcessDefinition.class);
            }

        } else if (processDefinitionKey != null && tenantId != null && !ProcessEngineConfiguration.NO_TENANT_ID.equals(tenantId)) {

            processDefinition = deploymentCache.findDeployedLatestProcessDefinitionByKeyAndTenantId(processDefinitionKey, tenantId);
            if (processDefinition == null) {
                throw new FlowableObjectNotFoundException("No process definition found for key '" + processDefinitionKey + "' for tenant identifier " + tenantId, ProcessDefinition.class);
            }

        } else {
            throw new FlowableIllegalArgumentException("processDefinitionKey and processDefinitionId are null");
        }

        processInstanceHelper = CommandContextUtil.getProcessEngineConfiguration(commandContext).getProcessInstanceHelper();
        ProcessInstance processInstance = processInstanceHelper.createProcessInstance(processDefinition, businessKey, processInstanceName, 
                        overrideDefinitionTenantId, variables, transientVariables, callbackId, callbackType, true);

        return processInstance;
}

//创建流程实例
public ProcessInstance createProcessInstance(ProcessDefinition processDefinition, String businessKey, String processInstanceName, 
                    String overrideDefinitionTenantId, Map variables, Map transientVariables, 
                    String callbackId, String callbackType, boolean startProcessInstance) {

        CommandContext commandContext = Context.getCommandContext();
        if (Flowable5Util.isFlowable5ProcessDefinition(processDefinition, commandContext)) {
            Flowable5CompatibilityHandler compatibilityHandler = Flowable5Util.getFlowable5CompatibilityHandler();
            return compatibilityHandler.startProcessInstance(processDefinition.getKey(), processDefinition.getId(),
                    variables, transientVariables, businessKey, processDefinition.getTenantId(), processInstanceName);
        }

        // Do not start process a process instance if the process definition is suspended
        if (ProcessDefinitionUtil.isProcessDefinitionSuspended(processDefinition.getId())) {
            throw new FlowableException("Cannot start process instance. Process definition " + processDefinition.getName() + " (id = " + processDefinition.getId() + ") is suspended");
        }

        // Get model from cache
        Process process = ProcessDefinitionUtil.getProcess(processDefinition.getId());
        if (process == null) {
            throw new FlowableException("Cannot start process instance. Process model " + processDefinition.getName() + " (id = " + processDefinition.getId() + ") could not be found");
        }

        FlowElement initialFlowElement = process.getInitialFlowElement();
        if (initialFlowElement == null) {
            throw new FlowableException("No start element found for process definition " + processDefinition.getId());
        }

        return createAndStartProcessInstanceWithInitialFlowElement(processDefinition, businessKey, processInstanceName, overrideDefinitionTenantId, 
                        initialFlowElement, process, variables, transientVariables, callbackId, callbackType, startProcessInstance);
}

//开启流程实例
public void startProcessInstance(ExecutionEntity processInstance, CommandContext commandContext, Map variables) {

        Process process = ProcessDefinitionUtil.getProcess(processInstance.getProcessDefinitionId());
        
        processAvailableEventSubProcesses(processInstance, process, commandContext);

        ExecutionEntity execution = processInstance.getExecutions().get(0); // There will always be one child execution created
        CommandContextUtil.getAgenda(commandContext).planContinueProcessOperation(execution);

        if (CommandContextUtil.getProcessEngineConfiguration().getEventDispatcher().isEnabled()) {
            FlowableEventDispatcher eventDispatcher = CommandContextUtil.getProcessEngineConfiguration().getEventDispatcher();
            eventDispatcher.dispatchEvent(FlowableEventBuilder.createProcessStartedEvent(execution, variables, false));
        }
}

大概流程:

首先创建助手类 -> 在创建流程实例 -> 创建执行实例 -> 创建子执行实例