摘要：當一個根級的結束時，就會進行上述的緩存對象統一的持久化。解決的辦法也很簡單，改為監聽，判斷是否時需要修改的任務實體即可。這樣后面要進行駁回時，只要通過這樣關系表，馬上就可以定位到要駁回到的任務了。

本文內容主要為以下兩點,因為內容有交叉，所以會放在一起介紹。

1.以自由跳轉為基礎實現不改變原先任務id的駁回
關于Activiti6動態跳轉可以查看我的另一篇文章Activiti6實現自由跳轉

2.java類方式進行Activiti6配置、spring boot集成
因為有一些自定義的需求,如流程字體、自動部署、自定義監聽器等，直接引入[activit-spring-boot]又沒有必要，所以參考activit6源碼中[activit-spring-boot]模塊的代碼完成。

關于自由跳轉的內容我就不再多說，主要介紹如何修改Activiti生成的實體的id，以達到駁回時重新生成的任務id與原先的任務id一致。(某些業務場景下可能會用到，例如某流程中A環節提交的表單與task id綁定，當環節提交又被駁回時，為保證表單內容與任務關系不變，駁回后的任務id與原先任務id要一致)

1.Activiti持久化實體的過程時先創建實體對象，記錄到緩存中，在完成執行后統一進行緩存對象的持久化，并清空緩存。

2.Activiti采用命令模式執行操作，所有操作都時一個CMD。執行一個CMD的時候會創建一個上下文環境，包含待持久化的實體緩存等，如果在CMD中嵌套執行CMD，新的CMD默認會使用上級上下文環境。當一個根級的CMD結束時，Activiti就會進行上述的緩存對象統一的持久化。

3.Activiti有豐富的事件類型(具體可以查看事件枚舉類ActivitiEventType)供我們實現相應監聽器，進行特殊業務處理。例如ENTITY_CREATED——實體創建完成(task、activity、Execution等所有實體)、TASK_CREATED——任務創建完成(針對task)、TASK_COMPLETED——任務完成等等。

結合上述內容我們就可以知道，只要在TASK_CREATED進行監聽，直接在監聽器中將id改為需要的值即可。理論上是這樣，但是需要注意，Activiti6中歷史任務實體創建是在TASK_CREATED之前的，如果你在TASK_CREATED中修改任務id，實際上歷史任務實體創建時是獲取不到的，這樣就會導致歷史任務的id與運行時任務id不一致。解決的辦法也很簡單，改為監聽ENTITY_CREATED，判斷是否時需要修改id的任務實體即可。

# 是否更新數據庫表
spring.activiti.databaseSchemaUpdate=true
# 是否激活異步執行器
spring.activiti.asyncExecutorActivate=false
# 流程歷史記錄登錄
spring.activiti.historyLevel=audit
# 是否檢查更新流程定義
spring.activiti.checkProcessDefinitions=false
# 流程定義所在前綴
spring.activiti.processDefinitionLocationPrefix=classpath*:/procDef/
# 流程定義后綴
spring.activiti.processDefinitionLocationSuffixes=**.bpmn
# 部署流程定義時是否生成圖片
spring.activiti.createDiagramOnDeploy=false
# 字體 下面內容為轉成unicode的"宋體"
spring.activiti.activityFontName=u5b8bu4f53
spring.activiti.labelFontName=u5b8bu4f53

@ConfigurationProperties("spring.activiti")
public class ActivitiProperties {
    private boolean checkProcessDefinitions = true;
    private boolean asyncExecutorActivate = true;
    private boolean restApiEnabled;
    private String deploymentName;
    private String mailServerHost = "localhost";
    private int mailServerPort = 1025;
    private String mailServerUserName;
    private String mailServerPassword;
    private String mailServerDefaultFrom;
    private boolean mailServerUseSsl;
    private boolean mailServerUseTls;
    private String databaseSchemaUpdate = "true";
    private String databaseSchema;
    private boolean isDbIdentityUsed = true;
    private boolean isDbHistoryUsed = true;
    private HistoryLevel historyLevel = HistoryLevel.AUDIT;
    private String processDefinitionLocationPrefix = "classpath:/processes/";
    private List processDefinitionLocationSuffixes = Arrays.asList("**.bpmn20.xml", "**.bpmn");
    private String restApiMapping = "/api/*";
    private String restApiServletName = "activitiRestApi";
    private boolean jpaEnabled = true; // true by default
    private List customMybatisMappers;
    private List customMybatisXMLMappers;

    private boolean createDiagramOnDeploy;
    private String activityFontName;
    private String labelFontName;
    //省略getter、setter
}

@Configuration
@EnableConfigurationProperties(ActivitiProperties.class)
public class ActivitiConfig {
    private static final Logger logger = LoggerFactory.getLogger(ActivitiConfig.class);
    @Autowired
    private ActivitiProperties activitiProperties;
    @Autowired
    private DataSource dataSource;
    @Autowired
    private PlatformTransactionManager transactionManager;
    @Autowired
    private TaskCreatedListener taskCreatedListener;
    @Autowired
    private TaskCompletedListener taskCompletedListener;
    @Autowired
    private EntityCreatedListener entityCreatedListener;
    @Autowired
    private ResourcePatternResolver resourceLoader;

    @Bean
    public SpringProcessEngineConfiguration processEngineConfiguration() throws IOException {
        SpringProcessEngineConfiguration configuration = new SpringProcessEngineConfiguration();
        configuration.setDataSource(dataSource);
        configuration.setTransactionManager(transactionManager);
        configuration.setDatabaseSchemaUpdate(activitiProperties.getDatabaseSchemaUpdate());
        configuration.setAsyncExecutorActivate(activitiProperties.isAsyncExecutorActivate());
        configuration.setHistory(activitiProperties.getHistoryLevel().getKey());
        configuration.setCreateDiagramOnDeploy(activitiProperties.isCreateDiagramOnDeploy());
        configuration.setActivityFontName(activitiProperties.getActivityFontName());
        configuration.setLabelFontName(activitiProperties.getLabelFontName());
        //todo 修改自動部署，當前自動部署直接搬自[activit-spring-boot]
        //如果checkProcessDefinitions為true，則發布新版流程定義，后續可能根據流程定義文件MD5等判斷是否真正變化而進行發布
        List procDefResources = discoverProcessDefinitionResources(activitiProperties.getProcessDefinitionLocationPrefix(),            activitiProperties.getProcessDefinitionLocationSuffixes(),this.activitiProperties.isCheckProcessDefinitions());
        configuration.setDeploymentResources(procDefResources.toArray(new Resource[procDefResources.size()]));
        Map> typedListeners = new HashMap<>();
        typedListeners.put("ENTITY_CREATED", Collections.singletonList(entityCreatedListener));
        typedListeners.put("TASK_CREATED", Collections.singletonList(taskCreatedListener));
        typedListeners.put("TASK_COMPLETED", Collections.singletonList(taskCompletedListener));
        configuration.setTypedEventListeners(typedListeners);
        return configuration;
    }
    private List discoverProcessDefinitionResources(String prefix, List suffixes, boolean checkPDs) throws IOException {
        if (checkPDs) {
            List result = new ArrayList<>();
            for (String suffix : suffixes) {
                String path = prefix + suffix;
                Resource[] resources = resourceLoader.getResources(path);
                if (resources != null && resources.length > 0) {
                    CollectionUtils.mergeArrayIntoCollection(resources, result);
                }
            }
            if (result.isEmpty()) {
                logger.info("No process definitions were found for autodeployment");
            }
            return result;
        }
        return new ArrayList<>();
    }
    @Bean
    public ProcessEngineFactoryBean processEngine() throws IOException {
        ProcessEngineFactoryBean factoryBean = new ProcessEngineFactoryBean();
        factoryBean.setProcessEngineConfiguration(processEngineConfiguration());
        return factoryBean;
    }
    @Bean
    public RuntimeService runtimeService(ProcessEngine processEngine) {
        return processEngine.getRuntimeService();
    }
    @Bean
    public RepositoryService repositoryService(ProcessEngine processEngine) {
        return processEngine.getRepositoryService();
    }
    @Bean
    public TaskService taskService(ProcessEngine processEngine) {
        return processEngine.getTaskService();
    }
    @Bean
    public HistoryService historyService(ProcessEngine processEngine) {
        return processEngine.getHistoryService();
    }
    @Bean
    public ManagementService managementService(ProcessEngine processEngine) {
        return processEngine.getManagementService();
    }
    @Bean
    public IdentityService identityService(ProcessEngine processEngine) {
        return processEngine.getIdentityService();
    }

@Component
public class EntityCreatedListener implements ActivitiEventListener {
    public void onEvent(ActivitiEvent event){
        Object entity = ((ActivitiEntityEvent)event).getEntity();
        if(entity instanceof TaskEntity){
            TaskEntity taskEntity = (TaskEntity)entity;
            // 這個要改變的id值，可以在上篇文章中的SetFLowNodeAndGoCmd中設置相應流程變量即可。
            String changeTaskId = (String)taskEntity.getVariable("changeTaskIdVarKey");
            if(!StringUtils.isEmpty(changeTaskId)){
                taskEntity.setId(changeTaskId);
                taskEntity.setVariable("changeTaskIdKey","");
            }
        }
    }
    public boolean isFailOnException(){
        return true;
    }
}

我們知道Activiti中有TASK_CREATED和TASK_COMPLETED事件，在同一個流程實例中，一個任務A如果不是最后的結束任務，那么在它完成后，必定會有一個新的任務B創建，而我們簡單理解為A為B的來源任務。(假設A是申請任務，B就時審批任務，B的處理人對當前審批不同意要駁回時，流程就要回退到任務A。)
這樣一來，我們可以監聽TASK_COMPLETED，在此時為流程設置一個變量fromTaskId，值為任務A的id，當任務A的TASK_COMPLETED結束后，就來到的了任務B的TASK_CREATED中，我們此時從流程變量中獲取fromTaskId，并將次id作為任務B的來源id持久化到一張自己創建的任務關系表中。這樣后面要進行駁回時，只要通過這樣關系表，馬上就可以定位到要駁回到的任務id了。

// 關于監聽器的注冊看上面配置類中typedListeners部分已有
@Component
public class TaskCompletedListener implements ActivitiEventListener {
    public void onEvent(ActivitiEvent event){
        TaskEntity taskEntity = (TaskEntity)((ActivitiEntityEvent)event).getEntity();
        taskEntity.setVariable("fromTaskIdVarKey", taskEntity.getId());
    }

    public boolean isFailOnException(){
        return true;
    }
}

@Component
public class TaskCreatedListener implements ActivitiEventListener {
    public void onEvent(ActivitiEvent event){
        TaskEntity taskEntity = (TaskEntity)((ActivitiEntityEvent)event).getEntity();
        String fromTaskId = (String)taskEntity.getVariable(WfVarKeyConstants.fromTaskId);
        if(StringUtils.isEmpty(fromTaskId)) return;
        xxxTaskInfo info = new xxxTaskInfo();
        info.setId(taskEntity.getId());
        info.setFromId(fromTaskId);
        //此處進行任務關系持久化，自行實現
        xxxTaskInfoRepository.save(info);
    }
    public boolean isFailOnException(){
        return true;
    }
}

本來打算做一個Activiti小貼士列表，不過看篇幅已經很長了，小貼士好像也湊不齊一篇文章，而且還沒人看:)
那就放到下次來說
todo
1.Activiti命令執行模式
2.持久化過程與會話緩存(CRUD)
3.BPMN流程執行計劃