Activiti實現流程自由跳轉

import org.activiti.engine.ProcessEngine;
import org.activiti.engine.TaskService;
import org.activiti.engine.impl.RepositoryServiceImpl;
import org.activiti.engine.impl.RuntimeServiceImpl;
import org.activiti.engine.impl.interceptor.Command;
import org.activiti.engine.impl.interceptor.CommandContext;
import org.activiti.engine.impl.persistence.entity.ExecutionEntity;
import org.activiti.engine.impl.persistence.entity.ProcessDefinitionEntity;
import org.activiti.engine.impl.persistence.entity.TaskEntity;
import org.activiti.engine.impl.pvm.process.ActivityImpl;

/**
 * Created by Administrator on 2016/11/11.
 */
public class TaskFlowControlService {
    ProcessEngine _processEngine;
    private String _processId;

    public TaskFlowControlService(ProcessEngine processEngine, String processId)
    {
        this._processEngine = processEngine;
        this._processId = processId;
    }

    /**
     *  跳轉至指定活動節點
     * @param targetTaskDefinitionKey
     */
    public void jump(String targetTaskDefinitionKey){
        TaskEntity currentTask = (TaskEntity)_processEngine.getTaskService()
                .createTaskQuery()
                .processInstanceId(_processId).singleResult();
        jump(currentTask,targetTaskDefinitionKey);
    }

    /**
     * @param currentTaskEntity 當前任務節點
     * @param targetTaskDefinitionKey  目標任務節點（在模型定義里面的節點名稱）
     */
    private void jump(final TaskEntity currentTaskEntity, String targetTaskDefinitionKey){
        final ActivityImpl activity = getActivity(_processEngine,
                currentTaskEntity.getProcessDefinitionId(),targetTaskDefinitionKey);
        final ExecutionEntity execution = (ExecutionEntity)_processEngine.getRuntimeService()
                .createExecutionQuery().executionId(currentTaskEntity.getExecutionId()).singleResult();
        final TaskService taskService = _processEngine.getTaskService();
        ((RuntimeServiceImpl)_processEngine.getRuntimeService()).getCommandExecutor()
                .execute(new Command<java.lang.Void>() {
                    public Void execute(CommandContext commandContext) {

                        //創建新任務
                        execution.setActivity(activity);
                        execution.executeActivity(activity);

                        //刪除當前的任務
                        //不能刪除當前正在執行的任務，所以要先清除掉關聯
                        currentTaskEntity.setExecutionId(null);
                        taskService.saveTask(currentTaskEntity);
                        taskService.deleteTask(currentTaskEntity.getId(),true);
                        return null;
                    }
                });
    }

    private ActivityImpl getActivity(ProcessEngine processEngine, String processDefId, String activityId)
    {
        ProcessDefinitionEntity pde = getProcessDefinition(processEngine, processDefId);
        return pde.findActivity(activityId);
    }

    private ProcessDefinitionEntity getProcessDefinition(ProcessEngine processEngine, String processDefId)
    {
        return (ProcessDefinitionEntity) ((RepositoryServiceImpl) processEngine.getRepositoryService())
                .getDeployedProcessDefinition(processDefId);
    }
}