Activiti之act_ge_property表引發的坑（dbSchemaUpdate）

參考文檔：

https://blog.csdn.net/lb19921223/article/details/79213851

 

上篇文章寫道，我學習acitiviti的時候，使用mysql的truncate把表中的數據都刪除了，然后重新部署流程，結果居然報錯了。

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans   http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!-- 流程引擎配置的bean -->
    <bean id="processEngineConfiguration"
        class="org.activiti.engine.impl.cfg.StandaloneProcessEngineConfiguration">
        <property name="jdbcUrl"
            value="jdbc:mysql://localhost:3306/db_activiti?serverTimezone=Asia/Shanghai" />
        <property name="jdbcDriver" value="com.mysql.cj.jdbc.Driver" />
        <property name="jdbcUsername" value="root" />
        <property name="jdbcPassword" value="123456" />
        <property name="databaseSchemaUpdate" value="true" />
    </bean>

</beans>

 

 

 

 

package com.yuanqiao.first_activiti.deployment;

import java.util.List;

import org.activiti.engine.ProcessEngine;
import org.activiti.engine.ProcessEngines;
import org.activiti.engine.RepositoryService;
import org.activiti.engine.repository.Deployment;
import org.activiti.engine.repository.DeploymentBuilder;
import org.activiti.engine.repository.ProcessDefinition;
import org.junit.Test;

import com.google.gson.Gson;

/**
 * 通過讀取bpmn文件，來部署流程圖
 * 
 * @author yuanqiao
 *
 */
public class DeploymentProcess {

	@Test
	public void deploymentFirstProcess() {
		ProcessEngine processEngine = ProcessEngines.getDefaultProcessEngine();

		RepositoryService repositoryService = processEngine.getRepositoryService();

		DeploymentBuilder deploymentBuilder = repositoryService.createDeployment().addClasspathResource("first.bpmn");

		Deployment deployment = deploymentBuilder.deploy();
		String deploymentId = deployment.getId();
		System.out.println(deploymentId);
		List<ProcessDefinition> processDefinitionList = repositoryService.createProcessDefinitionQuery()
				.deploymentId(deploymentId).list();
		Gson gson = new Gson();
		System.out.println(gson.toJson(processDefinitionList));

	}
}

　　

 

 

java.lang.NullPointerException
at org.activiti.engine.impl.db.DbSqlSession.dbSchemaUpdate(DbSqlSession.java:911)
at org.activiti.engine.impl.db.DbSqlSession.performSchemaOperationsProcessEngineBuild(DbSqlSession.java:1318)
at org.activiti.engine.impl.SchemaOperationsProcessEngineBuild.execute(SchemaOperationsProcessEngineBuild.java:28)
at org.activiti.engine.impl.interceptor.CommandInvoker$1.run(CommandInvoker.java:37)
at org.activiti.engine.impl.interceptor.CommandInvoker.executeOperation(CommandInvoker.java:78)
at org.activiti.engine.impl.interceptor.CommandInvoker.executeOperations(CommandInvoker.java:57)
at org.activiti.engine.impl.interceptor.CommandInvoker.execute(CommandInvoker.java:42)
at org.activiti.engine.impl.interceptor.TransactionContextInterceptor.execute(TransactionContextInterceptor.java:48)
at org.activiti.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:63)
at org.activiti.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:29)
at org.activiti.engine.impl.cfg.CommandExecutorImpl.execute(CommandExecutorImpl.java:44)
at org.activiti.engine.impl.ProcessEngineImpl.<init>(ProcessEngineImpl.java:81)
at org.activiti.engine.impl.cfg.ProcessEngineConfigurationImpl.buildProcessEngine(ProcessEngineConfigurationImpl.java:665)
at org.activiti.engine.ProcessEngines.buildProcessEngine(ProcessEngines.java:189)
at org.activiti.engine.ProcessEngines.initProcessEngineFromResource(ProcessEngines.java:162)
at org.activiti.engine.ProcessEngines.init(ProcessEngines.java:94)
at org.activiti.engine.ProcessEngines.getProcessEngine(ProcessEngines.java:223)
at org.activiti.engine.ProcessEngines.getDefaultProcessEngine(ProcessEngines.java:212)
at com.yuanqiao.first_activiti.deployment.DeploymentProcess.deploymentFirstProcess(DeploymentProcess.java:25)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)

 

 

解決辦法如下：

最近給客戶部署系統，系統中使用Activiti流程引擎，啟動Tomcat死活報錯，報錯如上邊信息。真是一頭霧水，剛開始以為是程序自身或者服務器環境問題（因為環境都是新裝的），沒往流程引擎上想。

上邊的異常只是截取的最關鍵的地方，其實在這之前還要報一片異常，把環境和程序配置檢查了一便，還是無果，最終把焦點集中在了org.activiti.engine.impl.db.DbSqlSession.dbSchemaUpdate，意思是流程表在更新表結構的時候出現異常，怎么會老是更新呢？查看了Activiti的配置，如上圖。

 databaseSchemaUpdate設置為true代表如果沒有表，則自動創建表；估計是這里的原因，我重新建了一個空的數據庫test1，然后程序連上test1數據庫，啟動tomcat，竟然成功了。成功了，心里的一塊石頭落了地。

但是還是感覺很奇怪，不知道真正原因是什么，后來才想到，act_ge_property表，該表是流程引擎的屬性表，里面的三條數據是基礎數據，不可以刪除。而我看了一下數據庫初始化sql，竟然沒有這三條數據，我這才恍然大悟，我准備程序包的時候，為了不把流程里面的數據帶過來，我只是導出的表結構，沒有導出數據。也就是說還原到服務器數據庫的時候，act_ge_property表里面壓根沒有數據，這就造成了當前這個問題。聰明反被聰明誤。。以后引以為戒吧。

總結：部署程序准備數據庫初始化sql時，對於流程表，以后就不要導出來，只導出業務表，流程表讓系統啟動時自己生成去。