TaskService 使用表达式调用spring bean 方法

Question

如题 部分流程文件如下

<serviceTask id="service" name="服务" activiti:expression="${testService.print(name)}"></serviceTask>

问题描述:
serviceTask 调用 testService的print方法; 其中testService为spring的一个bean

流程图如下

过程

• 创建bean 并加载流程文件

@Bean
public ProcessEngine processEngine(){
   ProcessEngineConfiguration cfg =ProcessEngineConfiguration.createStandaloneInMemProcessEngineConfiguration();
   ProcessEngine processEngine = cfg.buildProcessEngine();
   DeploymentBuilder deployment = processEngine.getRepositoryService().createDeployment();
   deployment.addClasspathResource("test1.bpmn20.xml");
   Deployment deploy = deployment.deploy();
   return processEngine;
}

• 启动项目

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class,args);
    }
}

• 测试代码

@RestController
public class TestController {
    @Autowired
    private ProcessEngine processEngine;
    @Autowired
    private TestService testService;
    @GetMapping("/test")
    public void test(){
        RuntimeService runtimeService = processEngine.getRuntimeService();
        Map<String,Object> context=new HashMap<>();
        context.put("name","Lucy");
        //context.put("testService",testService);
        ProcessInstance processInstance = runtimeService.startProcessInstanceByKey("test", context);
        System.out.println(processInstance.getId());
    }
}

错误信息如下

org.activiti.engine.ActivitiException: Could not execute service task expression
Caused by: org.activiti.engine.ActivitiException: Unknown property used in expression: ${testService.print(name)}
Caused by: javax.el.PropertyNotFoundException: Cannot resolve identifier 'testService'

尝试方法:

• 将testService放入流程的上下文
  若取消context.put("testService",testService); 的注释,报以下异常(不能序列化)

org.activiti.engine.ActivitiException: couldn't find a variable type that is able to serialize com.boco.mis.activiti.hello.TestService@216d848e

调整TestService的代码 实现Serializable,之后可以正常运行

@Service(value="testService")
public class TestService implements Serializable{
   public void print(String name){
       System.out.println("TestService1.print("+name+")");
   }
}

但是,正式环境中testService会依赖其他类,依赖类也必须实现Serializable,才可以,而依赖类又会依赖其他类,所以此方案不可行

后续又对activiti:class 和activiti:delegateExpression 进行了测试 均没有达到预期效果

所有测试代码均在https://github.com/jiabiaoli/activiti-hello

Answer 1

Jimmy 2019-11-22 14:14:44

问题出在 这里 

ProcessEngineConfiguration cfg =ProcessEngineConfiguration.createStandaloneInMemProcessEngineConfiguration();
  ProcessEngine processEngine = cfg.buildProcessEngine(); 

在spring环境下通过这种方式创建的ProcessEngine并没有把spring 容器的bean放到流程引擎中

解决的方法

独立声明一下 SpringProcessEngineConfiguration 成为一个bean

参考

@Bean

public SpringProcessEngineConfiguration processEngineConfiguration(){

    //具体参数需要配置

    renturn new SpringProcessEngineConfiguration()

}

• 提问者 破地瓜 #1

  @Bean
      public DataSource dataSource() {
          return DataSourceBuilder.create()
                  .username("sa")
                  .password("")
             .url("jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=false").build();
      }
      @Bean
      public PlatformTransactionManager transactionManager(){
          DataSourceTransactionManager transactionManager=new DataSourceTransactionManager();
          transactionManager.setDataSource(dataSource());
          return transactionManager;
      }
  
      @Bean
      public SpringProcessEngineConfiguration springProcessEngineConfiguration() {
          SpringProcessEngineConfiguration processEngineConfiguration = new SpringProcessEngineConfiguration();
          processEngineConfiguration.setDataSource(dataSource());
          processEngineConfiguration.setTransactionManager(transactionManager());
          processEngineConfiguration.setDatabaseSchemaUpdate("true");
          return processEngineConfiguration;
      }
  
  
  已经改造 仍然不好使,代码已提交github

• 提问者 破地瓜 #2

  经过测试 以上代码不够
  public ProcessEngineFactoryBean springProcessEngineBean() {
          ProcessEngineFactoryBean processEngineFactoryBean = new ProcessEngineFactoryBean();
          processEngineFactoryBean.setProcessEngineConfiguration(springProcessEngineConfiguration());
          processEngineFactoryBean.setApplicationContext(applicationContext);
          return processEngineFactoryBean;
      }
  
  通过processEngineFactoryBean.getObject() 获取才可以

• 提问者 破地瓜 #3

  写了篇文章 记录下
  https://www.jianshu.com/p/48e5f85a5568

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