Spring boot 集成工作流flowable去掉xml配置

工作流Flowable和Spring集成时，有一个xml是用来配置ProcessEngine的信息，xml的内容如下所示：

<beans xmlns="http://www.springframework.org/schema/beans" xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:context="http://www.springframework.org/schema/context" xmlns:jdbc="http://www.springframework.org/schema/jdbc"
    xmlns:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:jpa="http://www.springframework.org/schema/data/jpa"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/aop  http://www.springframework.org/schema/aop/spring-aop.xsd      
    http://www.springframework.org/schema/beans    http://www.springframework.org/schema/beans/spring-beans.xsd    
    http://www.springframework.org/schema/context     http://www.springframework.org/schema/context/spring-context.xsd  
    http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee.xsd       
    http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd   
    http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc.xsd
    http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd">

    
    <bean id="processEngineConfiguration" class="com.xxx.xxx.config.ExtProcessEngineConfiguration">
        <property name="dataSource" ref="dataSource" />
        <property name="transactionManager" ref="transactionManager" />
        <property name="databaseSchemaUpdate" value="true" />
        
        <property name="customSessionFactories">
            <list>
                <bean class="com.xxx.xxx.entity.EntityManagerFactory">
                    <constructor-arg index="0" value="org.flowable.idm.engine.impl.persistence.entity.UserEntityManager" />
                    <constructor-arg index="1">
                        <bean class="com.xxx.xxx.entity.SmartUserEntityManager"/>
                    constructor-arg>
                bean>
                <bean class="com.xxx.xxx.entity.EntityManagerFactory">
                    <constructor-arg index="0" value="org.flowable.idm.engine.impl.persistence.entity.GroupEntityManager" />
                    <constructor-arg index="1">
                        <bean class="com.xxx.xxx.entity.SmartGroupEntityManager"/>
                    constructor-arg>
                bean>
                <bean class="com.xxx.xxx.entity.EntityManagerFactory">
                    <constructor-arg index="0" value="org.flowable.idm.engine.impl.persistence.entity.MembershipEntityManager" />
                    <constructor-arg index="1">
                        <bean class="com.xxx.xxx.entity.SmartMembershipEntityManager"/>
                    constructor-arg>
                bean>
            list>
        property>


    bean>


    <bean id="processEngine" factory-bean="processEngineConfiguration" factory-method="buildProcessEngine" />


    <bean id="repositoryService" factory-bean="processEngineConfiguration" factory-method="getRepositoryService"  />
    <bean id="runtimeService" factory-bean="processEngineConfiguration" factory-method="getRuntimeService" />
    <bean id="taskService" factory-bean="processEngineConfiguration" factory-method="getTaskService" />
    <bean id="historyService" factory-bean="processEngineConfiguration" factory-method="getHistoryService" />
    <bean id="managementService" factory-bean="processEngineConfiguration" factory-method="getManagementService" />
    <bean id="formService" factory-bean="processEngineConfiguration" factory-method="getFormService" />
    <bean id="identityService" factory-bean="processEngineConfiguration" factory-method="getIdentityService" />

    <bean id="commandExecutor" factory-bean="processEngineConfiguration" factory-method="getCommandExecutor" />
    <bean id="processDefinitionCache" factory-bean="processEngineConfiguration" factory-method="getProcessDefinitionCache"/>


beans>

使用Spring boot之后推崇java配置取代xml配置，要对这个xml进行改造首先得搞清楚这个xml里面的内容，主要是定义了ExtProcessEngineConfiguration和它相关的属性，

1. 说明：
   constructor-arg：通过构造函数注入。
   property：通过setter对应的方法注入。
   factory-method：通过工厂方法来构造java Bean

2. 创建config配置文件WorkflowConfiguration，在这个类中通过@bean的注解构造ExtProcessEngineConfiguration 类，同时设置ExtProcessEngineConfiguration 需要的几个属性

@Configuration
public class WorkflowConfiguration {

  private final DataSource dataSource;
  private final PlatformTransactionManager transactionManager;

  public WorkflowConfiguration(DataSource dataSource,PlatformTransactionManager transactionManager){
    this.dataSource = dataSource;
    this.transactionManager = transactionManager;
  }

  @Bean
  public SmartUserEntityManager smartUserEntityManager() {
    return new SmartUserEntityManager(new ExtProcessEngineConfiguration());
  }

  @Bean
  public SmartGroupEntityManager smartGroupEntityManager() {
    return new SmartGroupEntityManager(new ExtProcessEngineConfiguration());
  }

  @Bean
  public SmartMembershipEntityManager smartMembershipEntityManager() {
    return new SmartMembershipEntityManager(new ExtProcessEngineConfiguration());
  }

  public EntityManagerFactory userEntityManagerFactory(){
    EntityManagerFactory entityManagerFactory = new EntityManagerFactory(UserEntityManager.class, smartUserEntityManager());
    return entityManagerFactory;
  }

  public EntityManagerFactory groupEntityManagerFactory(){
    EntityManagerFactory entityManagerFactory = new EntityManagerFactory(GroupEntityManager.class, smartGroupEntityManager());
    return entityManagerFactory;
  }

  public EntityManagerFactory membershipEntityManagerFactory(){
    EntityManagerFactory entityManagerFactory = new EntityManagerFactory(MembershipEntityManager.class, smartMembershipEntityManager());
    return entityManagerFactory;
  }


  @Bean
  public ExtProcessEngineConfiguration engineConfiguration(){
    ExtProcessEngineConfiguration engineConfiguration = new ExtProcessEngineConfiguration();
    engineConfiguration.setDatabaseSchemaUpdate("true");
    engineConfiguration.setDataSource(dataSource);
    engineConfiguration.setTransactionManager(transactionManager);

    List customSessionFactories = new ArrayList<>();
    customSessionFactories.add(userEntityManagerFactory());
    customSessionFactories.add(groupEntityManagerFactory());
    customSessionFactories.add(membershipEntityManagerFactory());
    engineConfiguration.setCustomSessionFactories(customSessionFactories);

    return engineConfiguration;

  }

}

其中核心的代码是：

@Bean
  public ExtProcessEngineConfiguration engineConfiguration()

这个方法。

其中有一个重点需要注意的地方是，在xml里面有一段：

<bean id="processEngine" factory-bean="processEngineConfiguration" factory-method="buildProcessEngine" />

这个是Spring使用实例工厂方法实例化Bean的一种方式，工作作流引擎Flowable的各个组件就是使用此方式实例化的。由于使用工厂实例化的Bean跟普通Bean不同，其返回的对象不是指定类的一个实例，其返回的是该FactoryBean的getObject方法所返回的对象。因此我们需要使用Spring Boot的方式来实例化Flowable的组件。有两种解决方法：

1. 自定义FactoryBean，实现FactoryBean中的getObject这个方法，返回ProcessEngine对象
2. 使用ProcessEngineFactoryBean，推荐使用这种方式，以下为ProcessEngineFactoryBean源码。

public class ProcessEngineFactoryBean implements FactoryBean ..{
    ...
    protected ProcessEngineImpl processEngine;

    public ProcessEngine getObject() throws Exception {
    initializeExpressionManager();
    initializeTransactionExternallyManaged();

    if (processEngineConfiguration.getBeans()==null) {
        processEngineConfiguration.setBeans(new SpringBeanFactoryProxyMap(applicationContext));
    }

    processEngine = (ProcessEngineImpl) processEngineConfiguration.buildProcessEngine();

    return processEngine;
    }

    ...
}

ProcessEngineFactoryBean最终返回的是processEngine对象，repositoryService、runtimeService、formService等等组件都是通过processEngine里的getXX方法获得的。

通过WorkflowConfiguration就可以取代xml配置文件了。

在我们需要继承flowable-restApi的时候发现需要进行权限校验，我们可以通过下面的注解去掉security权限校验，在启动类上加上下面的注解：

@SpringBootApplication(exclude = {
    org.springframework.boot.autoconfigure.security.SecurityAutoConfiguration.class,
    org.flowable.spring.boot.SecurityAutoConfiguration.class})