activiti学习笔记(四) 配置器

activiti配置器

activiti配置器的作用

       一般在构建流程实例的时候, 会进行初始化，配置器就是可以在获取了流程配置实例，以及初始化之后可以进行一些额外的配置

activiti配置器的机制

allConfigurators集合添加

       在ProcessEngineConfigurationImpl这个类中调用init方法中initConfigurators方法，将所有流程配置器添加到allConfigurators这个集合，流程配置器有两种获取形式，第一种是直接通过bean方式注入到configurators遍历添加到allConfigurators集合，第二种是通过调用spi模式，加载到allConfigurators集合。最后将所有的按照照priority的大小进行排序

public void initConfigurators() {    //一个list集合,存放所有ProcessEngineConfigurator    allConfigurators = new ArrayList<ProcessEngineConfigurator>();    //遍历Configurators将其添加到allConfigurators这个集合    if (configurators != null) {      for (ProcessEngineConfigurator configurator : configurators) {        allConfigurators.add(configurator);      }    }    //获取当前类加载器    if (enableConfiguratorServiceLoader) {      ClassLoader classLoader = getClassLoader();      if (classLoader == null) {        classLoader = ReflectUtil.getClassLoader();      }      //利用spi模式加载ProcessEngineConfigurator所有实现类 将其添加到allConfigurators集合      ServiceLoader<ProcessEngineConfigurator> configuratorServiceLoader = ServiceLoader.load(ProcessEngineConfigurator.class, classLoader);      int nrOfServiceLoadedConfigurators = 0;      for (ProcessEngineConfigurator configurator : configuratorServiceLoader) {        allConfigurators.add(configurator);        nrOfServiceLoadedConfigurators++;      }      if (nrOfServiceLoadedConfigurators > 0) {        log.info("Found {} auto-discoverable Process Engine Configurator{}", nrOfServiceLoadedConfigurators++, nrOfServiceLoadedConfigurators > 1 ? "s" : "");      }      //将allConfigurators进行排序,按照priority1的从大到小      if (!allConfigurators.isEmpty()) {        Collections.sort(allConfigurators, new Comparator<ProcessEngineConfigurator>() {          @Override          public int compare(ProcessEngineConfigurator configurator1, ProcessEngineConfigurator configurator2) {            int priority1 = configurator1.getPriority();            int priority2 = configurator2.getPriority();            if (priority1 < priority2) {              return -1;            } else if (priority1 > priority2) {              return 1;            }            return 0;          }        });        // Execute the configurators        log.info("Found {} Process Engine Configurators in total:", allConfigurators.size());        for (ProcessEngineConfigurator configurator : allConfigurators) {          log.info("{} (priority:{})", configurator.getClass(), configurator.getPriority());        }      }    }  }

初始化调用方法

在ProcessEngineConfigurationImpl调用init方法中configuratorsBeforeInit方法,它会遍历所有的allConfigurators,并调用其中的beforeInit

  /**调用所有配置器的beforeInit方法*/  public void configuratorsBeforeInit() {    for (ProcessEngineConfigurator configurator : allConfigurators) {      log.info("Executing beforeInit() of {} (priority:{})", configurator.getClass(), configurator.getPriority());      configurator.beforeInit(this);    }  }

初始化后配置方法调用

在ProcessEngineConfigurationImpl调用init方法中configuratorsAfterInit方法,它会遍历所有的allConfigurators,并调用其中的configure

 /**调用所有配置的configure方法*/  public void configuratorsAfterInit() {    for (ProcessEngineConfigurator configurator : allConfigurators) {      log.info("Executing configure() of {} (priority:{})", configurator.getClass(), configurator.getPriority());      configurator.configure(this);    }  }

activiti配置器的接口类

public interface ProcessEngineConfigurator {  /**init方法的第二个方法调用，第一个是获取所有ProcessEngineConfigurator（当前接口的实例） 在初始化前做一些操作*/  void beforeInit(ProcessEngineConfigurationImpl processEngineConfiguration);  /**init方法的最后一个调用，在初始化后可以做一些配置*/  void configure(ProcessEngineConfigurationImpl processEngineConfiguration);  /**使用实例时,首先按照priority进行裴谞，如果你有实例之间的依赖性,自己定义优先级序*/  int getPriority();}

activiti的bean方式配置文件

<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"><bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource"><property name="driverClassName"><value>com.mysql.jdbc.Driver</value></property><property name="url"><value>jdbc:mysql://127.0.0.1:3306/activiti?useUnicode=true&characterEncoding=UTF-8</value></property><property name="username"><value>root</value></property><property name="password" value="fadp" /></bean><bean id="processEngineConfigurator1" class="com.activiti_study.ch7.processEngineConfigurator1"></bean><bean id="processEngineConfigurator2"  class="com.activiti_study.ch7.processEngineConfigurator2"></bean><bean id="processEngineConfiguration"class="org.activiti.engine.impl.cfg.StandaloneProcessEngineConfiguration"><property name="dataSource" ref="dataSource" /><property name="processEngineName" value="shareniu" /><property name="configurators"><list>  <ref bean="processEngineConfigurator1"/>  <ref bean="processEngineConfigurator2"/></list></property></bean></beans>

activiti的实现类

public class processEngineConfigurator1 extends AbstractProcessEngineConfigurator{@Overridepublic void beforeInit(ProcessEngineConfigurationImpl processEngineConfiguration) {System.out.println("1:beforeInit ");processEngineConfiguration.setDatabaseSchemaUpdate("true");}@Overridepublic void configure(ProcessEngineConfigurationImpl processEngineConfiguration) {System.out.println("1:configure ");String databaseSchemaUpdate = processEngineConfiguration.getDatabaseSchemaUpdate();System.out.println(databaseSchemaUpdate+"-----------------");}}

public class processEngineConfigurator2 extends AbstractProcessEngineConfigurator{@Overridepublic void beforeInit(ProcessEngineConfigurationImpl processEngineConfiguration) {System.out.println("2:beforeInit ");processEngineConfiguration.setDatabaseSchemaUpdate("true");}@Overridepublic void configure(ProcessEngineConfigurationImpl processEngineConfiguration) {System.out.println("2:configure ");String databaseSchemaUpdate = processEngineConfiguration.getDatabaseSchemaUpdate();System.out.println(databaseSchemaUpdate+"-----------------");}}

activit配置器的测试代码

   

public class App {@Testpublic void getProcessEngine() {ProcessEngineConfiguration pec = ProcessEngineConfiguration.createProcessEngineConfigurationFromResource("com/activiti_study/ch7/activiti1.cfg.xml");ProcessEngine pe1 = pec.buildProcessEngine();}}

activiti配置器的测试结果

1:beforeInit 2:beforeInit 1:configure true-----------------2:configure true-----------------