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

public class processEngineConfigurator2 extends AbstractProcessEngineConfigurator{ @Override public void beforeInit( ProcessEngineConfigurationImpl processEngineConfiguration) { System.out.println("2:beforeInit "); processEngineConfiguration.setDatabaseSchemaUpdate("true"); } @Override public 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 { @Test public 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-----------------