从任务中调用服务的方法时，我在 Activiti Explorer 中使用 Spring 的自动装配功能时遇到问题。这个想法是让服务任务调用 Spring @Service bean 上的方法之一，以便使用 @Autowired JPARepository 持久化数据。
问题是，在执行服务任务后，由于 myService 中的 @Autowired 存储库未正确实例化，我得到一个空指针异常。
那么我的问题是，我怎样才能从任务服务中正确调用 Spring bean？
JavaDelegate 方法不适用于 Spring，我尝试采用“Expression”方法，如此处所建议的，但无济于事。
这是 Service Task 运行方法的代码，它的运行方式如下：
activiti:expression="${testServiceTask.doSomething()}"
//被调用的java类
public class testServiceTask {
@Autowired
private TestServiceDummy serviceDummy;
public void doSomething() {
serviceDummy.run(); // NPE here, the serviceDummy is null when called
}
// Getters and Setters for the testServiceDummy omitted for brevity
}
这是我的服务：
public interface TestServiceDummy {
public void createUser();
}
@Service(value = "testServiceDummyImpl")
@Transactional(readOnly = true)
public class TestServiceDummyImpl implements TestServiceDummy {
@Autowired
private UserRepository userRepo;
@Override
public void createUser() {
User u = new User();
userRepo.save(u);
}
// Getters and Setters for userRepo omitted for brevity
}
从我们的 web 应用程序调用时，同样的事情没有问题（将服务调用为 @ManagedProperty 工作正常），因此嵌入式项目的配置似乎没问题。
这是 Activiti Explorer 的 applicationContext 文件：
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:jpa="http://www.springframework.org/schema/data/jpa"
xmlns:jee="http://www.springframework.org/schema/jee"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-3.1.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.1.xsd
http://www.springframework.org/schema/data/jpa
http://www.springframework.org/schema/data/jpa/spring-jpa.xsd
http://www.springframework.org/schema/jdbc
http://www.springframework.org/schema/jdbc/spring-jdbc-3.1.xsd
http://www.springframework.org/schema/jee
http://www.springframework.org/schema/jee/spring-jee-3.1.xsd">
<import resource="classpath*:/applicationContextCore.xml" />
<context:property-placeholder location="classpath*:jdbc.properties" />
<!-- Scan this classpath for annotated components that will be auto-registered
as Spring beans -->
<context:annotation-config /> <!-- this should take care of the @Autowiring issue -->
<!-- scan the embedded project's components -->
<context:component-scan base-package="my.project.*" />
<jpa:repositories base-package="my.project.repositories*" />
<bean
class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />
<!-- Automatically translate hibernate/jpa exceptions into Spring's generic
DataAccessException hierarchy for those classes annotated with Repository -->
<bean
class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />
<bean id="testServiceDummy" class="edu.bedelias.services.TestServiceDummyImpl" />
<!-- JPA Entity Manager Factory -->
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="jpaVendorAdapter" ref="hibernateJpaVendorAdapter" />
<property name="packagesToScan">
<list>
<value>edu.bedelias.*</value>
</list>
</property>
<property name="jpaProperties">
<props>
<!-- set HibernateJpaVendorAdapter's behavior: 'create' = build a new
DB on each run; 'update' = modify an existing database; 'create-drop' = 'create'
and also drops tables when Hibernate closes; 'validate' = makes no changes
to the database -->
<prop key="hibernate.hbm2ddl.auto">create-drop</prop>
</props>
</property>
</bean>
<bean id="hibernateJpaVendorAdapter"
class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
<property name="showSql" value="true" />
<property name="generateDdl" value="false" />
<property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect" />
</bean>
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
destroy-method="close">
<property name="driverClass" value="${jdbc.driverClass}" />
<property name="jdbcUrl" value="${jdbc.jdbcUrl}" />
<property name="user" value="${jdbc.user}" />
<property name="password" value="${jdbc.password}" />
<property name="maxPoolSize" value="${jdbc.maxPoolSize}" />
<property name="maxStatements" value="${jdbc.maxStatements}" />
<property name="minPoolSize" value="${jdbc.minPoolSize}" />
</bean>
<!-- Transaction Manager is defined -->
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
<property name="dataSource" ref="dataSource" />
</bean>
<!-- Hijack the current @Session scope annotation on each @Service and make
it last only for the duration of the thread -->
<bean class="org.springframework.beans.factory.config.CustomScopeConfigurer">
<property name="scopes">
<map>
<entry key="session">
<bean class="org.springframework.context.support.SimpleThreadScope" />
</entry>
</map>
</property>
</bean>
<!-- Enable the configuration of transactional behavior based on annotations -->
<tx:annotation-driven />
<bean id="dbProperties"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location" value="classpath:db.properties" />
<!-- Allow other PropertyPlaceholderConfigurer to run as well -->
<property name="ignoreUnresolvablePlaceholders" value="true" />
</bean>
<bean id="demoDataGenerator" class="org.activiti.explorer.demo.DemoDataGenerator">
<property name="processEngine" ref="processEngine" />
</bean>
<bean id="processEngineConfiguration" class="org.activiti.spring.SpringProcessEngineConfiguration">
<property name="dataSource" ref="dataSource" />
<property name="transactionManager" ref="transactionManager" />
<property name="databaseSchemaUpdate" value="true" />
<property name="jobExecutorActivate" value="true" />
<property name="customFormTypes">
<list>
<ref bean="userFormType" />
</list>
</property>
</bean>
<bean id="processEngine" class="org.activiti.spring.ProcessEngineFactoryBean"
destroy-method="destroy">
<property name="processEngineConfiguration" ref="processEngineConfiguration" />
</bean>
<bean id="repositoryService" factory-bean="processEngine"
factory-method="getRepositoryService" />
<bean id="runtimeService" factory-bean="processEngine"
factory-method="getRuntimeService" />
<bean id="taskService" factory-bean="processEngine"
factory-method="getTaskService" />
<bean id="historyService" factory-bean="processEngine"
factory-method="getHistoryService" />
<bean id="managementService" factory-bean="processEngine"
factory-method="getManagementService" />
<bean id="identityService" factory-bean="processEngine"
factory-method="getIdentityService" />
<bean id="activitiLoginHandler" class="org.activiti.explorer.ui.login.DefaultLoginHandler">
<property name="identityService" ref="identityService" />
</bean>
<!-- Include the UI-related wiring. This UI context will be used in the
alfresco activiti admin UI -->
<import resource="activiti-ui-context.xml" />
<!-- Custom form types -->
<bean id="userFormType" class="org.activiti.explorer.form.UserFormType" />
如果有人好奇，该项目的 URL 在这里： Google Code 托管项目
提前致谢，
加斯顿