找到一篇jbpm session closed解决办法的文章

在处理删除参数的过程中，发现报org.hibernate.LazyInitializationException:failed to lazily initialize a collection of role: org.jbpm.pvm.internal.model.ExecutionImpl.variables, no session or session was closed

代码如下：

ExecutionService executionService = processEngine.getExecutionService();
ProcessInstance executionService.createProcessInstanceQuery().processDefinitionId(processInstanceId).list();
((ExecutionImpl)processInstance2).removeVariable("aa");//删除变量aa时报错。因为Variable设置是延迟加载解决方式一：如果采用的是BS开发模式可以在web.xml中配制OpenSessionInViewFilter（注意：必须写在struts的配置下面）<filter>
        <filter-name>OpenSessionInViewFilter</filter-name>
        <filter-class>
            org.springframework.orm.hibernate3.support.OpenSessionInViewFilter
        </filter-class>
    </filter>
    <filter-mapping>
        <filter-name>OpenSessionInViewFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>在application.xml中加入
<!-- 支持 @Transactional 标记 -->
    <tx:annotation-driven transaction-manager="transactionManager"/>

    <!-- 支持 @AspectJ 标记-->
    <aop:aspectj-autoproxy />

    <aop:config proxy-target-class="true">
        <aop:advisor pointcut="execution(* org.jbpm..*.*(..))"
            advice-ref="txAdvice" />
        <aop:advisor pointcut="execution(* com.jihong.jbpm.api.JbpmTemplate.*(..))"
                     advice-ref="txAdvice"/>
    </aop:config>

    <tx:advice id="txAdvice">
        <tx:attributes>
            <tx:method name="get*" read-only="true" />
            <tx:method name="find*" read-only="true" />
            <tx:method name="pagedQuery*" read-only="true" />
            <tx:method name="load*" read-only="true" />
            <tx:method name="remove*" read-only="true" />
            <tx:method name="*" />
        </tx:attributes>
    </tx:advice>

解决方式二：通过processEngine的execute方式可以将一段代码放到一个Hibernate的事务里执行这样就可以避免延迟加载。
public class RemoveVarCommand implements Command<Void> {
    private String processInstanceId;
    private String varKey;
    public RemoveVarCommand(String processInstanceId,String varKey){
        this.processInstanceId=processInstanceId;
        this.varKey=varKey;
    }
    @Override
    public Void execute(Environment environment) throws Exception {
        ExecutionService executionService = environment.get(ExecutionService.class);
        ProcessInstance processInstance= executionService.findProcessInstanceById(processInstanceId);
        ((ExecutionImpl)processInstance).removeVariable(varKey);
        return null;
    }
}

processEngine.execute(new RemoveVarCommand(processInstance.getId(), "aa"));
 
 每个命令都是一个独立的事务操作，每个excuete方法都被一个hibernate事务所包含,jbpm推荐使用这种方式扩展相关的功能。