spring AutowireCapableBeanFactor

背景

最近做spring与quartz整合。业务实现时，需要在job里引入spring的bean，但是job的初始化时quartz在执行时new出来的。不受spring的管理，无法注入相关的依赖bean。多方查阅资料后，发现AutowireCapableBeanFactory可以实现类似功能。下面就通过走读代码的方式来学习下这个类的用法。

进入正题

首先来看下AutowireCapableBeanFactory的定义：

public interface AutowireCapableBeanFactory extends BeanFactory {
    <T> T createBean(Class<T> beanClass) throws BeansException;
    void autowireBean(Object existingBean) throws BeansException;
    Object configureBean(Object existingBean, String beanName) throws BeansException;
    Object createBean(Class<?> beanClass, int autowireMode, boolean dependencyCheck) throws BeansException;
    Object autowire(Class<?> beanClass, int autowireMode, boolean dependencyCheck) throws BeansException;
    void autowireBeanProperties(Object existingBean, int autowireMode, boolean dependencyCheck)
            throws BeansException;
    void applyBeanPropertyValues(Object existingBean, String beanName) throws BeansException;
    Object initializeBean(Object existingBean, String beanName) throws BeansException;
    Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName)
            throws BeansException;
    Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName)
            throws BeansException;
    void destroyBean(Object existingBean);
    <T> NamedBeanHolder<T> resolveNamedBean(Class<T> requiredType) throws BeansException;
    Object resolveDependency(DependencyDescriptor descriptor, String requestingBeanName) throws BeansException;
    Object resolveDependency(DependencyDescriptor descriptor, String requestingBeanName,
            Set<String> autowiredBeanNames, TypeConverter typeConverter) throws BeansException;
}

该类的注释中有这么一句话Integration code for other frameworks can leverage this interface to wire and populate existing bean instances that Spring does not control the lifecycle of，意思是说该类可以填充那些不受spring容器控制的bean。
spring和quartz在集成的时候用了autowireBean方法。下面走读这个方法的代码来看处理逻辑。
autowireBean的实现在类AbstractAutowireCapableBeanFactory中。
代码如下

public void autowireBean(Object existingBean) {
        // Use non-singleton bean definition, to avoid registering bean as dependent bean.
        RootBeanDefinition bd = new RootBeanDefinition(ClassUtils.getUserClass(existingBean));
        bd.setScope(BeanDefinition.SCOPE_PROTOTYPE);
        bd.allowCaching = ClassUtils.isCacheSafe(bd.getBeanClass(), getBeanClassLoader());
        BeanWrapper bw = new BeanWrapperImpl(existingBean);
        initBeanWrapper(bw);
        populateBean(bd.getBeanClass().getName(), bd, bw);
    }

该方法的逻辑主要在populateBean中。这个方法是spring里很重要的一个方法，用于装配bean。这里逻辑很复杂，主要是通过反射获取我们new出来的对象的属性及注解。若注解是Autowired,Value,Inject时，进行bean的组装。此方法执行完成之后。我们new出来的对象里通过注解注入的bean就可以使用了。
关键代码展示：

protected void populateBean(String beanName, RootBeanDefinition mbd, BeanWrapper bw) {
    ......
        if (hasInstAwareBpps || needsDepCheck) {
            PropertyDescriptor[] filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
            if (hasInstAwareBpps) {
                for (BeanPostProcessor bp : getBeanPostProcessors()) {
                    if (bp instanceof InstantiationAwareBeanPostProcessor) {
                        InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
                      //依赖的bean注入在这里实现
                        pvs = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
                  //end
                        if (pvs == null) {
                            return;
                        }
                    }
                }
            }
            if (needsDepCheck) {
                checkDependencies(beanName, mbd, filteredPds, pvs);
            }
        }

        applyPropertyValues(beanName, mbd, bw, pvs);
    }

public PropertyValues postProcessPropertyValues(
            PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName) throws BeanCreationException {

            //获取注入的属性
        InjectionMetadata metadata = findAutowiringMetadata(beanName, bean.getClass(), pvs);
        try {
                    //注入
            metadata.inject(bean, beanName, pvs);
        }
        catch (BeanCreationException ex) {
            throw ex;
        }
        catch (Throwable ex) {
            throw new BeanCreationException(beanName, "Injection of autowired dependencies failed", ex);
        }
        return pvs;
    }

例子

quartz 的job里注入bean：
job 工厂：

public class JobFactory extends AdaptableJobFactory {

    @Autowired
    private AutowireCapableBeanFactory capableBeanFactory;

    @Override
    protected Object createJobInstance(TriggerFiredBundle bundle) throws Exception {
        //调用父类的方法
        Object jobInstance = super.createJobInstance(bundle);
        //进行注入
        capableBeanFactory.autowireBean(jobInstance);
        return jobInstance;
    }

}

job的具体处理逻辑

public final class InternalJob implements Job {

    private static final Logger logger = LoggerFactory.getLogger(InternalJob .class);

    @Autowired
    private CuratorFramework client;
    @Autowired
    private JobAlarmEventService jobAlarmEventService;

job的spring配置：

<bean id="jobFactory" class="com.test.scheduler.JobFactory"></bean>
    <bean id="schedulerFactoryBean" class="org.springframework.scheduling.quartz.SchedulerFactoryBean">
        <property name="jobFactory" ref="jobFactory"></property>
        <property name="schedulerName" value="scheduler"></property>
        <property name="configLocation"  value="classpath:META-INF/spring/quartz.properties"></property>    
    </bean>