Spring批处理问题w/CompositeItemWriter和ClassifierCompositeItemWriter

Question

我正在使用spring批处理为了从数据库中读取数据（使用分区）并将其写入基于输入键 - 1,2,3,4的一组文件。

我已经创建了一个CompositeItemWriter，它是两个ClassifierCompositeItemWriter（s）的组合。尽管我已经注册了独立作家流，我仍然得到以下异常：

org.springframework.batch.item.WriterNotOpenException: Writer must be open before it can be written to 

我甚至尝试注册ItemWriter1和ItemWriter2如流，但是，这给了我一个不同的错误：

Caused by: java.lang.IllegalStateException: Cannot convert value of type [com.sun.proxy.$Proxy13 implementing org.springframework.batch.item.ItemWriter,java.io.Serializable,org.springframework.aop.scope.ScopedObject,org.springframework.aop.framework.AopInfrastructureBean,org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised] to required type [org.springframework.batch.item.ItemStream] for property 'streams[0]': no matching editors or conversion strategy found 
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:264) 
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:128) 
    at org.springframework.beans.TypeConverterDelegate.convertToTypedArray(TypeConverterDelegate.java:463) 
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:195) 
    at org.springframework.beans.BeanWrapperImpl.convertIfNecessary(BeanWrapperImpl.java:448) 
    ... 74 more 

我甚至在编写器中实现了ItemStream，但它还没有工作。

public class WriterA1 implements ItemWriter<List<Object>>, ItemStream { 
... 
} 

下面是XML配置：

...

<job id="abcJob" xmlns="http://www.springframework.org/schema/batch" 
    restartable="true"> 

    <step id="masterStep"> 
     <partition step="slaveStep" partitioner="abcPartitioner"> 
      <handler grid-size="${grid-size}" task-executor="abcTaskExecutor" /> 
     </partition>    
    </step> 

</job> 

<step id="slaveStep" xmlns="http://www.springframework.org/schema/batch"> 
     <tasklet transaction-manager="transactionManager"> 
      <chunk reader="abcReader" writer="abcWriter" 
       processor="abcProcessor" commit-interval="${a}" skip-limit="${b}" retry-limit="${c}" > 

       <streams> 
        <!-- 
        <stream ref="ItemWriter1"/> 
        <stream ref="ItemWriter2"/> 
        -->       
        <stream ref="WriterA1"/> 
        <stream ref="WriterB2"/> 
        <stream ref="WriterC3"/> 
        <stream ref="WriterD4"/>            
        <stream ref="WriterA5"/> 
        <stream ref="WriterB6"/> 
        <stream ref="WriterC7"/> 
        <stream ref="WriterD8"/> 

       </streams>     

      </chunk> 
      <listeners> 
       ...          
      </listeners>             
     </tasklet>    
    </step> 


<bean id="abcWriter" class="org.springframework.batch.item.support.CompositeItemWriter" scope="step"> 
    <property name="delegates"> 
     <list>    
      <ref bean="ItemWriter1" /> 
      <ref bean="ItemWriter2" /> 
     </list> 
    </property> 
</bean> 

<bean id="ItemWriter1" class="org.springframework.batch.item.support.ClassifierCompositeItemWriter" scope="step"> 
    <property name="classifier"> 
     <bean 
      class="org.springframework.classify.BackToBackPatternClassifier"> 
      <property name="routerDelegate"> 
       <bean class="xxx.xxx.xxx.xxx.Classifier1" scope="step"/> 
      </property> 
      <property name="matcherMap"> 
       <map> 
        <entry key="1" value-ref="WriterA1" /> 
        <entry key="2" value-ref="WriterB2" /> 
        <entry key="3" value-ref="WriterC3" /> 
        <entry key="4" value-ref="WriterD4" /> 
       </map> 
      </property> 
     </bean>  
    </property> 
</bean> 

<bean id="ItemWriter2" class="org.springframework.batch.item.support.ClassifierCompositeItemWriter" scope="step"> 
    <property name="classifier"> 
     <bean 
      class="org.springframework.classify.BackToBackPatternClassifier"> 
      <property name="routerDelegate"> 
       <bean class="xxx.xxx.xxx.xxx.Classifier2" scope="step"/> 
      </property> 
      <property name="matcherMap"> 
       <map> 
        <entry key="1" value-ref="WriterA5" /> 
        <entry key="2" value-ref="WriterB6" /> 
        <entry key="3" value-ref="WriterC7" /> 
        <entry key="4" value-ref="WriterD8" /> 
       </map> 
      </property> 
     </bean>  
    </property> 
</bean> 

<bean id="WriterA1" class="xxx.xxx.xxx.xxx.WriterA1" scope="step"> 

</bean> 
<bean id="WriterB2" class="xxx.xxx.xxx.xxx.WriterB2" scope="step"> 

</bean> 
<bean id="WriterC3" class="xxx.xxx.xxx.xxx.WriterC3" scope="step"> 

</bean> 
<bean id="WriterD4" class="xxx.xxx.xxx.xxx.WriterD4" scope="step"> 

</bean> 
    <bean id="WriterA5" class="xxx.xxx.xxx.xxx.WriterA5" scope="step"> 

    </bean> 
    <bean id="WriterB6" class="xxx.xxx.xxx.xxx.WriterB6" scope="step"> 

    </bean> 
<bean id="WriterC7" class="xxx.xxx.xxx.xxx.WriterC7" scope="step"> 

</bean> 
<bean id="WriterD8" class="xxx.xxx.xxx.xxx.WriterD8" scope="step"> 

</bean> 

请指教。

Answer 1

你有三种类型的作家。从上至下：

• abcWriter是CompositeItemWriter。它通过将ItemStream方法调用委托给代表（此处为ItemWriter1和ItemWriter2）实施ItemStream，前提是他们实施了ItemStream。事实并非如此。但即使他们实施了ItemStream，您也不应该在步骤配置中单独将ItemWriter1和ItemWriter2注册为流（在下一个项目符号中有另一个独立原因）。

• ItemWriter1/ItemWriter2是ClassifierCompositeItemWriter s。这个类没有实现ItemStream，所以你一定不要在步骤配置中将它们注册为流。

• WriterA1属于BeanIOFlatFileItemWriter类型，因此实施ItemStream。因为包装它们的ClassifierCompositeItemWriter不称为它们的ItemStream方法（与CompositeItemWriter不同），所以必须将中的每一个都注册为步骤配置中的流。

但是，这是你声称你有。然而，您的作用域范围内的bean正在通过不实现ItemStream或ItemStreamWriter（而不是ItemWriter）的单例bean进行代理（使用接口代理模式）。确保您在<bean>元素内部执行的类具有实施ItemStream。您也可以尝试明确创建范围代理bean（使用ScopedProxyFactoryBean并设置interfaces属性）。或者你可以尝试在ScopedProxyFactoryBean::setBeanFactory中打破一个断点，当targetBeanName包含字符串WriterXX（它将类似于stepScopedTarget.WriterD8）并试图理解为什么ItemStream接口未被代理。