使用CompositeItemWriter和Classifier的Spring批处理发出CompositeItemWriter

Question

我使用spring批处理从数据库中读取数据（使用分区），并根据输入键-1,2,3,4将数据写入一组文件。

我创建了一个CompositeItemWriter，它是两个ClassifierCompositeItemWriter的组合。即使我已将单个Writer注册为stream，但仍然会遇到以下异常：

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

我甚至尝试将ItemWriter1和ItemWriter2注册为流,但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

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

<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。从上到下：

>

abcWriter是一个CompositeItemWriter。它通过将ItemStream方法调用委托给委托（这里是ItemWriter1和ItemWriter2)来实现ItemStream，前提是它们实现了ItemStream。事实并非如此。但是，即使他们实现了itemstream，您也不应该在步骤配置中将itemwriter1和itemwriter2单独注册为流（下一个要点中还有另一个独立的原因）。

ItemWriter1/ItemWriter2是分类器组合ItemWriter。该类不实现itemstream，因此您不能在步骤配置中将它们注册为流。