春季批处理：填充n个文件，但下一步显示为空

Question

I implemented a step in spring batch that reads records from the database and generates output files. The step is partitioned so that each slave step generates a different file. Then I implemented a step which is executed after the slaves, and what it does is to read each of these generated files and consolidate them into a single file (merge).

The problem I am having is that when run the consolidator step, the input files are empty (probably because no flush was performed), then tried to configure forceSync = true and transactional = false in the slave writer, but without effect.

When they finish the job, the files generated by the slaves contains data, and the merge file is empty. The problem, then, is that the input files are empty at the time of execution of consolidator step.

Can help me?, needs more information?

(sorry for my english)

thanks

<batch:job id="interfacesJob" xmlns="">
    <batch:step id="step.1" parent="readerParent" next="step.2"/>
    <batch:step id="step.2" parent="merge"/>
</batch:job>

<batch:step id="readerParent">
    <batch:partition step="slave" partitioner="partitioner">
        <batch:handler grid-size="50" task-executor="poolTaskExecutor" />
    </batch:partition>
</batch:step>

<batch:step id="slave">
    <batch:tasklet 
        transaction-manager="transactionManager">
        <batch:chunk
            reader="dummyReader" 
            processor="dummyProcessor"
            writer="dummyWriter" 
            commit-interval="1"
            skip-limit="50">
    </batch:tasklet>
</batch:step>

<bean id="dummyWriter"
      class="org.springframework.batch.item.file.FlatFileItemWriter"
      scope="step" >
    <property name="resource" value="file:operations_#{stepExecutionContext[fromId]}.txt" />
    <property name="forceSync" value="true" />
    <property name="transactional" value="false" />
    <property name="lineAggregator">
        <bean class="org.springframework.batch.item.file.transform.DelimitedLineAggregator">
            <property name="delimiter" value="," /> <!-- default -->
            <property name="fieldExtractor">
                <bean class="org.springframework.batch.item.file.transform.BeanWrapperFieldExtractor">
                    <property name="names" value="id,field1,field2" />
                </bean>
            </property>
        </bean>
        </property>
</bean>

<batch:step id="merge">
    <tasklet>
        <chunk reader="mergeReader" writer="mergeWriter" commit-interval="1" />
    </tasklet>
</batch:step>

<bean id="mergeReader" 
       class="org.springframework.batch.item.file.FlatFileItemReader">
       <property name="resources" value="file:operations_*.txt" />
       <property name="lineMapper">
        <bean class="org.springframework.batch.item.file.mapping.DefaultLineMapper">
          <property name="lineTokenizer">
            <bean class="org.springframework.batch.item.file.transform.DelimitedLineTokenizer">
                <property name="delimiter" value="," />
            <property name="names" value="id,field1,field2" />
            </bean>
              </property>
              <property name="fieldSetMapper">
            <bean class="org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper">
            <property name="prototypeBeanName" value="dummyPrototypeBean" />
            </bean>
              </property>
       </bean>
      </property>
</bean>

<bean id="mergeWriter"
      class="org.springframework.batch.item.file.FlatFileItemWriter">
      <property name="resource" value="file:final.txt" />
      <property name="lineAggregator">
    <bean class="org.springframework.batch.item.file.transform.DelimitedLineAggregator">
        <property name="delimiter" value="," /> 
        <property name="fieldExtractor">
            <bean class="org.springframework.batch.item.file.transform.BeanWrapperFieldExtractor">
                <property name="names" value="id,field1,field2" />
            </bean>
        </property>
    </bean>
      </property>
</bean>

I taste with a MultiResourceItemReader for the mergeReader, but still continue with the same problem:

<bean id="mergeReader"
 class="org.springframework.batch.item.file.MultiResourceItemReader">
   <property name="resources" value="file:operations_*.txt" />
   <property name="delegate" ref="mergeReaderSpecific" />
 </bean>



<bean id="mergeReaderSpecific" 
      class="org.springframework.batch.item.file.FlatFileItemReader">
       <property name="lineMapper">
           <bean class="org.springframework.batch.item.file.mapping.DefaultLineMapper">
               <property name="lineTokenizer">
                  <bean class="org.springframework.batch.item.file.transform.DelimitedLineTokenizer">
                      <property name="delimiter" value="," />
                      <property name="names" value="id,field1,field2" />
                   </bean>
               </property>
               <property name="fieldSetMapper">
                  <bean class="org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper">
                      <property name="prototypeBeanName" value="dummyPrototypeBean" />
                  </bean>
               </property>
          </bean>
       </property>
</bean>

Answer 1

Probably you have to use a MultiResourceItemReader as mergeReader using a FlatFileItemReader as delegate.
FlatFileItemReader.resource property is intended to be used on a single resource opposite to MultiResourceItemReader.resources (plurals).