How to write a spring batch step without an itemwriter

问题

I am trying to configure a spring batch step without an item writer using below configuraion. However i get error saying that writer element has neither a 'writer' attribute nor a element.

I went through the link spring batch : Tasklet without ItemWriter. But could not resolve issue. Could any one tell me the specific changes to be made in the code snippet I mentioned

<batch:job id="helloWorldJob">
        <batch:step id="step1">
            <batch:tasklet>
                <batch:chunk reader="cvsFileItemReader"
                    commit-interval="10">
                </batch:chunk>
            </batch:tasklet>
        </batch:step>
    </batch:job>

    <bean id="cvsFileItemReader" class="org.springframework.batch.item.file.FlatFileItemReader">

        <property name="resource" value="classpath:cvs/input/report.csv" />

        <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="names" value="id,sales,qty,staffName,date" />
                    </bean>
                </property>
                <property name="fieldSetMapper">
                    <bean class="com.mkyong.ReportFieldSetMapper" />

                    <!-- if no data type conversion, use BeanWrapperFieldSetMapper to map by name
                    <bean
                        class="org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper">
                        <property name="prototypeBeanName" value="report" />
                    </bean>
                     -->
                </property>
            </bean>
        </property>

    </bean>

回答1:

For chunk-based step reader and writer are mandatory.
If you don't want a writer use a No-operation ItemWriter that does nothing.

EDIT:
A no-op implementation is an empty implementation of interface tha does...nothing!
Just let your class implements desiderable inteface(s) with empty methods.

No-op ItemWriter:

public class NoOpItemWriter implements ItemWriter {
  void write(java.util.List<? extends T> items) throws java.lang.Exception {
    // no-op
  }
}

回答2:

I hope you got answer but I want to explain it for other readers, When we use chunk then usually we declare reader, processor and writer. In chunk reader and writer are mandatory and processor is optional. In your case if you don't need writer then u need to make a class which implements ItemWriter. Override write method and keep it blank. Now create a bean of writer class and pass it as reference of writer.

<batch:step id="recordProcessingStep" >
        <batch:tasklet>
            <batch:chunk reader="fileReader" processor="recordProcessor"
                writer="rocordWriter" commit-interval="1" />
        </batch:tasklet>
    </batch:step>

Your writer class will look like .

public class RecordWriter<T> implements ItemWriter<T> {
@Override
public void write(List<? extends T> items) throws Exception {
    // TODO Auto-generated method stub

}

}

回答3:

In maven repo you can find the framework "spring-batch-samples".
In this framework you will find this Writer :

org.springframework.batch.sample.support.DummyItemWriter

来源：https://stackoverflow.com/questions/26202241/how-to-write-a-spring-batch-step-without-an-itemwriter

标签

Spring

spring-batch