Spring Batch MultiResourceItemReader resources reference from another class

问题

Is there a way to customize the MultiResourceItemReader Resources other than getting the value from JobParameters or using the Value tag? I tried the following but it did not work.

<bean id="ItemReader" class="org.springframework.batch.item.file.MultiResourceItemReader" scope="step">
      <property name="resources" ref="fileResources" />
      <property name="delegate" ref="flatFileItemReader" />
</bean>

<bean id="fileResources" class="com.app.batch.fileloader.file.FileResources" />

<bean id="flatFileItemReader" class="com.app.batch.fileloader.file.MyFlatFileItemReader">
    <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="," />
                </bean>
            </property>
            <property name="fieldSetMapper">
                <bean class="com.app.batch.fileloader.file.MyFileFieldSetMapper" />
            </property>
        </bean>
    </property>
</bean>

In the FileResources Java class I extended the MultiResourceItemReader like this

public class FileResources extends MultiResourceItemReader<FileDTO>{

@Override
public void setResources(Resource[] resources){
    ResourcePatternResolver patternResolver = new PathMatchingResourcePatternResolver();
    try{
        resources = patternResolver.getResources("file:" + properties.getPath() + "/*.csv");
    }
    catch(IOException ex){
        LOG.error("The resources must not be null");
    }

    super.setResources(resources);
}

What am I doing wrong can someone please let me know. Thanks!

回答1:

Use a FactoryBean. Create an implementation that returns a Resource [] and inject that into your MultiResourceItemReader. Spring will call the factory bean and use the output to populate the dependency.

An example would look something like this:

<bean id="ItemReader" class="org.springframework.batch.item.file.MultiResourceItemReader" scope="step">
      <property name="resources" ref="fileResources" />
      <property name="delegate" ref="flatFileItemReader" />
</bean>

<bean id="fileResources" class="com.app.batch.fileloader.file.ResourcesFactoryBean" />

With the above configuration, you'd use the below FactoryBean implementation:

public class ResourcesFactoryBean implements FactoryBean<Resource[]>{

    @Override
    public Resource[] getObject() {
        ResourcePatternResolver patternResolver = new PathMatchingResourcePatternResolver();
        try{
            resources = patternResolver.getResources("file:" + properties.getPath() + "/*.csv");
        }
        catch(IOException ex){
            LOG.error("The resources must not be null");
        }

        return resources;
    }
   ...

You can read more about Spring's FactoryBean interface in the documentation here: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/beans/factory/FactoryBean.html

And here: https://docs.spring.io/spring/docs/5.0.3.RELEASE/spring-framework-reference/core.html#beans-factory-extension-factorybean

来源：https://stackoverflow.com/questions/48407408/spring-batch-multiresourceitemreader-resources-reference-from-another-class

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java

Spring

batch-file

spring-batch