java - 来自另一个类的 Spring Batch MultiResourceItemReader 资源引用

Question

除了从 JobParameters 获取值或使用 Value 标签之外，还有其他方法可以自定义 MultiResourceItemReader 资源吗？我尝试了以下方法，但没有成功。

<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>

在 FileResources Java 类中，我像这样扩展了 MultiResourceItemReader

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);
}

我做错了什么，有人可以告诉我吗？谢谢!

Answer 1

使用FactoryBean。创建一个返回 Resource [] 的实现，并将其注入(inject)到您的 MultiResourceItemReader 中。 Spring 将调用工厂 bean 并使用输出来填充依赖项。

一个例子看起来像这样:

<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" />  

通过上述配置，您将使用以下 FactoryBean 实现:

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;
    }
   ...

您可以在此处的文档中阅读有关 Spring 的 FactoryBean 接口(interface)的更多信息:https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/beans/factory/FactoryBean.html

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