java - Spring 批处理 : Create an ItemReader that reads an xml file from a web service

Question

我正在尝试创建一个 Spring Batch 作业，该作业将处理一个将通过 REST 调用提供的 xml 文件。

我正在尝试使用托管在 Internet 上的 XML 文件来对此进行测试。该文件位于:http://www.w3schools.com/xml/plant_catalog.xml

我在本地下载了这个文件并且能够将它转换为一个对象并写入它，但我不知道如果不在本地下载文件我该如何做同样的事情。这在本地有效，但我如何指定一个 URL 作为 xml 文件读取的资源？谢谢:)

启动上下文.xml

    <batch:job id="job1">
    <batch:step id="step1">
        <batch:tasklet transaction-manager="transactionManager" start-limit="100" >
            <batch:chunk reader="CustomPlantReader" writer="writer" commit-interval="1" />
        </batch:tasklet>
    </batch:step>
</batch:job>

自定义阅读器 bean:

    <bean id="CustomPlantReader" class="org.springframework.batch.item.xml.StaxEventItemReader" scope="step">
    <property name="fragmentRootElementName" value="PLANT" />
    <property name="resource" value="file:/C:/source/plant_catalog.xml" />
    <property name="unmarshaller" ref="PlantUnmarshaller" />
</bean>

<bean id="PlantUnmarshaller" class="org.springframework.oxm.castor.CastorMarshaller">
    <property name="ignoreExtraElements" value="true" />
    <property name="mappingLocation" value="linemapper/mapping.xml" />
</bean>

作为引用，如果有人想查看 mapping.xml 文件，这就是它的样子。它将 xml 节点映射到名为 Plant.java 的域对象

<mapping>
<class name="com.example.project.Plant">
    <map-to xml="PLANT" />

    <field name="common" type="string">
        <bind-xml name="COMMON" node="element"/>
    </field>
    <field name="botanical" type="string">
        <bind-xml name="BOTANICAL" node="element"/>
    </field>
    <field name="zone" type="string">
        <bind-xml name="ZONE" node="element"/>
    </field>
    <field name="light" type="string">
        <bind-xml name="LIGHT" node="element"/>
    </field>
    <field name="price" type="string">
        <bind-xml name="PRICE" node="element"/>
    </field>
    <field name="availability" type="string">
        <bind-xml name="AVAILABILITY" node="element"/>
    </field>

</class></mapping>

Answer 1

StaxEventItemReader 接受一个Resource。看看 documentation ，您将看到您可以轻松地使用不在您的文件系统上的资源。任何可以获得 InputStream 的东西都可能被转换为 Resource。据我所知，默认情况下使用 UrlResource 回退到 ClasspathResource。

4.3.1. UrlResource

The UrlResource wraps a java.net.URL, and may be used to access any object that is normally accessible via a URL, such as files, an HTTP target, an FTP target, etc. All URLs have a standardized String representation, such that appropriate standardized prefixes are used to indicate one URL type from another. This includes file: for accessing filesystem paths, http: for accessing resources via the HTTP protocol, ftp: for accessing resources via FTP, etc. A UrlResource is created by Java code explicitly using the UrlResource constructor, but will often be created implicitly when you call an API method which takes a String argument which is meant to represent a path. For the latter case, a JavaBeans PropertyEditor will ultimately decide which type of Resource to create. If the path string contains a few well-known (to it, that is) prefixes such as classpath:, it will create an appropriate specialized Resource for that prefix. However, if it doesn't recognize the prefix, it will assume the this is just a standard URL string, and will create a UrlResource.

所以你可以只使用这个:

<property name="resource" value="http://www.w3schools.com/xml/plant_catalog.xml" />