我有以下 xml:
<Package>
<PackageHeader>
<name>External Vendor File</name>
<description>External vendor file for some purpose</description>
<version>3.141694baR3</version>
</PackageHeader>
<PackageBody>
<Characteristic id="1">
<Size>
<value>1.68</value>
<scale>Meters</scale>
<comment>Size can vary, depending on temperature</comment>
</Size>
<Weight>
<value>9</value>
<scale>M*Tons</scale>
<comment>His mama is so fat, we had to use another scale</comment>
</Weight>
<rating>
<ratingCompany>ISO</ratingCompany>
<rating:details xmlns:rating="http://www.w3schools.com/ratingDetails">
<rating:value companyDepartment="Finance">A</rating:value>
<rating:expirationDate update="1/12/2010">1/1/2014</rating:expirationDate>
<rating:comment userID="z94234">You're not Silvia.</rating:comment>
<rating:comment userID="r24942">You're one of the Kung-Fu Creatures On The Rampage</rating:comment>
<rating:comment userID="i77880">TWO!</rating:comment>
<rating:priority>3</rating:priority>
</rating:details>
</rating>
</Characteristic>
<Characteristic id="2">
<Size/>
<Weight/>
<rating/>
</Characteristic>
...
<Characteristic id="n"/>
</PackageBody>
</Package>
以及以下 Java 代码:
public class XMLTest {
public static void main(String[] args) throws Exception {
Package currentPackage = new Package();
Package sourcePackage = new Package();
int totalCharacteristics;
PackageBody currentPackageBody = new PackageBody();
Characteristic currentCharacteristic = new Characteristic();
rating currentRating = new rating();
FileInputStream fis = new FileInputStream("sourceFile.xml");
JAXBContext myCurrentContext = JAXBContext.newInstance(Package.class);
Marshaller m = myCurrentContext.createMarshaller();
Unmarshaller um = myCurrentContext.createUnmarshaller();
sourcePackage = (Package)um.unmarshal(fis);
currentPackage.setPackageHeader(sourcePackage.getPackageHeader());
totalCharacteristics = sourcePackage.getPackageBody().getCharacteristics().size();
for (int i = 0; i < totalCharacteristics; i++)
{
currentRating = sourcePackage.getPackageBody().getCharacteristics().get(i).getrating();
}
currentCharacteristic.setrating(currentRating);
currentPackageBody.getCharacteristics().add(currentCharacteristic);
currentPackage.setPackageBody(currentPackageBody);
m.marshal(currentPackage, new File("targetFile.xml"));
fis.close();
}
}
这给了我下一个 XML:
<Package>
<PackageHeader>
<name>External Vendor File</name>
<description>External vendor file for some purpose</description>
<version>3.141694baR3</version>
</PackageHeader>
<PackageBody>
<Characteristic id="1">
<rating>
<ratingCompany>ISO</ratingCompany>
<rating:details xmlns:rating="http://www.w3schools.com/ratingDetails">
<rating:value companyDepartment="Finance">A</rating:value>
<rating:expirationDate update="1/12/2010">1/1/2014</rating:expirationDate>
<rating:comment userID="z94234">You're not Silvia.</rating:comment>
<rating:comment userID="r24942">You're one of the Kung-Fu Creatures On The Rampage</rating:comment>
<rating:comment userID="i77880">TWO!</rating:comment>
<rating:priority>3</rating:priority>
</rating:details>
</rating>
</Characteristic>
<Characteristic id="2">
<rating/>
</Characteristic>
...
<Characteristic id="n"/>
</PackageBody>
</Package>
这就是我需要的:
<Package>
<PackageHeader>
<name>External Vendor File</name>
<description>External vendor file for some purpose</description>
<version>3.141694baR3</version>
</PackageHeader>
<PackageBody>
<Characteristic>
<rating id="1">
<ratingCompany>ISO</ratingCompany>
<rating:details xmlns:rating="http://www.w3schools.com/ratingDetails">
<rating:comment userID="z94234">You're not Silvia.</rating:comment>
<rating:comment userID="r24942">You're one of the Kung-Fu Creatures On The Rampage</rating:comment>
<rating:comment userID="i77880">TWO!</rating:comment>
<rating:priority>3</rating:priority>
</rating:details>
</rating>
</Characteristic>
<Characteristic>
<rating id="2"/>
</Characteristic>
...
<Characteristic/>
</PackageBody>
</Package>
但是我有几个问题:
如何实现读取 4GB 文件的方法? (例如,使用 StAX 阅读)。
如果我想从源到目标过滤一些标签(如最后一个 xml 中所示),我是否必须将它们一一分配给 targetFile?是否有任何迭代器可以让我遍历所有子节点并分配它们?
如果 sourceFile 发生更改,我是否需要重新运行 xjc 并重新编译整个项目?
谢谢。
最佳答案
要读取巨大的 XML 文件,您肯定需要像 StAX 这样的流式解析器。此外,如果您希望使用 JAXB 组合,则可以有选择地将给定的 xml 片段映射到 java 对象。仅当架构更改时才需要重新生成 JAXB 类。如果应用程序代码发生更改,则无需重新生成。
关于java - 使用 JAXB 剪切 XML,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/11158079/