在编辑 xml 时,java 的 dom 为什么会删除 doctype?
得到这个 xml 文件:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!DOCTYPE map[ <!ELEMENT map (station*) >
<!ATTLIST station id ID #REQUIRED> ]>
<favoris>
<station id="5">test1</station>
<station id="6">test1</station>
<station id="8">test1</station>
</favoris>
我的功能非常基础:
public static void EditStationName(int id, InputStream is, String path, String name) throws ParserConfigurationException, SAXException, IOException, TransformerFactoryConfigurationError, TransformerException{
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document dom = builder.parse(is);
Element e = dom. getElementById(String.valueOf(id));
e.setTextContent(name);
// Write the DOM document to the file
Transformer xformer = TransformerFactory.newInstance().newTransformer();
FileOutputStream fos = new FileOutputStream(path);
Result result = new StreamResult(fos);
Source source = new DOMSource(dom);
xformer.setOutputProperty(
OutputKeys.STANDALONE,"yes"
);
xformer.transform(source, result);
}
它正在工作,但文档类型被删除了!我刚刚得到了整个文档,但没有文档类型部分,这对我来说很重要,因为它允许我通过 id 检索! 我们怎样才能保留文档类型?为什么要删除它? 我尝试了许多带有输出键的解决方案,例如或 omImpl.createDocumentType,但这些都没有用...
谢谢!
最佳答案
您输入的 XML 无效。那应该是:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!DOCTYPE favoris [
<!ELEMENT favoris (station)+>
<!ELEMENT station (#PCDATA)>
<!ATTLIST station id ID #REQUIRED>
]>
<favoris>
<station id="i5">test1</station>
<station id="i6">test1</station>
<station id="i8">test1</station>
</favoris>
因为@DevNull 写的是完全有效的,所以你不能写 <station id="5">test1</station>
(但是对于 Java,即使遇到这个问题,它仍然可以正常工作)。
DOCTYPE
在输出 XML 文档中被删除:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<favoris>
<station id="i5">new value</station>
<station id="i6">test1</station>
<station id="i8">test1</station>
</favoris>
我还没有找到丢失 DTD 的解决方案,但作为解决方法,您可以设置外部 DTD:
xformer.setOutputProperty(OutputKeys.DOCTYPE_SYSTEM, "favoris.dtd");
结果(示例)文档:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!DOCTYPE favoris SYSTEM "favoris.dtd">
<favoris>
<station id="i5">new value</station>
<station id="i6">test1</station>
<station id="i8">test1</station>
</favoris>
编辑:
我不认为使用 Transformer
可以保存内联 DTD类(视频here)。如果您不能使用外部 DTD 引用,那么您可以使用 DOM Level 3 LSSerializer
改为上课:
DOMImplementationLS domImplementationLS =
(DOMImplementationLS) dom.getImplementation().getFeature("LS","3.0");
LSOutput lsOutput = domImplementationLS.createLSOutput();
FileOutputStream outputStream = new FileOutputStream("output.xml");
lsOutput.setByteStream((OutputStream) outputStream);
LSSerializer lsSerializer = domImplementationLS.createLSSerializer();
lsSerializer.write(dom, lsOutput);
outputStream.close();
带有所需 DTD 的输出(我看不到任何使用 standalone="yes"
添加 LSSerializer
的选项 ...):
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE favoris [<!ELEMENT favoris (station)+>
<!ELEMENT station (#PCDATA)>
<!ATTLIST station id ID #REQUIRED>
]>
<favoris>
<station id="i5">new value</station>
<station id="i6">test1</station>
<station id="i8">test1</station>
</favoris>
另一种方法是使用 Apache Xerces2-J XMLSerializer
类:
import org.apache.xml.serialize.OutputFormat;
import org.apache.xml.serialize.XMLSerializer;
...
XMLSerializer serializer = new XMLSerializer();
serializer.setOutputCharStream(new java.io.FileWriter("output.xml"));
OutputFormat format = new OutputFormat();
format.setStandalone(true);
serializer.setOutputFormat(format);
serializer.serialize(dom);
结果:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!DOCTYPE favoris [<!ELEMENT favoris (station)+>
<!ELEMENT station (#PCDATA)>
<!ATTLIST station id ID #REQUIRED>
]>
<favoris>
<station id="i5">new value</station>
<station id="i6">test1</station>
<station id="i8">test1</station>
</favoris>
关于java - 使用 DOM 解析 xml,DOCTYPE 被删除,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/6637076/