Java DOM XML 正在跳过 xmlns 属性
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/1294981/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Java DOM XML is skipping xmlns properties
提问by Lliane
I need to generate an xml file in Java, so I chose to use DOM (until there everything is ok), here is the root tag of what i need to create
我需要用Java生成一个xml文件，所以我选择使用DOM（直到一切正常），这是我需要创建的根标签
<?xml version="1.0" encoding="utf-8"?>
<KeyContainer Version="1.0" xmlns="urn:ietf:params:xml:ns:keyprov:pskc:1.0" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:xenc="http://www.w3.org/2001/04/xmlenc#" xmlns:xml="http://www.w3.org/XML/1998/namespace">
Here is my source code
这是我的源代码
PrintWriter out = new PrintWriter(path);
Document xmldoc = null;
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
DOMImplementation impl = builder.getDOMImplementation();
Element e = null;
Node n = null;
xmldoc = impl.createDocument(null, "KeyContainer", null);
/* Noeuds non bouclés */
Element keycontainer = xmldoc.getDocumentElement();
keycontainer.setAttributeNS(null, "Version", "1.0");
keycontainer.setAttributeNS("http://www.w3.org/2000/xmlns/", "xmlns:ds","http://www.w3.org/2000/09/xmldsig#");
keycontainer.setAttributeNS("http://www.w3.org/2000/xmlns/", "xmlns:xenc", "http://www.w3.org/2001/04/xmlenc#");
keycontainer.setAttributeNS("http://www.w3.org/2000/xmlns/", "xmlns:xml", "http://www.w3.org/XML/1998/namespace");
keycontainer.setAttributeNS("http://www.w3.org/2000/xmlns/", "xmlns", "urn:ietf:params:xml:ns:keyprov:pskc:1.0");
/* Non relevant Info*/
DOMSource domSource = new DOMSource(xmldoc);
StreamResult streamResult = new StreamResult(out);
TransformerFactory tf = TransformerFactory.newInstance();
Transformer serializer = tf.newTransformer();
serializer.setOutputProperty(OutputKeys.ENCODING,"utf-8");
serializer.setOutputProperty(OutputKeys.VERSION,"1.0");
serializer.setOutputProperty(OutputKeys.INDENT,"yes");
serializer.setOutputProperty(OutputKeys.STANDALONE,"yes");
serializer.transform(domSource, streamResult);
And here is what I get
这就是我得到的
<?xml version="1.0" encoding="utf-8" standalone="no"?>
<KeyContainer xmlns="" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:xenc="http://www.w3.org/2001/04/xmlenc#" Version="1.0">
Problem is the xmlns property is empty, and xmlns:xml is missing, what can I do to get all information ?
问题是 xmlns 属性为空，并且缺少 xmlns:xml，我该怎么做才能获取所有信息？
Thanks a lot stackoverflow
非常感谢 stackoverflow
(PS : Got NAMESPACE_ERR if anything else than "http://www.w3.org/2000/xmlns/" in NamespaceURI field)
（PS：如果NamespaceURI 字段中除了“ http://www.w3.org/2000/xmlns/”之外还有其他内容，则会得到 NAMESPACE_ERR ）
采纳答案by laz
Two things are required to get rid of xmlns=""
需要两件事才能摆脱 xmlns=""
Create the Documentwith the desired namespace URI as such:
Document使用所需的命名空间 URI创建，如下所示：
xmldoc = impl.createDocument("urn:ietf:params:xml:ns:keyprov:pskc:1.0", "KeyContainer", null);
Remove the following line as it is now unnecessary:
删除以下行，因为它现在是不必要的：
keycontainer.setAttributeNS("http://www.w3.org/2000/xmlns/", "xmlns", "urn:ietf:params:xml:ns:keyprov:pskc:1.0");
Regarding the xmlns:xmlattribute, the API is silently dropping it. See line 173 of NamespaceMappings. A bit of research turns up that the behavior of declaring that particular namespace is undefined and is not recommended.
关于xmlns:xml属性，API 正在悄悄地删除它。见第 173 行NamespaceMappings。一些研究表明，声明特定命名空间的行为是未定义的，是不推荐的。
回答by Paul de Vrieze
To make DOM namespace aware, do not forget to enable it in the documentbuilderfactory using the setNamespaceAwaremethod.
要使 DOM 命名空间感知，不要忘记使用setNamespaceAware方法在 documentbuilderfactory 中启用它。
