java xml将节点转换为元素 [英] java xml cast Node to Element

问题描述

我知道这被问了很多次，但我仍然无法让它工作.我将 xml 字符串转换为 Document 对象，然后解析它.代码如下:

I know this was asked many times but I still cannot get it to work. I convert xml string to Document object and then parse it. Here is the code:

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.*;

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder;
try
{
  builder = factory.newDocumentBuilder();  
  Document document = builder.parse( new InputSource( new StringReader( result ) ) );
  Node head = document.getFirstChild();
  if(head != null)
  {                  
    NodeList airportList = head.getChildNodes();      
    for(int i=0; i<airportList.getLength(); i++) {
    Node n = airportList.item(i);                        
    Element airportElem = (Element)n;
  }
}
catch (Exception e) {
  e.printStackTrace();
} 

当我将 Node 对象 n 转换为 Element 时，我得到一个异常 java.lang.ClassCastException: org.apache.harmony.xml.dom.TextImpl cannot be cast to org.w3c.dom.Element.当我检查 Node 对象的节点类型时，它显示 Node.TEXT_NODE.我相信它应该是 Node.ELEMENT_NODE.我对吗?

When I cast the Node object n to Element I get an exception java.lang.ClassCastException: org.apache.harmony.xml.dom.TextImpl cannot be cast to org.w3c.dom.Element. When I check the node type of the Node object it says Node.TEXT_NODE. I believe it should be Node.ELEMENT_NODE. Am I right?

那么如何将 Node 转换为 Element，这样我就可以执行 element.getAttribute("attrName") 之类的操作.

So how do I convert Node to Element, so I can do something like element.getAttribute("attrName").

这是我的 XML:

<?xml version="1.0" encoding="utf-8" ?> 
<ArrayOfCity xmlns:xsd="http://www.w3.org/2001/XMLSchema"     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
<City>
  <strName>Abu Dhabi</strName> 
  <strCode>AUH</strCode> 
</City>
<City>
  <strName>Amsterdam</strName> 
  <strCode>AMS</strCode> 
</City>
<City>
  <strName>Antalya</strName> 
  <strCode>AYT</strCode> 
</City>
<City>
  <strName>Bangkok</strName> 
  <strCode>BKK</strCode> 
</City>
</ArrayOfCity>

提前致谢！

推荐答案

当我将 Node 对象 n 转换为 Element 时，我得到一个异常 java.lang.ClassCastException: org.apache.harmony.xml.dom.TextImpl cannot be cast to org.w3c.dom.Element.当我检查 Node 对象的节点类型时，它显示 Node.TEXT_NODE.我相信它应该是 Node.ELEMENT_NODE.我说的对吗?

When I cast the Node object n to Element I get an exception java.lang.ClassCastException: org.apache.harmony.xml.dom.TextImpl cannot be cast to org.w3c.dom.Element. When I check the node type of the Node object it says Node.TEXT_NODE. I believe it should be Node.ELEMENT_NODE. Am I right?

可能不是，解析器可能是正确的.这意味着您正在解析的某些节点是 文本节点.例如:

Probably not, the parser is probably right. It means that some of the nodes in what you're parsing are text nodes. For example:

<foo>bar</foo>

在上面，我们有一个包含文本节点的 foo 元素.(文本节点包含文本 "bar".)

In the above, we have a foo element containing a text node. (The text node contains the text "bar".)

同样，考虑:

<foo>
    <bar>baz</bar>
</foo>

如果您的 XML 文档 literally 与上面类似，则它包含一个根元素 foo 和这些子节点(按顺序):

If your XML document literally looks like the above, it contains a root element foo with these child nodes (in order):

• 一个带有空格的文本节点
• 一个 bar 元素
• 一个包含更多空格的文本节点

请注意，bar 元素不是 foo 的第一个子元素.如果它看起来像这样:

Note that the bar element is not the first child of foo. If it looked like this:

<foo><bar>baz</bar></foo>

那么 bar 元素将是 foo 的第一个子元素.

then the bar element would be the first child of foo.

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