解析 Java 的 XML。

huangapple
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英文:

parsing Xml for Java

问题

以下是翻译好的部分：

存在这样的XML文档：

  1. <?xml version="1.0" encoding="utf-8"?>
  2. <root>
  3.     <a/>
  4.     <a/>
  5.     <a/>
  6.     <b>
  7.         <c/>
  8.         <d/>
  9.         <c/>
  10.         <d/>
  11.         <c/>
  12.         <d/>
  13.     </b>
  14. </root>

以下代码用于获取 "a" 节点的NodeList：

  1. DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
  2. DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
  3. Document doc = dBuilder.parse(xmlfile);
  4. doc.getDocumentElement().normalize();
  5. NodeList aNodes = doc.getElementsByTagName("a");

但是，在Java中如何检索 "c" 节点的NodeList呢？
我尝试获取 "b" 节点的子节点，但是没有结果，getLength() = 0。

  1. NodeList bNodes = doc.getElementsByTagName("b");
  2. NodeList cNodes = bNodes.item(0).getChildNodes();
英文:

There exists XML document like this:
<?xml version="1.0" encoding="utf-8"?>

  1. &lt;root&gt;
  2. 	&lt;a/&gt;
  3. 	&lt;a/&gt;
  4. 	&lt;a/&gt;
  5. 	&lt;b&gt;
  6. 		&lt;c/&gt;
  7. 			&lt;d/&gt;
  8. 		&lt;c/&gt;
  9. 			&lt;d/&gt;
  10. 		&lt;c/&gt;
  11. 			&lt;d/&gt;
  12. 	&lt;/b&gt;
  13. &lt;/root&gt;

Following code is using to get "a" NodeList:

  1. DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
  2. DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
  3. Document doc = dBuilder.parse(xmlfile);
  4. doc.getDocumentElement().normalize();
  5. NodeList aNodes = doc.getElementsByTagName(&quot;a&quot;);

But how in Java I can retrieve NodeList of "c"?
I tried to get nodes of "b" nodes but it have not results, getlength() = 0.

  1. NodeList bNodes = doc.getElementsByTagName(&quot;b&quot;);
  2. NodeList cNodes = bNodes.item(0).getChildNodes();

答案1

得分: 1

你可以像这样使用 doc.getElementsByTagName(&quot;c&quot;) 来获取它们。

  1. NodeList cNodes = doc.getElementsByTagName(&quot;c&quot;);
  2. for (int i = 0; i &lt; cNodes.getLength(); ++i)
  3.     System.out.println(cNodes.item(i));

输出：

  1. [c: null]
  2. [c: null]
  3. [c: null]

我也可以检索到 "b" 的 NodeList。

  1. NodeList bNodes = doc.getElementsByTagName(&quot;b&quot;);
  2. NodeList bChildren = bNodes.item(0).getChildNodes();
  3. for (int i = 0; i &lt; bChildren.getLength(); ++i)
  4.     System.out.println(bChildren.item(i));

输出：

  1. [#text: 
  2.         ]
  3. [c: null]
  4. [#text: 
  5.             ]
  6. [d: null]
  7. [#text: 
  8.         ]
  9. [c: null]
  10. [#text: 
  11.             ]
  12. [d: null]
  13. [#text: 
  14.         ]
  15. [c: null]
  16. [#text: 
  17.             ]
  18. [d: null]
  19. [#text: 
  20.     ]
英文:

You can get them by doc.getElementsByTagName(&quot;c&quot;) like this.

  1. NodeList cNodes = doc.getElementsByTagName(&quot;c&quot;);
  2. for (int i = 0; i &lt; cNodes.getLength(); ++i)
  3.     System.out.println(cNodes.item(i));

output:

  1. [c: null]
  2. [c: null]
  3. [c: null]

I can also retrieve NodeList of "b".

  1. NodeList bNodes = doc.getElementsByTagName(&quot;b&quot;);
  2. NodeList bChildren = bNodes.item(0).getChildNodes();
  3. for (int i = 0; i &lt; bChildren.getLength(); ++i)
  4.     System.out.println(bChildren.item(i));

output:

  1. [#text: 
  2.         ]
  3. [c: null]
  4. [#text: 
  5.             ]
  6. [d: null]
  7. [#text: 
  8.         ]
  9. [c: null]
  10. [#text: 
  11.             ]
  12. [d: null]
  13. [#text: 
  14.         ]
  15. [c: null]
  16. [#text: 
  17.             ]
  18. [d: null]
  19. [#text: 
  20.     ]

huangapple
  • 本文由 发表于 2020年8月7日 12:47:29
  • 转载请务必保留本文链接：https://go.coder-hub.com/63295387.html
  • java
  • nodelist
  • xml
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