eclipse 在 Java 中删除 XML 元素
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Deleting XML element in Java
提问by Ross Abrahams
I have an XML:
我有一个 XML：
<?xml version="1.0" encoding="UTF-8"?>
<songs>
<song>
<title>Gracious</title>
<artist>Ben Howard</artist>
<genre>Singer/Songwriter</genre>
</song>
<song>
<title>Only Love</title>
<artist>Ben Howard</artist>
<genre>Singer/Songwriter</genre>
</song>
<song>
<title>Bad Blood</title>
<artist>Bastille</artist>
<genre>N/A</genre>
</song>
<song>
<title>Keep Your Head Up</title>
<artist>Ben Howard</artist>
<genre>Singer/Songwriter</genre>
</song>
<song>
<title>Intro</title>
<artist>Alt-J</artist>
<genre>Alternative</genre>
</song>
</songs>
and my Java code is:
我的Java代码是：
public static void deleteSong(Song song) {
String songTitle = song.getTitle();
String songArtist = song.getArtist();
String songGenre = song.getGenre();
try {
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
File file = new File("songs.xml");
Document doc = db.parse(file);
NodeList songList = doc.getElementsByTagName("song");
if (songList != null && songList.getLength() > 0) {
for (int i = 0; i < songList.getLength(); i++) {
Node node = songList.item(i);
Element e = (Element) node;
NodeList nodeList = e.getElementsByTagName("title");
String title = nodeList.item(0).getChildNodes().item(0)
.getNodeValue();
nodeList = e.getElementsByTagName("artist");
String artist = nodeList.item(0).getChildNodes().item(0)
.getNodeValue();
nodeList = e.getElementsByTagName("genre");
String genre = nodeList.item(0).getChildNodes().item(0)
.getNodeValue();
System.out.println(title + " Title");
System.out.println(songTitle + " SongTitle");
if (title.equals(songTitle)) {
if (artist.equals(songArtist)) {
if (genre.equals(songGenre)) {
doc.getFirstChild().removeChild(node);
}
}
}
}
}
MainDisplay.main(null);
} catch (Exception e) {
System.out.println(e);
}
}
The song to be deleted is passed into the method and then compared to the songs in the xml file. However, if the song matches a song in the xml, it isn't deleted? No exceptions come up.
将要删除的歌曲传入该方法，然后与 xml 文件中的歌曲进行比较。但是，如果歌曲与xml中的歌曲匹配，它不会被删除？没有异常出现。
采纳答案by Alpesh Gediya
You need to remove relevant node, in you code you are removing node of firstchild which seems to be incorrect.
您需要删除相关节点，在您的代码中，您正在删除似乎不正确的 firstchild 节点。
And write back your changes to the file.
并将您的更改写回文件。
if (title.equals(songTitle) && artist.equals(songArtist) && genre.equals(songGenre) ) {
node.getParentNode().removeChild(node);
}
// write back to xml file
//写回xml文件
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(new File(filepath));
transformer.transform(source, result);
回答by rethab
From what I see, you are only reading the documents. At some point, you will have to flush the changes back to the XML file.
据我所知，您只是在阅读文档。在某些时候，您必须将更改刷新回 XML 文件。
