Java Parse XML files, add nodes, and delete operations

1. java code:
Mainly uses dom for operations
Copy codeThe Code is as follows:
Package test;
Import java. io. IOException;
Import javax. xml. parsers. DocumentBuilder;
Import javax. xml. parsers. DocumentBuilderFactory;
Import javax. xml. parsers. ParserConfigurationException;
Import javax. xml. transform. Transformer;
Import javax. xml. transform. TransformerConfigurationException;
Import javax. xml. transform. TransformerException;
Import javax. xml. transform. TransformerFactory;
Import javax. xml. transform. dom. DOMSource;
Import javax. xml. transform. stream. StreamResult;
Import org. w3c. dom. Document;
Import org. w3c. dom. Element;
Import org. w3c. dom. NodeList;
Import org. w3c. dom. Text;
Import org. xml. sax. SAXException;
Public class XmlOprate {
Document doc;
DocumentBuilderFactory factory = DocumentBuilderFactory. newInstance ();
DocumentBuilder builder;
NodeList imags;
String path;
Public NodeList getImags (){
Return imags;
}
Public void setImags (NodeList imags ){
This. imags = imags;
}
/**
* Constructor
* @ Param path: path of the xml file
* @ Param nodes: name of the xml node to be parsed
*/
Public XmlOprate (String path ){
Super ();
This. path = path;
System. out. println (System. getProperty ("user. dir "));
}
/**
* Parse XML
* @ Param path
*/
Public void readXml (){
Try {
Builder = factory. newDocumentBuilder ();
Document doc = builder. parse (path );
Doc. normalize ();
NodeList imags = doc. getElementsByTagName ("imags ");
This. setImags (imags );
For (int I = 0; I <imags. getLength (); I ++ ){
Element link = (Element) imags. item (I );
System. out. print ("title :");
System. out. println (link. getElementsByTagName ("title"). item (0). getFirstChild (). getNodeValue ());
System. out. print ("URL :");
System. out. println (link. getElementsByTagName ("url"). item (0). getFirstChild (). getNodeValue ());
System. out. print ("imgsrc :");
System. out. println (link. getElementsByTagName ("imgsrc"). item (0). getFirstChild (). getNodeValue ());
System. out. println ();
}
} Catch (ParserConfigurationException e ){
E. printStackTrace ();
} Catch (SAXException e ){
E. printStackTrace ();
} Catch (IOException e ){
E. printStackTrace ();
}
}
/**
* AddCode
* @ Param path
*/
Public void addXmlCode (String imgsrc, String title, String url ){
Try {
Builder = factory. newDocumentBuilder ();
Document doc = builder. parse (path );
Doc. normalize ();
Text textseg;
Element imag = doc. createElement ("imags ");
Element linkimgsrc = doc. createElement ("imgsrc ");
Textseg = doc. createTextNode (imgsrc );
Linkimgsrc. appendChild (textseg );
Imag. appendChild (linkimgsrc );
Element linktitle = doc. createElement ("title ");
Textseg = doc. createTextNode (title );
Linktitle. appendChild (textseg );
Imag. appendChild (linktitle );
Element linkurl = doc. createElement ("url ");
Textseg = doc. createTextNode (url );
Linkurl. appendChild (textseg );
Imag. appendChild (linkurl );
Doc. getDocumentElement (). appendChild (imag );
TransformerFactory tFactory = TransformerFactory. newInstance ();
Transformer transformer;
Transformer = tFactory. newTransformer ();
DOMSource source = new DOMSource (doc );
StreamResult result = new StreamResult (new java. io. File (path ));
Transformer. transform (source, result );
} Catch (Exception e ){
}
}
/**
* Delete xml code
* @ Param path
*/
Public void delXmlCode (){
Try {
Builder = factory. newDocumentBuilder ();
Doc = builder. parse (path );
Doc. normalize ();
NodeList imags = doc. getElementsByTagName ("imags ");
Element elink = (Element) imags. item (0 );
Elink. removeChild (elink. getElementsByTagName ("imgsrc"). item (0 ));
Elink. removeChild (elink. getElementsByTagName ("title"). item (0 ));
Elink. removeChild (elink. getElementsByTagName ("url"). item (0 ));
Doc. getFirstChild (). removeChild (elink );
TransformerFactory tFactory = TransformerFactory. newInstance ();
Transformer transformer = tFactory. newTransformer ();
DOMSource source = new DOMSource (doc );
StreamResult result = new StreamResult (new java. io. File (path ));
Transformer. transform (source, result );
} Catch (ParserConfigurationException e ){
E. printStackTrace ();
} Catch (SAXException e ){
E. printStackTrace ();
} Catch (IOException e ){
E. printStackTrace ();
} Catch (TransformerConfigurationException e ){
E. printStackTrace ();
} Catch (TransformerException e ){
E. printStackTrace ();
}
}
}

2. xml section
Copy codeThe Code is as follows:
<? Xml version = "1.0" encoding = "UTF-8"?>
<Root>
<Imags>
images/ad-01.jpg </imgsrc>
<Title> Ho Chi Minh City </title>
<Url> http://torchrelay.beijing2008.cn/cn/journey/hochiminhcity/ </url>
</Imags>
<Imags>
images/ad-02.jpg </imgsrc>
<Title> Hong Kong 2 </title>
<Url> http://torchrelay.beijing2008.cn/cn/journey/hongkong/ </url>
</Imags>
</Root>

3. Summary:
The three methods for xml operations (read, write, and delete) have the same initialization statement:
Copy codeThe Code is as follows:
Builder = factory. newDocumentBuilder ();
Document doc = builder. parse (path );
Doc. normalize ();

At first, I plan to write the same part in the constructor, but in the test, it is found that the NULL pointer error will always be reported (it took me a long time );
Instead
Builder = factory. newDocumentBuilder ();
When it is placed in the builder's initialization statement, the reading is okay, but an error is returned when writing or deleting the statement;
So I wrote it like this now. It seems a bit messy, but I didn't expect any good method. I posted it here first, and it may be used later.