Dom
Turn from: http://blog.csdn.net/hk2000c/archive/2003/09/26/15239.aspx
JDOM Introduction and Use Guide
Introduction to JDOM JDOM is an open source project, which is based on a tree structure, using pure Java technology to parse, generate, serialize, and manipulate XML documents. JDOM directly for Java programming services. It leverages the many features of the more powerful Java language (method overload, set concepts, and mappings) to effectively combine the functionality of Sax and DOM. Hide the complexity of the original XML process as much as possible with the design. Using Jdom to process XML documents is easy and easy. JDOM was developed by Brett McLaughlin and Jason Hunter in the spring of 2000 to make up for the shortcomings of Dom and sax in practical applications. These deficiencies are largely due to the fact that SAX does not have document modification, random access, and output functionality, and for DOM, Java programmers are often less comfortable to use when used. The main disadvantage of DOM is that because DOM is an interface Definition language (IDL), its task is one of the lowest common standards in different language implementations, and is not specifically designed for Java. The latest version of Jdom is Jdom Beta 9. The recent jdom has been included in the JSR-102, marking Jdom as part of the Java platform.
Second, the JDOM package Overview JDOM is composed of the following packages Org.JDOMorg.JDOM.inputorg.JDOM.outputorg.JDOM.adaptersorg.JDOM.transform
Iii. description of the JDOM class
Org. Jdom the class in this package is all the data types you use to parse the XML file. Attributecdatacomentdoctypedocumentelemententityrefnamespaceproscessinginstructiontext
Org. Jdom.transform should use the following 2 classes when it comes to XSLT format conversions Jdomsourcejdomresult
Org. Jdom.input input class, commonly used for document creation Saxbuilderdombuilderresultsetbuilder
Org. Jdom.output output class, for document conversion output Xmloutputtersaxoutputterdomoutputterjtreeoutputter
Pre-use Precautions: 1. Jdom support for JAXP and TRax jdom support JAXP1.1: You can use any Parser tool class in your program, and by default, JAXP parser. The development of special parser can be saxbuilder parser = new Saxbuilder ("Org.apache.crimson.parser.XMLReaderImpl") in the following form; Document doc = Parser.build ("http://www.cafeconleche.org/"); Work with the document ... JDOM also supports trax:xslt through Jdomsource and Jdomresult classes (see chapters later) 2. Note that the document class in JDOM is represented by Org.JDOM.Document. This is different from the document in Org.w3c.dom, and how these 2 formats are converted will be explained later. The following, if not specified, refers to the document in Jdom.
Iv. Jdom main methods of Use 1.Ducument Class (1) Document operation method: Element root = new Element ("greeting");D ocument doc = new Document (root); Root.settext ("Hello jdom!"); or simply use document DOC = new document (New Element ("greeting"). SetText ("Hello jdom!t"));
This is different from DOM. DOM requires more complex code, as follows: Documentbuilderfactory factory =documentbuilderfactory.newinstance ();D Ocumentbuilder builder = Factory.newdocumentbuilder ();D ocument doc = Builder.newdocument (); Element root =doc.createelement ("root"); Text text = Doc.createtext ("This is the root"); Root.appendchild (text);d oc.appendchild (root);
Note: Jdom does not allow the same node to be associated with 2 or more documents at the same time, to use nodes in the original old document in document 2nd. First you need to use detach () to separate this node. (2) Get Document object from file, stream, System ID, url: dombuilder builder = new Dombuilder ();D ocument doc = builder.build (new file ("Jdom_ Test.xml "));
Saxbuilder builder = new Saxbuilder ();D ocument doc = builder.build (URL); Dombuilder has been deprecated in the new version. Dombuilder.builder (URL), with sax efficiency will be faster.
Here's a small example of using a string object directly as an XML data source for the sake of simplicity:
public jdomtest () { String textxml = null; textxml = "<note>"; & nbsp; textxml = Textxml + "<to>aaa</to><from>bbb </from>
It's a simple move.
(3) The conversion between Dom's document and Jdom's document is simple! Dombuilder builder = new Dombuilder (); Org.jdom.Document jdomdocument = Builder.build (DOMDocument);//work with the Jdom do Cument ...
Domoutputter converter = new Domoutputter (); Org.w3c.dom.Document DOMDocument = Converter.output (jdomdocument);//Work With the DOM document ...
2.XML Document output Xmloutputter class: Jdom output is very flexible, support many kinds of IO format and style output document DOC = new document (...); Xmloutputter OUTP = new Xmloutputter ()//Raw Outputoutp.output (Doc, FileOutputStream);//Compressed Outputoutp.settexttrim (True); Outp.output (Doc, Socket.getoutputstream ());//Pretty Outputoutp.setindent (""); o Utp.setnewlines (True); Outp.output (Doc, System.out); See the latest Jdom API manual for details
3.Element class: (1) Browse the element tree/get the root element elementelement root = Doc.getrootelement ();//Get a listlist of all child elements Allchildren = Root.getchildren ()///obtains the listlist Namedchildren = Root.getchildren ("name") of the specified name child element;//Gets the first child element of the specified name, Root.getchild ("name"); (the List here is Java.util.List)
Jdom gives us a lot of very flexible use methods to manage the child element list Allchildren = Root.getchildren ();//delete the fourth child element Allchildren.remove (3);/delete Call "Jack." The child element Allchildren.removeall (Root.getchildren ("Jack"));
Root.removechildren ("Jack"); Easy to spell//join Allchildren.add (New Element ("Jane"));
Root.addcontent (New Element ("Jane")); Convenient writing allchildren.add (0, New Element ("a");
(2) Mobile elements: very simple in jdom element movable = new Element ("movable");p arent1.addcontent (movable); Placeparent1.removecontent (movable); Removeparent2.addcontent (movable); Add
In DOM element movable = doc1.createelement ("movable");p arent1.appendchild (movable); Placeparent1.removechild (movable); Removeparent2.appendchild (movable); Error!
Add: The element constructor for error-correcting jdom (and its other functions) checks whether the element is legitimate. And its Add/remove method will check the tree structure, check the contents as follows: 1. Is there a link point 2 in any tree? Whether there is only one root node 3. Is there a consistent namespace (namespaces)
(3) element's text content read <description>a cool demo</description>
The text is directly available//Returns "\ A cool demo\n" String desc = Element.gettext ();
There ' s a convenient shortcut//Returns "a cool demo" String desc = Element.gettexttrim ();
(4) Elment Content Modification Element.settext ("A new description"); 3. Can correctly interpret special characters element.settext ("<xml> content"); 4.CDATA data writes, Read out element.addcontent (new CDATA ("<xml> content")); String nodifference = Element.gettext ();
A mixed content element may contain a variety of content, such as
<table><!--Some Comment-->some text<tr>some child element</tr></table>
Takes the child element of the table trstring Text = Table.gettexttrim (); Element tr = table.getchild ("tr");
You can also use another simpler method list Mixedco = Table.getcontent (); iterator ITR = Mixedco.iterator (); while (Itr.hasnext ()) {Object o = i.ne XT (); if (o instanceof Comment) {...} This can be written as comment, Element, Text, cdata,processinginstruction, or EntityRef type}//Now remove comment, note that the cursor should be 1. This is because the ENTER key is also parsed into the text class, so the comment entry should be 1. Mixedco.remove (1);
4.Attribute class <table width= "100%" border= "0" > </table>//obtained attributestring width = table.getattributevalue ( "width"); int border = Table.getattribute ("width"). Getintvalue ();//Set Attributetable.setattribute ("Vspace", "0"); Delete one or all Attributetable.removeattribute ("vspace"); Table.getattributes (). Clear ();
5. Processing instruction (processing instructions) operates an example of pls <?br?><?cocoon-process type= "xslt"?> | | | | Target data
Processing target name (target) String target = Pi.gettarget (), all data is obtained, all data after Target is returned. String data = Pi.getdata (); Gets the data string type = Pi.getvalue ("type") of the specified property; Gets the name list ls = Pi.getnames () of all properties;
6. Namespace operations <xhtml:html xmlns:xhtml= "http://www.w3.org/1999/xhtml" ><xhtml:title>home page</xhtml: Title></xhtml:html>
Namespace xhtml = Namespace.getnamespace ("xhtml", "http://www.w3.org/1999/xhtml"); List kids = Html.getchildren ("title", XHTML); Element kid = html.getchild ("title", XHTML); Kid.addcontent (New Element ("table", XHTML);
7.XSLT format conversion Use the following function to convert to XSLT finally if you need to use the document of the consortium you need to convert it. public static Document transform (String stylesheet,document in) throws Jdomexception { try { Transformer Transformer = transformerfactory.newinstance () Newtransformer (New Streamsource (stylesheet)); Jdomresult out = new Jdomresult (); Transformer.transform (New Jdomsource (in), out); return out.getdeocument (); } catch (TransformerException e) { throw new Jdomexception ("XSLT trandformation failed", e); } }
Bibliography:
1.JDOM Official website: http://www.jdom.org
2.<<processing XML with java>> elliotte Rusty Harold 2002
3.JDOM API Documentation
4.<<jdom makes XML Easy>>jason Hunter co-creator JDOM Project
5.WSDP Tutorial
