java类库详细讲解

				
				
				
				Getting the Root Element in a DOM Document
				(Java Developers Almanac Example)
				
				
				
				
				
				
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				The Java Developers Almanac 1.4
				
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				    org.w3c.dom
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				        Getting Nodes
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				    e1071.  
				    Getting the Root Element in a DOM Document
				
				The root element of an XML file is not the same as the root element of
				a DOM document.  In particular, the XML root element is a child of the
				DOM's root element. The reason is that the XML root element can have
				siblings, such as a DocumentType or a Comment node.  The XML
				root node can be found by looking for an element node among the
				children of the DOM's root node.  However, there is a convenient
				method, Document.getDocumentElement(), that does the same thing.
				This example demonstrates both methods:
				
				
				
				    // Create a document; this method is implemented in
				    // e510 The Quintessential Program to Create a DOM Document from an XML File
				    Document doc = parseXmlFile("infilename.xml", false);
				    
				    Element root = null;
				    
				    // Get the XML root node by examining the children nodes
				    NodeList list = doc.getChildNodes();
				    for (int i=0; i<list.getLength(); i++) {
				        if (list.item(i) instanceof Element) {
				            root = (Element)list.item(i);
				            break;
				        }
				    }
				    
				    // Get the XML root node the easy way
				    root = doc.getDocumentElement();
				
				
				
				
				             Related Examples
				        
				
				
				
				
				e527. 
				    Getting a Node Relative to Another Node in a DOM Document
				
				
				
				e528. 
				    Getting the Notations in a DOM Document
				
				
				
				e529. 
				    Getting the Declared Entities in a DOM Document
				
				
				
				e530. 
				    Getting the Value of an Entity Reference in a DOM Document
				
				
				
				
				
				
				
				
				        See also: 
				
				    Adding and Removing Nodes
				  
				
				
				    Element Attributes
				  
				
				
				    Elements
				  
				
				
				    Text Nodes
				  
				
				
				    XPath
				  
				
				
				
				
				
				
				
				
				
				© 2002 Addison-Wesley.