␡
- Defining the Document Object Model
- DOM Core Level I
- Creating Document Objects
- Node Interface
- NodeList and NamedNodeMap
- Document Interface
- Element Interface
- Attr Interface
- Additional Interfaces
- Creating DOM Elements
- DOM Level II
- The DOM Core Defined
- Implementation Anomalies
- Summary
- Suggested for Further Study
- Further Reading
This chapter is from the book
This chapter is from the book
This chapter is from the book
This chapter is from the book
Additional Interfaces
There are nine additional interfaces that we will not examine in low-level detail but will be required for many applications. The first four have to do with actual content:
CharacterData The CharacterData interface extends Node. No DOM objects of type CharacterData exist but rather this object represents common methods inherited by other DOM interfaces. The CharacterData interface contains eight methods for setting, getting, inserting, appending, and otherwise manipulating normal character data information.
Comment The Comment interface extends CharacterData and represents a comment in an XML document. No additional methods are defined on this interface.
Text The Text interface extends CharacterData. The Text interface contains a single method splitText(int offset) that allows the given text node to be split at an offset into two text nodes which may later be recombined with normalize();.
CDATASection The CDATASection interface extends Text and allows for blocks of text to be contained within a DOM node that would otherwise be considered markup without the need to escape markup characters. No additional methods are defined in this interface.
The next five interfaces represent other elements in XML.
Entity Extends Node. Represents the Entities within an XML document. Depending on validation, these entities may or may not be expanded and the object may (not expanded, non-validating parsers) or may not (expanded) have children. Defines three methods for accessing entity information.
Notation Extends Node. Represents the Notation elements of an XML document. Defines two methods for accessing information about a Notation.
DocumentType Extends Node. The DocumentType interface is used to gather information about the Document itself and has three methods for accessing Entities, Notations, and the name of the DTD itself.
ProcessingInstruction Extends Node. The ProcessingInstruction interface represents processing instruction information. This interface specifies three methods for accessing and manipulating processing instruction information.
DocumentFragment Extends Node. Contains no additional methods beyond the Node interface. The DocumentFragment interface is designed to allow users and developers to develop XML documents that are not well formed. A document fragment can be built that represents data at any level in an XML tree. After being inserted back into a Document object, the underlying children are inserted and not the DocumentFragment object itself. For these reasons, DocumentFragments can be thought of as lightweight Documents.
Listing 3.7, DumpXMLOracle.java, uses the Oracle DOM and wraps up all of the DOM Core Level I interfaces into one neat package that displays, in semi human-readable format, any given XML document. The output is shown in Listing 3.8.
Listing 3.7 DumpXMLOracle.java
1: /*
2: * @(#)DumpXMLOracle.java 1.0 99/05/28
3: *
4: * Copyright (c) 1999 Sams Publishing. All Rights Reserved.
5: *
6: */
7: package sams.chp3;
8:
9: import java.io.*;
10: import java.net.*;
11:
12: import oracle.xml.parser.XMLParser;
13:
14: import org.w3c.dom.*;
15:
16: public class DumpXMLOracle
17: {
18: // map the type to a string
19: static String mapNodeTypeToString(short nodeType)
20: {
21: switch(nodeType)
22: {
23: case org.w3c.dom.Node.ATTRIBUTE_NODE: return "ATTRIBUTE_NODE";
24: case org.w3c.dom.Node.CDATA_SECTION_NODE:return "CDATA_SECTION_NODE";
25: case org.w3c.dom.Node.COMMENT_NODE: return "COMMENT_NODE";
26: case org.w3c.dom.Node.DOCUMENT_FRAGMENT_NODE: return
"DOCUMENT_FRAGMENT_NODE";
27: case org.w3c.dom.Node.DOCUMENT_NODE: return "DOCUMENT_NODE";
28: case org.w3c.dom.Node.DOCUMENT_TYPE_NODE: return "DOCUMENT_TYPE_NODE";
29: case org.w3c.dom.Node.ELEMENT_NODE: return "ELEMENT_NODE";
30: case org.w3c.dom.Node.ENTITY_NODE: return "ENTITY_NODE";
31: case org.w3c.dom.Node.ENTITY_REFERENCE_NODE: return
"ENTITY_REFERENCE_NODE";
32: case org.w3c.dom.Node.NOTATION_NODE: return "NOTATION_NODE";
33: case org.w3c.dom.Node.PROCESSING_INSTRUCTION_NODE: return
"PROCESSING_INSTRUCTION_NODE";
34: case org.w3c.dom.Node.TEXT_NODE: return "TEXT_NODE";
35:
36: }
37: return "Unknown";
38: }
39:
40: // Display attribute information
41: static void displayAttributeInfo(String prefix, Node node)
42: {
43: // only elements have attributes
44: if (node.getNodeType() != org.w3c.dom.Node.ELEMENT_NODE) return;
45:
46: NamedNodeMap attributes = node.getAttributes();
47: if ( null == attributes || attributes.getLength() == 0)
48: {
49: return;
50: }
51:
52: System.out.println(prefix +"has " + attributes.getLength() + "
attributes");
53: System.out.println(prefix + attributes.toString());
54: for (int i = 0; i < attributes.getLength(); i++)
55: {
56: Node attribute = attributes.item(i);
57: System.out.print(prefix+"["+i+"] " + attribute.getNodeName());
58: System.out.println(" = " + attribute.getNodeValue());
59: }
60:
61: }
62:
63: // Display generalized node properties
64: static void displayNodeInfo(String prefix,Node node)
65: {
66: System.out.println(prefix+ "----------------");
67: System.out.println(prefix + "name:"+node.getNodeName());
68: System.out.println(prefix + "type:("+node.getNodeType()+ ")"
+mapNodeTypeToString(node.getNodeType()));
69: System.out.println(prefix + "value:"+ node.getNodeValue());
70: displayAttributeInfo(prefix,node);
71: if (node.getNodeType() != org.w3c.dom.Node.TEXT_NODE)
72: {
73: NodeList children = node.getChildNodes();
74: System.out.println(prefix + "Children("+ children.getLength()+"):");
75: if ( children.getLength() > 0)
76: {
77: System.out.print(prefix+ " ");
78: for (int i = 0; i < children.getLength(); i++)
79: {
80: Node child = children.item(i);
81: System.out.print(" ["+i+"] " + child.getNodeName());
82: }
83: System.out.println();
84: }
85:
86: }
87: }
88: // Display Entity Information
89: static void displayEntityInfo(String prefix, Entity entity)
90: {
91: System.out.println(prefix + "Entity information");
92: System.out.println(prefix + " public id:"+ entity.getPublicId());
93: System.out.println(prefix + " system id:"+ entity.getSystemId());
94: System.out.println(prefix + " notation name:"+ entity.getNotationName());
95: displayNodeInfo(prefix,entity);
96:
97: NodeList children = entity.getChildNodes();
98: if ( children.getLength() == 0)
99: System.out.println(prefix + " Has 0 children");
100: else
101: System.out.println(prefix + " Children(" + children.getLength()+
")");
102:
103: for (int i = 0; i < children.getLength(); i++)
104: {
105: Node child = (Entity)children.item(i);
106: System.out.println(" child(" + i + ")");
107: displayNodeInfo(" ",child);
108: }
109:
110: }
111: // Display Document information
112: static void displayDocumentInfo(Document document)
113: {
114: DocumentType docTypeInfo = document.getDoctype();
115: System.out.println(" ");
116: System.out.println("Document Type Information");
117: System.out.println("----------------");
118: System.out.println("name:"+document.getNodeName());
119: System.out.println("type:("+document.getNodeType()+ ")"
+mapNodeTypeToString(document.getNodeType()));
120: System.out.println("value:"+ document.getNodeValue());
121: System.out.println(" Properties");
122: System.out.println(" Name Property:"+docTypeInfo.getName());
123: NamedNodeMap entities = docTypeInfo.getEntities();
124: System.out.println(" contains " + entities.getLength() + " entities");
125: NamedNodeMap notations = docTypeInfo.getNotations();
126: if ( notations != null)
127: System.out.println(" contains " + notations.getLength() +
" notations");
128: else
129: System.out.println(" contains (null) notations");
130:
131: if ( entities != null && entities.getLength() > 0)
132: {
133: System.out.println(" Entities");
134: for (int i = 0; i < entities.getLength(); i++)
135: {
136: //
137: // Note that in the SUN implementation this works as expected
138: // The IBM implementation causes a class cast exception.
139: try
140: {
141: Entity entity = (Entity)entities.item(i);
142: System.out.println(" Entity(" + i + ")");
143: displayEntityInfo(" ",entity);
144: }
145: catch (Exception e) { System.out.println("exception! "
+ e); } ;
146: }
147: }
148:
149: if ( notations != null && notations.getLength() > 0)
150: {
151: System.out.println(" Notations");
152: for (int i = 0; i < notations.getLength(); i++)
153: {
154: Node node = notations.item(i);
155: System.out.println(" Notation(" + i + ")");
156: displayNodeInfo(" ",node);
157: }
158: }
159:
160:
161: }
162:
163: // Process all the children of a node.
164: public static void displayChildren(String prefix,Node parent)
165: {
166: NodeList children = parent.getChildNodes();
167: if ( children == null || children.getLength() == 0) return;
168: for (int i = 0; i < children.getLength(); i++)
169: {
170: try
171: {
172: Node node = children.item(i);
173: displayNodeInfo(prefix,node);
174: displayChildren(prefix + " ",node);
175: }
176: catch (Exception e)
177: {
178: }
179: }
180:
181:
182: }
183:
184:
185: public static void main (String argv [])
186: {
187: if (argv.length != 1)
188: {
189:
190: System.err.println( "Usage: java sams.chp3.DumpXMLOracle filename");
191: System.exit(1);
192: }
193:
194: try
195: {
196: XMLParser parser = new XMLParser();
197: FileInputStream inStream = new FileInputStream(argv[0]);
198: parser.setErrorStream(System.err);
199: parser.setValidationMode(true);
200: parser.showWarnings(true);
201:
202: parser.parse(inStream);
203:
204: Document document = parser.getDocument();
205: System.out.println("Sucessfully created document on " +
argv[0]);
206:
207: //
208: // Print relevent info about the document type
209: //
210: displayDocumentInfo(document);
211: displayNodeInfo("",document);
212:
213: //
214: // Now walk the document itself displaying data
215: //
216: displayChildren(" ",document);
217: }
218: catch (Exception e)
219: {
220: System.out.println("Unexpected exception reading document!" +e);
221: System.out.println(e);
222: System.exit (0);
223: }
224:
225:
226: }
Listing 3.8 Abbreviated Output of DumpXMLOracle.java
1: C:\java sams.chp3.DumpXMLOracle 2: Sucessfully created document on catalog.xml 3: 4: Document Type Information 5: ---------------- 6: name:#document 7: type:(9)DOCUMENT_NODE 8: value:null 9: Properties 10: Name Property:catalog 11: contains 2 entities 12: contains (null) notations 13: Entities 14: Entity(0) 15: Entity information 16: public id:null 17: system id:null 18: notation name:null 19: ---------------- 20: name:PublisherInfo 21: type:(6)ENTITY_NODE 22: value:MCP 23: Children(0): 24: Has 0 children 25: Entity(1) 26: Entity information 27: public id:null 28: system id:null 29: notation name:null 30: ---------------- 31: name:AuthorName 32: type:(6)ENTITY_NODE 33: value:Albert J. Saganich Jr 34: Children(0): 35: Has 0 children 36: ---------------- 37: name:#document 38: type:(9)DOCUMENT_NODE 39: value:null 40: Children(4): 41: [0] xml [1] #comment [2] catalog [3] catalog 42: ---------------- 43: name:xml 44: type:(7)PROCESSING_INSTRUCTION_NODE 45: value: version = '1.0'encoding = 'UTF-8' 46: Children(0): 47: ---------------- 48: name:#comment 49: type:(8)COMMENT_NODE 50: value: 51: 52: A Simple catalog of books a bookstore might carry 53: 54: Al Saganich for Macmillan Computer Publishing 55: 56: Children(0): 57: ---------------- 58: name:catalog 59: type:(10)DOCUMENT_TYPE_NODE 60: value:null 61: Children(0): 62: ---------------- 63: name:catalog 64: type:(1)ELEMENT_NODE 65: value:null 66: Children(7): 67: [0] #comment [1] catheader [2] entry [3] entry [4] entry [5] entry [6]