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Chapter 9 Java and XML

Chapter 9 Java and XML. x.zhang@seu.edu.cn. Content. XML Pilot http://www.w3school.com.cn/ Parsing XML Document DOM Objects in DOM Java Programming using DOM. XML Pilot. XML 可扩展标记语言 eXtensible Markup Language Motivate: Data Exchange. XML Text. Student Info System.

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Chapter 9 Java and XML

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  1. Chapter 9 Javaand XML x.zhang@seu.edu.cn

  2. Content • XML Pilot http://www.w3school.com.cn/ • Parsing XMLDocument • DOM • Objects in DOM • Java Programming using DOM COSE Java 2009

  3. XMLPilot • XML 可扩展标记语言 • eXtensible Markup Language • Motivate: Data Exchange XMLText Student Info System Student Marks System Data Exchange Student Info Database Student Marks Database

  4. XMLPilot • Origin • SGML 标准通用化标记语言 • Powerful • Extensible • Expensive • HTML 超文本标记语言 • Limited function • Not extensible • Free Java CoSE 2009

  5. XML Pilot– An Example • Johnwrote to Georgein XML • An XMLdocuments includes at least: • An XMLdeclaration • An XMLroot element

  6. XMLPilot– An Example

  7. XMLPilot– XMLTree Structure

  8. XML vs. HTML • All XML element must have a close tag • XML tag is case-sensitive • XML element must be properly nested Java CoSE 2009

  9. XML vs. HTML • XML document must have an root element • XML attribute must be quoted Java CoSE 2009

  10. Entity Reference and Comments • In XML, some characters have special meaning • Five reserved Entity Reference • XMLcomments Java CoSE 2009

  11. XML Element • XMLElement can have • Sub-element • Attribute • Text • Naming of elements • Letters, numbers and other char • Cannot begin with figure, or punctuation, and “XML” • Cannot contain spaces Java CoSE 2009

  12. CDATA • Long text in XMLcan be represented in CDATA • All content in CDATA will be interpreted as text • No entity reference in CDATA • CDATAgrammar: • Begin with “<!CDATA[” • End with “]]>” Java CoSE 2009

  13. Well-formed XML • A “Well-formed” XML should be: • XML document having root element • All elements being properly closed • Case-sensitive • All elements being properly nested • All attributes being properly quoted Java CoSE 2009

  14. Validated XML • Well-formed XML only indicates that the format of XML document is correct • We still need a way to check whether the data structure in XML document is right too • Each book price in bookstore should be positive float • Each book contains at least one title • The way to validate XML • DTD （Document Type Definition） • XML Schema Java CoSE 2009

  15. namespace • Name confliction may happen when two XML contains elements with same name: Java CoSE 2009

  16. namespace • Using namespace to avoid naming confliction Java CoSE 2009

  17. DOM • Document Object Model 文档对象模型 • DOM is • Programming interface for handling XML document • Define how to visit and manipulate XML document • Represent XML document in a tree structure • Feature • Independent with platform • Independent with language

  18. DOMObject • org.w3c.dom.Document // XMLdoc entrance • org.w3c.dom.Node// nodes in XML doc • org.w3c.dom.Element// element node in XMLdoc • org.w3c.dom.Attr // attribute node in XMLdoc • org.w3c.dom.Text// text node in XML doc • org.w3c.dom.NodeList// ordered nodelist in XMLdoc • org.w3c.dom.NamedNodeMap// a mapping between node and node name

  19. DOM Tree

  20. DOM树中的对象 #document Document Element Node Attribute NodeList Text

  21. NodeInterface • An interface for all nodes in XMLdoc tree • Derive all other interfaces in DOM • The type of a node is marked in nodetype • Method • getNodeType() /NodeName() / NodeValue() • getParentNode() / getChildNodes() • getFirstChild () /getLastChild() / getChild • getNextSibling()

  22. DocumentInterface • Inherited from Nodeinterface • A virtual root element– the entrance of XML doc • Method • getElementsByTagName(String tagname) • getDocumentElement() • createElement(String tagName) • createAttribute(String name) • createTextNode(String data)

  23. ElementInterface • Inherited from NodeInterface • Representing XMLelements • Method • getAttributes() / setAttribute() • getTextContent() / setTextContent() • getOwnerDocument()

  24. AttrInterface • Inherited from NodeInterface • Representing XMLattributes • Methods • getOwnerElement() • getSpecified() • getValue() / setValue()

  25. NodeListInterface • Ordered list of nodes • For example: an ordered list of all nodes derived by getChildNodes() of book element • Methods • getLength() • item(int index)

  26. NamedNodeMapInterface • A Mapping between nodes and node names • For example: a collection of all attributes derived by getAttributes() of an element • Methods • getNamedItem(String name) • setNamedItem(Node node)

  27. JAXPImplementing DOM • JAXP : Java API for XML Parsing • Using JAXP to parse XML Java CoSE 2009

  28. Episode– Factory Pattern • Sample s = new Sample(); • If Sampleis an interface, then • Sample s1 = new MySample1(); • Sample s2 = new MySample2(); • Using factory pattern Java CoSE 2009

  29. Create a DOM Tree in Memory

  30. Create a DOM Tree in Memory

  31. Create a DOM Tree in Memory

  32. Create a DOM Tree in Memory

  33. Create a DOM Tree in Memory

  34. Think: How to Traverse XML Nodes Java CoSE 2009

  35. Self-study • XML Document Model • DOM • SAX • XML Parser • JAXP • Xerces • JDOM • DOM4J Java CoSE 2009

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