java读取解析xml文件实例

DOM解析的特性就是读取xml文件转换为 dom树形结构，通过节点进行遍历。

这是W3c关于节点的概念

如果xml中包含有大量的数据，由于dom一次性把xml装入内存中的特性，所以dom不适合于包含大量数据的xml解析。当包含有大量xml的时候，用SAX进行解析比较节省内存。

下面是一个运用DOM进行解析xml文件的例子：

xml文件结构如下：

<?xml version="1.0" encoding="ISO-8859-1"?>  <bookstore>   <book category="cooking">   <title>Everyday Italian</title>   <author>Giada De Laurentiis</author>   <year>2005</year>   <price>30.00</price>   </book>   <book category="children">   <title>Harry Potter</title>   <author>J K. Rowling</author>   <year>2005</year>   <price>29.99</price>   </book>   <book category="web">   <title>XQuery Kick Start</title>   <author>James McGovern</author>   <year>2003</year>   <price>49.99</price>   </book>   <book category="web" cover="paperback">   <title>Learning XML</title>   <author>Erik T. Ray</author>   <year>2003</year>   <price>39.95</price>   </book>  </bookstore>

创建解析xml的类如下：

package xml.dom;     import java.io.File;  import javax.xml.parsers.DocumentBuilder;  import javax.xml.parsers.DocumentBuilderFactory;  import org.w3c.dom.Document;  import org.w3c.dom.Element;  import org.w3c.dom.Node;  import org.w3c.dom.NodeList;     public class ReadXmlFile {       public static void main(String[] args) {       try{         File xmlFile = new File("src/resource/book.xml");         DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();         DocumentBuilder builder = builderFactory.newDocumentBuilder();         Document doc = builder.parse(xmlFile);         doc.getDocumentElement().normalize();         System.out.println("Root element: "+doc.getDocumentElement().getNodeName());         NodeList nList = doc.getElementsByTagName("book");         for(int i = 0 ; i<nList.getLength();i++){         Node node = nList.item(i);         System.out.println("Node name: "+ node.getNodeName());    Element ele = (Element)node;         System.out.println("----------------------------");    if(node.getNodeType() == Element.ELEMENT_NODE){         System.out.println("book category: "+ ele.getAttribute("category"));         System.out.println("title name: "+ ele.getElementsByTagName("title").item(0).getTextContent());         System.out.println("author name: "+ele.getElementsByTagName("author").item(0).getTextContent());         System.out.println("year :"+ele.getElementsByTagName("year").item(0).getTextContent());         System.out.println("price : "+ele.getElementsByTagName("price").item(0).getTextContent());         System.out.println("-------------------------");              }              }

解析结果：

Root element: bookstore  Node name: book  ----------------------------  book category: cooking  title name: Everyday Italian  author name: Giada De Laurentiis  year :2005  price : 30.00  -------------------------  Node name: book  ----------------------------  book category: children  title name: Harry Potter  author name: J K. Rowling  year :2005  price : 29.99  -------------------------  Node name: book  ----------------------------  book category: web  title name: XQuery Kick Start  author name: James McGovern  year :2003  price : 49.99  -------------------------  Node name: book  ----------------------------  book category: web  title name: Learning XML  author name: Erik T. Ray  year :2003  price : 39.95  -------------------------

以上是通过name获得对应的值，下面利用循环节点的方式输出：循环节点输出方式的代码如下：

package xml.dom;     import java.io.File;     import javax.xml.parsers.DocumentBuilder;  import javax.xml.parsers.DocumentBuilderFactory;     import org.w3c.dom.Document;  import org.w3c.dom.NamedNodeMap;  import org.w3c.dom.Node;  import org.w3c.dom.NodeList;     public class ReadXmlFile2 {       public static void main(String[] args) {   try{         File xmlFile = new File("src/resource/book.xml");         DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();         DocumentBuilder builder = builderFactory.newDocumentBuilder();         Document doc = builder.parse(xmlFile);         doc.getDocumentElement().normalize();         System.out.println("Root element: "+doc.getDocumentElement().getNodeName());              if(doc.hasChildNodes()){         printNode(doc.getChildNodes());    }   }catch(Exception e){       e.printStackTrace();       }       }       public static void printNode(NodeList nodeList){   System.out.println("------------------------");   // System.out.println(nodeList.getLength());   for(int i = 0; i<nodeList.getLength(); i++){       Node node = (Node)nodeList.item(i);           if(node.getNodeType() == Node.ELEMENT_NODE){       System.out.println("node name: "+node.getNodeName());       System.out.println("node value: "+node.getTextContent());       if(node.hasAttributes()){    NamedNodeMap nodeMap = node.getAttributes();         for(int j = 0; j < nodeMap.getLength() ; j++){         Node nodenew = nodeMap.item(j);         System.out.println("node name "+nodenew.getNodeName());    System.out.println("node value "+nodenew.getNodeValue());    }   }   if(node.hasChildNodes()){    printNode(node.getChildNodes());   }   }       }       }     }

输出结果如下：

Root element: bookstore  ------------------------  node name: bookstore  node value:        Everyday Italian   Giada De Laurentiis   2005   30.00           Harry Potter   J K. Rowling   2005   29.99           XQuery Kick Start   James McGovern   2003   49.99           Learning XML   Erik T. Ray   2003   39.95         ------------------------  node name: book  node value:    Everyday Italian   Giada De Laurentiis   2005   30.00      node name category  node value cooking  ------------------------  node name: title  node value: Everyday Italian  node name lang  node value en  ------------------------  node name: author  node value: Giada De Laurentiis  ------------------------  node name: year  node value: 2005  ------------------------  node name: price  node value: 30.00  ------------------------  node name: book  node value:    Harry Potter   J K. Rowling   2005   29.99      node name category  node value children  ------------------------  node name: title  node value: Harry Potter  node name lang  node value en  ------------------------  node name: author  node value: J K. Rowling  ------------------------  node name: year  node value: 2005  ------------------------  node name: price  node value: 29.99  ------------------------  node name: book  node value:    XQuery Kick Start   James McGovern   2003   49.99      node name category  node value web  ------------------------  node name: title  node value: XQuery Kick Start  node name lang  node value en  ------------------------  node name: author  node value: James McGovern  ------------------------  node name: year  node value: 2003  ------------------------  node name: price  node value: 49.99  ------------------------  node name: book  node value:    Learning XML   Erik T. Ray   2003   39.95      node name category  node value web  node name cover  node value paperback  ------------------------  node name: title  node value: Learning XML  node name lang  node value en  ------------------------  node name: author  node value: Erik T. Ray  ------------------------  node name: year  node value: 2003  ------------------------  node name: price  node value: 39.95  ------------------------

关于节点的问题：

<book category="cooking">  <title>Everyday Italian</title>  <author>Giada De Laurentiis</author>  <year>2005</year>  <price>30.00</price>  </book>

对于 book应用：doc.getChildNodes() 得到一个NodeList其中NodeList的长度为99个节点分别如下：title节点lang节点 Everyday节点 author节点 Giada De Laurentiis节点 year节点 2005节点 price节点 30.00节点

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