（4.1.30）XML解析之DOM、SAX

dom

/* * Copyright (C) 2009 Teleca Poland Sp. z o.o. <[e-mail]> * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package com.android.yunshi.util;import java.io.IOException;import java.io.StringReader;import javax.xml.parsers.DocumentBuilder;import javax.xml.parsers.DocumentBuilderFactory;import javax.xml.parsers.ParserConfigurationException;import org.w3c.dom.Document;import org.xml.sax.InputSource;import org.xml.sax.SAXException;//xml的转换解析器/** * @author Lukasz Wisniewski */public class XMLUtil {    /**     * singleton     */    private static DocumentBuilderFactory documentBuilderFactory = null;    /**     * DocumentBuilderFactory instance (lazy initialization)     *      * @return     */    private static DocumentBuilderFactory getDocumentBuilderFactory(){        if(documentBuilderFactory == null){            documentBuilderFactory = DocumentBuilderFactory.newInstance();        }        return documentBuilderFactory;    }    /**     * DocumentBuilder instance     *      * @return     */    private static DocumentBuilder getDocumentBuilder(){        try {            return getDocumentBuilderFactory().newDocumentBuilder();        } catch (ParserConfigurationException e) {            return null;        }    }    /**     * Converts String containing XML code to Document     *      * @param xmlString     * @return <code>Document</code> interface     */    public static Document stringToDocument(String xmlString){//字符串到xml的解析        if(xmlString == null)            return null;        DocumentBuilder documentBuilder = getDocumentBuilder();        InputSource inputSource = new InputSource(new StringReader(xmlString));        try {            return documentBuilder.parse(inputSource);        } catch (SAXException e) {            e.printStackTrace();            return null;        } catch (IOException e) {            e.printStackTrace();            return null;        }    }}

package com.android.yunshi.fun;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import org.w3c.dom.Document;import org.w3c.dom.Element;import org.w3c.dom.Node;import org.w3c.dom.NodeList;import com.android.yunshi.util.XMLUtil;//解析运势字符串，并封装为实体类public class YunshiFunctions {    private static Document document = null;    private static Element root = null;    public static Map<String, String> ResolveResultString(String xmlString,            String rootstring) {        // TODO Auto-generated method stub        Map<String, String> entity = new HashMap();        NodeList nodes;        int size;        document = XMLUtil.stringToDocument(xmlString);        if (document == null) {            return null;        }        root = document.getDocumentElement();        nodes = root.getElementsByTagName(rootstring);        Element TableName = (Element) nodes.item(0);        nodes = TableName.getChildNodes();        size = nodes.getLength();        for (int i = 0; i < size; i++) {            Node node = (Node) nodes.item(i);            NodeList nodes2 = node.getChildNodes();            int size2 = nodes2.getLength();            for (int j = 0; j < size2; j++) {                Node node2 = (Node) nodes2.item(j);                if (node2.getNodeType() == Node.ELEMENT_NODE) {                    Element childNode = (Element) node2;                    entity.put(childNode.getNodeName(),                            childNode.getTextContent());                }            }        }        return entity;    }    public static String ResolveResultStringToString(String xmlString,            String rootstring) {        // TODO Auto-generated method stub        String entity;        NodeList nodes;        int size;        document = XMLUtil.stringToDocument(xmlString);        if (document == null) {            return null;        }        root = document.getDocumentElement();        nodes = root.getChildNodes();        entity = nodes.item(0).getTextContent();        return entity;    }    public static List<Map<String, String>> ResolveResultStringToList(            String xmlString, String rootstring) {        List<Map<String, String>> list = new ArrayList<Map<String, String>>();        NodeList nodes;        int size;        document = XMLUtil.stringToDocument(xmlString);        if (document == null) {            return null;        }        root = document.getDocumentElement();        nodes = root.getElementsByTagName(rootstring);        Element TableName = (Element) nodes.item(0);        nodes = TableName.getChildNodes();        size = nodes.getLength();        for (int i = 0; i < size; i++) {            Node node = (Node) nodes.item(i);            NodeList nodes2 = node.getChildNodes();            int size2 = nodes2.getLength();            Map<String, String> entity = new HashMap();            for (int j = 0; j < size2; j++) {                Node node2 = (Node) nodes2.item(j);                if (node2.getNodeType() == Node.ELEMENT_NODE) {                    Element childNode = (Element) node2;                    entity.put(childNode.getNodeName(),                            childNode.getTextContent());                }            }            list.add(entity);        }        return list;    }}

SAX

JAVA 解析 XML 通常有两种方式，DOM 和 SAX。即java中的JDK已经内置了SAX和DOM解析的相关包，因此这里不用导入第三方的jar包。 SAX的全称是Simple APIs for XML，也即XML简单应用程序接口。与DOM不同，SAX提供的访问模式是一种顺序模式，这是一种快速读写XML数据的方式。当使用SAX分析器XML文档进行分析时，会触发一系列事件，并激活相应的事件处理函数，应用程序通过这些事件处理函数实现对XML文档的访问，因而SAX接口也被称作事件驱动接口。
下面是sax解析xml 的示例：

1、要解析的person.xml文件

2、获取服务器端xml文件输入流的工具类HttpUtil.java

public class HttpUtil{    public static InputStream getXML(String path)    {        InputStream in = null;        try        {            URL url = new URL(path);            if (url != null)            {                HttpURLConnection httpConn = (HttpURLConnection) url                        .openConnection();                httpConn.setConnectTimeout(3000);                httpConn.setDoInput(true);                httpConn.setRequestMethod("GET");                int code = httpConn.getResponseCode();                if (code == 200)                {                    in = httpConn.getInputStream();                }            }        }        catch (Exception e)        {            // TODO Auto-generated catch block            e.printStackTrace();        }        return in;    }}

3.处理XML文件的核心类，该类一定要继承DefaultHandler 并覆盖相应的方法

package com.sax.handler;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.jar.Attributes.Name;import org.xml.sax.Attributes;import org.xml.sax.SAXException;import org.xml.sax.helpers.DefaultHandler;public class MyHandler extends DefaultHandler {    private HashMap map = null;// 存储单个解析的完整对象    private List> list = null;// 存储所有的解析对象    private String currentTag = null;// 正在解析的元素的标签    private String currentValue = null;// 解析当前元素的值    private String nodeName = null;// 解析当前的节点名称    public MyHandler(String nodeName) {        // TODO Auto-generated constructor stub        this.nodeName = nodeName;    }    public List> getList() {        return list;    }    @Override    public void startDocument() throws SAXException {        // TODO Auto-generated method stub        // 当读到第一个开始标签的时候，会触发这个方法        list = new ArrayList>();    }    @Override    public void startElement(String uri, String localName, String qName,            Attributes attributes) throws SAXException {        // 当遇到文档的开头的时候，调用这个方法        if (qName.equals(nodeName)) {            map = new HashMap();        }        if (attributes != null && map != null) {            for (int i = 0; i < attributes.getLength(); i++) {                map.put(attributes.getQName(i), attributes.getValue(i));            }        }        currentTag = qName;    }    @Override    public void characters(char[] ch, int start, int length)            throws SAXException {        // TODO Auto-generated method stub        // 这个方法是用来处理xml文件所读取到的内容        if (currentTag != null && map != null) {            currentValue = new String(ch, start, length);            if (currentValue != null && !currentValue.trim().equals("")                    && !currentValue.trim().equals("\n")) {                map.put(currentTag, currentValue);            }        }        currentTag = null;// 把当前的节点的对应的值和标签设置为空        currentValue = null;    }    @Override    public void endElement(String uri, String localName, String qName)            throws SAXException {        // TODO Auto-generated method stub        // 遇到结束标记的时候，会调用这个方法        if (qName.equals(nodeName)) {            list.add(map);            map = null;        }        super.endElement(uri, localName, qName);    }}

4、SAX解析的业务逻辑层

public class SaxService{    public SaxService()    {        // TODO Auto-generated constructor stub    }    public static List> readXML(InputStream in,            String nodeName)    {        try        {//获取SAx的实例工厂，并获取解析实例            SAXParserFactory spf = SAXParserFactory.newInstance();            SAXParser parser = spf.newSAXParser();            MyHandler handler = new MyHandler(nodeName);            parser.parse(in, handler);// 开始解析XML文件            in.close();            return handler.getList();        }        catch (ParserConfigurationException e)        {            // TODO Auto-generated catch block            e.printStackTrace();        }        catch (SAXException e)        {            // TODO Auto-generated catch block            e.printStackTrace();        }        catch (IOException e)        {            // TODO Auto-generated catch block            e.printStackTrace();        }        return null;    }}

5、测试类

public class TestSax{    public static void main(String[] args)    {        //要访问的xml文件的服务器地址        String url = "http://localhost:8081/jspchat/person.xml";        //获取服务器端xml文件的输入流        InputStream in = HttpUtil.getXML(url);        //调用业务逻辑层访问xml文件中元素为person的的节点        List> list = SaxService.readXML(in, "person");        for (HashMap map : list)        {            System.out.println(map.toString());        }    }}