SAX 解析XML文件

　　SAX 解析XML文件，并将结果存放到map中：

实体类：

package buildXML;

import java.io.Serializable;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;

/**
 * XML实体类
 * 该实体类可通过元素名称获得元素值
 * 或通过detail id获得detail对象
 * @author caij
 *
 */
public class XMLEntity implements Serializable{
    /**
     * 
     */
    private static final long serialVersionUID = -698796041627370949L;
    //xml head标签下的内容
    public Map<String,String> head = new HashMap<String,String>();
    //xml body标签下的内容，生成xml是需要元素有顺序，所以采用LinkedHashMap
    public Map<String,Object> body = new LinkedHashMap<String, Object>();
    
    public XMLEntity(){
    }
    
    public XMLEntity(Map<String, String> head, Map<String, Object> body) {
        super();
        this.head = head;
        this.body = body;
    }

    public Map<String, String> getHead() {
        return head;
    }

    public void setHead(Map<String, String> head) {
        this.head = head;
    }

    public Map<String, Object> getBody() {
        return body;
    }

    public void setBody(Map<String, Object> body) {
        this.body = body;
    }
    
}

解析XML类，继承DefaultHandler

package buildXML;

import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

/**
 * 
 *  类名: ParseXMLImpl.java
 *  功能:解析C端传入的xml文件
 *  
 *     修改:   
 *  
 *  @author caij  
 *    DateTime 2013-4-19 下午3:20:30
 */
public class ParseXMLImpl extends DefaultHandler {
    private XMLEntity xmlEntity = new XMLEntity();//定义xml实体对象
    private Map<String, String> detailNode = new HashMap<String, String>();// 存放detail中的内容
    private String flag = "";//判断目前解析的是哪一部分
    private String key; //插入map的key值
    private String attribute; //detail 的 属性值
    
    /**
     * 获得sax解析器对象
     * @return
     */
    private static SAXParser getSAXParser(){
        SAXParserFactory factory = SAXParserFactory.newInstance();
        SAXParser parser = null;
        try {
            parser = factory.newSAXParser();
        } catch (ParserConfigurationException e) {
            e.printStackTrace();
        } catch (SAXException e) {
            e.printStackTrace();
        }
        return parser;
    }

    public XMLEntity parseAllXML(InputStream is) throws SAXException, IOException {
        SAXParser parser = getSAXParser();
        ParseXMLImpl parseXMLImpl = new ParseXMLImpl();
        parser.parse(is, parseXMLImpl);
        return xmlEntity;
    }

    public Map<String, String> parseXMLHead(InputStream is) throws SAXException, IOException {
        parseAllXML(is);
        return xmlEntity.head;
    }

    public Map<String, Object> parseXMLBody(InputStream is) throws SAXException, IOException {
        parseAllXML(is);
        return xmlEntity.body;
    }

    public String getValueByFieldNameInHead(InputStream is, String fieldName) throws SAXException, IOException {
        parseAllXML(is);
        Map<String,String> head = xmlEntity.head;
        String value = head.get(fieldName);
        return value;
    }
    
    @Override
    public void startDocument() throws SAXException {
        super.startDocument();
    }

    @Override
    public void endDocument() throws SAXException {
        super.endDocument();
    }

    @Override
    public void startPrefixMapping(String prefix, String uri)
            throws SAXException {
        super.startPrefixMapping(prefix, uri);
    }

    @Override
    public void startElement(String uri, String localName, String qName,
            Attributes attributes) throws SAXException {
        // 判断元素属于哪一部分
        if ("head".equals(qName)) {
            flag = "head";
        } else if ("body".equals(qName)) {
            flag = "body";
        } else if ("detail".equals(qName)) {
            flag = "detail" + attributes.getValue(0);
        }
        // 确定key值
        if ("head".equals(flag) && !flag.equals(qName)) {// head的子节点，加入到head的map中
            key = qName;
        } else if ("body".equals(flag) && !flag.equals(qName)) {// body的子节点，加入body的map中
            key = qName;
        } else if (flag.startsWith("detail") && flag.startsWith(qName)) {// 如果element的名称为detail，则把该节点放入detailList中
            attribute = attributes.getValue(0);
        } else if (flag.startsWith("detail") && !flag.startsWith(qName)) {// detail的子节点，加入到detail的map中，map的key为detail的id属性
            key = qName;
        }
        super.startElement(uri, localName, qName, attributes);
    }

    @Override
    public void endElement(String uri, String localName, String qName)
            throws SAXException {
        Map<String, String> d = new HashMap<String, String>();// 新建一个map对象便于存入body中
        d = detailNode;
        if (flag.startsWith("detail") && "detail".equals(qName)
                && detailNode.isEmpty() != true && attribute != null) {
            xmlEntity.body.put(attribute.toString(), d);
            detailNode = new HashMap<String, String>();
            attribute = null;
        }
        super.endElement(uri, localName, qName);
    }

    @Override
    public void characters(char[] ch, int start, int length)
            throws SAXException {
        String s = new String(ch, start, length);

        if (!s.startsWith("\n")) {
            if ("head".equals(flag)) {// head的子节点，加入到head的map中
                xmlEntity.head.put(key, s);
                key = null;
            } else if ("body".equals(flag)) {// body的子节点，加入body的map中
                xmlEntity.body.put(key, s);
                key = null;
            } else if (flag.startsWith("detail") && key != null) {// detail的子节点，加入到detail的map中，map的key为detail的id属性
                detailNode.put(key, s);
                key = null;
            }
        }
        super.characters(ch, start, length);
    }

}

调用：

public static void main(String[] args) throws SAXException, IOException {
        InputStream input = new BufferedInputStream(new FileInputStream(uri));

        parseAllXML(input);
        System.out.println(xmlEntity.body.size());
    }