1.简介

Dom解析功能强大，可增删改查，操作时会将XML文档读到内存，因此适用于小文档；

SAX解析是从头到尾逐行逐个元素解析，修改较为不便，但适用于只读的大文档；

SAX采用事件驱动的方式解析XML。套用网友的解释：如同在电影院看电影一样，从头到尾看一遍，不能回退（Dom可来来回回读取），在看电影的过程中，每遇到一个情节，都会调用大脑去接收处理这些信息。SAX也是相同的原理，每遇到一个元素节点，都会调用相应的方法来处理。在SAX的解析过程中，读取到文档开头、文档结尾，元素的开头和元素结尾都会调用相应方法，我们可以在这些方法中进行相应事件处理。

对应方法：

public void startDocument() throws SAXException {
}
public void endDocument() throws SAXException {
}
public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
}
public void endElement(String uri, String localName, String qName) throws SAXException {
}

我们还需一个方法来处理元素节点中间的文本节点（我们常误以为元素节点的文本值）

public void characters(char[] ch, int start, int length) throws SAXException {
}

2.解析

解析步骤：

（1）通过SAXParserFactory的静态方法newInstance()方法获取SAXParserFactory实例对象factory

SAXParserFactory factory = SAXParserFactory.newInstance();

（2）通过SAXParserFactory实例的newSAXParser()方法返回SAXParser实例parser

SAXParser parser = factory.newSAXParser();

（3）创建一个类继承DefaultHandler,重写其中的一些方法进行业务处理

package com.qunar.handler;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
public class SAXParserHandler extends DefaultHandler{
	
	// 用来标示解析开始
	@Override
	public void startDocument() throws SAXException {
		
	}
	// 用来标示解析结束
	@Override
	public void endDocument() throws SAXException {
		
	}
	// 用来遍历XML文件的开始标签
	@Override
	public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
		super.startElement(uri, localName, qName, attributes);
	}
	// 用来遍历XML文件的结束标签
	@Override
	public void endElement(String uri, String localName, String qName) throws SAXException {
		super.endElement(uri, localName, qName);
	}
	@Override
	public void characters(char[] ch, int start, int length) throws SAXException {
		super.characters(ch, start, length);
	}
}

（4）创建Handler类对象实例

// 定义SAXParserHandler对象
SAXParserHandler handler = new SAXParserHandler();

（5）解析XML文档

<?xml version="1.0" encoding="utf-8"?><bookstore>
	<book category="Java">
		<title lang="chi">Java多线程编程核心技术</title> 
		<author>高洪岩</author> 
		<year>2015</year> 
		<price>69.00</price> 
	</book>
	<book category="C++">
		<title lang="en">Effective C++: 55 Specific Ways to Improve Your Programs and Designs</title> 
		<author>Scott Meyers</author> 
		<year>2006</year> 
		<price>58.00</price> 
	</book>
	<book category="Web">
		<title lang="en">Learning XML</title> 
		<author>Erik T. Ray</author> 
		<year>2016</year>
		<price>39.95</price> 
	</book>
</bookstore>

3.具体实例：

package com.qunar.handler;
 
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
 
 
public class SAXParserHandler extends DefaultHandler{
	private int bookIndex = 0;
	
	// 用来标示解析开始
	@Override
	public void startDocument() throws SAXException {
		System.out.println("SAX解析开始...");
	}
	// 用来标示解析结束
	@Override
	public void endDocument() throws SAXException {
		System.out.println("SAX解析结束...");
	}
	// 用来遍历XML文件的开始标签
	@Override
	public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
		// 调用DefaultHandler类的startElement方法
		super.startElement(uri, localName, qName, attributes);
		// 开始解析book元素节点
		if(qName.equals("book")){
			++ bookIndex;
			System.out.println("开始解析第" + bookIndex + "本书...");
			// 已知book元素节点下的属性名称，根据属性名称获取属性值
			/*String value = attributes.getValue("category");
			System.out.println("value->"+value);*/
			// 不知道book元素节点下的属性名称以及个数
			int size = attributes.getLength();
			for(int i = 0;i < size;++i){
				System.out.println(attributes.getQName(i) + "：" + attributes.getValue(i));
			}//for
		}//if
		else if(!qName.equals("bookstore")){
			System.out.print(qName + "：");
		}//else
	}
	// 用来遍历XML文件的结束标签
	@Override
	public void endElement(String uri, String localName, String qName) throws SAXException {
		super.endElement(uri, localName, qName);
		// 判断一本书是否解析完
		if(qName.equals("book")){
			System.out.println("结束解析第" + bookIndex + "本书...");
		}//if
	}
	@Override
	public void characters(char[] ch, int start, int length) throws SAXException {
		super.characters(ch, start, length);
		String text = new String(ch, start, length);
		if(!text.trim().equals("")){
			System.out.println(text);
		}//if
	}
}

package com.qunar.xml;
 
import java.io.IOException;
 
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
 
import org.xml.sax.SAXException;
 
import com.qunar.handler.SAXParserHandler;
 
 
/**
 * SAX方式解析XML文档
 * @author sjf0115
 *
 */
public class SAXXMLCode {
 
	public static void main(String[] args) {
		String path = "D:\\bookstore.xml";
		try {
			// 通过SAXParserFactory的静态方法newInstance()方法获取SAXParserFactory实例对象factory
			SAXParserFactory factory = SAXParserFactory.newInstance();
			// 通过SAXParserFactory实例的newSAXParser()方法返回SAXParser实例parser
			SAXParser saxParser = factory.newSAXParser();
			// 定义SAXParserHandler对象
			SAXParserHandler handler = new SAXParserHandler();
			// 解析XML文档
			saxParser.parse(path, handler);
		} catch (ParserConfigurationException e) {
			e.printStackTrace();
		} catch (SAXException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

运行结果：

<table cellspacing="0" cellpadding="0" style="border-collapse:collapse; border:1px solid rgb(187,187,187); width:1050px"><tbody><tr><td style="border-collapse:collapse; border:1px solid rgb(187,187,187); width:1049px"><br/><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">SAX解析开始...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">开始解析第1本书...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">category：Java</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">title：Java多线程编程核心技术</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">author：高洪岩</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">year：2015</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">price：69.00</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">结束解析第1本书...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">开始解析第2本书...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">category：C++</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">title：Effective C++: 55 Specific Ways to Improve Your Programs and Designs</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">author：Scott Meyers</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">year：2006</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">price：58.00</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">结束解析第2本书...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">开始解析第3本书...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">category：Web</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">title：Learning XML</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">author：Erik T. Ray</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">year：2016</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">price：39.95</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">结束解析第3本书...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">SAX解析结束...</span></div></td></tr></tbody></table>

4.解析并储存于对象中

package com.qunar.bean;
 
/**
 * book实体类
 * @author sjf0115
 *
 */
public class Book {
	private String category;
	private String title;
	private String author;
	private String year;
	private String price;
	private String lang;
	
	public String getCategory() {
		return category;
	}
	public void setCategory(String category) {
		this.category = category;
	}
	public String getTitle() {
		return title;
	}
	public void setTitle(String title) {
		this.title = title;
	}
	public String getAuthor() {
		return author;
	}
	public void setAuthor(String author) {
		this.author = author;
	}
	public String getYear() {
		return year;
	}
	public void setYear(String year) {
		this.year = year;
	}
	public String getPrice() {
		return price;
	}
	public void setPrice(String price) {
		this.price = price;
	}
	public String getLang() {
		return lang;
	}
	public void setLang(String lang) {
		this.lang = lang;
	}
	@Override
	public String toString() {
		return "category：" + category + "  lang：" + lang + "   title：" + title + "   author：" + author + "   year：" + year + "   price："  + price;
	}
}

package com.qunar.handler;
 
import java.util.ArrayList;
import java.util.List;
 
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
 
import com.qunar.bean.Book;
 
 
public class SAXParserHandler extends DefaultHandler{
	private Book book;
	private int bookIndex = 0;
	// 节点文本内容
	private String text;
	private List<Book> bookList = new ArrayList<Book>();
	
	public List<Book> getBookList() {
		return bookList;
	}
	// 用来标示解析开始
	@Override
	public void startDocument() throws SAXException {
		System.out.println("SAX解析开始...");
	}
	// 用来标示解析结束
	@Override
	public void endDocument() throws SAXException {
		System.out.println("SAX解析结束...");
	}
	// 用来遍历XML文件的开始标签
	@Override
	public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
		// 调用DefaultHandler类的startElement方法
		super.startElement(uri, localName, qName, attributes);
		// 开始解析book元素节点
		if(qName.equals("book")){
			// 创建一个book对象
			book = new Book();
			++ bookIndex;
			System.out.println("开始解析第" + bookIndex + "本书...");
			int size = attributes.getLength();
			for(int i = 0;i < size;++i){
				String attr = attributes.getQName(i);
				// 属性category
				if(attr.equals("category")){
					book.setCategory(attributes.getValue(i));
				}//if
			}//for
		}//if
		// 用于遍历title节点中的属性
		else if(qName.equals("title")){
			int size = attributes.getLength();
			for(int i = 0;i < size;++i){
				String attr = attributes.getQName(i);
				// 属性category
				if(attr.equals("lang")){
					book.setLang(attributes.getValue(i));
				}//if
			}//for
		}//else
	}
	// 用来遍历XML文件的结束标签
	@Override
	public void endElement(String uri, String localName, String qName) throws SAXException {
		super.endElement(uri, localName, qName);
		// 判断一本书是否解析完
		if(qName.equals("book")){
			bookList.add(book);
			book = null;
			System.out.println("结束解析第" + bookIndex + "本书...");
		}//if
		else if(qName.equals("title")){
			book.setTitle(text);
		}//else
		else if(qName.equals("author")){
			book.setAuthor(text);
		}//else
		else if(qName.equals("year")){
			book.setYear(text);
		}//else
		else if(qName.equals("price")){
			book.setPrice(text);
		}//else
	}
	// 文本值
	@Override
	public void characters(char[] ch, int start, int length) throws SAXException {
		super.characters(ch, start, length);
		text = new String(ch, start, length);
	}
}

package com.qunar.xml;
 
import java.io.IOException;
import java.util.List;
 
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
 
import org.xml.sax.SAXException;
 
import com.qunar.bean.Book;
import com.qunar.handler.SAXParserHandler;
 
 
/**
 * SAX方式解析XML文档
 * @author sjf0115
 *
 */
public class SAXXMLCode {
 
	public static void main(String[] args) {
		String path = "D:\\bookstore.xml";
		try {
			// 通过SAXParserFactory的静态方法newInstance()方法获取SAXParserFactory实例对象factory
			SAXParserFactory factory = SAXParserFactory.newInstance();
			// 通过SAXParserFactory实例的newSAXParser()方法返回SAXParser实例parser
			SAXParser saxParser = factory.newSAXParser();
			// 定义SAXParserHandler对象
			SAXParserHandler handler = new SAXParserHandler();
			// 解析XML文档
			saxParser.parse(path, handler);
			// 得到遍历结果
			List<Book> bookList = handler.getBookList();
			System.out.println("遍历结果：");
			for (Book book : bookList) {
				System.out.println(book);
			}//for
		} catch (ParserConfigurationException e) {
			e.printStackTrace();
		} catch (SAXException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

运行结果：

<table cellspacing="0" cellpadding="0" style="border-collapse:collapse; border:1px solid rgb(187,187,187); width:1050px"><tbody><tr><td style="border-collapse:collapse; border:1px solid rgb(187,187,187); width:1049px"><br/><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">SAX解析开始...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">开始解析第1本书...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">结束解析第1本书...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">开始解析第2本书...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">结束解析第2本书...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">开始解析第3本书...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">结束解析第3本书...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">SAX解析结束...</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">遍历结果：</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">category：Java lang：chi title：Java多线程编程核心技术 author：高洪岩 year：2015 price：69.00</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">category：C++ lang：en title：Effective C++: 55 Specific Ways to Improve Your Programs and Designs author：Scott Meyers year：2006 price：58.00</span></div><div><span style="font-size:14pt; color:windowtext; font-family:微软雅黑">category：Web lang：en title：Learning XML author：Erik T. Ray year：2016 price：39.95</span></div></td></tr></tbody></table>

[Java开发之路]（11）SAX解析XML文档

1.简介

2.解析

3.具体实例：

4.解析并储存于对象中

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