Java解析xml文档之SAX解析

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sax解析是一种边读边解析，仅向前读取，不能修改，用来读。

sax创建XMLReader三步：

SAXParserFactory factory = SAXParserFactory.newInstance();        SAXParser parser = factory.newSAXParser();        XMLReader reader = parser.getXMLReader();

sax是使用类似于监听机制和适配器思想来做解析的，里面去覆盖方法：

reader.setContentHandler(new DefaultHandler(){}

具体实例代码如下：

sxaDemo

package cn.hncu.sax_stax;import java.awt.Button;import java.awt.event.MouseEvent;import java.awt.event.MouseListener;import javax.xml.parsers.SAXParser;import javax.xml.parsers.SAXParserFactory;import org.junit.Test;import org.xml.sax.Attributes;import org.xml.sax.SAXException;import org.xml.sax.XMLReader;import org.xml.sax.helpers.DefaultHandler;public class SaxDemo {    @Test //了解Sax解析的生命周期(工作流程)   public void SaxDemo1() throws Exception{       SAXParserFactory factory = SAXParserFactory.newInstance();       SAXParser parser = factory.newSAXParser();        XMLReader reader=parser.getXMLReader();        reader.setContentHandler( new DefaultHandler(){            @Override            public void startDocument() throws SAXException {                System.out.println("1 开始读取文档了....");            }            @Override            public void endDocument() throws SAXException {                System.out.println("10 文档读取结束了....");            }            @Override            public void startElement(String uri, String localName,                    String qName, Attributes attributes) throws SAXException {                System.out.println("一个元素开始....");            }            @Override            public void endElement(String uri, String localName, String qName)                    throws SAXException {                System.out.println("一个元素结束....");            }        });        reader.parse("./xml5/users.xml");        System.out.println("Over.....");   }    //用SAX解析xml的基本套路    @Test     public void SaxDemo2() throws Exception{        SAXParserFactory factory = SAXParserFactory.newInstance();//1        SAXParser parser = factory.newSAXParser();//2        XMLReader reader = parser.getXMLReader();//3        reader.setContentHandler(new DefaultHandler(){            //覆盖相应的事件处理方法---最核心的步骤※※※※        });//4        reader.parse("./xml5/users.xml");//5    }    /*     * 需求：输出xml文档的数据信息，格式如下：     * id:A001        name:Jack        age:25        ------------        id:A002        name:张三        age:80        -----------        。。。。。     */    private String elementName="@#";    @Test     public void SaxDemo3() throws Exception{        SAXParserFactory factory = SAXParserFactory.newInstance();//1        SAXParser parser = factory.newSAXParser();//2        XMLReader reader = parser.getXMLReader();//3        reader.setContentHandler(new DefaultHandler(){            @Override            public void startElement(String uri, String localName,                    String qName, Attributes attributes) throws SAXException {                if(qName.equals("user")){                    String id = attributes.getValue("id");                    System.out.println("id:"+id);                }else if(qName.equals("name") || qName.equals("age")){                    elementName = qName;                }            }            @Override            public void endElement(String uri, String localName, String qName)                    throws SAXException {                if(qName.equals("name") || qName.equals("age")){                    elementName ="@#";                }else if(qName.equals("user")){                    System.out.println("--------------");                }            }            //读取：xml文档中的“文本内容”---不包含属性和标签，但是含有空格和换行等空白符            @Override            public void characters(char[] ch, int start, int length)                    throws SAXException {                if(!elementName.equals("@#"))                System.out.println(elementName+":"+new String(ch,start,length));            }        });//4        reader.parse("./xml5/users.xml");//5    }}

users.xml

<?xml version="1.0" encoding="utf-8"?><users>   <user id="A001">     <name>jack</name>      <age>23</age>   </user>    <user id="b001">     <name>Mike</name>      <age>25</age>   </user> </users>

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