XML SAX解析xml文件

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SAX解析xml文件


一、student.xml(解析的文件)

<?xml version="1.0" encoding="utf-8" ?><!--xml文档声明--><!--DTD约束--><!DOCTYPE class [        <!ELEMENT student (name,age,sex,height)>        <!ELEMENT name (#PCDATA)>        <!ELEMENT age (#PCDATA)>        <!ELEMENT sex (#PCDATA)>        <!ELEMENT height (#PCDATA)>        ]><!--只能有一个根标签--><class>    <!--设置属性-->    <student id="1" user="lisi">        <name>李四</name>        <age>18</age>        <sex>男</sex>        <height>182</height>    </student>    <student id="2" user="wangwu">        <name>王五</name>        <age>19</age>        <sex>男</sex>        <height>172</height>    </student></class>


二、解析代码(SAXParseMain.java)

package com.xml.main;import org.xml.sax.Attributes;import org.xml.sax.SAXException;import org.xml.sax.helpers.DefaultHandler;import javax.xml.parsers.ParserConfigurationException;import javax.xml.parsers.SAXParser;import javax.xml.parsers.SAXParserFactory;import java.io.IOException;import java.util.ArrayList;public class SAXParseMain {    public static void main(String[] args) {        try {            //步骤一:创建SAX解析工厂实例            SAXParserFactory factory = SAXParserFactory.newInstance();            //步骤二:通过工厂创建一个SAX解析器            SAXParser sax = factory.newSAXParser();            MyHandler myHandler = new MyHandler();            //步骤三:指定用相应的解析器开始解析XML文档            sax.parse("student.xml", myHandler);            ArrayList<Student> list = myHandler.getList();            for (int i = 0; i < list.size(); i++) {                Student student = list.get(i);                System.out.println(student.toString());            }        } catch (ParserConfigurationException e) {            e.printStackTrace();        } catch (SAXException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        } finally {        }    }}//指定解析处理器,编写解析规则class MyHandler extends DefaultHandler {    ArrayList<Student> list = new ArrayList<>();    public ArrayList<Student> getList() {        return list;    }    private Student student;    private String target = "";    //    解析到文档的开始    @Override    public void startDocument() throws SAXException {    }//    解析到开始的元素节点(包括根节点)    /**     * @param uri        命名空间     * @param localName  元素名称【不支持了】     * @param qName      [前缀:]元素名称(没有命名空间就不存在前缀)     * @param attributes 属性集     * @throws SAXException 异常     */    @Override    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {        if ("student".equals(qName)) {            student = new Student();            String id = attributes.getValue("id");            String user = attributes.getValue("user");            student.setId(Integer.parseInt(id));            student.setUser(user);        }        target = qName;    }    /**     * 解析到文本内容(包括回车,空格,换行)     *     * @param ch     SAX并不是把整个文档加载到内存中,SAX会把解析到的内容缓存起来(缓存8192字节),char[] ch就是解析到的缓存内容     * @param start  遇到文本的开始字符位置     * @param length 当前整个文本从一个标签到下一个标签的长度     * @throws SAXException     */    @Override    public void characters(char[] ch, int start, int length) throws SAXException {        String content = new String(ch, start, length);        switch (target) {            case "name":                student.setName(content);                break;            case "age":                student.setAge(Integer.parseInt(content));                break;            case "sex":                student.setSex(content);                break;            case "height":                student.setHeight(Double.parseDouble(content));                break;        }    }    /**     * 解析到结束的元素节点     *     * @param uri     * @param localName     * @param qName     * @throws SAXException     */    @Override    public void endElement(String uri, String localName, String qName) throws SAXException {        if ("student".equals(qName)) {            list.add(student);        }        target = "";    }    /**     * 解析到文档的结束     *     * @throws SAXException     */    @Override    public void endDocument() throws SAXException {    }}


三、Student.java

package com.xml.main;public class Student {    private int id;    private String user;    private String name;    private String sex;    private int age;    private double height;    public Student() {    }    public Student(int id, String user, String name, String sex, int age, double height) {        this.id = id;        this.user = user;        this.name = name;        this.sex = sex;        this.age = age;        this.height = height;    }    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getUser() {        return user;    }    public void setUser(String user) {        this.user = user;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getSex() {        return sex;    }    public void setSex(String sex) {        this.sex = sex;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }    public double getHeight() {        return height;    }    public void setHeight(double height) {        this.height = height;    }    @Override    public String toString() {        return "Student{" +                "id=" + id +                ", user='" + user + '\'' +                ", name='" + name + '\'' +                ", sex='" + sex + '\'' +                ", age=" + age +                ", height=" + height +                '}';    }}


四、解析结果



注:读边解析,应用于大型XML文档

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