解析XML文档之三：使用DOM解析

dom解析方法是将整个xml文档装载到内存当中，然后通过树形结构方式去解析的，这种方式只适合于在pc端的开发，不是很适合手机端的开发，毕竟来说手机的内存是没法跟pc相提并论的。

具体实现步骤如下：

第一步：准备好解析的xml文档

<?xml version="1.0" encoding="UTF-8"?>
<students>
    <student id="A001">
        <name>zhangsan</name>
        <sex>male</sex>
        <age>12</age>
        <address>beijing</address>
    </student>    
    <student id="A002">
        <name>lisi</name>
        <sex>male</sex>
        <age>13</age>
        <address>beijing</address>
    </student>
</students>

第二步：定义一个实体类（这个实体类其实就是xml文档中的内容了）

package com.bjhksj.dom;

public class Student {
    private String id;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    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 String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    private String name;
    private String sex;
    private int age;
    private String address;
}

第三步：下载xml文档

package com.bjhksj.dom;

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpDownload {
    public static InputStream downloader(String path) {
        InputStream inputStream = null;
        try {
            URL url = new URL(path);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            inputStream = conn.getInputStream();
        } catch (Exception e) {
            // TODO: handle exception
        }
        return inputStream;
    }
}

第四部：解析过程

package com.bjhksj.dom;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

public class DomXMLParser {
    public static List<Student> domXMLParser(InputStream inputStream) {
        // 创建一个Document解析器工厂对象
        List<Student> studnetList = new ArrayList<Student>();
        try {
            DocumentBuilderFactory factory = DocumentBuilderFactory
                    .newInstance();
            DocumentBuilder documentBuilder = factory.newDocumentBuilder();
            Document document = documentBuilder.parse(inputStream);
            NodeList studentNodes = document.getElementsByTagName("student");
            for (int i = 0; i < studentNodes.getLength(); i++) {
                Element element = (Element) studentNodes.item(i);
                Student student = new Student();
                student.setId(element.getAttribute("id"));
                NodeList childNodes = element.getChildNodes();
                for (int j = 0; j < childNodes.getLength(); j++) {
                    if ("name".equals(childNodes.item(j).getNodeName())) {
                        student.setName(childNodes.item(j).getFirstChild()
                                .getNodeValue());
                    } else if ("sex".equals(childNodes.item(j).getNodeName())) {
                        student.setSex(childNodes.item(j).getFirstChild()
                                .getNodeValue());
                    } else if ("age".equals(childNodes.item(j).getNodeName())) {
                        student.setAge(Integer.parseInt(childNodes.item(j)
                                .getFirstChild().getNodeValue()));
                    } else if ("address".equals(childNodes.item(j)
                            .getNodeName())) {

                        student.setAddress(childNodes.item(j).getFirstChild()
                                .getNodeValue());
                    }

                }
                studnetList.add(student);
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            try {
                inputStream.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        return studnetList;
    }
}