Java ： DOM解析xml 文件/ 字符串

Posted 2021-06-30 Mars-xq

参考：

Java解析XML文件的常用方法介绍

Android XML解析的三种方式

一、xml源文件:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<students>
    <student>
        <name sex="man">小明</name>
        <nickName>明明</nickName>
    </student>
    <student>
        <name sex="woman">小红</name>
        <nickName>红红</nickName>
    </student>
    <student>
        <name sex="man">小亮</name>
        <nickName>亮亮</nickName>
    </student>
</students>

二、实体类

package day210624;

public class Student {
    private String name;
    private String sex;
    private String nickName;

    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 String getNickName() {
        return nickName;
    }

    public void setNickName(String nickName) {
        this.nickName = nickName;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\\'' +
                ", sex='" + sex + '\\'' +
                ", nickName='" + nickName + '\\'' +
                '}';
    }
}

三、解析工具

package day210624;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

import java.io.File;
import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.List;

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

public class Parser {

    public static Document getDocumentFromString(String xml)
            throws ParserConfigurationException, SAXException, IOException {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        InputSource inputSource = new InputSource(new StringReader(xml));
        return builder.parse(inputSource);
    }

    public static Document getDocumentFromFile(File file)
            throws ParserConfigurationException, SAXException, IOException {
        //一系列的初始化
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        //获得Document对象
        return builder.parse(file);
    }

    public static List<Student> parse(Document document) {
        /*============获得Document对象即可解析xml======================*/
        List<Student> list = new ArrayList<>();
        //获得student的List
        NodeList studentList = document.getElementsByTagName("student");
        //遍历student标签
        for (int i = 0; i < studentList.getLength(); i++) {
            //获得student标签
            Node node_student = studentList.item(i);
            //获得student标签里面的标签
            NodeList childNodes = node_student.getChildNodes();
            //新建student对象
            Student student = new Student();
            //遍历student标签里面的标签
            for (int j = 0; j < childNodes.getLength(); j++) {
                //获得name和nickName标签
                Node childNode = childNodes.item(j);
                //判断是name还是nickName
                if ("name".equals(childNode.getNodeName())) {
                    String name = childNode.getTextContent();
                    student.setName(name);
                    //获取name的属性
                    NamedNodeMap nnm = childNode.getAttributes();
                    //获取sex属性，由于只有一个属性，所以取0
                    Node n = nnm.item(0);
                    student.setSex(n.getTextContent());
                } else if ("nickName".equals(childNode.getNodeName())) {
                    String nickName = childNode.getTextContent();
                    student.setNickName(nickName);
                }
            }
            //加到List中
            list.add(student);
        }
        return list;
    }

    /*
     * 添加元素到XML中
     */
    public static void createElement(Document doc) {
        Element root = doc.getDocumentElement();
        // 通过Document对象的getDocumentElement()方法得到根节点
        Element newStudent = doc.createElement("student");
        // 通过Document对象的createElement(String tagName)方法得到新的元素

        Element newName = doc.createElement("name");
        // 通过Document对象的createElement(String tagName)方法得到新的元素
        newName.setTextContent("xq");
        // 通过调用Element对象的setTextContent(String textContent)方法为赋值
        newName.setAttribute("sex", "man");
        // 通过调用Element对象的setAttribute(String name,String value)方法为id赋值
        newStudent.appendChild(newName);

        Element newNickName = doc.createElement("nickName");
        // 通过Document对象的createElement(String tagName)方法得到新的元素
        newNickName.setTextContent("able");
        // 通过调用Element对象的setTextContent(String textContent)方法为赋值
        newStudent.appendChild(newNickName);

        root.appendChild(newStudent);
        // 添加到根节点中
    }

}

四、测试解析：

package day210624;

import org.w3c.dom.Document;

import java.io.File;
import java.util.List;

public class Test1 {

    public static void main(String[] args) {
        try {
            //解析xml文件
            File file = new File("/Users/tmk/IdeaProjects/JavaDemo/src/day210624/student.xml");
            Document documentFromFile = Parser.getDocumentFromFile(file);
            List<Student> students = Parser.parse(documentFromFile);
            System.out.println("students = " + students);

            //解析xml字符串
            String xml =
                    "<?xml version=\\"1.0\\" encoding=\\"UTF-8\\" standalone=\\"no\\"?>" +
                            "<students>" +
                            "<student>" +
                            "<name sex=\\"man\\">小明</name>" +
                            "<nickName>明明</nickName>" +
                            "</student>" +
                            "<student>" +
                            "<name sex=\\"woman\\">小红</name>" +
                            "<nickName>红红</nickName>" +
                            "</student>" +
                            "<student>" +
                            "<name sex=\\"man\\">小亮</name>" +
                            "<nickName>亮亮</nickName>" +
                            "</student>" +
                            "</students>";
            Document documentFromString = Parser.getDocumentFromString(xml);
            Parser.createElement(documentFromString);//添加一个节点
            List<Student> list = Parser.parse(documentFromString);
            System.out.println("list = " + list);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
//students = 
// [Student{name='小明', sex='man', nickName='明明'}, 
// Student{name='小红', sex='woman', nickName='红红'},
// Student{name='小亮', sex='man', nickName='亮亮'}]
//list = 
// [Student{name='小明', sex='man', nickName='明明'}, 
// Student{name='小红', sex='woman', nickName='红红'}, 
// Student{name='小亮', sex='man', nickName='亮亮'}, 
// Student{name='xq', sex='man', nickName='able'}]