5、java操作xml，dom4j

、

1、首先在项目路径下引入dom4j-1.6.1.jar和jaxen-1.1-beta-6.jar包，jaxp方式解析xml文件

<?xml version="1.0" encoding="UTF-8"?>
<students>
<student name="cn.itcast_0001">
    <name>dogdogdog</name>
    <age>21</age>
    <sex>男</sex>
</student>
</students>

package cn.itcast_020;

import java.io.File;

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

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
//解析xml文件  jaxp解析方式
public class Demo1 {
    // 获得所有学生的信息
    public static void main(String[] args) {
        // 1 获得jaxp工厂
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        // 2通过工厂获得解析器实现类
        try {
            DocumentBuilder builder = factory.newDocumentBuilder();
            // 3使用解析器加载xml文档==>document
            Document doc = builder.parse(new File("src/student.xml"));
            // 4获得所有学生元素的集合
            NodeList studentList = doc.getElementsByTagName("student");
            // 5遍历集合
            for (int i = 0; i < studentList.getLength(); i++) {
                Element stuEle = (Element) studentList.item(i);
                // 获得学生元素的number属性
                String number = stuEle.getAttribute("number");
                // 获得学生节点下的所有子节点(包括文本在内的一共7个)
                NodeList children = stuEle.getChildNodes();
                for (int j = 0; j < children.getLength(); j++) {
                    Node node = children.item(j);
                    if (node.getNodeType() == Node.ELEMENT_NODE) {
                        Element child = (Element) node;
                        if (child.getNodeName().equals("name")) {
                            String name = child.getTextContent();
                            System.out.println(name);
                        } else if (child.getNodeName().equals("age")) {
                            String age = child.getTextContent();
                            System.out.println(age);
                        } else if (child.getNodeName().equals("sex")) {
                            String sex = child.getTextContent();
                            System.out.println(sex);
                        }
                    }

                }
            }

        } catch (Exception e) {

        }
    }
}

2、自己背着敲的代码

package cn.itcast_020;

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

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
//解析xml文件  jaxp解析方式
public class Demo2 {
    
    public static void main(String[] args) {
        // 创建jaxp解析工厂
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        // 获得jaxp解析器
        try {
            DocumentBuilder builder = factory.newDocumentBuilder();
            Document document = builder.parse("src/student.xml");
            NodeList nodelist = document.getElementsByTagName("student");
            for (int i = 0; i < nodelist.getLength(); i++) {
                Element element = (Element) nodelist.item(i);

                String number = element.getAttribute("number");
                NodeList nodes = element.getChildNodes();
                for (int j = 0; j < nodes.getLength(); j++) {
                    Node node = nodes.item(j);
                    if (node.getNodeType() == Node.ELEMENT_NODE) {// 由于得到的数组中有可能有空字符串，所以要判断是不是Element
                        Element child = (Element) node;
                        if (child.getNodeName().equals("name")) {
                            String name = child.getTextContent();
                            System.out.println(name);
                        } else if (child.getNodeName().equals("sex")) {
                            String sex = child.getTextContent();
                            System.out.println(sex);
                        } else {
                            String age = child.getTextContent();
                            System.out.println(age);
                        }

                    }
                }

            }

        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}

3、使用dom4j进行解析，一个读，一个写  （addElement）

package cn.itcast_020;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.SAXWriter;
import org.dom4j.io.XMLWriter;

public class Dom4jAddElement {
    public static void main(String[] args) {
        SAXReader reader = new SAXReader();
        try {
            Document doc = reader.read(new File("src/student.xml"));
            // 1获得根元素
            Element rootElement = doc.getRootElement();
            // 2添加Element,添加number属性
            Element ele = rootElement.addElement("student").addAttribute(
                    "number", "cn.itcast_0011");
            // 3添加name age sex子元素并添加子元素中的文本
            ele.addElement("name").addText("狗");
            ele.addElement("age").addText("16");
            ele.addElement("sex").addText("男");
            // 4将document对象写到文件中
            // 创建格式化器
            OutputFormat format = OutputFormat.createPrettyPrint();
            format.setEncoding("UTF-8");
            try {
                // 创建写入器
                // 使用字节流绝对不会出现乱码
                XMLWriter xml = new XMLWriter(new FileOutputStream(
                        "src/student2.xml"), format);
                // 写入
                xml.write(doc);
                // 关闭资源
                xml.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        } catch (DocumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}

4、dom4j ，RemoveElement

package cn.itcast_020;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

public class Dom4jRemoveElementWithXPath {
    public static void main(String[] args) {
        SAXReader reader = new SAXReader();
        try {
            Document doc = reader.read(new File("src/student2.xml"));
            //获得根元素
            Element root = doc.getRootElement();
            //使用xpath找到我们需要的元素
            //定义xpath
            String XPath = "//student[@number='cn.itcast_0011']";
            Element node = (Element) root.selectSingleNode(XPath);
            //删除
            System.out.println(node.getParent().remove(node));
            OutputFormat format = OutputFormat.createPrettyPrint();

            XMLWriter writer = new XMLWriter(new FileOutputStream(
                    "src/student3.xml"), format);

            writer.write(doc);
            writer.close();

        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}

5、Dom4jXPath修改学生

package cn.itcast_020;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.UnsupportedEncodingException;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

public class Dom4jXPath修改学生 {
    public static void main(String[] args) {
        SAXReader reader = new SAXReader();
        try {
            Document doc = reader.read(new File("src/student2.xml"));
            Element ele = doc.getRootElement();
            String xpath = "//student[@number='cn.itcast_0011']";
            Element student = (Element) ele.selectSingleNode(xpath);
            student.element("age").setText("22");
            student.element("sex").setText("男");
            student.element("name").setText("赵维真");
            OutputFormat format = OutputFormat.createPrettyPrint();

            XMLWriter writer = new XMLWriter(new FileOutputStream(
                    "src/student4.xml"), format);
            writer.write(doc);
            writer.close();

        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}

6、dom解析与sax解析的区别

package cn.itcast_020;

import java.io.File;
import java.util.Iterator;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
//dom4j解析适用于含有根元素的Xml文档
//而sax解析和dom解析适用于各种文档
//sax解析占用的内存比较少，效率高，但是不可以增删改查
//dom解析占用的内存多，但是可以增删改查
public class Dom4j解析 {
    public static void main(String[] args) {
        SAXReader reader = new SAXReader();
        Document doc;
        try {
            doc = reader.read(new File("src/student.xml"));
            //1获得根元素
            Element root = doc.getRootElement();
            //2迭代根元素下的所有名叫student的子元素
            for (Iterator it = root.elementIterator(); it.hasNext();) {
                Element ele = (Element) it.next();
                //3获得student元素的number属性
                String number = ele.attributeValue("name");
                System.out.println("number" + number);
                //4获得stuent子元素的内容(name age sex)
                String name = ele.elementText("name");
                System.out.println("name" + name);
                String age = ele.elementText("age");
                System.out.println("age" + age);

                String sex = ele.elementText("sex");
                System.out.println("sex" + sex);
            }
        } catch (DocumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}

7、sax解析

package cn.itcast_020;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

public class MyHandler extends DefaultHandler {

    @Override
    public void startDocument() throws SAXException {
        // TODO Auto-generated method stub
        super.startDocument();
        System.out.println("文档开始解析啦");
    }

    @Override
    public void endDocument() throws SAXException {
        // TODO Auto-generated method stub
        super.endDocument();
        System.out.println("文档解析完毕");
    }

    @Override
    public void startElement(String uri, String localName, String qName,
            Attributes attributes) throws SAXException {
        // 该方法主要获得元素的名称和属性
        super.startElement(uri, localName, qName, attributes);
        if (qName.equals("student")) {
            String name = attributes.getValue("number");
            System.out.println("number" + name);
        }
    }

    @Override
    public void endElement(String uri, String localName, String qName)
            throws SAXException {
        // TODO Auto-generated method stub
        super.endElement(uri, localName, qName);
    }

    @Override
    public void characters(char[] ch, int start, int length)
            throws SAXException {
        // 主要解析文档的中node中节点中的内容
        super.characters(ch, start, length);
        String content = new String(ch, start, length);
        System.out.println(content);
    }

}

8、sax解析

package cn.itcast_020;

import java.io.File;
import java.io.IOException;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.SAXException;

public class SAX解析 {
    public static void main(String[] args) {
        // 1 创建sax解析工厂
        SAXParserFactory factory = SAXParserFactory.newInstance();
        // 2获取sax解析器
        try {
            SAXParser parser = factory.newSAXParser();
            // 3解析文档
            parser.parse(new File("src/student.xml"), new MyHandler());

        } catch (ParserConfigurationException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SAXException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}

9、sax解析形成的dao

package cn.itcast_020;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

public class StudentXMLDao {
    private StudentXMLDao() {
    }

    public StudentXMLDao newInstance() {
        return new StudentXMLDao();
    }

    public boolean Add(Student stu) {

        SAXReader reader = new SAXReader();
        try {

            Document doc = reader.read(new File(this.getClass()
                    .getClassLoader().getResource("student.xml").getPath()));
            // 1获得根元素
            Element rootElement = doc.getRootElement();
            // 2添加Element,添加number属性
            Element ele = rootElement.addElement("student");
            // 3添加name age sex子元素并添加子元素中的文本
            ele.addElement("name").addText(stu.getName());
            ele.addElement("age").addText(String.valueOf(stu.getAge()));
            ele.addElement("sex").addText(stu.getSex());
            // 4将document对象写到文件中
            // 创建格式化器
            OutputFormat format = OutputFormat.createPrettyPrint();
            format.setEncoding("UTF-8");
            try {
                // 创建写入器
                // 使用字节流绝对不会出现乱码
                XMLWriter xml = new XMLWriter(new FileOutputStream(
                        "src/student2.xml"), format);
                // 写入
                xml.write(doc);
                // 关闭资源
                xml.close();
                return true;
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                return false;
            }

        } catch (DocumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return false;
        }
    }
}