5、java操作xml，dom4j

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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;        }    }}