java实现xml读写操作

今天带大家实现java中读写xml的操作，不说废话，直接进入主题吧

这里读取xml分为四种情况

• JAVA官方提供的
  DOM： 一次性将整个xml文件加载到内存中，进行解析
  SAX： 逐层向下解析
• 需要引入对应的jar包
  DOM4J， JDOM

读取xml

我们分别做解析，先来看看需要我们解析的xml文件内容

<?xml version="1.0" encoding="UTF-8"?><Peoples>    <people id="1">       <name>张三</name>       <age>22</age>       <job>医生</job>    </people>    <people id="2">       <name>李四</name>       <age>33</age>       <job>老师</job>    </people></Peoples>

使用Dom读取xml

import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.StringWriter;import javax.xml.parsers.DocumentBuilder;import javax.xml.parsers.DocumentBuilderFactory;import javax.xml.parsers.ParserConfigurationException;import javax.xml.transform.Transformer;import javax.xml.transform.TransformerException;import javax.xml.transform.TransformerFactory;import javax.xml.transform.dom.DOMSource;import javax.xml.transform.stream.StreamResult;import org.w3c.dom.Document;import org.w3c.dom.Element;import org.w3c.dom.Node;import org.w3c.dom.NodeList;import org.xml.sax.SAXException;private static void readXmlByDom() {        try {            // 1. 创建DocumentBuilderFactory对象            DocumentBuilderFactory dFactory = DocumentBuilderFactory.newInstance();            // 2. 创建DocumentBuilder对象            DocumentBuilder dBuilder = dFactory.newDocumentBuilder();            // 3. 通过DocumentBuilder的parse方法解析xml            org.w3c.dom.Document doc = dBuilder.parse("people.xml");            // 4. 根据根节点名称获取所有的people节点            org.w3c.dom.NodeList peopleList = doc.getElementsByTagName("people");            // 5. 遍历所有的people节点            for (int i = 0; i < peopleList.getLength(); i++) {                System.out.println(peopleList.item(i).getNodeName());                Node peopleNode = peopleList.item(i);                // A. 获取所有的属性名称 和 对应的属性值                org.w3c.dom.NamedNodeMap namedNodeMap = peopleNode.getAttributes();                // B. 遍历people的所有属性                for (int j = 0; j < namedNodeMap.getLength(); j++) {                    System.out.println("属性 ="+namedNodeMap.item(j).getNodeName()+"   :值 = "+namedNodeMap.item(j).getNodeValue());                }                NodeList nodeList = peopleNode.getChildNodes();                for (int k = 0; k < nodeList.getLength(); k++) {                    Node node = nodeList.item(k);                    if (node.getNodeType() == Node.ELEMENT_NODE) {                        System.out.println("节点名："+node.getNodeName()+ "    节点值："+node.getFirstChild().getNodeValue());                        //                      System.out.println("节点名："+node.getNodeName()+ "    节点值："+node.getTextContent());                    }                }            }        } catch (ParserConfigurationException e) {            e.printStackTrace();        } catch (SAXException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }

此时效果如下：

使用Sax读取xml

import java.io.IOException;import javax.xml.parsers.ParserConfigurationException;import javax.xml.parsers.SAXParser;import javax.xml.parsers.SAXParserFactory;import org.xml.sax.Attributes;import org.xml.sax.SAXException;import org.xml.sax.helpers.DefaultHandler;public class SaxTest {    public static void main(String[] args) {        try {            // 1. 获取SAXParserFactory实例            SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();            // 2. 获取SAXParser实例            SAXParser saxParser = saxParserFactory.newSAXParser();            // 3. 加载xml实例            saxParser.parse("people.xml", new SelfHandler());        } catch (ParserConfigurationException e) {            e.printStackTrace();        } catch (SAXException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }    static class SelfHandler extends DefaultHandler {        /**         * 遍历xml文件的开始标签         */        @Override        public void startElement(String uri, String localName, String qName, Attributes attributes)                throws SAXException {            super.startElement(uri, localName, qName, attributes);            if ("people".equals(qName)) {                for (int i = 0; i < attributes.getLength(); i++) {                    System.out.println("people 标签第"+(i+1)+" 个属性名是:"+attributes.getQName(i)+"   属性值是： "+attributes.getValue(attributes.getQName(i)));                }            } else if (!"peoples".equals(qName) && !"people".equals(qName)) {                System.out.print("节点名是： "+qName+"------");            }        }        /**         * 遍历xml文件的结束标签         */        @Override        public void endElement(String uri, String localName, String qName) throws SAXException {            super.endElement(uri, localName, qName);        }        @Override        public void characters(char[] ch, int start, int length) throws SAXException {            super.characters(ch, start, length);            String value = new String(ch, start,length);            if (!"".equals(value.trim())) {                System.out.println("节点值是： "+value);            }        }        /**         * 标识解析开始         */        @Override        public void startDocument() throws SAXException {            super.startDocument();            System.out.println("开始sax解析.......");        }        /**         * 标识解析结束         */        @Override        public void endDocument() throws SAXException {            super.endDocument();            System.out.println("结束sax解析.......");        }    }}

此时效果如下：

使用Jdom读取xml

import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.util.List;import org.jdom.Document;import org.jdom.Attribute;import org.jdom.Element;import org.jdom.JDOMException;import org.jdom.input.SAXBuilder;import org.jdom.output.XMLOutputter;private static void readXmlByJdom() {        try {            // 1. 创建org.jdom.input.SAXBuilder对象            SAXBuilder saxBuilder = new SAXBuilder();            // 2. 创建一个输入流, 用来加载xml文件            InputStream ins = new FileInputStream("people.xml");            org.jdom.Document document = saxBuilder.build(ins);            // 3. 获取根节点            Element rootElement = document.getRootElement();            // 4. 获取根节点下的子节点            List<Element> lists = rootElement.getChildren();            for (Element people : lists) {                // A.获取所有的属性                // System.out.println("====属性值："+people.getAttributeValue("id"));                List<Attribute> attributeList = people.getAttributes();                for (Attribute element : attributeList) {                    System.out.println("属性名："+element.getName()+"====属性值："+element.getValue());                }                // B. 遍历people节点下所有的节点名和节点值                List<Element> childList = people.getChildren();                for (Element object : childList) {                    System.out.println("节点名："+object.getName()+"========节点值："+object.getValue());                }            }        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (JDOMException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }

此时效果如下：

使用Dom4J读取xml

import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.UnsupportedEncodingException;import java.util.Iterator;import java.util.List;import org.dom4j.Attribute;import org.dom4j.Document;import org.dom4j.DocumentException;import org.dom4j.DocumentHelper;import org.dom4j.Element;import org.dom4j.io.OutputFormat;import org.dom4j.io.SAXReader;import org.dom4j.io.XMLWriter;private static void readXmlByDom4J() {        try {            // 1. 创建org.dom4j.io.SAXReader对象            SAXReader saxReader = new SAXReader();            InputStream ins = new FileInputStream("people.xml");            Document document =  saxReader.read(ins);            Element rootElement = document.getRootElement();            System.out.println("根节点的名称是："+rootElement.getName());            Iterator iterator = rootElement.elementIterator();            while (iterator.hasNext()) {                Element element = (Element) iterator.next();                // 获取所有属性名和属性值                List<Attribute>attributesList = element.attributes();                for (Attribute attribute : attributesList) {                    System.out.println("属性名："+attribute.getName()+"======属性值"+attribute.getValue());                }                // 遍历子节点                Iterator childIterator = element.elementIterator();                while (childIterator.hasNext()) {                    Element child = (Element) childIterator.next();                    System.out.println("属性名："+child.getName()+"======属性值"+child.getStringValue());                }            }        } catch (FileNotFoundException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (DocumentException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }

此时读取到的效果如下：

需要注意的是，jdom和dom4j需要引入对应的jar文件

写入xml

使用Dom写入xml

private static void writeXmlByDom() {        try {              DocumentBuilderFactory factory =  DocumentBuilderFactory.newInstance();              DocumentBuilder builder = factory.newDocumentBuilder();              Document document = builder.newDocument();               //创建属性名、赋值              Element root = document.createElement("peoples");              //创建第一个根节点、赋值              Element lan = document.createElement("people");              lan.setAttribute("id", "1");              Element name = document.createElement("name");              name.setTextContent("张三");              Element ide = document.createElement("age");              ide.setTextContent("45");              lan.appendChild(name);              lan.appendChild(ide);              //创建第二个根节点、赋值              Element lan2 = document.createElement("lan");              lan2.setAttribute("id", "2");              Element name2 = document.createElement("name");              name2.setTextContent("李四");              Element ide2 = document.createElement("age");              ide2.setTextContent("88");              lan2.appendChild(name2);              lan2.appendChild(ide2);              //添加到属性中、              root.appendChild(lan);              root.appendChild(lan2);                  document.appendChild(root);              //定义了用于处理转换指令，以及执行从源到结果的转换的              TransformerFactory transformerFactory = TransformerFactory.newInstance();              Transformer transformer = transformerFactory.newTransformer();              transformer.setOutputProperty("encoding", "UTF-8");              StringWriter writer = new StringWriter();              transformer.transform(new DOMSource(document), new StreamResult(writer));              //          System.out.println(writer.toString());              transformer.transform(new DOMSource(document), new StreamResult(new File("D:/newxml.xml")));             } catch (ParserConfigurationException | TransformerException e) {              e.printStackTrace();          }     }

这里创建”D:/newxml.xml”这样的xml文件，效果如下：

使用JDom写入xml

private static void writeXmlByJdom() {        //定义一个root作为xml文档的根元素        Element root = new Element("peoples");         //生成一个文档        Document Doc = new Document(root);           for (int j = 1; j <= 3; j++) {             Element elements = new Element("people");               //设置属性名和属性值            elements.setAttribute("id", "" + j);               elements.addContent(new Element("name").setText("张三"));            elements.addContent(new Element("age").setText("22"));              elements.addContent(new Element("job").setText("老师"));              //将已经设置好值的elements赋给root            root.addContent(elements);          }         //定义一个用于输出xml文档的类        XMLOutputter XMLOut = new XMLOutputter();          try {            //将生成的xml文档Doc输出到文件            XMLOut.output(Doc, new FileOutputStream("d:/jdompeople.xml"));        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }

此时写入的文件内容如下：

使用Dom4j写入xml

private static void writeXmlByDom4J() {        try {            // 创建文档并设置文档的根元素节点               Element root = DocumentHelper.createElement("peoples");              Document document = DocumentHelper.createDocument(root);              //根节点              root.addAttribute("name","peoplesvalue");              //子节点              Element element1 = root.addElement("people");              element1.addAttribute( "id", "1" );            element1.addElement("name", "小王");             element1.addElement("age","22");            Element element2 = root.addElement("people");              element2.addAttribute( "id", "2" );            element2.addElement("name", "老王");             element2.addElement("age","23");            //添加              XMLWriter xmlwriter2 = new XMLWriter();              xmlwriter2.write(document);              //创建文件              OutputFormat format = new OutputFormat();              format = OutputFormat.createPrettyPrint();            //设定编码            format.setEncoding("UTF-8");            XMLWriter xmlwriter = new XMLWriter(new FileOutputStream("d:/dom4jpeople.xml"), format);            xmlwriter.write(document);            xmlwriter.flush();        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (UnsupportedEncodingException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }      }  

此时使用dom4j写入的xml内容如下：

好了，今天就到这里啦，好久没写代码了，以后要坚持，睡觉了
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