JAVA原生DOM解析XML

DOM需要把整个XML放进内存中,如果数据量少没有什么影响,如果数据量太大,将会给服务器带来很大的负担。

下面是一个XML的实体类Linkman

public class Linkman {
	private String id;
	private String name;
	private String address;
	private String email;
	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 getAddress() {
		return address;
	}
	public void setAddress(String address) {
		this.address = address;
	}
	public String getEmail() {
		return email;
	}
	public void setEmail(String email) {
		this.email = email;
	}
	@Override
	public String toString() {
		return "Linkman [id=" + id + ", name=" + name + ", address=" + address + ", email=" + email + "]";
	}
}

然后是XML的内容:

	王美丽
西南医学院
[email protected]
	张三
泸职院
[email protected]
	张三1
泸职院22
[email protected]
	bbb
aaaa
[email protected]
张无忌
高新区创业园
[email protected]

然后是一个测试类：其中包含五个方法,增删改,根据查询单个,查询全部

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

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
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.NodeList;

public class XmlParseTest {
	public static void main(String[] args) {
		XmlParseTest test = new XmlParseTest();
		Linkman linkman = new Linkman();
		linkman.setId("5");
		linkman.setName("西门吹雪");
		linkman.setAddress("高新区创业园");
		linkman.setEmail("[email protected]");
//		test.insert(linkman);
//		test.delete("5");
		Linkman lkm = test.selectOneById("5");
		lkm.setName("张无忌");
		test.update(lkm);
		List list = new XmlParseTest().selectAll();
		for (Linkman lm : list) {
			System.err.println(lm);
		}
	}

	public void insert(Linkman linkman) {
		try {
			// 获取工厂对象
			DocumentBuilderFactory bbf = DocumentBuilderFactory.newInstance();
			// 获取构建对象
			DocumentBuilder builder = bbf.newDocumentBuilder();
			// 解析路径得到文档对象
			Document doc = builder.parse(new File("resource/linkman.xml"));
			// 获取根元素
			Element root = doc.getDocumentElement();
			// 创建linkman元素
			Element linkmanEl = doc.createElement("linkman");
			linkmanEl.setAttribute("id", linkman.getId());
			// 把linkman作为root的子节点
			root.appendChild(linkmanEl);
			// 创建name、address、email
			Element nameEl = doc.createElement("name");
			Element addressEl = doc.createElement("address");
			Element emailEl = doc.createElement("email");
			// 给他们赋值内容
			nameEl.setTextContent(linkman.getName());
			addressEl.setTextContent(linkman.getAddress());
			emailEl.setTextContent(linkman.getEmail());
			// 建立name、address、email和linkman标签的关系
			linkmanEl.appendChild(nameEl);
			linkmanEl.appendChild(addressEl);
			linkmanEl.appendChild(emailEl);

			// 同步 将内存中的xml树,写到文件中
			TransformerFactory factory = TransformerFactory.newInstance();
			Transformer transformer = factory.newTransformer();
			transformer.transform(new DOMSource(doc), new StreamResult("resource/linkman.xml"));
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public void update(Linkman linkman) {//id=5 name ="林青霞"
		try {
			// 获取工厂对象
			DocumentBuilderFactory bbf = DocumentBuilderFactory.newInstance();
			// 获取构建对象
			DocumentBuilder builder = bbf.newDocumentBuilder();
			// 解析路径得到文档对象
			Document doc = builder.parse(new File("resource/linkman.xml"));
			// 获取根元素
			Element root = doc.getDocumentElement();
			// 获取所有的Linkman元素
			NodeList nodeList = root.getElementsByTagName("linkman");
			for (int i = 0; i < nodeList.getLength(); i++) {
				// 获取linkman元素的id属性值,来判断
				Element linkmanEl = (Element) nodeList.item(i);
				String linkmanId = linkmanEl.getAttribute("id");
				if (linkmanId.equals(linkman.getId())) {
					linkmanEl.getElementsByTagName("name").item(0).setTextContent(linkman.getName());
					linkmanEl.getElementsByTagName("address").item(0).setTextContent(linkman.getAddress());
					linkmanEl.getElementsByTagName("email").item(0).setTextContent(linkman.getEmail());
					//同步
					TransformerFactory.newInstance().newTransformer().transform(new DOMSource(doc),
							new StreamResult("resource/linkman.xml"));
					return;
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public void delete(String id) {
		try {
			// 获取工厂对象
			DocumentBuilderFactory bbf = DocumentBuilderFactory.newInstance();
			// 获取构建对象
			DocumentBuilder builder = bbf.newDocumentBuilder();
			// 解析路径得到文档对象
			Document doc = builder.parse(new File("resource/linkman.xml"));
			// 获取根元素
			Element root = doc.getDocumentElement();
			// 获取所有的Linkman元素
			NodeList nodeList = root.getElementsByTagName("linkman");
			for (int i = 0; i < nodeList.getLength(); i++) {
				// 获取linkman元素的id属性值,来判断
				Element linkmanEl = (Element) nodeList.item(i);
				String linkmanId = linkmanEl.getAttribute("id");
				if (linkmanId.equals(id)) {
					// 删除
					root.removeChild(linkmanEl);
					// 同步
					TransformerFactory.newInstance().newTransformer().transform(new DOMSource(doc),
							new StreamResult("resource/linkman.xml"));
					return;
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public Linkman selectOneById(String id) {
		try {
			// 获取工厂对象
			DocumentBuilderFactory bbf = DocumentBuilderFactory.newInstance();
			// 获取构建对象
			DocumentBuilder builder = bbf.newDocumentBuilder();
			// 解析路径得到文档对象
			Document doc = builder.parse(new File("resource/linkman.xml"));
			// 获取根元素
			Element root = doc.getDocumentElement();
			// 获取所有的Linkman元素
			NodeList nodeList = root.getElementsByTagName("linkman");
			for (int i = 0; i < nodeList.getLength(); i++) {
				// 获取linkman元素的id属性值,来判断
				Element linkmanEl = (Element) nodeList.item(i);
				String linkmanId = linkmanEl.getAttribute("id");
				if (linkmanId.equals(id)) {
					// 如果等于参数id,就去获取对应的name、address、email
					String name = linkmanEl.getElementsByTagName("name").item(0).getTextContent();
					String address = linkmanEl.getElementsByTagName("address").item(0).getTextContent();
					String email = linkmanEl.getElementsByTagName("email").item(0).getTextContent();
					// 创建Linkman对象
					Linkman linkman = new Linkman();
					linkman.setId(id);
					linkman.setName(name);
					linkman.setAddress(address);
					linkman.setEmail(email);
					return linkman;
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}

	public List selectAll() {
		List list = new ArrayList<>();
		// Dom方法
		// 获取Document对象
		// 1.获取DocumentBuilderFactory对象
		DocumentBuilderFactory bbf = DocumentBuilderFactory.newInstance();
		// 2.使用DocumentBuilderFactory创建DocumentBuilder对象
		try {
			DocumentBuilder builder = bbf.newDocumentBuilder();
			// 3.使用DocumentBuilder解析一个xml路径，得到一个Document对象
			Document doc = builder.parse(new File("resource/linkman.xml"));
			// 获取根元素
			Element root = doc.getDocumentElement();
			// 获取所有的linkman
			NodeList linkmans = root.getElementsByTagName("linkman");
			for (int i = 0; i < linkmans.getLength(); i++) {
				// 遍历得到每一个linkman标签
				Element linkmanEl = (Element) linkmans.item(i);
				// 通过linkman标签 去获取name标签、address标签、email标签
				Element nameEl = (Element) linkmanEl.getElementsByTagName("name").item(0);
				Element addressEl = (Element) linkmanEl.getElementsByTagName("address").item(0);
				Element emailEl = (Element) linkmanEl.getElementsByTagName("email").item(0);
				// 获取name、address、email的值
				String name = nameEl.getTextContent();
				String address = addressEl.getTextContent();
				String email = emailEl.getTextContent();
				// 获取linkman标签的id属性
				String id = linkmanEl.getAttribute("id");

				// 创建Linkman对象
				Linkman linkman = new Linkman();
				linkman.setId(id);
				linkman.setName(name);
				linkman.setAddress(address);
				linkman.setEmail(email);
				// 将linkman对象添加到集合
				list.add(linkman);
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return list;
	}

}