java dom4j 增删改查[通俗易懂]

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package cn.itcast.dom4j;

import java.io.FileOutputStream;
import java.io.OutputStream;
import java.util.List;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
import org.junit.Assert;
import org.junit.Test;


public class Dom4JDemo {
//	1、得到某个具体的节点内容:第2本书的作者
	@Test
	public void test1() throws Exception{
		//得到Document对象
		SAXReader reader = new SAXReader();
		Document document = reader.read("src/book.xml");
		//得到根元素
		Element root = document.getRootElement();
		//依次得到第2本书的作者
		List<Element> es = root.elements("书");
		Element e = es.get(1);
		Element author = e.element("作者");
		//拿到内容打印输出
//		System.out.println(author.getText());
		Assert.assertEquals("毕向东", author.getText());
	}
	@Test
	public void test11() throws Exception{
		//得到Document对象
		SAXReader reader = new SAXReader();
		Document document = reader.read("src/book.xml");
		
		String xpath = "//书[2]/作者";
		Node author = document.selectSingleNode(xpath);
		
		//Assert.assertEquals("毕向东", author.getText());
	}
//	2、遍历所有元素节点:
	@Test
	public void test2() throws Exception{
		//得到Document对象
		SAXReader reader = new SAXReader();
		Document document = reader.read("src/book.xml");
		//得到根元素
		Element root = document.getRootElement();
		treeWalk(root);//遍历所有的元素，打印他的名称
	}
	private void treeWalk(Element root) {
		System.out.println(root.getName());
		List<Element> es = root.elements();
		for(Element e:es){
			treeWalk(e);
		}
	}
//	private void treeWalk(Element root){
//		System.out.println(root.getName());
//		//节点的数量
//		int count = root.nodeCount();
//		for(int i=0;i<count;i++){
//			Node node = root.node(i);//取索引上节点
//			if(node.getNodeType()==Node.ELEMENT_NODE){
//				treeWalk((Element)node);
//			}
//		}
//	}
	
//	3、修改某个元素节点的主体内容:修改第2本书的售价
	@Test
	public void test3() throws Exception{
		//得到Document对象
		SAXReader reader = new SAXReader();
		Document document = reader.read("src/book.xml");
		//得到根元素
		Element root = document.getRootElement();
		//得到第2本书的售价
		Element secondBook = (Element) root.elements().get(1);
		Element secondBookPrice = secondBook.element("售价");
		//设置主体内容
		secondBookPrice.setText("8.00");
		//写回XML文档
		OutputStream out = new FileOutputStream("src/book.xml");
		OutputFormat format = OutputFormat.createPrettyPrint();
//		format.setEncoding("UTF-8");//指定编码：这是默认编码
		XMLWriter writer = new XMLWriter(out, format);
		writer.write(document);
		writer.close();
	}
//	4、向指定元素节点中增加子元素节点:给第1本书添加批发价
	@Test
	public void test4()throws Exception{
		//得到Document对象
		SAXReader reader = new SAXReader();
		Document document = reader.read("src/book.xml");
		//得到根元素
		Element root = document.getRootElement();
		
		//找到第1本书：直接添加新元素
		Element firstBook = root.element("书");
		firstBook.addElement("批发价").setText("1");
		
		
		//写回XML文档
		OutputStream out = new FileOutputStream("src/book.xml");
		OutputFormat format = OutputFormat.createPrettyPrint();
//		format.setEncoding("UTF-8");//指定编码：这是默认编码
		XMLWriter writer = new XMLWriter(out, format);
		writer.write(document);
		writer.close();
	}
//	5、向指定元素节点上增加同级元素节点:在第一本书的售价前面添加内部价
	@Test
	public void test5()throws Exception{
		//得到Document对象
		SAXReader reader = new SAXReader();
		Document document = reader.read("src/book.xml");
		//得到根元素
		Element root = document.getRootElement();
		
		//找到第1本书
		Element firstBook = root.element("书");
		//得到第1本书的所有子元素：List
		List<Element> children = firstBook.elements();
		//借助DocumentHelper创建内部价元素
		Element price = DocumentHelper.createElement("内部价");
		price.setText("99");
		//挂接到老3的位置上
		children.add(2, price);
		
		//写回XML文档
		OutputStream out = new FileOutputStream("src/book.xml");
		OutputFormat format = OutputFormat.createPrettyPrint();
//		format.setEncoding("UTF-8");//指定编码：这是默认编码
		XMLWriter writer = new XMLWriter(out, format);
		writer.write(document);
		writer.close();
	}
//	6、删除指定元素节点:删除批发价
	@Test
	public void test6()throws Exception{
		//得到Document对象
		SAXReader reader = new SAXReader();
		Document document = reader.read("src/book.xml");
		//得到根元素
		Element root = document.getRootElement();
		
		//找到第1本书
		Element firstBook = root.element("书");
		
		//自己不能删自己
		Element price = firstBook.element("批发价");
		firstBook.remove(price);
		
		
		//写回XML文档
		OutputStream out = new FileOutputStream("src/book.xml");
		OutputFormat format = OutputFormat.createPrettyPrint();
//		format.setEncoding("UTF-8");//指定编码：这是默认编码
		XMLWriter writer = new XMLWriter(out, format);
		writer.write(document);
		writer.close();
	}
//	7、操作XML文件属性:第1本书添加一个出版社属性
	@Test
	public void test7()throws Exception{
		//得到Document对象
		SAXReader reader = new SAXReader();
		Document document = reader.read("src/book.xml");
		//得到根元素
		Element root = document.getRootElement();
		
		//找到第1本书
		Element firstBook = root.element("书");
		
		firstBook.addAttribute("出版社", "传智播客");
		
		
		//写回XML文档
		OutputStream out = new FileOutputStream("src/book.xml");
		OutputFormat format = OutputFormat.createPrettyPrint();
//		format.setEncoding("UTF-8");//指定编码：这是默认编码
		XMLWriter writer = new XMLWriter(out, format);
		writer.write(document);
		writer.close();
	}
	//获取第一本书的出版社属性值
	@Test
	public void test8()throws Exception{
		//得到Document对象
		SAXReader reader = new SAXReader();
		Document document = reader.read("src/book.xml");
		//得到根元素
		Element root = document.getRootElement();
		
		//找到第1本书
		Element firstBook = root.element("书");
		
		String value = firstBook.attributeValue("出版社");
		Assert.assertEquals("传智播客", value);
		
		
	}
}