Dom4j使用

最新推荐文章于 2023-07-03 10:56:52 发布

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最新推荐文章于 2023-07-03 10:56:52 发布

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分类专栏： Java

本文链接：https://blog.youkuaiyun.com/hongloumengmm/article/details/47047267

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Dom4j相关操作

只要不是最末端标签，都可以做

1）Element element(String Qname)获取某一层标签下的名为 Qname的标签

这获得是就是一层标签，不是一个标签范围；通过这一层标签可以获得下一层标签

2）List elements() 获取某一层标签下的所有标签的列表

一．不使用XPath表达式

///////////////////////////添加标签/////////////////////////////

/**
	 * 在固定的位置上添加一个新的标签
	 * 主要是运用list添加元素的的操作
	 */
		public static void addByLocation() throws Exception {
			//首先的三步
			SAXReader saxReader = new SAXReader();
			Document document = saxReader.read("src/xml/xml1.xml");
			Element root = document.getRootElement();
			//获取所有一级目录的列表
			List<Element> allList = root.elements("student");
				//获取一级目录的第一组
			Element firstE  = allList.get(0);
				//获取第一组的所有标签
			List<Element> list1 = firstE.elements();
				//创建要插入的标签和属性
			Element school = DocumentHelper.createElement("school");
			school.setText("红星");
				//在list1 中插入
			list1.add(1,school);
			//回写
			XMLWriter xmlWriter = new XMLWriter(new FileOutputStream("src/xml/xml1.xml"), 
					OutputFormat.createPrettyPrint());
xmlWriter.write(document);//把document中的内容写到输出流中
			xmlWriter.close();
	}

//////////////////////////////////////////////////////////////

/**
       * 在末尾添加一个新标签
       */
   public static void addOne() throws Exception {
      SAXReader saxReader = new SAXReader();
      Document document = saxReader.read("src/xml/xml1.xml");
      Element root = document.getRootElement();
      List<Element> list = root.elements("student");
      Element fe = list.get(0);
      Elementsex1 = fe.addElement("sex");
      sex1.setText("女");//注意这里是在sex1上添加，不是fe
      XMLWriter xmlWriter = new XMLWriter(new FileOutputStream("src/xml/xml1.xml"),
            OutputFormat.createPrettyPrint());
      xmlWriter.write(document);
      xmlWriter.close();
   }

///////////////////////////查询标签/////////////////////////////

/**
    *显示所有的人的名字
    */
   public static void showAll() throws Exception {
      SAXReader saxReader = new SAXReader();
      Document document = saxReader.read("src/xml/xml1.xml");
      Element root = document.getRootElement();
      List<Element> list = root.elements("student");
      for (Element element : list) {
         Element e = element.element("name");
         System.out.println(e.getText());
      }
   }
}

/////////////////////////修改标签属性///////////////////////////

/**
    *修改一个标签的值
    */
   public static void modifyBy() throws Exception {
      SAXReader saxReader = new SAXReader();
      Document document = saxReader.read("src/xml/xml1.xml");
      Element root = document.getRootElement();
     
      List<Element> allList = root.elements("student");
      Element firstE = allList.get(0);
      Element id = firstE.element("id");
      id.setText("10");
      XMLWriter xmlWriter = new XMLWriter(new FileOutputStream("src/xml/xml1.xml"),
            OutputFormat.createPrettyPrint());
      xmlWriter.write(document);
      xmlWriter.close();
   }

/////////////////////////删除标签/////////////////////////////

/**
    *删除某个属性标签
    *和在末尾添加一样，找到父节点，在父节点上remove一个要删除的标签
    */
   public static void deleteBy() throws Exception {
      SAXReader saxReader = new SAXReader();
      Document document = saxReader.read("src/xml/xml1.xml");
      Element root = document.getRootElement();
      List<Element> allList = root.elements("student");
      Element firstE = allList.get(0);//父节点
      Elementsex = firstE.element("sex");//要删除的标签
      firstE.remove(sex);
      XMLWriter xmlWriter = new XMLWriter(
new FileOutputStream(PATH),
            OutputFormat.createPrettyPrint());
      xmlWriter.write(document);
      xmlWriter.close();
   }

/////////////////////////获取标签属性///////////////////////////

比如：

<id>10</id> 女

</student>

要得到ID的值

/**
    * 获取给定标签的属性值
    */
   public  static void getAttribute() throws Exception {
      SAXReader saxReader = new SAXReader();
      Document document = saxReader.read(PATH);
      Element root = document.getRootElement();
      List<Element> allList = root.elements("student");
      Element firstE = allList.get(0);
      String id = firstE.attributeValue("ID");
      System.out.println(id);
   }

一．使用XPath表达式

常用的六种表达式：

/////////////////////////查询标签///////////////////////////

/**

* 使用XPath表达式简化xml操作

* 查询

public static void test1() throws Exception {

SAXReader saxReader = new SAXReader();

Document document = saxReader.read(PATH);

List<Node> list = document.selectNodes("//name");

for (Node node : list) {

String name = node.getText();

System.out.println(name);

}

public static void test2() throws Exception {

SAXReader saxReader = new SAXReader();

Document document = saxReader.read(PATH);

Node node1 =document.selectSingleNode("//student[@ID='0']/name");

String name = node1.getText();

System.out.println(name);

}

小项目：

////////////////////////学生信息增删查///////////////////////////

方法类

public class StudentService {
   private static final String PATH = "src/xml/data.xml";
 
   /*
    * 添加
    */
   public void addStu(StudentInfo stu) throws Exception {
      String name = stu.getName();
      String age = stu.getAge();
      String id = stu.getId();
      SAXReader saxReader = new SAXReader();
      Document document = saxReader.read(PATH);
      Element root = document.getRootElement();
      Element e = root.addElement("info");
      Element e1 = e.addElement("id");
      Element e2 = e.addElement("name");
      Element e3 = e.addElement("age");
      e1.setText(id);
      e2.setText(name);
      e3.setText(age);
      XMLWriter xmlWriter = new XMLWriter(new FileOutputStream(PATH),
            OutputFormat.createPrettyPrint());
      xmlWriter.write(document);
      xmlWriter.close();
   }
 
   /*
    * 删除
    */
   public void deleteStu(String id) throws Exception {
      SAXReader saxReader = new SAXReader();
      Document document = saxReader.read(PATH);
      List<Node> list = document.selectNodes("//id");
      for (Node node : list) {
         String idc = node.getText();
         if (idc.equals(id)) {
            Element fa = node.getParent();
            Element fafa = fa.getParent();
            fafa.remove(fa);
         }
      }
      XMLWriter xmlWriter = new XMLWriter(new FileOutputStream(PATH),
            OutputFormat.createPrettyPrint());
      xmlWriter.write(document);
      xmlWriter.close();
   }
   /*
    * 查询
    */
   public StudentInfo selectStu(String id ) throws Exception{
      SAXReader saxReader = new SAXReader();
      Document document = saxReader.read(PATH);
      List<Node> list = document.selectNodes("//id");
      StudentInfo stu = new StudentInfo();
      for (Node node : list) {
         String idc = node.getText();
         if(idc.equals(id)){
            Element fa = node.getParent();
            Element name = fa.element("name");
            Element age = fa.element("age");
            String namec = name.getText();
            String agc = age.getText();
            stu.setName(namec);
            stu.setAge(agc);
            stu.setId(idc);
         }
      }
      return stu;
   }
   /*
    * 修改姓名为name的学生的学号为ID
    */
   public void changeStu(String name,String id) throws Exception{
      SAXReader saxReader = new SAXReader();
      Document document = saxReader.read(PATH);
      List<Node> list = document.selectNodes("//name");
      for (Node node : list) {
         String namec = node.getText();
         if (namec.equals(name)) {
            Element fa = node.getParent();
            Element idE = fa.element("id");
            idE.setText(id);
         }
      }
      XMLWriter xmlWriter = new XMLWriter(new FileOutputStream(PATH),
            OutputFormat.createPrettyPrint());
      xmlWriter.write(document);
      xmlWriter.close();
   }
}<span style="font-family:宋体;color:#ff0000;"><span style="font-size: 11pt;"><strong>
 
</strong></span></span>

学生信息类：

public class StudentInfo {
	private String name;
	private String id;
	private String age ;
	public StudentInfo() {
		super();
	}
	public String getName() {
		return name;
	}
	public StudentInfo(String name, String id, String age) {
		this.name = name;
		this.id = id;
		this.age = age;
	}
	
	public void setName(String name) {
		this.name = name;
	}
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getAge() {
		return age;
	}
	public void setAge(String age) {
		this.age = age;
	}
	@Override
	public String toString() {
		return "Information [name=" + name + ", id=" + id + ", age=" + age
				+ "]";
	}
	
}

主函数：

public class Test {

	/**
	 */
	public static void main(String[] args) throws Exception {
		StudentService service = new StudentService();
		/*
		 * 添加操作
		 */
//		StudentInfo stu1 = new StudentInfo("张三","0","20");
//		StudentInfo stu2 = new StudentInfo("李四","1","21");
//		StudentInfo stu3 = new StudentInfo("王五","2","22");
//		service.addStu(stu1);
//		service.addStu(stu2);
//		service.addStu(stu3);
		/*
		 * 删除操作
		 */
//		service.deleteStu("0");
		/*
		 * 查询操作
//		 */
//		StudentInfo stu = service.selectStu("2");
//		System.out.println(stu.toString());
		/*
		 * 修改操作
		 */
		service.changeStu("王五", "20");
	}

}

xml文件：

<?xml version="1.0" encoding="UTF-8"?>

<student> 
  <info> 
    <id>1</id>  
    <name>李四</name>  
    <age>21</age> 
  </info>  
  <info> 
    <id>20</id>  
    <name>王五</name>  
    <age>22</age> 
  </info> 
</student>