matlab分析xml文件_如何在Java中读取XML文件（DOM分析器）

雨点打透心脏的1/2处 2023-02-28 08:41 96阅读 0赞

matlab分析xml文件

Today we will learn how to read the XML file in Java. We will also learn how to parse an XML file in java to object using DOM parser.

今天，我们将学习如何使用Java读取XML文件。 我们还将学习如何使用DOM解析器将Java中的XML文件解析为对象。

DOM XML Parser is easiest to understand. It loads the XML object into memory as Document, then you can easily traverse different elements and nodes in the object. The traversing of elements and nodes are not required to be in order.

DOM XML分析器最容易理解。 它将XML对象作为Document加载到内存中，然后您可以轻松地遍历对象中的不同元素和节点。 元素和节点的遍历不需要按顺序进行。

## 如何用Java读取XML文件 **(****How to read XML File in Java****)** ##

![how to read xml file in java, java dom parser, java parse xml file][how to read xml file in java_ java dom parser_ java parse xml file]

DOM Parser are good for small XML documents but since it loads complete XML file into memory, it’s not good for large XML files. For large XML files, you should use [SAX Parser][].

DOM Parser对于小型XML文档很有用，但是由于它将完整的XML文件加载到内存中，因此对于大型XML文件不是很好。 对于大型XML文件，应使用[SAX Parser][] 。

In this tutorial, we will read the XML file and parse it to create an object from it.

在本教程中，我们将读取XML文件并进行解析以从中创建对象。

Here is the XML file that will be read in this program.

这是将在此程序中读取的XML文件。

`employee.xml`

<?xml version="1.0"?>
    <Employees>
    	<Employee>
    		<name>Pankaj</name>
    		<age>29</age>
    		<role>Java Developer</role>
    		<gender>Male</gender>
    	</Employee>
    	<Employee>
    		<name>Lisa</name>
    		<age>35</age>
    		<role>CSS Developer</role>
    		<gender>Female</gender>
    	</Employee>
    </Employees>

So this XML is the list of employees, to read this XML file I will create a bean object Employee and then we will parse the XML to get the [list][] of employees.

因此，此XML是雇员列表，要读取此XML文件，我将创建一个bean对象Employee，然后我们将解析XML以获取雇员[列表][list] 。

Here is the Employee bean object.

这是Employee bean对象。

package com.journaldev.xml;
    
    public class Employee {
        private String name;
        private String gender;
        private int age;
        private String role;
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public String getGender() {
            return gender;
        }
        public void setGender(String gender) {
            this.gender = gender;
        }
        public int getAge() {
            return age;
        }
        public void setAge(int age) {
            this.age = age;
        }
        public String getRole() {
            return role;
        }
        public void setRole(String role) {
            this.role = role;
        }
        
        @Override
        public String toString() {
            return "Employee:: Name=" + this.name + " Age=" + this.age + " Gender=" + this.gender +
                    " Role=" + this.role;
        }
        
    }

Notice that I have overridden toString() method to print useful information about the employee.

注意，我已经重写了toString（）方法以打印有关员工的有用信息。

Read this post to know you should always use [@Override annotation][Override annotation] to override methods.

阅读这篇文章，以了解您应该始终使用[@Override注解][Override annotation]覆盖方法。

If you are new to annotations, read [java annotations tutorial][].

如果您不熟悉注释，请阅读[Java注释教程][java annotations tutorial] 。

### Java DOM解析器 **(****Java DOM Parser****)** ###

Here is the java program that uses DOM Parser to read and parse XML file to get the list of Employee object.

这是使用DOM解析器读取和解析XML文件以获得Employee对象列表的Java程序。

package com.journaldev.xml;
    
    import java.io.File;
    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.List;
    
    import javax.xml.parsers.DocumentBuilder;
    import javax.xml.parsers.DocumentBuilderFactory;
    import javax.xml.parsers.ParserConfigurationException;
    
    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;
    
    
    public class XMLReaderDOM {
    
        public static void main(String[] args) {
            String filePath = "employee.xml";
            File xmlFile = new File(filePath);
            DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder dBuilder;
            try {
                dBuilder = dbFactory.newDocumentBuilder();
                Document doc = dBuilder.parse(xmlFile);
                doc.getDocumentElement().normalize();
                System.out.println("Root element :" + doc.getDocumentElement().getNodeName());
                NodeList nodeList = doc.getElementsByTagName("Employee");
                //now XML is loaded as Document in memory, lets convert it to Object List
                List<Employee> empList = new ArrayList<Employee>();
                for (int i = 0; i < nodeList.getLength(); i++) {
                    empList.add(getEmployee(nodeList.item(i)));
                }
                //lets print Employee list information
                for (Employee emp : empList) {
                    System.out.println(emp.toString());
                }
            } catch (SAXException | ParserConfigurationException | IOException e1) {
                e1.printStackTrace();
            }
    
        }
    
    
        private static Employee getEmployee(Node node) {
            //XMLReaderDOM domReader = new XMLReaderDOM();
            Employee emp = new Employee();
            if (node.getNodeType() == Node.ELEMENT_NODE) {
                Element element = (Element) node;
                emp.setName(getTagValue("name", element));
                emp.setAge(Integer.parseInt(getTagValue("age", element)));
                emp.setGender(getTagValue("gender", element));
                emp.setRole(getTagValue("role", element));
            }
    
            return emp;
        }
    
    
        private static String getTagValue(String tag, Element element) {
            NodeList nodeList = element.getElementsByTagName(tag).item(0).getChildNodes();
            Node node = (Node) nodeList.item(0);
            return node.getNodeValue();
        }
    
    }

Output of the above program is:

上面程序的输出是：

Root element :Employees
    Employee:: Name=Pankaj Age=29 Gender=Male Role=Java Developer
    Employee:: Name=Lisa Age=35 Gender=Female Role=CSS Developer

In real life, it’s not a bad idea to validate XML file before parsing it to objects, learn how to [validate XML against XSD][] in java. That’s all about how to read xml file or parse xml file in java.

在现实生活中，在将XML文件解析为对象之前验证XML文件，学习如何在Java中[针对XSD验证XML][validate XML against XSD]并不是一个坏主意。 这就是如何在Java中读取xml文件或解析xml文件的全部内容。

Reference: [Official W3.org Doc][]

参考： [W3.org官方文档][Official W3.org Doc]

> 翻译自: [https://www.journaldev.com/898/read-xml-file-java-dom-parser][https_www.journaldev.com_898_read-xml-file-java-dom-parser]

matlab分析xml文件

[how to read xml file in java_ java dom parser_ java parse xml file]: /images/20230209/9d6588b21ec3458a9b8759d6e97456d4.png
[SAX Parser]: https://www.journaldev.com/1198/java-sax-parser-example
[list]: https://www.journaldev.com/11444/java-list
[Override annotation]: https://www.journaldev.com/817/java-override-method-overriding
[java annotations tutorial]: https://www.journaldev.com/721/java-annotations
[validate XML against XSD]: https://www.journaldev.com/895/how-to-validate-xml-against-xsd-in-java
[Official W3.org Doc]: https://www.w3.org/TR/DOM-Parsing/
[https_www.journaldev.com_898_read-xml-file-java-dom-parser]: https://www.journaldev.com/898/read-xml-file-java-dom-parser