Java&Xml教程（四）使用DOM方式生成XML文件

墨蓝 2022-08-18 08:19 160阅读 0赞

在前面的教程中，我们学习了使用DOM解析方式读取和修改XML文件内容，今天我们来学习如何使用DOM解析机制生成XML文件。  
下面是我们对要生成的XML文件的具体要求：  
1.根节点元素为”Employees”,命名空间为”[http://www.journaldev.com/employee][http_www.journaldev.com_employee]“,根节点下包含一系列的Employee元素。  
2.员工的信息通过Employee节点表示，生成的XML文件有两条员工的信息。  
3.每个员工有个”id”属性。  
4.Employee 元素有四个子元素- “name”, “age”, “role”, “gender”。  
下面是程序代码：

package com.journaldev.xml;
    
    
    import java.io.File;
    
    import javax.xml.parsers.DocumentBuilder;
    import javax.xml.parsers.DocumentBuilderFactory;
    import javax.xml.transform.OutputKeys;
    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.Node;
    
    
    public class XMLWriterDOM {
    
        public static void main(String[] args) {
            DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder dBuilder;
            try {
                dBuilder = dbFactory.newDocumentBuilder();
                Document doc = dBuilder.newDocument();
                //add elements to Document
                Element rootElement =
                    doc.createElementNS("http://www.journaldev.com/employee", "Employees");
                //append root element to document
                doc.appendChild(rootElement);
    
                //append first child element to root element
                rootElement.appendChild(getEmployee(doc, "1", "Pankaj", "29", "Java Developer", "Male"));
    
                //append second child
                rootElement.appendChild(getEmployee(doc, "2", "Lisa", "35", "Manager", "Female"));
    
                //for output to file, console
                TransformerFactory transformerFactory = TransformerFactory.newInstance();
                Transformer transformer = transformerFactory.newTransformer();
                //for pretty print
                transformer.setOutputProperty(OutputKeys.INDENT, "yes");
                DOMSource source = new DOMSource(doc);
    
                //write to console or file
                StreamResult console = new StreamResult(System.out);
                StreamResult file = new StreamResult(new File("/Users/pankaj/emps.xml"));
    
                //write data
                transformer.transform(source, console);
                transformer.transform(source, file);
                System.out.println("DONE");
    
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    
    
        private static Node getEmployee(Document doc, String id, String name, String age, String role,
                String gender) {
            Element employee = doc.createElement("Employee");
    
            //set id attribute
            employee.setAttribute("id", id);
    
            //create name element
            employee.appendChild(getEmployeeElements(doc, employee, "name", name));
    
            //create age element
            employee.appendChild(getEmployeeElements(doc, employee, "age", age));
    
            //create role element
            employee.appendChild(getEmployeeElements(doc, employee, "role", role));
    
            //create gender element
            employee.appendChild(getEmployeeElements(doc, employee, "gender", gender));
    
            return employee;
        }
    
    
        //utility method to create text node
        private static Node getEmployeeElements(Document doc, Element element, String name, String value) {
            Element node = doc.createElement(name);
            node.appendChild(doc.createTextNode(value));
            return node;
        }
    
    }

需要注意的是代码中创建了两个StreamResult对象，一个是出于调试的目的將XML文件内容输出到控制台中，另一个將XML内容写到文件中。  
程序输出的XML内容：

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
    <Employees xmlns="http://www.journaldev.com/employee">
    <Employee id="1">
    <name>Pankaj</name>
    <age>29</age>
    <role>Java Developer</role>
    <gender>Male</gender>
    </Employee>
    <Employee id="2">
    <name>Lisa</name>
    <age>35</age>
    <role>Manager</role>
    <gender>Female</gender>
    </Employee>
    </Employees>

该XML内容没有格式化，如果你需要对XML内容做适当的格式化，参考这篇文章[Java中格式化XML][Java_XML]

[http_www.journaldev.com_employee]: http://www.journaldev.com/employee
[Java_XML]: http://www.journaldev.com/71/utility-java-class-to-format-xml-document-to-xml-string-and-xml-to-document