Java XML 到字符串 - 将 XML 对象写入文件示例

读取 XML 文件和打印 XML 字符串以控制或将 XML 写入文件的 Java 示例。

1) 将 XML 转换为字符串

转换 XML 对象即 org.w3c.dom.Document 成字符串，你需要以下类：

• javax.xml.transform.Transformer ：此类的实例可以使用它的 transform() 方法将源树转换为结果树。
• javax.xml.transform.TransformerFactory ：创建 Transformer 实例的工厂。
• javax.xml.transform.dom.DOMSource：文档对象模型 (DOM) 树形式的源代码树。
• javax.xml.transform.stream.StreamResult：转换结果树的持有者，它可以是 XML、纯文本、HTML 或一些其他形式的标记。

1.1) 将 XML 打印到控制台或日志文件

private static void writeXmlDocumentToXmlFile(Document xmlDocument)
{
	TransformerFactory tf = TransformerFactory.newInstance();
    Transformer transformer;
    try {
        transformer = tf.newTransformer();
        
        // Uncomment if you do not require XML declaration
        // transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
        
        //A character stream that collects its output in a string buffer, 
        //which can then be used to construct a string.
        StringWriter writer = new StringWriter();

        //transform document to string 
        transformer.transform(new DOMSource(xmlDocument), new StreamResult(writer));

        String xmlString = writer.getBuffer().toString();	
        System.out.println(xmlString);						//Print to console or logs
    } 
    catch (TransformerException e) 
    {
        e.printStackTrace();
    }
    catch (Exception e) 
    {
        e.printStackTrace();
    }
}

1.2) 将 XML 写入文件

private static void writeXmlDocumentToXmlFile(Document xmlDocument, String fileName)
{
	TransformerFactory tf = TransformerFactory.newInstance();
    Transformer transformer;
    try {
        transformer = tf.newTransformer();
        
        //Uncomment if you do not require XML declaration
        //transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
        
        //Write XML to file
        FileOutputStream outStream = new FileOutputStream(new File(fileName)); 

        transformer.transform(new DOMSource(xmlDocument), new StreamResult(outStream));
    } 
    catch (TransformerException e) 
    {
        e.printStackTrace();
    }
    catch (Exception e) 
    {
        e.printStackTrace();
    }
}

2) 从文件中读取 XML

将 XML 从 .xml 文件读取到 Document 对象的示例。

private static Document convertXMLFileToXMLDocument(String filePath) 
{
	//Parser that produces DOM object trees from XML content
	DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
	
	//API to obtain DOM Document instance
	DocumentBuilder builder = null;
	try 
	{
		//Create DocumentBuilder with default configuration
		builder = factory.newDocumentBuilder();
		
		//Parse the content to Document object
		Document xmlDocument = builder.parse(new File(filePath));
		
		return xmlDocument;
	} 
	catch (Exception e) 
	{
		e.printStackTrace();
	}
	return null;
}

3) 完整示例

用于运行示例的完整代码。

package com.howtodoinjava.demo;

import java.io.File;
import java.io.FileOutputStream;
import java.io.StringWriter;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;

public class XmlToStringExample 
{
	public static void main(String[] args) 
	{
		final String xmlFilePath = "employees.xml";
		
		//Use method to convert XML string content to XML Document object
		Document xmlDocument = convertXMLFileToXMLDocument( xmlFilePath );
		
		//Write to file or print XML
		writeXmlDocumentToXmlFile(xmlDocument, "newEmployees.xml");
	}

	private static Document convertXMLFileToXMLDocument(String filePath) 
	{
		//Parser that produces DOM object trees from XML content
		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
		
		//API to obtain DOM Document instance
		DocumentBuilder builder = null;
		try 
		{
			//Create DocumentBuilder with default configuration
			builder = factory.newDocumentBuilder();
			
			//Parse the content to Document object
			Document xmlDocument = builder.parse(new File(filePath));
			
			return xmlDocument;
		} 
		catch (Exception e) 
		{
			e.printStackTrace();
		}
		return null;
	}
	
	private static void writeXmlDocumentToXmlFile(Document xmlDocument, String fileName)
	{
		TransformerFactory tf = TransformerFactory.newInstance();
        Transformer transformer;
        try {
            transformer = tf.newTransformer();
            
            // Uncomment if you do not require XML declaration
            // transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
            
            //Print XML or Logs or Console
            StringWriter writer = new StringWriter();
            transformer.transform(new DOMSource(xmlDocument), new StreamResult(writer));
            String xmlString = writer.getBuffer().toString();	
            System.out.println(xmlString);			
            
            //Write XML to file
            FileOutputStream outStream = new FileOutputStream(new File(fileName)); 
            transformer.transform(new DOMSource(xmlDocument), new StreamResult(outStream));
        } 
        catch (TransformerException e) 
        {
            e.printStackTrace();
        }
        catch (Exception e) 
        {
            e.printStackTrace();
        }
	}
}

输入文件。

<employees>
	<employee id="101">
		 <name>Lokesh Gupta</name>
	    <title>Author</title>
	</employee>
	<employee id="102">
		 <name>Brian Lara</name>
	    <title>Cricketer</title>
	</employee>
</employees>

输出文件。

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<employees>
	<employee id="101">
		 <name>Lokesh Gupta</name>
	    <title>Author</title>
	</employee>
	<employee id="102">
		 <name>Brian Lara</name>
	    <title>Cricketer</title>
	</employee>
</employees>

标签2： Java XML XML Files Java

地址：https://www.cundage.com/article/xml-to-string-write-xml-file.html