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Java 内置的文档对象模型 API 用于在 Java 中创建和写入 XML 文件。本教程演示如何将 XML 写入 Java 中的控制台和文件。

Java 写入 XML

如上所述，DOM API 用于将 XML 写入 Java 中的文件。这是一个用 Java 将 XML 写入文件的简单示例。

package Delfstack;

import org.w3c.dom.Document;
import org.w3c.dom.Element;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.*;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;

public class Write_XML {

    public static void main(String[] args)
            throws ParserConfigurationException, TransformerException {

        DocumentBuilderFactory Doc_Build_Factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder Document_Builder = Doc_Build_Factory.newDocumentBuilder();

        // the root elements for DOM Document
        //create XML fields, elements, etc.
        Document document = Document_Builder.newDocument();
        Element Root_Element = document.createElement("School");
        document.appendChild(Root_Element);
        document.createElement("Teacher");
        Root_Element.appendChild(document.createElement("Teacher"));
        document.createElement("Student");
        Root_Element.appendChild(document.createElement("Student"));



        // write DOM document in a file
        try (FileOutputStream output_file = new FileOutputStream("school.xml")) {
        	Write_Xml(document, output_file);
        	System.out.println("The XML has been successfully written to school.xml");
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    // Method to generate XML. Writing output stream
    private static void Write_Xml(Document document, OutputStream output_file)
            throws TransformerException {

        TransformerFactory Transformer_Factory = TransformerFactory.newInstance();
        Transformer New_Transformer = Transformer_Factory.newTransformer();
        DOMSource Source_XML = new DOMSource(document);
        StreamResult Result_XML = new StreamResult(output_file);

        New_Transformer.transform(Source_XML, Result_XML);

    }
}

上面的代码将创建一个文件并向其写入 XML 语法。见输出：

The XML has been successfully written to school.xml

让我们尝试另一个包含更多字段的示例，该示例将 XML 写入文件和控制台。参见示例：

package Delfstack;

import java.io.File;

import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
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 Write_XML {

    public static void main(String[] args) {
        DocumentBuilderFactory Doc_Builder_Factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder Document_Builder;
        try {
        	Document_Builder = Doc_Builder_Factory.newDocumentBuilder();
            Document document = Document_Builder.newDocument();
            //adding elements to Document
            Element Root_Element = document.createElementNS("https://www.delftstack.com/", "Tutorials");
            document.appendChild(Root_Element);

            //add a first child element to the root element
            Root_Element.appendChild(Get_Tutorial(document, "1", "Perform String to String Array Conversion in Java",
            		"https://www.delftstack.com/howto/java/how-to-perform-string-to-string-array-conversion-in-java/",
            		"Java", "May-21, 2020"));

            //add a second child
            Root_Element.appendChild(Get_Tutorial(document, "2", "Compile a C++ Program Using GCC",
            		"https://www.delftstack.com/howto/cpp/gcc-compile-cpp/",
            		"C++", "March-25, 2022"));
            //add third child
            Root_Element.appendChild(Get_Tutorial(document, "3", "Python Tutorial - Introduction",
            		"https://www.delftstack.com/tutorial/python-3-basic-tutorial/python-introduction/",
            		"Python", "January-29, 2018"));

            //create output
            TransformerFactory Transformer_Factory = TransformerFactory.newInstance();
            Transformer transformer = Transformer_Factory.newTransformer();
            //open indent for the xml code
            transformer.setOutputProperty(OutputKeys.INDENT, "yes");
            DOMSource Dom_Source = new DOMSource(document);

            //write to file and console both
            StreamResult XML_file = new StreamResult(new File("delftstack.xml"));
            StreamResult XML_console = new StreamResult(System.out);
            //write data
            transformer.transform(Dom_Source, XML_file);
            transformer.transform(Dom_Source, XML_console);

            System.out.println("The XML Has been written to the file and console");

        } catch (Exception e) {
            e.printStackTrace();
        }
    }


    private static Node Get_Tutorial(Document document, String id, String article_name, String link, String programming_language, String date_created) {
        Element tutorial = document.createElement("Tutorial");

        //set the tutorial id attribute
        tutorial.setAttribute("Id", id);

        //create article name element
        tutorial.appendChild(Get_Tutorial_Elements(document, tutorial, "ArticleName", article_name));

        //create the Link element
        tutorial.appendChild(Get_Tutorial_Elements(document, tutorial, "Link", link));

        //create the Programming Language element
        tutorial.appendChild(Get_Tutorial_Elements(document, tutorial, "ProgrammingLanguage", programming_language));

        //create Date Created element
        tutorial.appendChild(Get_Tutorial_Elements(document, tutorial, "DateCreated", date_created));

        return tutorial;
    }


    //method to create text node
    private static Node Get_Tutorial_Elements(Document document, Element element, String element_name, String element_value) {
        Element element_node = document.createElement(element_name);
        element_node.appendChild(document.createTextNode(element_value));
        return element_node;
    }

}

上面的代码将为 delftstack.com 的教程创建一个 XML 文件。每个教程包含四个字段，ArticleName、Link、ProgrammingLanguage 和 DateCreated。

该代码将创建 XML 文件并将 XML 写入控制台。查看输出：

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<Tutorials xmlns="https://www.delftstack.com/">
    <Tutorial Id="1">
        <ArticleName>Perform String to String Array Conversion in Java</ArticleName>
        <Link>https://www.delftstack.com/howto/java/how-to-perform-string-to-string-array-conversion-in-java/</Link>
        <ProgrammingLanguage>Java</ProgrammingLanguage>
        <DateCreated>May-21, 2020</DateCreated>
    </Tutorial>
    <Tutorial Id="2">
        <ArticleName>Compile a C++ Program Using GCC</ArticleName>
        <Link>https://www.delftstack.com/howto/cpp/gcc-compile-cpp/</Link>
        <ProgrammingLanguage>C++</ProgrammingLanguage>
        <DateCreated>March-25, 2022</DateCreated>
    </Tutorial>
    <Tutorial Id="3">
        <ArticleName>Python Tutorial - Introduction</ArticleName>
        <Link>https://www.delftstack.com/tutorial/python-3-basic-tutorial/python-introduction/</Link>
        <ProgrammingLanguage>Python</ProgrammingLanguage>
        <DateCreated>January-29, 2018</DateCreated>
    </Tutorial>
</Tutorials>
The XML Has been written to the file and console