dom4j中修改XML第一行 ＜?xml version = ....?＞

在dom4j中，XML声明没有表示为单独的元素。相反，它是XML文档格式选项的一部分。要修改XML声明，您需要使用OutputFormat类。

（In dom4j, the XML declaration is not represented as a separate element. Instead, it is part of the XML document's formatting options. To modify the XML declaration, you need to use the OutputFormat class.Here's an example of how you can modify the XML declaration using dom4j）

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

public class Dom4jModifyXMLDeclarationExample {

    public static void main(String[] args) {
        String filePath = "path/to/your/xml/file.xml";

        try {
            // Load the XML document
            Document document = DocumentHelper.parse(new File(filePath));

            // Modify the XML declaration text
            String newDeclarationText = "<?xml version=\"1.1\" encoding=\"UTF-8\"?>";

            // Create a new OutputFormat with the modified XML declaration
            OutputFormat format = OutputFormat.createPrettyPrint();
            format.setNewLineAfterDeclaration(false); // Prevent adding a new line after the declaration
            format.setSuppressDeclaration(true); // Suppress the default XML declaration
            format.setEncoding("UTF-8"); // Set the desired encoding

            // Serialize the modified document back to XML
            XMLWriter writer = new XMLWriter(new FileWriter(filePath), format);
            writer.write(document);
            writer.close();

            System.out.println("XML declaration modified successfully.");

        } catch (DocumentException | IOException e) {
            e.printStackTrace();
        }
    }
}

当然，还有更好的方法，比如自己写一个WriteXML类，这样生成的XML调整encoding样式会更方便

public static void WriteXML(File file,Document document){
    //切记，OutputFormat是来自dom4j.io包的，而非apach的
    OutputFormat format = OutputFormat.createPrettyPrint();
    format.setNewLineAfterDeclaration(false);
    format.setEncoding("UTF-8");   // 更改编码样式

    XMLWriter writer = new XMLWriter(new FileOutputStream(file),format);
    writer.setEscapeText(false);
    writer.write(document);
    writer.close();

}