Pretty print XML in java 8

dom pretty-print java xml

2022-09-01 09:25:43

我有一个XML文件存储为DOM文档，我想把它打印到控制台上，最好不要使用外部库。我知道这个问题在这个网站上被问过很多次，但是以前的答案都不适合我。我使用的是java 8，所以也许这是我的代码与之前的问题不同的地方？我还尝试使用从Web上找到的代码手动设置转换器，但是这只会导致错误。not found

这是我的代码，它目前只在控制台左侧的新行上输出每个xml元素。

import java.io.*;
import javax.xml.parsers.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;


public class Test {
    public Test(){
        try {
            //java.lang.System.setProperty("javax.xml.transform.TransformerFactory", "org.apache.xalan.xsltc.trax.TransformerFactoryImpl");

            DocumentBuilderFactory dbFactory;
            DocumentBuilder dBuilder;
            Document original = null;
            try {
                dbFactory = DocumentBuilderFactory.newInstance();
                dBuilder = dbFactory.newDocumentBuilder();
                original = dBuilder.parse(new InputSource(new InputStreamReader(new FileInputStream("xml Store - Copy.xml"))));
            } catch (SAXException | IOException | ParserConfigurationException e) {
                e.printStackTrace();
            }
            StringWriter stringWriter = new StringWriter();
            StreamResult xmlOutput = new StreamResult(stringWriter);
            TransformerFactory tf = TransformerFactory.newInstance();
            //tf.setAttribute("indent-number", 2);
            Transformer transformer = tf.newTransformer();
            transformer.setOutputProperty(OutputKeys.METHOD, "xml");
            transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");
            transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "no");
            transformer.setOutputProperty(OutputKeys.INDENT, "yes");
            transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
            transformer.transform(new DOMSource(original), xmlOutput);
            java.lang.System.out.println(xmlOutput.getWriter().toString());
        } catch (Exception ex) {
            throw new RuntimeException("Error converting to String", ex);
        }
    }

    public static void main(String[] args){
        new Test();
    }

}

答案 1

在回复Espinosa的评论时，这是一个解决方案，当“原始xml尚未（部分）缩进或包含新行”时。

背景

本文摘录（请参阅下面的参考资料）启发了此解决方案：

根据 DOM 规范，标记外部的空格是完全有效的，并且它们被正确保留。要删除它们，我们可以使用 XPath 的规范化空间来查找所有空白节点并首先删除它们。

Java Code

public static String toPrettyString(String xml, int indent) {
    try {
        // Turn xml string into a document
        Document document = DocumentBuilderFactory.newInstance()
                .newDocumentBuilder()
                .parse(new InputSource(new ByteArrayInputStream(xml.getBytes("utf-8"))));

        // Remove whitespaces outside tags
        document.normalize();
        XPath xPath = XPathFactory.newInstance().newXPath();
        NodeList nodeList = (NodeList) xPath.evaluate("//text()[normalize-space()='']",
                                                      document,
                                                      XPathConstants.NODESET);

        for (int i = 0; i < nodeList.getLength(); ++i) {
            Node node = nodeList.item(i);
            node.getParentNode().removeChild(node);
        }

        // Setup pretty print options
        TransformerFactory transformerFactory = TransformerFactory.newInstance();
        transformerFactory.setAttribute("indent-number", indent);
        Transformer transformer = transformerFactory.newTransformer();
        transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
        transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
        transformer.setOutputProperty(OutputKeys.INDENT, "yes");

        // Return pretty print xml string
        StringWriter stringWriter = new StringWriter();
        transformer.transform(new DOMSource(document), new StreamResult(stringWriter));
        return stringWriter.toString();
    } catch (Exception e) {
        throw new RuntimeException(e);
    }
}

示例用法

String xml = "<root>" + //
             "\n   "  + //
             "\n<name>Coco Puff</name>" + //
             "\n        <total>10</total>    </root>";

System.out.println(toPrettyString(xml, 4));

输出

<root>
    <name>Coco Puff</name>
    <total>10</total>
</root>

引用

Java：正确缩进MyShittyCode上发布的XML字符串
将新的 XML 节点保存到文件

答案 2

我猜问题与原始文件中的空白文本节点（即只有空格的文本节点）有关。您应该尝试在分析后立即使用以下代码以编程方式删除它们。如果您不删除它们，则会保留它们。Transformer

original.getDocumentElement().normalize();
XPathExpression xpath = XPathFactory.newInstance().newXPath().compile("//text()[normalize-space(.) = '']");
NodeList blankTextNodes = (NodeList) xpath.evaluate(original, XPathConstants.NODESET);

for (int i = 0; i < blankTextNodes.getLength(); i++) {
     blankTextNodes.item(i).getParentNode().removeChild(blankTextNodes.item(i));
}