java 8中的漂亮打印XML

Question

我有一个XML文件存储为DOM文档,我想将它打印到控制台,最好不使用外部库.我知道这个问题已在本网站上被多次询问,但以前的答案都没有对我有用.我正在使用java 8,所以也许这是我的代码与以前的问题不同的地方？我还尝试使用从网络上找到的代码手动设置变换器,但这只是导致not found错误.

这是我的代码,它当前只是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();
    }

}

Answer 1

在回复Espinosa的评论时,这里是" 原始xml尚未(部分)缩进或包含新行 "的解决方案.

背景

启发此解决方案的文章摘录(参见下面的参考资料):

根据DOM规范,标记之外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的规范化空间来定位所有空白节点并首先删除它们.

Java代码

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);
    }
}

样品用法

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

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

产量

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

参考

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

Answer 2

我猜这个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.您应该尝试使用以下代码在解析后立即以编程方式删除它们.如果你不删除它们,Transformer它将保留它们.

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));
}

Answer 3

这适用于 Java 8：

public static void main (String[] args) throws Exception {
    String xmlString = "<hello><from>ME</from></hello>";
    DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
    DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
    Document document = documentBuilder.parse(new InputSource(new StringReader(xmlString)));
    pretty(document, System.out, 2);
}

private static void pretty(Document document, OutputStream outputStream, int indent) throws Exception {
    TransformerFactory transformerFactory = TransformerFactory.newInstance();
    Transformer transformer = transformerFactory.newTransformer();
    transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
    if (indent > 0) {
        transformer.setOutputProperty(OutputKeys.INDENT, "yes");
        transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", Integer.toString(indent));
    }
    Result result = new StreamResult(outputStream);
    Source source = new DOMSource(document);
    transformer.transform(source, result);
}