我有一个包含 XML 的 Java 字符串，没有换行符或缩进。我想把它变成一个格式很好的 XML 的字符串。我该怎么做呢？
String unformattedXml = "<tag><nested>hello</nested></tag>";
String formattedXml = new [UnknownClass]().format(unformattedXml);
注意：我的输入是String。我的输出是一个String。
（基本）模拟结果：
<?xml version="1.0" encoding="UTF-8"?>
<root>
<tag>
<nested>hello</nested>
</tag>
</root>
Transformer transformer = TransformerFactory.newInstance().newTransformer();
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
// initialize StreamResult with File object to save to file
StreamResult result = new StreamResult(new StringWriter());
DOMSource source = new DOMSource(doc);
transformer.transform(source, result);
String xmlString = result.getWriter().toString();
System.out.println(xmlString);
注意：结果可能因 Java 版本而异。搜索特定于您的平台的解决方法。
这是我自己的问题的答案。我结合了各种结果的答案，编写了一个漂亮地打印 XML 的类。
不保证它如何响应无效的 XML 或大型文档。
package ecb.sdw.pretty;
import org.apache.xml.serialize.OutputFormat;
import org.apache.xml.serialize.XMLSerializer;
import org.w3c.dom.Document;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.Writer;
/**
* Pretty-prints xml, supplied as a string.
* <p/>
* eg.
* <code>
* String formattedXml = new XmlFormatter().format("<tag><nested>hello</nested></tag>");
* </code>
*/
public class XmlFormatter {
public XmlFormatter() {
}
public String format(String unformattedXml) {
try {
final Document document = parseXmlFile(unformattedXml);
OutputFormat format = new OutputFormat(document);
format.setLineWidth(65);
format.setIndenting(true);
format.setIndent(2);
Writer out = new StringWriter();
XMLSerializer serializer = new XMLSerializer(out, format);
serializer.serialize(document);
return out.toString();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
private Document parseXmlFile(String in) {
try {
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
InputSource is = new InputSource(new StringReader(in));
return db.parse(is);
} catch (ParserConfigurationException e) {
throw new RuntimeException(e);
} catch (SAXException e) {
throw new RuntimeException(e);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
public static void main(String[] args) {
String unformattedXml =
"<?xml version=\"1.0\" encoding=\"UTF-8\"?><QueryMessage\n" +
" xmlns=\"http://www.SDMX.org/resources/SDMXML/schemas/v2_0/message\"\n" +
" xmlns:query=\"http://www.SDMX.org/resources/SDMXML/schemas/v2_0/query\">\n" +
" <Query>\n" +
" <query:CategorySchemeWhere>\n" +
" \t\t\t\t\t <query:AgencyID>ECB\n\n\n\n</query:AgencyID>\n" +
" </query:CategorySchemeWhere>\n" +
" </Query>\n\n\n\n\n" +
"</QueryMessage>";
System.out.println(new XmlFormatter().format(unformattedXml));
}
}
public static String prettyFormat(String input, int indent) {
try {
Source xmlInput = new StreamSource(new StringReader(input));
StringWriter stringWriter = new StringWriter();
StreamResult xmlOutput = new StreamResult(stringWriter);
TransformerFactory transformerFactory = TransformerFactory.newInstance();
transformerFactory.setAttribute("indent-number", indent);
transformerFactory.setAttribute(XMLConstants.ACCESS_EXTERNAL_DTD, "");
transformerFactory.setAttribute(XMLConstants.ACCESS_EXTERNAL_STYLESHEET, "");
Transformer transformer = transformerFactory.newTransformer();
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.transform(xmlInput, xmlOutput);
return xmlOutput.getWriter().toString();
} catch (Exception e) {
throw new RuntimeException(e); // simple exception handling, please review it
}
}
public static String prettyFormat(String input) {
return prettyFormat(input, 2);
}
测试用例：
prettyFormat("<root><child>aaa</child><child/></root>");
返回：
<?xml version="1.0" encoding="UTF-8"?>
<root>
<child>aaa</child>
<child/>
</root>
//忽略：原始编辑只需要在代码中的类名中缺少s。添加了多余的六个字符以在 SO 上获得超过 6 个字符的验证
现在是 2012 年，Java 可以比以前使用 XML 做更多的事情，我想为我接受的答案添加一个替代方案。这在 Java 6 之外没有依赖关系。
import org.w3c.dom.Node;
import org.w3c.dom.bootstrap.DOMImplementationRegistry;
import org.w3c.dom.ls.DOMImplementationLS;
import org.w3c.dom.ls.LSSerializer;
import org.xml.sax.InputSource;
import javax.xml.parsers.DocumentBuilderFactory;
import java.io.StringReader;
/**
* Pretty-prints xml, supplied as a string.
* <p/>
* eg.
* <code>
* String formattedXml = new XmlFormatter().format("<tag><nested>hello</nested></tag>");
* </code>
*/
public class XmlFormatter {
public String format(String xml) {
try {
final InputSource src = new InputSource(new StringReader(xml));
final Node document = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(src).getDocumentElement();
final Boolean keepDeclaration = Boolean.valueOf(xml.startsWith("<?xml"));
//May need this: System.setProperty(DOMImplementationRegistry.PROPERTY,"com.sun.org.apache.xerces.internal.dom.DOMImplementationSourceImpl");
final DOMImplementationRegistry registry = DOMImplementationRegistry.newInstance();
final DOMImplementationLS impl = (DOMImplementationLS) registry.getDOMImplementation("LS");
final LSSerializer writer = impl.createLSSerializer();
writer.getDomConfig().setParameter("format-pretty-print", Boolean.TRUE); // Set this to true if the output needs to be beautified.
writer.getDomConfig().setParameter("xml-declaration", keepDeclaration); // Set this to true if the declaration is needed to be outputted.
return writer.writeToString(document);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
public static void main(String[] args) {
String unformattedXml =
"<?xml version=\"1.0\" encoding=\"UTF-8\"?><QueryMessage\n" +
" xmlns=\"http://www.SDMX.org/resources/SDMXML/schemas/v2_0/message\"\n" +
" xmlns:query=\"http://www.SDMX.org/resources/SDMXML/schemas/v2_0/query\">\n" +
" <Query>\n" +
" <query:CategorySchemeWhere>\n" +
" \t\t\t\t\t <query:AgencyID>ECB\n\n\n\n</query:AgencyID>\n" +
" </query:CategorySchemeWhere>\n" +
" </Query>\n\n\n\n\n" +
"</QueryMessage>";
System.out.println(new XmlFormatter().format(unformattedXml));
}
}
请注意，评分最高的答案需要使用 xerces。
如果您不想添加此外部依赖项，则可以简单地使用标准 jdk 库（实际上是在内部使用 xerces 构建的）。
注意 jdk 1.5 版有一个错误，请参阅http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6296446但现在已解决。
（注意如果发生错误，这将返回原始文本）
package com.test;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.sax.SAXSource;
import javax.xml.transform.sax.SAXTransformerFactory;
import javax.xml.transform.stream.StreamResult;
import org.xml.sax.InputSource;
public class XmlTest {
public static void main(String[] args) {
XmlTest t = new XmlTest();
System.out.println(t.formatXml("<a><b><c/><d>text D</d><e value='0'/></b></a>"));
}
public String formatXml(String xml){
try{
Transformer serializer= SAXTransformerFactory.newInstance().newTransformer();
serializer.setOutputProperty(OutputKeys.INDENT, "yes");
//serializer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
serializer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
//serializer.setOutputProperty("{http://xml.customer.org/xslt}indent-amount", "2");
Source xmlSource=new SAXSource(new InputSource(new ByteArrayInputStream(xml.getBytes())));
StreamResult res = new StreamResult(new ByteArrayOutputStream());
serializer.transform(xmlSource, res);
return new String(((ByteArrayOutputStream)res.getOutputStream()).toByteArray());
}catch(Exception e){
//TODO log error
return xml;
}
}
}
我过去使用org.dom4j.io.OutputFormat.createPrettyPrint()方法打印得很漂亮
public String prettyPrint(final String xml){
if (StringUtils.isBlank(xml)) {
throw new RuntimeException("xml was null or blank in prettyPrint()");
}
final StringWriter sw;
try {
final OutputFormat format = OutputFormat.createPrettyPrint();
final org.dom4j.Document document = DocumentHelper.parseText(xml);
sw = new StringWriter();
final XMLWriter writer = new XMLWriter(sw, format);
writer.write(document);
}
catch (Exception e) {
throw new RuntimeException("Error pretty printing xml:\n" + xml, e);
}
return sw.toString();
}
这是使用dom4j的一种方法：
进口：
import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
代码：
String xml = "<your xml='here'/>";
Document doc = DocumentHelper.parseText(xml);
StringWriter sw = new StringWriter();
OutputFormat format = OutputFormat.createPrettyPrint();
XMLWriter xw = new XMLWriter(sw, format);
xw.write(doc);
String result = sw.toString();
由于String您是DOM从. 但是，如果您知道您的 XML 字符串是有效的，并且您不想产生将字符串解析为 DOM 的内存开销，那么在 DOM 上运行转换以获取字符串 - 您可以做一些老式的逐个字符解析。在每个字符后插入一个换行符和空格，保留并缩进计数器（以确定空格数），为每个字符递增，为每个看到的字符递减。NodeTransformer</...><...></...>
免责声明 - 我对以下函数进行了剪切/粘贴/文本编辑，因此它们可能无法按原样编译。
public static final Element createDOM(String strXML)
throws ParserConfigurationException, SAXException, IOException {
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
dbf.setValidating(true);
DocumentBuilder db = dbf.newDocumentBuilder();
InputSource sourceXML = new InputSource(new StringReader(strXML));
Document xmlDoc = db.parse(sourceXML);
Element e = xmlDoc.getDocumentElement();
e.normalize();
return e;
}
public static final void prettyPrint(Node xml, OutputStream out)
throws TransformerConfigurationException, TransformerFactoryConfigurationError, TransformerException {
Transformer tf = TransformerFactory.newInstance().newTransformer();
tf.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
tf.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
tf.setOutputProperty(OutputKeys.INDENT, "yes");
tf.transform(new DOMSource(xml), new StreamResult(out));
}
Kevin Hakanson 说：“但是，如果您知道您的 XML 字符串是有效的，并且您不想招致将字符串解析为 DOM 的内存开销，然后在 DOM 上运行转换以获取字符串 - 您可以只需逐个字符解析一些老式字符。在每个字符后插入换行符和空格，保留并缩进计数器（以确定空格数），为每个 <...> 增加并为每个看到的减少。
同意。这种方法要快得多，并且依赖性要少得多。
示例解决方案：
/**
* XML utils, including formatting.
*/
public class XmlUtils
{
private static XmlFormatter formatter = new XmlFormatter(2, 80);
public static String formatXml(String s)
{
return formatter.format(s, 0);
}
public static String formatXml(String s, int initialIndent)
{
return formatter.format(s, initialIndent);
}
private static class XmlFormatter
{
private int indentNumChars;
private int lineLength;
private boolean singleLine;
public XmlFormatter(int indentNumChars, int lineLength)
{
this.indentNumChars = indentNumChars;
this.lineLength = lineLength;
}
public synchronized String format(String s, int initialIndent)
{
int indent = initialIndent;
StringBuilder sb = new StringBuilder();
for (int i = 0; i < s.length(); i++)
{
char currentChar = s.charAt(i);
if (currentChar == '<')
{
char nextChar = s.charAt(i + 1);
if (nextChar == '/')
indent -= indentNumChars;
if (!singleLine) // Don't indent before closing element if we're creating opening and closing elements on a single line.
sb.append(buildWhitespace(indent));
if (nextChar != '?' && nextChar != '!' && nextChar != '/')
indent += indentNumChars;
singleLine = false; // Reset flag.
}
sb.append(currentChar);
if (currentChar == '>')
{
if (s.charAt(i - 1) == '/')
{
indent -= indentNumChars;
sb.append("\n");
}
else
{
int nextStartElementPos = s.indexOf('<', i);
if (nextStartElementPos > i + 1)
{
String textBetweenElements = s.substring(i + 1, nextStartElementPos);
// If the space between elements is solely newlines, let them through to preserve additional newlines in source document.
if (textBetweenElements.replaceAll("\n", "").length() == 0)
{
sb.append(textBetweenElements + "\n");
}
// Put tags and text on a single line if the text is short.
else if (textBetweenElements.length() <= lineLength * 0.5)
{
sb.append(textBetweenElements);
singleLine = true;
}
// For larger amounts of text, wrap lines to a maximum line length.
else
{
sb.append("\n" + lineWrap(textBetweenElements, lineLength, indent, null) + "\n");
}
i = nextStartElementPos - 1;
}
else
{
sb.append("\n");
}
}
}
}
return sb.toString();
}
}
private static String buildWhitespace(int numChars)
{
StringBuilder sb = new StringBuilder();
for (int i = 0; i < numChars; i++)
sb.append(" ");
return sb.toString();
}
/**
* Wraps the supplied text to the specified line length.
* @lineLength the maximum length of each line in the returned string (not including indent if specified).
* @indent optional number of whitespace characters to prepend to each line before the text.
* @linePrefix optional string to append to the indent (before the text).
* @returns the supplied text wrapped so that no line exceeds the specified line length + indent, optionally with
* indent and prefix applied to each line.
*/
private static String lineWrap(String s, int lineLength, Integer indent, String linePrefix)
{
if (s == null)
return null;
StringBuilder sb = new StringBuilder();
int lineStartPos = 0;
int lineEndPos;
boolean firstLine = true;
while(lineStartPos < s.length())
{
if (!firstLine)
sb.append("\n");
else
firstLine = false;
if (lineStartPos + lineLength > s.length())
lineEndPos = s.length() - 1;
else
{
lineEndPos = lineStartPos + lineLength - 1;
while (lineEndPos > lineStartPos && (s.charAt(lineEndPos) != ' ' && s.charAt(lineEndPos) != '\t'))
lineEndPos--;
}
sb.append(buildWhitespace(indent));
if (linePrefix != null)
sb.append(linePrefix);
sb.append(s.substring(lineStartPos, lineEndPos + 1));
lineStartPos = lineEndPos + 1;
}
return sb.toString();
}
// other utils removed for brevity
}
如果可以使用 3rd 方 XML 库，那么您可以使用比当前投票率最高的 答案建议 的要简单得多的东西。
据说输入和输出都应该是字符串，所以这是一个使用XOM库实现的实用方法：
import nu.xom.*;
import java.io.*;
[...]
public static String format(String xml) throws ParsingException, IOException {
ByteArrayOutputStream out = new ByteArrayOutputStream();
Serializer serializer = new Serializer(out);
serializer.setIndent(4); // or whatever you like
serializer.write(new Builder().build(xml, ""));
return out.toString("UTF-8");
}
我测试了它是否有效，结果不取决于您的 JRE 版本或类似的东西。要了解如何根据自己的喜好自定义输出格式，请查看SerializerAPI。
这实际上比我想象的要长 - 需要一些额外的行，因为Serializer想要OutputStream写入。但请注意，这里几乎没有用于实际操作 XML 的代码。
（这个答案是我对 XOM 的评估的一部分，在我关于替换 dom4j 的最佳 Java XML 库的问题中，它被建议作为一个选项。作为记录，使用 dom4j，您可以使用和类似轻松地实现这一点。编辑：.. .如mlo55的回答所示。）XMLWriterOutputFormat
嗯......遇到了这样的事情，这是一个已知的错误......只需添加这个 OutputProperty ..
transformer.setOutputProperty(OutputPropertiesFactory.S_KEY_INDENT_AMOUNT, "8");
希望这可以帮助 ...
关于“您必须首先构建 DOM 树”的评论：不，您不需要也不应该这样做。
相反，创建一个 StreamSource (new StreamSource(new StringReader(str))，并将其提供给提到的身份转换器。这将使用 SAX 解析器，结果会更快。在这种情况下，构建中间树纯粹是开销。否则排名靠前的答案是好的。
使用斯卡拉：
import xml._
val xml = XML.loadString("<tag><nested>hello</nested></tag>")
val formatted = new PrettyPrinter(150, 2).format(xml)
println(formatted)
如果您依赖 scala-library.jar，您也可以在 Java 中执行此操作。它看起来像这样：
import scala.xml.*;
public class FormatXML {
public static void main(String[] args) {
String unformattedXml = "<tag><nested>hello</nested></tag>";
PrettyPrinter pp = new PrettyPrinter(150, 3);
String formatted = pp.format(XML.loadString(unformattedXml), TopScope$.MODULE$);
System.out.println(formatted);
}
}
该PrettyPrinter对象由两个整数构成，第一个是最大行长，第二个是缩进步骤。
来自milosmns的略微改进的版本......
public static String getPrettyXml(String xml) {
if (xml == null || xml.trim().length() == 0) return "";
int stack = 0;
StringBuilder pretty = new StringBuilder();
String[] rows = xml.trim().replaceAll(">", ">\n").replaceAll("<", "\n<").split("\n");
for (int i = 0; i < rows.length; i++) {
if (rows[i] == null || rows[i].trim().length() == 0) continue;
String row = rows[i].trim();
if (row.startsWith("<?")) {
pretty.append(row + "\n");
} else if (row.startsWith("</")) {
String indent = repeatString(--stack);
pretty.append(indent + row + "\n");
} else if (row.startsWith("<") && row.endsWith("/>") == false) {
String indent = repeatString(stack++);
pretty.append(indent + row + "\n");
if (row.endsWith("]]>")) stack--;
} else {
String indent = repeatString(stack);
pretty.append(indent + row + "\n");
}
}
return pretty.toString().trim();
}
private static String repeatString(int stack) {
StringBuilder indent = new StringBuilder();
for (int i = 0; i < stack; i++) {
indent.append(" ");
}
return indent.toString();
}
仅供将来参考，这是一个对我有用的解决方案（感谢@George Hawkins 在其中一个答案中发布的评论）：
DOMImplementationRegistry registry = DOMImplementationRegistry.newInstance();
DOMImplementationLS impl = (DOMImplementationLS) registry.getDOMImplementation("LS");
LSSerializer writer = impl.createLSSerializer();
writer.getDomConfig().setParameter("format-pretty-print", Boolean.TRUE);
LSOutput output = impl.createLSOutput();
ByteArrayOutputStream out = new ByteArrayOutputStream();
output.setByteStream(out);
writer.write(document, output);
String xmlStr = new String(out.toByteArray());
以上所有解决方案都对我不起作用，然后我发现了这个http://myshittycode.com/2014/02/10/java-properly-indenting-xml-string/
线索是使用 XPath 删除空格
String xml = "<root>" +
"\n " +
"\n<name>Coco Puff</name>" +
"\n <total>10</total> </root>";
try {
Document document = DocumentBuilderFactory.newInstance()
.newDocumentBuilder()
.parse(new InputSource(new ByteArrayInputStream(xml.getBytes("utf-8"))));
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);
}
Transformer transformer = TransformerFactory.newInstance().newTransformer();
transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");
StringWriter stringWriter = new StringWriter();
StreamResult streamResult = new StreamResult(stringWriter);
transformer.transform(new DOMSource(document), streamResult);
System.out.println(stringWriter.toString());
}
catch (Exception e) {
e.printStackTrace();
}
下面的代码完美运行
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;
String formattedXml1 = prettyFormat("<root><child>aaa</child><child/></root>");
public static String prettyFormat(String input) {
return prettyFormat(input, "2");
}
public static String prettyFormat(String input, String indent) {
Source xmlInput = new StreamSource(new StringReader(input));
StringWriter stringWriter = new StringWriter();
try {
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", indent);
transformer.transform(xmlInput, new StreamResult(stringWriter));
String pretty = stringWriter.toString();
pretty = pretty.replace("\r\n", "\n");
return pretty;
} catch (Exception e) {
throw new RuntimeException(e);
}
}
我混合所有这些并编写一个小程序。它正在从 xml 文件中读取并打印出来。只是代替 xzy 给你的文件路径。
public static void main(String[] args) throws Exception {
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
dbf.setValidating(false);
DocumentBuilder db = dbf.newDocumentBuilder();
Document doc = db.parse(new FileInputStream(new File("C:/Users/xyz.xml")));
prettyPrint(doc);
}
private static String prettyPrint(Document document)
throws TransformerException {
TransformerFactory transformerFactory = TransformerFactory
.newInstance();
Transformer transformer = transformerFactory.newTransformer();
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "no");
DOMSource source = new DOMSource(document);
StringWriter strWriter = new StringWriter();
StreamResult result = new StreamResult(strWriter);transformer.transform(source, result);
System.out.println(strWriter.getBuffer().toString());
return strWriter.getBuffer().toString();
}
如果您确定您有一个有效的 XML，那么这个很简单，并且避免了 XML DOM 树。也许有一些错误，如果您看到任何内容，请发表评论
public String prettyPrint(String xml) {
if (xml == null || xml.trim().length() == 0) return "";
int stack = 0;
StringBuilder pretty = new StringBuilder();
String[] rows = xml.trim().replaceAll(">", ">\n").replaceAll("<", "\n<").split("\n");
for (int i = 0; i < rows.length; i++) {
if (rows[i] == null || rows[i].trim().length() == 0) continue;
String row = rows[i].trim();
if (row.startsWith("<?")) {
// xml version tag
pretty.append(row + "\n");
} else if (row.startsWith("</")) {
// closing tag
String indent = repeatString(" ", --stack);
pretty.append(indent + row + "\n");
} else if (row.startsWith("<")) {
// starting tag
String indent = repeatString(" ", stack++);
pretty.append(indent + row + "\n");
} else {
// tag data
String indent = repeatString(" ", stack);
pretty.append(indent + row + "\n");
}
}
return pretty.toString().trim();
}
对我们有用的另一种解决方案
import java.io.StringWriter;
import org.dom4j.DocumentHelper;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
**
* Pretty Print XML String
*
* @param inputXmlString
* @return
*/
public static String prettyPrintXml(String xml) {
final StringWriter sw;
try {
final OutputFormat format = OutputFormat.createPrettyPrint();
final org.dom4j.Document document = DocumentHelper.parseText(xml);
sw = new StringWriter();
final XMLWriter writer = new XMLWriter(sw, format);
writer.write(document);
}
catch (Exception e) {
throw new RuntimeException("Error pretty printing xml:\n" + xml, e);
}
return sw.toString();
}
使用 jdom2： http: //www.jdom.org/
import java.io.StringReader;
import org.jdom2.input.SAXBuilder;
import org.jdom2.output.Format;
import org.jdom2.output.XMLOutputter;
String prettyXml = new XMLOutputter(Format.getPrettyFormat()).
outputString(new SAXBuilder().build(new StringReader(uglyXml)));
作为max、codeskraps、David Easley和milosmns答案的替代方案，请查看我的轻量级、高性能漂亮打印机库：xml-formatter
// construct lightweight, threadsafe, instance
PrettyPrinter prettyPrinter = PrettyPrinterBuilder.newPrettyPrinter().build();
StringBuilder buffer = new StringBuilder();
String xml = ..; // also works with char[] or Reader
if(prettyPrinter.process(xml, buffer)) {
// valid XML, print buffer
} else {
// invalid XML, print xml
}
有时，就像直接从文件运行模拟的 SOAP 服务时，最好有一个漂亮的打印机，它也可以处理已经漂亮打印的 XML：
PrettyPrinter prettyPrinter = PrettyPrinterBuilder.newPrettyPrinter().ignoreWhitespace().build();
正如一些人评论的那样，漂亮的打印只是以更易于阅读的形式呈现 XML 的一种方式 - 空格严格不属于您的 XML 数据。
该库旨在用于日志记录的漂亮打印，还包括用于过滤（子树删除/匿名化）和在 CDATA 和文本节点中漂亮打印 XML 的功能。
我有同样的问题，我在 JTidy 上取得了巨大的成功（http://jtidy.sourceforge.net/index.html）
例子：
Tidy t = new Tidy();
t.setIndentContent(true);
Document d = t.parseDOM(
new ByteArrayInputStream("HTML goes here", null);
OutputStream out = new ByteArrayOutputStream();
t.pprint(d, out);
String html = out.toString();
对于那些寻找快速而肮脏的解决方案的人 - 不需要 XML 100% 有效。例如，在 REST / SOAP 日志记录的情况下（你永远不知道其他人发送了什么;-)）
我发现并改进了我在网上找到的代码片段，我认为这里仍然缺少它作为一种有效的可能方法：
public static String prettyPrintXMLAsString(String xmlString) {
/* Remove new lines */
final String LINE_BREAK = "\n";
xmlString = xmlString.replaceAll(LINE_BREAK, "");
StringBuffer prettyPrintXml = new StringBuffer();
/* Group the xml tags */
Pattern pattern = Pattern.compile("(<[^/][^>]+>)?([^<]*)(</[^>]+>)?(<[^/][^>]+/>)?");
Matcher matcher = pattern.matcher(xmlString);
int tabCount = 0;
while (matcher.find()) {
String str1 = (null == matcher.group(1) || "null".equals(matcher.group())) ? "" : matcher.group(1);
String str2 = (null == matcher.group(2) || "null".equals(matcher.group())) ? "" : matcher.group(2);
String str3 = (null == matcher.group(3) || "null".equals(matcher.group())) ? "" : matcher.group(3);
String str4 = (null == matcher.group(4) || "null".equals(matcher.group())) ? "" : matcher.group(4);
if (matcher.group() != null && !matcher.group().trim().equals("")) {
printTabs(tabCount, prettyPrintXml);
if (!str1.equals("") && str3.equals("")) {
++tabCount;
}
if (str1.equals("") && !str3.equals("")) {
--tabCount;
prettyPrintXml.deleteCharAt(prettyPrintXml.length() - 1);
}
prettyPrintXml.append(str1);
prettyPrintXml.append(str2);
prettyPrintXml.append(str3);
if (!str4.equals("")) {
prettyPrintXml.append(LINE_BREAK);
printTabs(tabCount, prettyPrintXml);
prettyPrintXml.append(str4);
}
prettyPrintXml.append(LINE_BREAK);
}
}
return prettyPrintXml.toString();
}
private static void printTabs(int count, StringBuffer stringBuffer) {
for (int i = 0; i < count; i++) {
stringBuffer.append("\t");
}
}
public static void main(String[] args) {
String x = new String(
"<soap:Envelope xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\"><soap:Body><soap:Fault><faultcode>soap:Client</faultcode><faultstring>INVALID_MESSAGE</faultstring><detail><ns3:XcbSoapFault xmlns=\"\" xmlns:ns3=\"http://www.someapp.eu/xcb/types/xcb/v1\"><CauseCode>20007</CauseCode><CauseText>INVALID_MESSAGE</CauseText><DebugInfo>Problems creating SAAJ object model</DebugInfo></ns3:XcbSoapFault></detail></soap:Fault></soap:Body></soap:Envelope>");
System.out.println(prettyPrintXMLAsString(x));
}
这是输出：
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body>
<soap:Fault>
<faultcode>soap:Client</faultcode>
<faultstring>INVALID_MESSAGE</faultstring>
<detail>
<ns3:XcbSoapFault xmlns="" xmlns:ns3="http://www.someapp.eu/xcb/types/xcb/v1">
<CauseCode>20007</CauseCode>
<CauseText>INVALID_MESSAGE</CauseText>
<DebugInfo>Problems creating SAAJ object model</DebugInfo>
</ns3:XcbSoapFault>
</detail>
</soap:Fault>
</soap:Body>
</soap:Envelope>
我总是使用以下功能：
public static String prettyPrintXml(String xmlStringToBeFormatted) {
String formattedXmlString = null;
try {
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
documentBuilderFactory.setValidating(true);
DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
InputSource inputSource = new InputSource(new StringReader(xmlStringToBeFormatted));
Document document = documentBuilder.parse(inputSource);
Transformer transformer = TransformerFactory.newInstance().newTransformer();
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
StreamResult streamResult = new StreamResult(new StringWriter());
DOMSource dOMSource = new DOMSource(document);
transformer.transform(dOMSource, streamResult);
formattedXmlString = streamResult.getWriter().toString().trim();
} catch (Exception ex) {
StringWriter sw = new StringWriter();
ex.printStackTrace(new PrintWriter(sw));
System.err.println(sw.toString());
}
return formattedXmlString;
}
有一个非常好的命令行 XML 实用程序，称为 xmlstarlet( http://xmlstar.sourceforge.net/ )，它可以做很多人使用的很多事情。
您可以使用 Runtime.exec 以编程方式执行该程序，然后读入格式化的输出文件。它具有比几行 Java 代码所能提供的更多选项和更好的错误报告。
下载 xmlstarlet： http: //sourceforge.net/project/showfiles.php ?group_id=66612&package_id=64589
我发现在 Java 1.6.0_32 中，漂亮打印 XML字符串的常规方法（使用带有 null 或标识 xslt 的 Transformer）的行为不像我想要的那样，如果标签仅由空格分隔，而不是没有分隔文本。我尝试<xsl:strip-space elements="*"/>在我的模板中使用无济于事。我发现的最简单的解决方案是使用 SAXSource 和 XML 过滤器以我想要的方式剥离空间。由于我的解决方案是用于日志记录，因此我还将其扩展为处理不完整的 XML 片段。请注意，如果您使用 DOMSource，正常方法似乎可以正常工作，但由于不完整和内存开销，我不想使用它。
public static class WhitespaceIgnoreFilter extends XMLFilterImpl
{
@Override
public void ignorableWhitespace(char[] arg0,
int arg1,
int arg2) throws SAXException
{
//Ignore it then...
}
@Override
public void characters( char[] ch,
int start,
int length) throws SAXException
{
if (!new String(ch, start, length).trim().equals(""))
super.characters(ch, start, length);
}
}
public static String prettyXML(String logMsg, boolean allowBadlyFormedFragments) throws SAXException, IOException, TransformerException
{
TransformerFactory transFactory = TransformerFactory.newInstance();
transFactory.setAttribute("indent-number", new Integer(2));
Transformer transformer = transFactory.newTransformer();
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");
StringWriter out = new StringWriter();
XMLReader masterParser = SAXHelper.getSAXParser(true);
XMLFilter parser = new WhitespaceIgnoreFilter();
parser.setParent(masterParser);
if(allowBadlyFormedFragments)
{
transformer.setErrorListener(new ErrorListener()
{
@Override
public void warning(TransformerException exception) throws TransformerException
{
}
@Override
public void fatalError(TransformerException exception) throws TransformerException
{
}
@Override
public void error(TransformerException exception) throws TransformerException
{
}
});
}
try
{
transformer.transform(new SAXSource(parser, new InputSource(new StringReader(logMsg))), new StreamResult(out));
}
catch (TransformerException e)
{
if(e.getCause() != null && e.getCause() instanceof SAXParseException)
{
if(!allowBadlyFormedFragments || !"XML document structures must start and end within the same entity.".equals(e.getCause().getMessage()))
{
throw e;
}
}
else
{
throw e;
}
}
out.flush();
return out.toString();
}
如果代码已经格式化，我在这里找到的 Java 1.6+ 解决方案不会重新格式化代码。对我有用的一个（并重新格式化了已经格式化的代码）如下。
import org.apache.xml.security.c14n.CanonicalizationException;
import org.apache.xml.security.c14n.Canonicalizer;
import org.apache.xml.security.c14n.InvalidCanonicalizerException;
import org.w3c.dom.Element;
import org.w3c.dom.bootstrap.DOMImplementationRegistry;
import org.w3c.dom.ls.DOMImplementationLS;
import org.w3c.dom.ls.LSSerializer;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.TransformerException;
import java.io.IOException;
import java.io.StringReader;
public class XmlUtils {
public static String toCanonicalXml(String xml) throws InvalidCanonicalizerException, ParserConfigurationException, SAXException, CanonicalizationException, IOException {
Canonicalizer canon = Canonicalizer.getInstance(Canonicalizer.ALGO_ID_C14N_OMIT_COMMENTS);
byte canonXmlBytes[] = canon.canonicalize(xml.getBytes());
return new String(canonXmlBytes);
}
public static String prettyFormat(String input) throws TransformerException, ParserConfigurationException, IOException, SAXException, InstantiationException, IllegalAccessException, ClassNotFoundException {
InputSource src = new InputSource(new StringReader(input));
Element document = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(src).getDocumentElement();
Boolean keepDeclaration = input.startsWith("<?xml");
DOMImplementationRegistry registry = DOMImplementationRegistry.newInstance();
DOMImplementationLS impl = (DOMImplementationLS) registry.getDOMImplementation("LS");
LSSerializer writer = impl.createLSSerializer();
writer.getDomConfig().setParameter("format-pretty-print", Boolean.TRUE);
writer.getDomConfig().setParameter("xml-declaration", keepDeclaration);
return writer.writeToString(document);
}
}
它是在单元测试中用于全字符串 xml 比较的好工具。
private void assertXMLEqual(String expected, String actual) throws ParserConfigurationException, IOException, SAXException, CanonicalizationException, InvalidCanonicalizerException, TransformerException, IllegalAccessException, ClassNotFoundException, InstantiationException {
String canonicalExpected = prettyFormat(toCanonicalXml(expected));
String canonicalActual = prettyFormat(toCanonicalXml(actual));
assertEquals(canonicalExpected, canonicalActual);
}
我看到一个答案Scala是 ，所以这里是另一个答案，Groovy以防万一有人觉得它有趣。默认缩进为 2 步，XmlNodePrinter构造函数也可以传递另一个值。
def xml = "<tag><nested>hello</nested></tag>"
def stringWriter = new StringWriter()
def node = new XmlParser().parseText(xml);
new XmlNodePrinter(new PrintWriter(stringWriter)).print(node)
println stringWriter.toString()
如果 groovy jar 在类路径中，则使用 Java
String xml = "<tag><nested>hello</nested></tag>";
StringWriter stringWriter = new StringWriter();
Node node = new XmlParser().parseText(xml);
new XmlNodePrinter(new PrintWriter(stringWriter)).print(node);
System.out.println(stringWriter.toString());
如果您不需要缩进那么多，但需要几个换行符，那么简单的正则表达式就足够了......
String leastPrettifiedXml = uglyXml.replaceAll("><", ">\n<");
代码很好，不是因为缺少缩进而导致的结果。
（有关缩进的解决方案，请参阅其他答案。）
Underscore-java有静态方法U.formatXml(string)。活生生的例子
import com.github.underscore.U;
public class MyClass {
public static void main(String args[]) {
String xml = "<tag><nested>hello</nested></tag>";
System.out.println(U.formatXml("<?xml version=\"1.0\" encoding=\"UTF-8\"?><root>" + xml + "</root>"));
}
}
输出：
<?xml version="1.0" encoding="UTF-8"?>
<root>
<tag>
<nested>hello</nested>
</tag>
</root>
试试这个：
try
{
TransformerFactory transFactory = TransformerFactory.newInstance();
Transformer transformer = null;
transformer = transFactory.newTransformer();
StringWriter buffer = new StringWriter();
transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
transformer.transform(new DOMSource(element),
new StreamResult(buffer));
String str = buffer.toString();
System.out.println("XML INSIDE IS #########################################"+str);
return element;
}
catch (TransformerConfigurationException e)
{
e.printStackTrace();
}
catch (TransformerException e)
{
e.printStackTrace();
}
在提出自己的解决方案之前，我应该先查找此页面！无论如何，我的使用 Java 递归来解析 xml 页面。此代码完全独立，不依赖第三方库。另外..它使用递归！
// you call this method passing in the xml text
public static void prettyPrint(String text){
prettyPrint(text, 0);
}
// "index" corresponds to the number of levels of nesting and/or the number of tabs to print before printing the tag
public static void prettyPrint(String xmlText, int index){
boolean foundTagStart = false;
StringBuilder tagChars = new StringBuilder();
String startTag = "";
String endTag = "";
String[] chars = xmlText.split("");
// find the next start tag
for(String ch : chars){
if(ch.equalsIgnoreCase("<")){
tagChars.append(ch);
foundTagStart = true;
} else if(ch.equalsIgnoreCase(">") && foundTagStart){
startTag = tagChars.append(ch).toString();
String tempTag = startTag;
endTag = (tempTag.contains("\"") ? (tempTag.split(" ")[0] + ">") : tempTag).replace("<", "</"); // <startTag attr1=1 attr2=2> => </startTag>
break;
} else if(foundTagStart){
tagChars.append(ch);
}
}
// once start and end tag are calculated, print start tag, then content, then end tag
if(foundTagStart){
int startIndex = xmlText.indexOf(startTag);
int endIndex = xmlText.indexOf(endTag);
// handle if matching tags NOT found
if((startIndex < 0) || (endIndex < 0)){
if(startIndex < 0) {
// no start tag found
return;
} else {
// start tag found, no end tag found (handles single tags aka "<mytag/>" or "<?xml ...>")
printTabs(index);
System.out.println(startTag);
// move on to the next tag
// NOTE: "index" (not index+1) because next tag is on same level as this one
prettyPrint(xmlText.substring(startIndex+startTag.length(), xmlText.length()), index);
return;
}
// handle when matching tags found
} else {
String content = xmlText.substring(startIndex+startTag.length(), endIndex);
boolean isTagContainsTags = content.contains("<"); // content contains tags
printTabs(index);
if(isTagContainsTags){ // ie: <tag1><tag2>stuff</tag2></tag1>
System.out.println(startTag);
prettyPrint(content, index+1); // "index+1" because "content" is nested
printTabs(index);
} else {
System.out.print(startTag); // ie: <tag1>stuff</tag1> or <tag1></tag1>
System.out.print(content);
}
System.out.println(endTag);
int nextIndex = endIndex + endTag.length();
if(xmlText.length() > nextIndex){ // if there are more tags on this level, continue
prettyPrint(xmlText.substring(nextIndex, xmlText.length()), index);
}
}
} else {
System.out.print(xmlText);
}
}
private static void printTabs(int counter){
while(counter-- > 0){
System.out.print("\t");
}
}
我试图实现类似的东西，但没有任何外部依赖。该应用程序已经在使用 DOM 来格式化只是为了记录 XML！
这是我的示例片段
public void formatXML(final String unformattedXML) {
final int length = unformattedXML.length();
final int indentSpace = 3;
final StringBuilder newString = new StringBuilder(length + length / 10);
final char space = ' ';
int i = 0;
int indentCount = 0;
char currentChar = unformattedXML.charAt(i++);
char previousChar = currentChar;
boolean nodeStarted = true;
newString.append(currentChar);
for (; i < length - 1;) {
currentChar = unformattedXML.charAt(i++);
if(((int) currentChar < 33) && !nodeStarted) {
continue;
}
switch (currentChar) {
case '<':
if ('>' == previousChar && '/' != unformattedXML.charAt(i - 1) && '/' != unformattedXML.charAt(i) && '!' != unformattedXML.charAt(i)) {
indentCount++;
}
newString.append(System.lineSeparator());
for (int j = indentCount * indentSpace; j > 0; j--) {
newString.append(space);
}
newString.append(currentChar);
nodeStarted = true;
break;
case '>':
newString.append(currentChar);
nodeStarted = false;
break;
case '/':
if ('<' == previousChar || '>' == unformattedXML.charAt(i)) {
indentCount--;
}
newString.append(currentChar);
break;
default:
newString.append(currentChar);
}
previousChar = currentChar;
}
newString.append(unformattedXML.charAt(length - 1));
System.out.println(newString.toString());
}