Java 将字符串转换为 XML 文档以及将 XML 文档转换为字符串

有时在使用 Java 编程时，我们得到的String实际上是 XML，为了处理它，我们需要将其转换为 XML 文档 ( org.w3c.dom.Document)。此外，出于调试目的或发送给其他函数，我们可能需要将 Document 对象转换为字符串。这里我提供了两个实用函数。

1. Document convertStringToDocument(String xmlStr)：此方法将以字符串形式输入，然后将其转换为 DOM 文档并返回。我们将使用 InputSource 和 StringReader 进行此转换。
2. String convertDocumentToString(Document doc)：此方法将以 Document 作为输入并将其转换为字符串。我们将为此使用Transformer和。StringWriterStreamResult

package com.journaldev.xml;

import java.io.StringReader;
import java.io.StringWriter;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

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

public class StringToDocumentToString {

    public static void main(String[] args) {
        final String xmlStr = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>\n"+
                                "<Emp id=\"1\"><name>Pankaj</name><age>25</age>\n"+
                                "<role>Developer</role><gen>Male</gen></Emp>";
        Document doc = convertStringToDocument(xmlStr);

        String str = convertDocumentToString(doc);
        System.out.println(str);
    }

    private static String convertDocumentToString(Document doc) {
        TransformerFactory tf = TransformerFactory.newInstance();
        Transformer transformer;
        try {
            transformer = tf.newTransformer();
            // below code to remove XML declaration
            // transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
            StringWriter writer = new StringWriter();
            transformer.transform(new DOMSource(doc), new StreamResult(writer));
            String output = writer.getBuffer().toString();
            return output;
        } catch (TransformerException e) {
            e.printStackTrace();
        }

        return null;
    }

    private static Document convertStringToDocument(String xmlStr) {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder;
        try
        {
            builder = factory.newDocumentBuilder();
            Document doc = builder.parse( new InputSource( new StringReader( xmlStr ) ) );
            return doc;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

}

当我们运行上述程序时，我们得到与创建 DOM 文档相同的字符串输出。

<?xml version="1.0" encoding="UTF-8"?><Emp id="1"><name>Pankaj</name><age>25</age>
<role>Developer</role><gen>Male</gen></Emp>

您可以使用replaceAll("\n|\r", "")从字符串中删除换行符并以紧凑格式获取它。