Java – Convert XML to a properties file
This article shows how to convert an XML file to a properties file.
Table of contents
- 1. Properties – Convert XML file to a properties file
- 2. DOM – Convert XML file to a properties file
- 3. Download Source Code
- 4. References
P.S Tested with Java 11.
1. Properties – Convert XML file to a properties file
The below example uses Properties#loadFromXML() to loads an XML file and converts it to properties values.
1.1 An XML file using the properties.dtd.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
<properties>
<comment>Server config file</comment>
<entry key="http.port">8080</entry>
<entry key="email.support">[email protected]</entry>
<entry key="http.server">localhost</entry>
<entry key="http.port">8080</entry>
</properties>
1.2 We can use Properties#loadFromXML() to loads an XML file into the properties values.
package com.mkyong.xml.tips;
import java.io.*;
import java.util.Properties;
public class ConvertXmlToProperties {
public static void main(String[] args) throws IOException {
Properties props = new Properties();
try (InputStream input =
new FileInputStream("src/main/resources/server.xml")) {
// loads from XML into a properties file
props.loadFromXML(input);
}
try (OutputStream output =
new FileOutputStream("c:\\test\\server.properties")) {
props.store(output, "");
}
}
}
1.3 Output – c:\\test\\server.properties
#
#Sun May 16 16:51:31 SGT 2021
http.port=8080
[email protected]
http.server=localhost
1.4 For Properties#loadFromXML() to work properly, the XML document must have the following DOCTYPE declaration:
<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
Since we declare the DOCTYPE and properties.dtd, the XML document must also follow the following properties.dtd format.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
<properties>
<entry key="key1">value1</entry>
</properties>
If the XML file failed to follow the above format defined in properties.dtd, JDK would throw an error message from loading the XML file.
2. DOM – Convert XML file to a properties file
This example uses a DOM parser to read the XML file and convert the value into a properties file.
2.1 An XML file.
<?xml version="1.0" encoding="utf-8"?>
<company>
<staff id="1001">
<name>mkyong</name>
</staff>
<staff id="1002">
<name>yflow</name>
</staff>
</company>
2.2 DOM parser to read XML and convert it to Properties object.
package com.mkyong.xml.tips;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import java.io.*;
import java.util.Properties;
public class ConvertXmlToPropertiesDom {
public static void main(String[] args)
throws IOException, ParserConfigurationException, SAXException {
Document doc;
Properties prop = new Properties();
try (FileInputStream input =
new FileInputStream("src/main/resources/staff.xml")) {
// convert XML file to Document
doc = parse(input);
}
NodeList list = doc.getElementsByTagName("staff");
for (int temp = 0; temp < list.getLength(); temp++) {
Node node = list.item(temp);
if (node.getNodeType() == Node.ELEMENT_NODE) {
Element element = (Element) node;
// get staff's id
String id = element.getAttribute("id");
// get text
String name = element.getElementsByTagName("name")
.item(0).getTextContent();
// write value to properties
// prop does not guarantee on the order
prop.setProperty("company.staff" + temp + ".id", id);
prop.setProperty("company.staff" + temp + ".name", name);
}
}
// write to console for testing
prop.store(System.out, "");
// write to a properties file
/*try (FileOutputStream output =
new FileOutputStream("c:\\test\\staff.properties")) {
prop.store(output, "");
}*/
}
// get document
private static Document parse(InputStream input)
throws ParserConfigurationException, IOException, SAXException {
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
Document doc = db.parse(input);
return doc;
}
}
Output
#
#Sun May 16 17:43:20 SGT 2021
company.staff0.name=mkyong
company.staff0.id=1001
company.staff1.name=yflow
company.staff1.id=1002
How about SAX, StAX, JDOM, and JAXB?
The above DOM parser idea works for all the other XML parsers such as SAX, StAX, JDOM, or JAXB. We use an XML parser to read the XML values and store them in a Properties object.
3. Download Source Code
$ git clone https://github.com/mkyong/core-java
$ cd java-xml
$ cd src/main/java/com/mkyong/xml/tips/
4. References
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