在编写xml文档时删除自闭合标记中的空格

import xml.etree.ElementTree as ET

xml_string = '''<root>
   <element1/>
   <element2>
       <element3/>
    </element2>
</root>'''

root = ET.fromstring(xml_string)

for elem in root.iter():
    elem.text = None
    elem.tail = None

ET.dump(root)

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Root {
    private Element1 element1;
    private Element2 element2;

    // getters and setters
}

public class Element1 {
}

public class Element2 {
    private Element3 element3;

    // getters and setters
}

public class Element3 {
}

public class Main {
    public static void main(String[] args) {
        Root root = new Root();
        root.setElement1(new Element1());
        root.setElement2(new Element2());
        root.getElement2().setElement3(new Element3());

        try {
            JAXBContext jaxbContext = JAXBContext.newInstance(Root.class);
            Marshaller marshaller = jaxbContext.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
            marshaller.marshal(root, System.out);
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }
}

xmllint --format input.xml > output.xml