How does dom4j generate xmlns attributes?

Recently, a problem was found when using dom4j to generate an XML file. When the xmlns attribute is added to the element, it is not output in the file and then searched online, we can solve the problem by passing parameters when creating element objects.

E. g:

<Beans
Xmlns = "http://www.springframework.org/schema/beans"
Xmlns: xsi = "http://www.w3.org/2001/XMLSchema-instance"
Xmlns: P = "http://www.springframework.org/schema/p"
Xsi: schemalocation = "http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

......

</Beans>

At the beginning (incorrect method ):

Element root = Document. addelement ("beans ");
Root. addattribute ("xmlns", "http://www.springframework.org/schema/beans ");
Root. addattribute ("xmlns: xsi", "http://www.w3.org/2001/XMLSchema-instance ");
Root. addattribute ("xmlns: P", "http://www.springframework.org/schema/p ");
Root. addattriation ("xsi: schemalocation", "http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd ");

Generate an XML file (xmlns is not displayed)

<Beans
Xmlns: xsi = "http://www.w3.org/2001/XMLSchema-instance"
Xmlns: P = "http://www.springframework.org/schema/p"
Xsi: schemalocation = "http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

......

</Beans>

The correct method:

Element root = Document. addelement ("beans ","Http://www.springframework.org/schema/beans");
Root. addattribute ("xmlns: xsi", "http://www.w3.org/2001/XMLSchema-instance ");
Root. addattribute ("xmlns: P", "http://www.springframework.org/schema/p ");
Root. addattriation ("xsi: schemalocation", "http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd ");

Generate an XML file (xmlns may appear)

<Beans
Xmlns = "http://www.springframework.org/schema/beans"
Xmlns: xsi = "http://www.w3.org/2001/XMLSchema-instance"
Xmlns: P = "http://www.springframework.org/schema/p"
Xsi: schemalocation = "http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

......

</Beans>