使用RDF::Writer类型的对象时，我对rdf:resource出错了吗？
require 'rdf/rdfxml'
output = RDF::Writer.for(:rdfxml).buffer do |writer|
subject = RDF::Node.new
writer << [subject, RDF.type, RDF::FOAF.Person]
writer << [subject, RDF::FOAF.name, "J. Random Hacker"]
writer << [subject, RDF::FOAF.mbox, RDF::URI("mailto:jhacker@example.org")]
writer << [subject, RDF::FOAF.nick, "jhacker"]
end
puts output.dump()
输出如下：
<?xml version='1.0' encoding='utf-8' ?>
<rdf:RDF xmlns:ns0='http://xmlns.com/foaf/0.1/' xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
<ns0:Person>
<ns0:mbox rdf:resource='mailto:jhacker@example.org'>
<ns0:name>J. Random Hacker</ns0:name>
<ns0:nick>jhacker</ns0:nick>
</ns0:Person>
</rdf:RDF>
我是对的，未关闭的标签<ns0:mbox rdf:resource='mailto:jhacker@example.org'>是错的吗？我应该如何关闭这个标签？