[英]How do I save a record in Apache Jena?
I want to create a person with nick name jd
and e-mail john.doe@provider.com
in a persistent Apache Jena database. 我想在一个持久的Apache Jena数据库中创建一个昵称
jd
的人,并发送电子邮件john.doe@provider.com
。
I wrote following code: 我写了以下代码:
var dataSet:Dataset? = null
val Dir = "data/MyDataSet"
dataSet = TDBFactory.createDataset(Dir)
dataSet.begin(ReadWrite.WRITE)
val model = dataSet.defaultModel
createPerson("john.doe@provider.com", model, "jd")
dataSet.end()
dataSet.close()
private fun createPerson(email: String, model: Model, nick: String) {
val uuid = UUID.randomUUID()
val uri = "http://mycompany.com/data/p-${uuid}"
val person = model.createResource(uri)
person.addProperty(VCARD.EMAIL, email)
person.addProperty(VCARD.N,
model.createResource()
.addProperty(VCARD.NICKNAME, nick))
}
When I run it, I get no errors. 运行它时,没有任何错误。
But when I try to read the data from the file (see code below), the query doesn't find anything. 但是,当我尝试从文件中读取数据时(请参见下面的代码),查询找不到任何内容。
ds.begin(ReadWrite.READ)
val query = QueryFactory.create("""SELECT ?x
WHERE { ?x <http://www.w3.org/2001/vcard-rdf/3.0#EMAIL> "john.doe@provider.com" }""")
val qexec: QueryExecution
try {
qexec = QueryExecutionFactory.create(query, ds.defaultModel)
val rs = qexec.execSelect()
while (rs.hasNext()) {
val solution = rs.nextSolution()
System.out.println("")
}
}
catch (throwable:Throwable) {
logger.error("", throwable)
}
finally {
ds.end()
}
What's wrong with my code? 我的代码有什么问题?
You should get a warning at end
because you have not committed the transaction. 由于尚未提交事务,因此应该在
end
收到警告。
dataSet.begin(ReadWrite.WRITE)
val model = dataSet.defaultModel
createPerson("john.doe@provider.com", model, "jd")
dataSet.commit()
dataSet.end()
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