Question

我有一个rdf文件，我希望看到的数量少于30的书。但它不会产生任何输出。

这是rdf文件：

<?xml version="1.0" encoding="UTF-8"?>

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:booktique ="http://www.w3.org/2001/booktique-rdf/3.0#">

    <rdf:Description rdf:about="http://booktique.com/books/124">
        <rdf:type rdf:resource="http://booktique.com/Resource/Book"/>
        <booktique:bookID>124</booktique:bookID>
        <booktique:title>Geography</booktique:title>
        <booktique:price>10$</booktique:price>
        <booktique:author rdf:resource="http://booktique.com/authors/12999"/>
        <booktique:publisher rdf:resource="http://booktique.com/publishers/Mcgill"/>
    </rdf:Description>

    <rdf:Description rdf:about="http://booktique.com/books/258">
        <rdf:type rdf:resource="http://booktique.com/Resource/Book"/>
        <booktique:bookID>258</booktique:bookID>
        <booktique:title>Physics</booktique:title>
        <booktique:price>20$</booktique:price>
        <booktique:author rdf:resource="http://booktique.com/authors/12999"/>
        <booktique:publisher rdf:resource="http://booktique.com/publishers/Swan"/>
    </rdf:Description>`

    <rdf:Description rdf:about="http://booktique.com/books/356">
        <rdf:type rdf:resource="http://booktique.com/Resource/Book"/>
        <booktique:bookID>356</booktique:bookID>
        <booktique:title>Phyton</booktique:title>
        <booktique:price>25$</booktique:price>
        <booktique:author rdf:resource="http://booktique.com/authors/13274"/>
        <booktique:publisher rdf:resource="http://booktique.com/publishers/Connoly"/>
    </rdf:Description>



    <rdf:Description rdf:about="http://booktique.com/authors/12999">
        <rdf:type rdf:resource="http://booktique.com/Resource/Author"/>
        <booktique:name>James Brown</booktique:name>
        <booktique:authorID>12999</booktique:authorID>
        <booktique:e-mail>brown@gmail.com</booktique:e-mail>
    </rdf:Description>

    <rdf:Description rdf:about="http://booktique.com/authors/13274">
        <rdf:type rdf:resource="http://booktique.com/Resource/Author"/>
        <booktique:name>Kelly Smith</booktique:name>
        <booktique:authorID>13274</booktique:authorID>
        <booktique:e-mail>smith@gmail.com</booktique:e-mail>
    </rdf:Description>

    <rdf:Description rdf:about="http://booktique.com/publishers/Connoly">
        <rdf:type rdf:resource="http://booktique.com/Resource/Publisher"/>
        <booktique:name>Connoly</booktique:name>
        <booktique:address>US</booktique:address>
    </rdf:Description>

    <rdf:Description rdf:about="http://booktique.com/publishers/Mcgill">
        <rdf:type rdf:resource="http://booktique.com/Resource/Publisher"/>
        <booktique:name>Mcgill</booktique:name>
        <booktique:address>UK</booktique:address>
    </rdf:Description>

    <rdf:Description rdf:about="http://booktique.com/publishers/Swan">
        <rdf:type rdf:resource="http://booktique.com/Resource/Publisher"/>
        <booktique:name>Swan</booktique:name>
        <booktique:address>FRA</booktique:address>
    </rdf:Description>

    <rdf:Description rdf:about="http://booktique.com/sales/book/124">
        <rdf:type rdf:resource="http://booktique.com/Resource/SalesOrder"/>
        <booktique:bookID rdf:resource="http://booktique.com/books/124"/>
        <booktique:amount>100</booktique:amount>

    </rdf:Description>

    <rdf:Description rdf:about="http://booktique.com/sales/book/258">
        <rdf:type rdf:resource="http://booktique.com/Resource/SalesOrder"/>
        <booktique:bookID rdf:resource="http://booktique.com/books/258"/>
        <booktique:amount>12</booktique:amount>

    </rdf:Description>

    <rdf:Description rdf:about="http://booktique.com/sales/book/356">
        <rdf:type rdf:resource="http://booktique.com/Resource/SalesOrder"/>
        <booktique:bookID rdf:resource="http://booktique.com/books/356"/>
        <booktique:amount>20</booktique:amount>

    </rdf:Description>

JENA代码：

static void sparqltest()

{

FileManager.get().addLocatorClassLoader(Test.class.getClassLoader());
Model model= FileManager.get().loadModel("booktique.rdf");
String queryString="PREFIX rdf:<http://www.w3.org/2001/booktique-rdf/3.0#>"+ 
"SELECT * WHERE {?s rdf:amount ?x."+
                    "FILTER (?x<30)}";
Query query= QueryFactory.create(queryString);
QueryExecution qexec=QueryExecutionFactory.create(query, model);

try { ResultSet results = qexec.execSelect();while ( results.hasNext()){ QuerySolution soln = results.nextSolution(); Literal amount = soln.getLiteral("x"); System.out.println(amount); } }

我检查了apache网站和许多网站，无论我尝试过什么都无法解决问题。我有2个来源，其数量少于30个。所以我该如何解决这个问题？感谢。

Answer 1

<booktique:amount>12</booktique:amount>是一个包含字符＆＃34; 1＆＃34;的字符串值。和＆＃34; 2＆＃34;。这不是一个数字。

您需要：

在数据中，为属性值指定数据类型。
将其投放到查询xsd:integrer(?x) < 30中的整数。

jena sparql filter doen不给任何输出

1 个答案: