Jena增删改查java API

最新推荐文章于 2022-05-12 10:08:11 发布

原创最新推荐文章于 2022-05-12 10:08:11 发布 · 408 阅读

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CC 4.0 BY-SA版权

本文详细介绍使用SPARQL进行数据插入、更新及查询的方法，包括构造SPARQL查询语句的具体步骤，以及如何通过UpdateRequest和QueryExecutionFactory执行这些操作。

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撸了今年阿里、头条和美团的面试，我有一个重要发现.......>>>

插入、更新数据

public static void insert(){
        String query = "PREFIX book: <http://www.book.com/jinyong/> \n" +
                "                INSERT DATA \n" +
                "                {  \n" +
                "                <http://www.book.com/book#001> book:书名 \"天龙八部\".\n" +
                "                <http://www.book.com/book#001> book:人物 \"乔峰\".\n" +
                "                }";
        UpdateRequest updates = UpdateFactory.create(query);
        UpdateProcessor updateProcessor = UpdateExecutionFactory.createRemote(updates, "http://localhost:3030/test/update");
        updateProcessor.execute();
    }

更新数据操作是先删除原先的三元组，在添加新的三元组

public static void update(){
        String query = "PREFIX book: <http://www.book.com/jinyong/> \n" +
                "DELETE  \n" +
                "{  \n" +
                "  <http://www.book.com/book#001> book:人物 \"乔峰\"\n" +
                "}\n" +
                "insert\n" +
                "{\n" +
                "  <http://www.book.com/book#001> book:人物 \"萧峰\"\n" +
                "}\n" +
                "where\n" +
                "{\n" +
                "\t<http://www.book.com/book#001> book:人物 \"乔峰\"\n" +
                "}";
        UpdateRequest updates = UpdateFactory.create(query);
        UpdateProcessor updateProcessor = UpdateExecutionFactory.createRemote(updates, "http://localhost:3030/test/update");
        updateProcessor.execute();
    }

查询

public List<String> queryEndPoint(){
        String queryStr ="\n" +
                "SELECT ?subject ?predicate ?object\n" +
                "WHERE {\n" +
                "  ?subject ?predicate ?object\n" +
                "}\n" +
                "LIMIT 25";
        String serviceEndPoint="http://localhost:3030/test";
        Query query = QueryFactory.create(queryStr);
        List<String> result=new ArrayList<>();
        try ( QueryExecution qexec = QueryExecutionFactory.sparqlService(serviceEndPoint, query) ) {
            ResultSet rs = qexec.execSelect();

            for ( ; rs.hasNext() ; )
            {
                QuerySolution soln = rs.nextSolution() ;
                RDFNode object = soln.get("object");
                RDFNode subject = soln.get("subject");
                RDFNode predicate = soln.get("predicate");

                System.out.println(object.toString()+","+subject.toString() + ","+predicate.toString());
            qexec.close();
            }
        } catch (Exception e) {
            System.out.println("aaaaaaaaaaaaa");
            e.printStackTrace();
        }
        return result;
    }