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BAEL-9120: Introduction to RDF and Apache Jena (#18769)
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‎libraries-7/pom.xml‎

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<artifactId>record-builder-core</artifactId>
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<version>${record-builder.version}</version>
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</dependency>
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<dependency>
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<groupId>org.apache.jena</groupId>
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<artifactId>apache-jena-libs</artifactId>
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<type>pom</type>
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<version>${jena.version}</version>
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</dependency>
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</dependencies>
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<build>
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<yavi.version>0.14.1</yavi.version>
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<manifold.version>2024.1.20</manifold.version>
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<record-builder.version>47</record-builder.version>
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<jena.version>5.5.0</jena.version>
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</properties>
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</project>

‎libraries-7/src/test/java/com/baeldung/jena/ModelUnitTest.java‎

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package com.baeldung.jena;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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import org.apache.jena.rdf.model.Model;
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import org.apache.jena.rdf.model.ModelFactory;
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import org.apache.jena.rdf.model.Resource;
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import org.apache.jena.vocabulary.SchemaDO;
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import org.junit.jupiter.api.Test;
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public class ModelUnitTest {
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@Test
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void whenWeHaveABlogModelThenWeCanAccessTheProperties() {
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Model model = ModelFactory.createDefaultModel();
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{
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Resource baeldung = model.createResource("/users/Baeldung")
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.addProperty(SchemaDO.name, "Baeldung")
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.addProperty(SchemaDO.url, "https://baeldung.com");
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Resource joeBloggs = model.createResource("/users/JoeBloggs")
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.addProperty(SchemaDO.name, "Joe Bloggs")
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.addProperty(SchemaDO.email, "[email protected]");
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Resource comment = model.createResource("/blog/posts/123/comments/1")
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.addProperty(SchemaDO.text, "What a great article!")
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.addProperty(SchemaDO.author, joeBloggs);
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Resource blogPost = model.createResource("/blog/posts/123");
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blogPost.addProperty(SchemaDO.headline, "Introduction to RDF and Apache Jena");
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blogPost.addProperty(SchemaDO.wordCount, "835");
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blogPost.addProperty(SchemaDO.author, baeldung);
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blogPost.addProperty(SchemaDO.comment, comment);
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}
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{
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Resource blogPost = model.getResource("/blog/posts/123");
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assertEquals("Introduction to RDF and Apache Jena", blogPost.getProperty(SchemaDO.headline).getString());
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Resource author = blogPost.getProperty(SchemaDO.author).getResource();
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assertEquals("Baeldung", author.getProperty(SchemaDO.name).getString());
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}
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}
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}

‎libraries-7/src/test/java/com/baeldung/jena/NTripleUnitTest.java‎

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package com.baeldung.jena;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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import static org.junit.jupiter.api.Assertions.assertTrue;
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import java.io.ByteArrayOutputStream;
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import java.nio.charset.StandardCharsets;
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import org.apache.jena.rdf.model.Model;
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import org.apache.jena.rdf.model.ModelFactory;
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import org.apache.jena.riot.Lang;
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import org.apache.jena.riot.RDFDataMgr;
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import org.apache.jena.vocabulary.SchemaDO;
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import org.junit.jupiter.api.Test;
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public class NTripleUnitTest {
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@Test
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void whenWeHaveAModel_ThenWeCanSerializeAsNTriples() {
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Model model = ModelFactory.createDefaultModel();
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model.createResource("/blog/posts/123")
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.addProperty(SchemaDO.headline, "Introduction to RDF and Apache Jena")
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.addProperty(SchemaDO.wordCount, "835")
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.addProperty(SchemaDO.author, model.createResource("/users/Baeldung")
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.addProperty(SchemaDO.name, "Baeldung")
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.addProperty(SchemaDO.url, "https://baeldung.com"))
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.addProperty(SchemaDO.comment, model.createResource("/blog/posts/123/comments/1")
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.addProperty(SchemaDO.text, "What a great article!")
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.addProperty(SchemaDO.author, model.createResource("/users/JoeBloggs")
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.addProperty(SchemaDO.name, "Joe Bloggs")
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.addProperty(SchemaDO.email, "[email protected]")));
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ByteArrayOutputStream out = new ByteArrayOutputStream();
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RDFDataMgr.write(out, model, Lang.NTRIPLES);
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assertEquals("""
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</blog/posts/123/comments/1> <https://schema.org/author> </users/JoeBloggs> .
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</blog/posts/123/comments/1> <https://schema.org/text> "What a great article!" .
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</users/Baeldung> <https://schema.org/url> "https://baeldung.com" .
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</users/Baeldung> <https://schema.org/name> "Baeldung" .
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</users/JoeBloggs> <https://schema.org/email> "[email protected]" .
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</users/JoeBloggs> <https://schema.org/name> "Joe Bloggs" .
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</blog/posts/123> <https://schema.org/comment> </blog/posts/123/comments/1> .
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</blog/posts/123> <https://schema.org/author> </users/Baeldung> .
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</blog/posts/123> <https://schema.org/wordCount> "835" .
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</blog/posts/123> <https://schema.org/headline> "Introduction to RDF and Apache Jena" .
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""", out.toString());
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}
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}

‎libraries-7/src/test/java/com/baeldung/jena/RDFXMLUnitTest.java‎

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package com.baeldung.jena;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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import java.io.ByteArrayOutputStream;
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import java.io.StringReader;
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import org.apache.jena.rdf.model.Model;
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import org.apache.jena.rdf.model.ModelFactory;
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import org.apache.jena.rdf.model.Resource;
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import org.apache.jena.riot.Lang;
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import org.apache.jena.riot.RDFDataMgr;
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import org.apache.jena.vocabulary.SchemaDO;
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import org.junit.jupiter.api.Test;
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public class RDFXMLUnitTest {
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@Test
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void whenWeHaveAModel_ThenWeCanSerializeAsRDFXMLUsingRDFDataMgr() {
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Model model = ModelFactory.createDefaultModel();
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model.createResource("tag:baeldung:/blog/posts/123")
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.addProperty(SchemaDO.headline, "Introduction to RDF and Apache Jena")
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.addProperty(SchemaDO.wordCount, "835")
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.addProperty(SchemaDO.author, model.createResource("tag:baeldung:/users/Baeldung")
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.addProperty(SchemaDO.name, "Baeldung")
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.addProperty(SchemaDO.url, "https://baeldung.com"))
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.addProperty(SchemaDO.comment, model.createResource("tag:baeldung:/blog/posts/123/comments/1")
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.addProperty(SchemaDO.text, "What a great article!")
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.addProperty(SchemaDO.author, model.createResource("tag:baeldung:/users/JoeBloggs")
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.addProperty(SchemaDO.name, "Joe Bloggs")
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.addProperty(SchemaDO.email, "[email protected]")));
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ByteArrayOutputStream out = new ByteArrayOutputStream();
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RDFDataMgr.write(out, model, Lang.RDFXML);
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assertEquals("""
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<rdf:RDF
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xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
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xmlns:j.0="https://schema.org/">
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<rdf:Description rdf:about="tag:baeldung:/blog/posts/123">
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<j.0:comment>
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<rdf:Description rdf:about="tag:baeldung:/blog/posts/123/comments/1">
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<j.0:author>
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<rdf:Description rdf:about="tag:baeldung:/users/JoeBloggs">
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<j.0:email>[email protected]</j.0:email>
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<j.0:name>Joe Bloggs</j.0:name>
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</rdf:Description>
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</j.0:author>
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<j.0:text>What a great article!</j.0:text>
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</rdf:Description>
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</j.0:comment>
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<j.0:author>
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<rdf:Description rdf:about="tag:baeldung:/users/Baeldung">
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<j.0:url>https://baeldung.com</j.0:url>
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<j.0:name>Baeldung</j.0:name>
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</rdf:Description>
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</j.0:author>
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<j.0:wordCount>835</j.0:wordCount>
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<j.0:headline>Introduction to RDF and Apache Jena</j.0:headline>
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</rdf:Description>
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</rdf:RDF>
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""", out.toString());
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}
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@Test
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void whenWeHaveAModel_ThenWeCanSerializeAsRDFXMLUsingWrite() {
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Model model = ModelFactory.createDefaultModel();
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model.createResource("tag:baeldung:/blog/posts/123")
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.addProperty(SchemaDO.headline, "Introduction to RDF and Apache Jena")
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.addProperty(SchemaDO.wordCount, "835")
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.addProperty(SchemaDO.author, model.createResource("tag:baeldung:/users/Baeldung")
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.addProperty(SchemaDO.name, "Baeldung")
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.addProperty(SchemaDO.url, "https://baeldung.com"))
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.addProperty(SchemaDO.comment, model.createResource("tag:baeldung:/blog/posts/123/comments/1")
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.addProperty(SchemaDO.text, "What a great article!")
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.addProperty(SchemaDO.author, model.createResource("tag:baeldung:/users/JoeBloggs")
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.addProperty(SchemaDO.name, "Joe Bloggs")
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.addProperty(SchemaDO.email, "[email protected]")));
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ByteArrayOutputStream out = new ByteArrayOutputStream();
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model.write(out);
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assertEquals("""
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<rdf:RDF
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xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
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xmlns:j.0="https://schema.org/">
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<rdf:Description rdf:about="tag:baeldung:/blog/posts/123">
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<j.0:comment>
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<rdf:Description rdf:about="tag:baeldung:/blog/posts/123/comments/1">
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<j.0:author>
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<rdf:Description rdf:about="tag:baeldung:/users/JoeBloggs">
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<j.0:email>[email protected]</j.0:email>
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<j.0:name>Joe Bloggs</j.0:name>
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</rdf:Description>
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</j.0:author>
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<j.0:text>What a great article!</j.0:text>
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</rdf:Description>
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</j.0:comment>
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<j.0:author>
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<rdf:Description rdf:about="tag:baeldung:/users/Baeldung">
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<j.0:url>https://baeldung.com</j.0:url>
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<j.0:name>Baeldung</j.0:name>
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</rdf:Description>
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</j.0:author>
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<j.0:wordCount>835</j.0:wordCount>
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<j.0:headline>Introduction to RDF and Apache Jena</j.0:headline>
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</rdf:Description>
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</rdf:RDF>
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""", out.toString());
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}
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@Test
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void whenWeHaveRDFXML_thenWeCanParseThis() {
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String rdfxml = """
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<rdf:RDF
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xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
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xmlns:j.0="https://schema.org/">
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<rdf:Description rdf:about="tag:baeldung:/blog/posts/123">
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<j.0:comment>
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<rdf:Description rdf:about="tag:baeldung:/blog/posts/123/comments/1">
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<j.0:author>
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<rdf:Description rdf:about="tag:baeldung:/users/JoeBloggs">
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<j.0:email>[email protected]</j.0:email>
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<j.0:name>Joe Bloggs</j.0:name>
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</rdf:Description>
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</j.0:author>
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<j.0:text>What a great article!</j.0:text>
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</rdf:Description>
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</j.0:comment>
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<j.0:author>
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<rdf:Description rdf:about="tag:baeldung:/users/Baeldung">
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<j.0:url>https://baeldung.com</j.0:url>
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<j.0:name>Baeldung</j.0:name>
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</rdf:Description>
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</j.0:author>
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<j.0:wordCount>835</j.0:wordCount>
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<j.0:headline>Introduction to RDF and Apache Jena</j.0:headline>
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</rdf:Description>
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</rdf:RDF>
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""";
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Model model = ModelFactory.createDefaultModel();
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model.read(new StringReader(rdfxml), null);
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Resource blogPost = model.getResource("tag:baeldung:/blog/posts/123");
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assertEquals("Introduction to RDF and Apache Jena", blogPost.getProperty(SchemaDO.headline).getString());
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Resource author = blogPost.getProperty(SchemaDO.author).getResource();
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assertEquals("Baeldung", author.getProperty(SchemaDO.name).getString());
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}
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}

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