[英]A code example of serialization JSON to JSON-LD in Java?
我需要将以JSON
形式表示的大量数据转换为JSON-LD
。 我想用这个JSON-LD
Java 实现来做到这一点,但我不明白,我该怎么办。
我看了几个教程,在网上看了一些关于JSON-LD
东西,但是不明白最简单的事情:如何将JSON
转换为JSON-LD
?
例如,我在 JSON 中有这个代码:
{
"name" : "Andreas",
"age" : 20,
"profession" : "student",
"personalWebsite" : "example.com"
}
我现在该怎么办? 类似context.add("example.com")
?
InputStream inputStream = new FileInputStream("C:\Users\Username\input.json");
Object jsonObject = JsonUtils.fromInputStream(inputStream);
Map context = new HashMap();
JsonLdOptions options = new JsonLdOptions();
将“@context”条目添加到您的数据中。
{
"name" : "Andreas",
"age" : 20,
"profession" : "student",
"personalWebsite" : "example.com",
"@context":"http://schema.org/"
}
您的 JSON-LD 处理器将完成剩下的工作(从 0.9 版开始)
作为测试,您可以将 json 转换为 rdf。
package overflow.stack2449461;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.io.StringWriter;
import java.util.Collection;
import org.eclipse.rdf4j.model.Statement;
import org.eclipse.rdf4j.rio.RDFFormat;
import org.eclipse.rdf4j.rio.RDFHandlerException;
import org.eclipse.rdf4j.rio.RDFParser;
import org.eclipse.rdf4j.rio.RDFWriter;
import org.eclipse.rdf4j.rio.Rio;
import org.eclipse.rdf4j.rio.helpers.StatementCollector;
public class Test {
@org.junit.Test
public void testForYourCode() {
String data = "{\"name\" : \"Andreas\",\"age\" : 20,\"profession\" : \"student\", \"personalWebsite\" : \"example.com\",\"@context\": \"http://schema.org/\"}";
try (InputStream in = new ByteArrayInputStream(data.getBytes("utf-8"))) {
String dataAsRdf = readRdfToString(in, RDFFormat.JSONLD, RDFFormat.NTRIPLES, "");
System.out.println(dataAsRdf);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
/**
* @param in
* a rdf input stream
* @param inf
* the rdf format of the input stream
* @param outf
* the output format
* @param baseUrl
* usually the url of the resource
* @return a string representation
*/
public static String readRdfToString(InputStream in, RDFFormat inf, RDFFormat outf, String baseUrl) {
Collection<Statement> myGraph = null;
myGraph = readRdfToGraph(in, inf, baseUrl);
return graphToString(myGraph, outf);
}
/**
* @param inputStream
* an Input stream containing rdf data
* @param inf
* the rdf format
* @param baseUrl
* see sesame docu
* @return a Graph representing the rdf in the input stream
*/
public static Collection<Statement> readRdfToGraph(final InputStream inputStream, final RDFFormat inf,
final String baseUrl) {
try {
final RDFParser rdfParser = Rio.createParser(inf);
final StatementCollector collector = new StatementCollector();
rdfParser.setRDFHandler(collector);
rdfParser.parse(inputStream, baseUrl);
return collector.getStatements();
} catch (final Exception e) {
throw new RuntimeException(e);
}
}
/**
* Transforms a graph to a string.
*
* @param myGraph
* a sesame rdf graph
* @param outf
* the expected output format
* @return a rdf string
*/
public static String graphToString(Collection<Statement> myGraph, RDFFormat outf) {
StringWriter out = new StringWriter();
RDFWriter writer = Rio.createWriter(outf, out);
try {
writer.startRDF();
for (Statement st : myGraph) {
writer.handleStatement(st);
}
writer.endRDF();
} catch (RDFHandlerException e) {
throw new RuntimeException(e);
}
return out.getBuffer().toString();
}
}
使用 pom.xml
<dependency>
<groupId>org.eclipse.rdf4j</groupId>
<artifactId>rdf4j-runtime</artifactId>
<version>2.2</version>
<type>pom</type>
</dependency>
<dependency>
<groupId>com.github.jsonld-java</groupId>
<artifactId>jsonld-java</artifactId>
<version>0.10.0</version>
</dependency>
它会将您的 json 字符串打印为 rdf NTRIPLES
_:b0 <http://schema.org/age> "20"^^<http://www.w3.org/2001/XMLSchema#integer> .
_:b0 <http://schema.org/name> "Andreas" .
_:b0 <http://schema.org/personalWebsite> "example.com" .
_:b0 <http://schema.org/profession> "student" .
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