我正在尝试读取目录中的所有RDF文件,但似乎我只是在读取第一个文件。我首先使用File对象获取文件名,然后尝试迭代它们,读取每个文件。如果我必须做一些像
这样的事情,我不知道该怎么办model = ModelFactory.createDefaultModel();
每次迭代后或关闭输入和输出流或其他内容。到目前为止,我的代码如下:
String inputFileName = "";
Model model = ModelFactory.createDefaultModel();
StringWriter out;
File folder = new File("D:/filepath");
File[] listOfFiles = folder.listFiles();
String result="";
for (int i = 0; i < listOfFiles.length; i++) {
inputFileName= listOfFiles[i].getName();
inputFileName = "D:/filepath/" +inputFileName;
System.out.println(inputFileName);
InputStream in = FileManager.get().open( inputFileName );
if (in == null) {
throw new IllegalArgumentException( "File: " + inputFileName + " not found");
}
model.read(in, "");
String syntax = "RDF/XML-ABBREV";
out = new StringWriter();
model.write(out, syntax);
result = out.toString();
// extractSomethingFrom(result);
model = ModelFactory.createDefaultModel();
in.close();
out.close();
}
答案 0 :(得分:1)
Model.read
将语句添加到模型中,因此代码如
Model model = ...
for ( ... ) {
model.read( ... );
}
// do things with model
将为您提供一个模型,其中包含您阅读过的所有内容中的所有三元组。但是,当您执行
时,您将在每次迭代时为model
分配一个新的空模型
model = ModelFactory.createDefaultModel();
循环内部。这就是为什么每次你写出模型时,你只能看到你在那次迭代中读到的文件中的三元组。
以下代码演示了此行为。有两个包含RDF文本的字符串,您可以在之间创建新模型的情况下连续read
查看它们的效果。
import java.io.ByteArrayInputStream;
import java.io.IOException;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.ModelFactory;
public class ReadMultipleDocuments {
public static void main(String[] args) throws IOException {
final String text1 = "@prefix : <urn:ex:>. :a :b :c .";
final String text2 = "@prefix : <urn:ex:>. :d :e :f .";
final String[] texts = new String[] { text1, text2 };
// reset determines whether or not a new model is assigned
// to model after reading each text.
for ( final boolean reset : new boolean[] { true, false } ) {
System.out.println( "* reset = "+reset );
// create the first model
Model model = ModelFactory.createDefaultModel();
for ( final String text : texts ) {
// read the RDF from the text. This is analogous to reading
// the data from a file.
model.read( new ByteArrayInputStream( text.getBytes() ), null, "TTL" );
System.out.println( " * after reading, model size is "+model.size() );
// if a new model is created and assigned to the variable
// model, then the triples read during this iteration will
// no longer be available (since you've lost the model that
// they were in).
if ( reset ) {
model = ModelFactory.createDefaultModel();
}
}
}
}
}
使用Java中的新文件IO实际上使这个问题变得更加容易。您可以简单地创建模型,遍历文件系统,并将read
每个文件的内容放入模型中。这是代码:
import java.io.IOException;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.ModelFactory;
public class ReadRDFFilesInDirectory {
public static void main(String[] args) throws IOException {
final Model model = ModelFactory.createDefaultModel();
Files.walkFileTree( Paths.get( "/home/taylorj/tmp/rdfs/" ), new SimpleFileVisitor<Path>() {
@Override
public FileVisitResult visitFile( final Path file, final BasicFileAttributes attrs) throws IOException {
model.read( file.toUri().toString() );
return super.visitFile(file, attrs);
}
});
model.write( System.out );
}
}
在目录"/home/taylorj/tmp/rdfs/"
中,我有三个文件。
one.n3:
@prefix : <urn:ex:>.
:a :b :c .
two.n3:
@prefix : <urn:ex:>.
:d :e :f .
three.n3:
@prefix : <urn:ex:>.
:g :h :i .
代码读取所有内容并将三元组放入model
。输出是:
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns="urn:ex:" >
<rdf:Description rdf:about="urn:ex:d">
<e rdf:resource="urn:ex:f"/>
</rdf:Description>
<rdf:Description rdf:about="urn:ex:a">
<b rdf:resource="urn:ex:c"/>
</rdf:Description>
<rdf:Description rdf:about="urn:ex:g">
<h rdf:resource="urn:ex:i"/>
</rdf:Description>
</rdf:RDF>
答案 1 :(得分:0)
还有一个库,它会查看文件夹并尝试解析链接数据文件,然后返回RDF图中文件夹中的内容。&#34;