java - Reading all the RDF files in a directory -

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i trying read rdf files in directory, seems reading first file. first file names using file object , try iterate through them, reading each one. dont know if have like

model = modelfactory.createdefaultmodel();

after each iteration or close input , output streams or else. code far follows:

string inputfilename  = ""; model model = modelfactory.createdefaultmodel(); stringwriter out; file folder = new file("d:/filepath"); file[] listoffiles = folder.listfiles(); string result="";  (int = 0; < 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(); }

the problem existing code

model.read adds statements model, code like

model model = ... ( ... ) {   model.read( ... ); } // things model

will give model containing triples things you've read. however, you're assigning new, empty model model on each iteration when do

model = modelfactory.createdefaultmodel();

inside loop. that's why each time write out model you're seeing triples file read on iteration.

the following code demonstrates behavior. there 2 strings containing rdf text, , can see effect of reading them successively , without creating new model in between.

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 new model assigned              // model after reading each text.         ( final boolean reset : new boolean[] { true, false } ) {             system.out.println( "* reset = "+reset );                     // create first model             model model = modelfactory.createdefaultmodel();             ( final string text : texts ) {                             // read rdf text. analogous reading                             // data file.                 model.read( new bytearrayinputstream( text.getbytes() ), null, "ttl" );                 system.out.println( "  * after reading, model size "+model.size() );                             // if new model created , assigned variable                             // model, triples read during iteration                              // no longer available (since you've lost model                              // in).                 if ( reset ) {                     model = modelfactory.createdefaultmodel();                 }             }         }     } }

how read rdf files in directory single model

this problem made easier new file io in java. can create model, walk filesystem, , read contents of each file model. here's code that:

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 );     } }

in directory "/home/taylorj/tmp/rdfs/", i've got 3 files.

one.n3:

@prefix : <urn:ex:>.  :a :b :c .

two.n3:

@prefix : <urn:ex:>.  :d :e :f .

three.n3:

@prefix : <urn:ex:>.  :g :h :i .

the code reads of them , puts triples model. output is:

<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>

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