VirtTipsAndTricksGuideMultithreadJDBC

<docbook><section><title>VirtTipsAndTricksGuideMultithreadJDBC</title><title>How can I make Multi Thread Virtuoso connection using JDBC?</title>How can I make Multi Thread Virtuoso connection using JDBC?
<para>This sample demonstrates simple java code for performing Multi Thread Virtuoso connection using JDBC.
It starts 3 threads: one thread executes SPARQL select and two threads execute SPARQL inserts:</para>
<programlisting>import java.util.*;
import java.sql.*;
import java.math.*;

public class MTtest extends Thread {

  int mode = 0;
  int startId = 0;

  static  String urlDB = &quot;jdbc:virtuoso://localhost:1111&quot;;

 
 public MTtest(int _mode, int _init) {
   mode = _mode;
   startId = _init;
 }


 void prnRs(ResultSet rs)
 {
   try {
     ResultSetMetaData rsmd;

     System.out.println(&quot;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&quot;);
     rsmd = rs.getMetaData();
     int cnt = rsmd.getColumnCount();

       while(rs.next()) {
         Object o;

         System.out.print(&quot;Thread:&quot;+Thread.currentThread().getId()+&quot;  &quot;);
         for (int i = 1; i &lt;= cnt; i++) {
           o = rs.getObject(i);
           if (rs.wasNull())
             System.out.print(&quot;&lt;NULL&gt; &quot;);
           else
             System.out.print(&quot;[&quot;+ o + &quot;] &quot;);
         }
         System.out.println();
       }

   } catch (Exception e) {
     System.out.println(e);
     e.printStackTrace();
   }
   System.out.println(&quot;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&quot;);
 }


 public static void main(String argv[])
 {
  try {

    Class.forName(&quot;virtuoso.jdbc3.Driver&quot;);

    Connection conn = DriverManager.getConnection(urlDB,&quot;dba&quot;,&quot;dba&quot;);
    Statement st = conn.createStatement();

    st.execute(&quot;sparql clear graph &lt;mttest&gt;&quot;);
    st.execute(&quot;sparql insert into graph &lt;mttest&gt; { &lt;xxx&gt; &lt;P01&gt; \&quot;test1\&quot; }&quot;);
    st.execute(&quot;sparql insert into graph &lt;mttest&gt; { &lt;xxx&gt; &lt;P01&gt; \&quot;test2\&quot; }&quot;);
    st.execute(&quot;sparql insert into graph &lt;mttest&gt; { &lt;xxx&gt; &lt;P01&gt; \&quot;test3\&quot; }&quot;);
    st.execute(&quot;sparql insert into graph &lt;mttest&gt; { &lt;xxx&gt; &lt;P01&gt; \&quot;test4\&quot; }&quot;);
    st.execute(&quot;sparql insert into graph &lt;mttest&gt; { &lt;xxx&gt; &lt;P01&gt; \&quot;test5\&quot; }&quot;);
    conn.close();


    int init = 0;

    for(int i=0; i &lt; 2; i++) {
      MTtest thr1 = new MTtest(1, init);
      init+=10;

      MTtest thr2 = new MTtest(0, init);
      init+=10;

      MTtest thr3 = new MTtest(0, init);
      init+=10;

      thr1.start();
      thr2.start();
      thr3.start();

      thr1.join();
      thr2.join();
      thr3.join();
    }

    System.out.println(&quot;===End===&quot;);

  } catch (Exception e) {
    System.out.print(e);
    e.printStackTrace();
  }
 }


 public void run( ) 
 {
  try {

    Connection conn = DriverManager.getConnection(urlDB,&quot;dba&quot;,&quot;dba&quot;);
    Statement st;

    st = conn.createStatement();

    if (mode == 1) 
    {
      String query = &quot;sparql SELECT * from &lt;mttest&gt; WHERE {?s ?p ?o}&quot;;
      ResultSet rs = st.executeQuery(query);
      prnRs(rs);
    }
    else
    {
      long id = Thread.currentThread().getId();
      for (int i =0; i &lt; 5; i++)
        st.execute(&quot;sparql insert into graph &lt;mttest&gt; { &lt;xxx&quot;+startId+&quot;&gt; &lt;P&quot;+id+&quot;&gt; \&quot;test&quot;+i+&quot;\&quot; }&quot;);

      System.out.println(&quot;\nThread:&quot;+Thread.currentThread().getId()+&quot;  ===Rows Inserted===&quot;);
    }


    conn.close();
  
  } catch (SQLException e) {
        System.out.println(&quot;===========================================================&quot;);
        System.out.println(&quot;&gt;&gt;[&quot;+e.getMessage()+&quot;]&quot;);
        System.out.println(&quot;&gt;&gt;[&quot;+e.getErrorCode()+&quot;]&quot;);
        System.out.println(&quot;&gt;&gt;[&quot;+e.getSQLState()+&quot;]&quot;);
        System.out.println(e);
        System.out.println(&quot;===========================================================&quot;);
        e.printStackTrace();
        System.exit(-1);
  } catch (Exception e) {
        System.out.println(&quot;===========================================================&quot;);
        System.out.println(e);
        System.out.println(&quot;===========================================================&quot;);
        e.printStackTrace();
        System.exit(-1);
  }
 } // run( )


}
</programlisting><para> </para>
<bridgehead class="http://www.w3.org/1999/xhtml:h3">Related</bridgehead>
<itemizedlist mark="bullet" spacing="compact"><listitem><ulink url="VirtTipsAndTricksGuide">Virtuoso Tips and Tricks Collection</ulink> </listitem>
<listitem><ulink url="http://docs.openlinksw.com/virtuoso/VirtuosoDriverJDBC.html">Virtuoso Driver for JDBC</ulink> </listitem>
</itemizedlist></section></docbook>