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:
import java.util.*;
import java.sql.*;
import java.math.*;
public class MTtest extends Thread {
int mode = 0;
int startId = 0;
static String urlDB = "jdbc:virtuoso://localhost:1111";
public MTtest(int _mode, int _init) {
mode = _mode;
startId = _init;
}
void prnRs(ResultSet rs)
{
try {
ResultSetMetaData rsmd;
System.out.println(">>>>>>>>");
rsmd = rs.getMetaData();
int cnt = rsmd.getColumnCount();
while(rs.next()) {
Object o;
System.out.print("Thread:"+Thread.currentThread().getId()+" ");
for (int i = 1; i <= cnt; i++) {
o = rs.getObject(i);
if (rs.wasNull())
System.out.print("<NULL> ");
else
System.out.print("["+ o + "] ");
}
System.out.println();
}
} catch (Exception e) {
System.out.println(e);
e.printStackTrace();
}
System.out.println(">>>>>>>>");
}
public static void main(String argv[])
{
try {
Class.forName("virtuoso.jdbc3.Driver");
Connection conn = DriverManager.getConnection(urlDB,"dba","dba");
Statement st = conn.createStatement();
st.execute("sparql clear graph <mttest>");
st.execute("sparql insert into graph <mttest> { <xxx> <P01> \"test1\" }");
st.execute("sparql insert into graph <mttest> { <xxx> <P01> \"test2\" }");
st.execute("sparql insert into graph <mttest> { <xxx> <P01> \"test3\" }");
st.execute("sparql insert into graph <mttest> { <xxx> <P01> \"test4\" }");
st.execute("sparql insert into graph <mttest> { <xxx> <P01> \"test5\" }");
conn.close();
int init = 0;
for(int i=0; i < 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("===End===");
} catch (Exception e) {
System.out.print(e);
e.printStackTrace();
}
}
public void run( )
{
try {
Connection conn = DriverManager.getConnection(urlDB,"dba","dba");
Statement st;
st = conn.createStatement();
if (mode == 1)
{
String query = "sparql SELECT * from <mttest> WHERE {?s ?p ?o}";
ResultSet rs = st.executeQuery(query);
prnRs(rs);
}
else
{
long id = Thread.currentThread().getId();
for (int i =0; i < 5; i++)
st.execute("sparql insert into graph <mttest> { <xxx"+startId+"> <P"+id+"> \"test"+i+"\" }");
System.out.println("\nThread:"+Thread.currentThread().getId()+" ===Rows Inserted===");
}
conn.close();
} catch (SQLException e) {
System.out.println("===========================================================");
System.out.println(">>["+e.getMessage()+"]");
System.out.println(">>["+e.getErrorCode()+"]");
System.out.println(">>["+e.getSQLState()+"]");
System.out.println(e);
System.out.println("===========================================================");
e.printStackTrace();
System.exit(-1);
} catch (Exception e) {
System.out.println("===========================================================");
System.out.println(e);
System.out.println("===========================================================");
e.printStackTrace();
System.exit(-1);
}
} // run( )
}