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WorkerTask.java
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WorkerTask.java
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import java.io.*;
import java.net.Socket;
import java.nio.charset.StandardCharsets;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.json.JSONObject;
public class WorkerTask implements Runnable {
// Table column names.
private static String[] columns = {"name", "dob", "major", "level", "year"};
private Socket loadBalancerSocket;
private Connection conn;
WorkerTask(Socket loadBalancerSocket, Connection conn){
this.loadBalancerSocket = loadBalancerSocket;
this.conn = conn;
}
@Override
public void run() {
try {
BufferedWriter lbWriter = new BufferedWriter(new OutputStreamWriter(loadBalancerSocket.getOutputStream(), StandardCharsets.UTF_8));
BufferedReader lbReader = new BufferedReader(new InputStreamReader(loadBalancerSocket.getInputStream(), StandardCharsets.UTF_8));
// Get student ID sent by client(via Load Balancer).
String sid = lbReader.readLine();
// Query student data from database.
String query = "SELECT name, dob, major, level, year FROM studentinfo WHERE sid="+sid;
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(query);
rs.first();
// Create json from data.
JSONObject json = new JSONObject();
for(int i=0; i<5; i++)
json.put(columns[i], rs.getString(i+1));
rs.close();
System.out.println("Sending info for Student with ID: "+sid);
// Send json response to load balancer.
lbWriter.write(json.toString()+"\n");
lbWriter.flush();
} catch (IOException | SQLException e) {
e.printStackTrace();
}
}
}