Valor da URL

package fso;

import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.ResultSet;

 
/**
 *
 * Author:  Glauber
 * Scope:   Servlet de geração de imagem
 * Version: 1.0
 */
 
public class GeraImagem extends HttpServlet {
    
    private Connection con;
    private Statement stmt;
    private String trace;
    
    /**
     * Setup database connection and create SQL statement
     */
    public void init( ServletConfig config ) throws ServletException
    {
        // Try database connection
        try{
            // The call to Class.forName explicitly loads the driver class
            //Class.forName("org.gjt.mm.mysql.Driver"); 
            Class.forName("org.postgresql.Driver").newInstance(); 
            //jdbc:mysql://<HOST>:<PORT>/<DB>
            //Connection con = DriverManager.getConnection("jdbc:mysql://localhost/mydb?user=''&password=''");
            con = DriverManager.getConnection("jdbc:postgresql://localhost:5432/sistemas","postgres","senhabanco");
            // Once a connection has been established we can create an instance 
            // of Statement, through which we will send queries to the database.
            stmt = con.createStatement();  
        }
        catch (Exception exception ) {
            exception.printStackTrace();
            throw new UnavailableException(exception.getMessage());
        }
    } // End init()
    
    /**
     * Forward to doGet
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
    {
        doPost(request, response);
    }
    
    /*
     * NOTE: doPost -> HTTP post requests | doGet -> HTTP get resuest
     */
    public void doPost(HttpServletRequest request, HttpServletResponse response)
    throws IOException, ServletException
    {
        // Simple trace variable for debugging...
        trace = "";
        
        try {
            String SQL = "select * from figuras where id=";
            
            ResultSet rs = stmt.executeQuery(SQL);
            rs.next();
            
            int intId = rs.getInt("id");
            int intCt = 0;
            
            //Blob blob = null;
            //blob = rs.getBlob("imagem");
            response.setContentType("image/jpeg");
            //InputStream in = blob.getBinaryStream();
            InputStream in = rs.getBinaryStream("im_figura");
            String strTeste= rs.getString("im_figura");
            OutputStream out = response.getOutputStream();
            int b;
            while ((b = in.read()) != -1) {
                out.write(b);
                intCt++;
            }
            //salvar("c:/teste.txt",strTeste, false);
            in.close();
            out.flush();
            out.close(); 
        }
        catch (Exception exception ) {
            System.out.println("Erro---> " + exception);
            throw new ServletException("Error");
        }
    } // end doPost()
         
    public static void salvar(String arquivo, String conteudo, boolean adicionar) throws IOException {
        FileWriter fw = new FileWriter(arquivo, adicionar);
        fw.write(conteudo);
        fw.close();
    }
    
    /*
     * Close SQL statements & database connection
     */
    public void destroy()
    {
        // Attempt to close statements and database connection
        try{
            stmt.close();
            con.close();
        }       
        
        // Handle database exceptions by returning error to client
        catch (SQLException sqlException){
            sqlException.printStackTrace();
        }
    } // End destroy()    
} // End class showImage

String SQL = "select * from figuras where id="+valor recebido;

String strId = String.valueOf(getExternalContext().getRequestParameterMap().get("figId"));