Dedicated Connection Servlet : Database « Servlets « Java

Dedicated Connection Servlet

Java Programming with Oracle JDBC
by Donald Bales 
ISBN: 059600088X
Publisher: O'Reilly

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.UnavailableException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class DedicatedConnectionServlet extends HttpServlet {
  Connection connection;

  long connected;

  public void init(ServletConfig config) throws ServletException {
    try {
      // load the driver
    } catch (ClassNotFoundException e) {
      throw new UnavailableException(
          "DedicatedConnection.init() ClassNotFoundException: "
              + e.getMessage());
    } catch (IllegalAccessException e) {
      throw new UnavailableException(
          "DedicatedConnection.init() IllegalAccessException: "
              + e.getMessage());
    } catch (InstantiationException e) {
      throw new UnavailableException(
          "DedicatedConnection.init() InstantiationException: "
              + e.getMessage());

    try {
      // establish a connection
      connection = DriverManager.getConnection(
          "jdbc:oracle:thin:@dssw2k01:1521:orcl", "scott", "tiger");
      connected = System.currentTimeMillis();
    } catch (SQLException e) {
      throw new UnavailableException(
          "DedicatedConnection.init() SQLException: "
              + e.getMessage());

  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws IOException, ServletException {

    PrintWriter out = response.getWriter();
    out.println("<title>A Dedicated Connection</title>");

    Statement statement = null;
    ResultSet resultSet = null;
    String userName = null;
    try {
      // test the connection
      statement = connection.createStatement();
      resultSet = statement
          .executeQuery("select initcap(user) from sys.dual");
      if (
        userName = resultSet.getString(1);
    } catch (SQLException e) {
      out.println("DedicatedConnection.doGet() SQLException: "
          + e.getMessage() + "<p>");
    } finally {
      if (resultSet != null)
        try {
        } catch (SQLException ignore) {
      if (statement != null)
        try {
        } catch (SQLException ignore) {
    out.println("Hello " + userName + "!<p>");
    out.println("This Servlet's database connection was created on "
        + new java.util.Date(connected) + "<p>");

  public void doPost(HttpServletRequest request, HttpServletResponse response)
      throws IOException, ServletException {
    doGet(request, response);

  public void destroy() {
    // close the connection
    if (connection != null)
      try {
      } catch (SQLException ignore) {

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