UpdateServlet.java 2.6 KB

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  1. package hello;
  2. import java.io.IOException;
  3. import java.sql.Connection;
  4. import java.sql.PreparedStatement;
  5. import java.sql.ResultSet;
  6. import java.sql.SQLException;
  7. import java.util.Random;
  8. import java.util.concurrent.ThreadLocalRandom;
  9. import javax.annotation.Resource;
  10. import javax.servlet.ServletException;
  11. import javax.servlet.http.HttpServlet;
  12. import javax.servlet.http.HttpServletRequest;
  13. import javax.servlet.http.HttpServletResponse;
  14. import javax.sql.DataSource;
  15. /**
  16. * Database connectivity (with a Servlet-container managed pool) test.
  17. */
  18. @SuppressWarnings("serial")
  19. public class UpdateServlet extends HttpServlet {
  20. private static final String PARAMETER_QUERIES = "queries";
  21. // Database details.
  22. private static final String DB_QUERY = "SELECT * FROM World WHERE id = ?";
  23. private static final String UPDATE_QUERY = "UPDATE World SET randomNumber = ? WHERE id = ?";
  24. private static final int DB_ROWS = 10000;
  25. private static final int LIMIT = DB_ROWS + 1;
  26. // Database connection pool.
  27. @Resource(name = "jdbc/hello_world")
  28. private DataSource mysqlDataSource;
  29. @Override
  30. protected void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException,
  31. IOException {
  32. // Reference the data source.
  33. final DataSource source = mysqlDataSource;
  34. final int count = Common.normalise(req.getParameter(PARAMETER_QUERIES));
  35. final World[] worlds = new World[count];
  36. final Random random = ThreadLocalRandom.current();
  37. try (Connection conn = source.getConnection();
  38. PreparedStatement statement = conn.prepareStatement(DB_QUERY,
  39. ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
  40. PreparedStatement statement2 = conn.prepareStatement(UPDATE_QUERY,
  41. ResultSet.TYPE_FORWARD_ONLY)) {
  42. // Run the query the number of times requested.
  43. for (int i = 0; i < count; i++) {
  44. final int id = random.nextInt(LIMIT);
  45. statement.setInt(1, id);
  46. try (ResultSet results = statement.executeQuery()) {
  47. if (results.next()) {
  48. worlds[i] = new World(id, results.getInt("randomNumber"));
  49. // Update row
  50. worlds[i].setRandomNumber(random.nextInt(LIMIT));
  51. statement2.setInt(1, worlds[i].getRandomNumber());
  52. statement2.setInt(2, id);
  53. // Add update statement to batch update
  54. statement2.addBatch();
  55. }
  56. }
  57. // Execute batch update
  58. statement2.executeBatch();
  59. }
  60. } catch (SQLException sqlex) {
  61. throw new ServletException(sqlex);
  62. }
  63. // Set content type to JSON
  64. res.setHeader(Common.HEADER_CONTENT_TYPE, Common.CONTENT_TYPE_JSON);
  65. // Write JSON encoded message to the response.
  66. Common.MAPPER.writeValue(res.getOutputStream(), worlds);
  67. }
  68. }