Source Code : Display Clob Servlet

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Display Clob Servlet 

import java.io.IOException;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class DisplayClobServlet extends HttpServlet {
  public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException,
      ServletException {

    Clob fileAsCLOB = null;
    Connection conn = null;
    Statement stmt = null;
    ResultSet rs = null;

    String id = "001";
    String query = "select fileBody from DataFiles where id = " + id;
    ServletOutputStream out = response.getOutputStream();

    // all responses will be in text/html format
    response.setContentType("text/html");

    try {
      conn = getHSQLConnection();
    } catch (Exception e) {
      out.println("<html><head><title>CLOB Example</title></head>");
      out.println("<body><h4>Database Connection Problem.</h4>");
      out.println("<h5>" + e.getMessage() + "</h5></body></html>");
      return;
    }

    try {
      stmt = conn.createStatement();
      rs = stmt.executeQuery(query);
      if (rs.next()) {
        fileAsCLOB = rs.getClob(1);
      } else {
        out.println("<html><head><title>CLOB Example</title></head>");
        out.println("<body><h4>No file found for id=" + id + "</h4></body></html>");
        return;
      }

      // Materialize the CLOB as a String object (get the whole clob).
      long length = fileAsCLOB.length();
      // note that the first character is at position 1
      String fileAsString = fileAsCLOB.getSubString(1, (int) length);

      // write it for display
      out.println(fileAsString);
      System.out.println("CLOB writing done.");
    } catch (SQLException e) {
      out.println("<html><head><title>Error: CLOB Example</title></head>");
      out.println("<body><h4>Error=" + e.getMessage() + "</h4></body></html>");
      return;
    } finally {
      try {
        rs.close();
        stmt.close();
        conn.close();
      } catch (SQLException e) {
        e.printStackTrace();
      }
    }
  }

  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }

  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";

    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }

  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:databaseName";
    String username = "username";
    String password = "password";

    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }

}

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