package net.hnspi.util;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

public class Db {

 private static Db db = null;

 private static String driver = "com.mysql.jdbc.Driver";

 private static String url = "jdbc:mysql://localhost:3306/guestbook";

 private static String dbUser = "root";

 private static String password = "123";

 private Connection conn = null;

 private Statement stmt = null;

 private ResultSet rs = null;

 private Db() {

 }

 public static Db getDb() {

  if (null == db) {

   synchronized (Db.class) {

    if (null == db) {

     db = new Db();

    }

    return db;

   }

  } else {

   return db;

  }

 }

 public Connection getConnection() {

   try {

    Class.forName(driver);

    conn = DriverManager.getConnection(url, dbUser, password);

   } catch (ClassNotFoundException e) {

    e.printStackTrace();

   } catch (SQLException e) {

    e.printStackTrace();

   } 

   return conn;

 }

 

 public Statement getStatement(Connection conn){

  try {

   stmt = conn.createStatement();

  } catch (SQLException e) {

   e.printStackTrace();

  }

  return stmt;

 }

 

 public ResultSet getResultSet(Statement stmt, String sql){

  try {

   rs = stmt.executeQuery(sql);

  } catch (SQLException e) {

   e.printStackTrace();

  }

  return rs;

 }

 

 public void free(ResultSet rs, Statement stmt, Connection conn){

  if(null != rs){

   try {

    rs.close();

   } catch (SQLException e) {

    e.printStackTrace();

   }finally{

    rs = null;

   }

  }

  if(null != stmt){

   try {

    stmt.close();

   } catch (SQLException e) {

    e.printStackTrace();

   }finally{

    stmt = null;

   }

  }

  if(null != conn){

   try {

    conn.close();

   } catch (SQLException e) {

    e.printStackTrace();

   }finally{

    conn = null;

   }

  }

 }

}