JDBC small instance tutorial

Public class Base {public static void main (String [] args) 

throws Exception {

// TODO Auto-generated method stubtemplate ();

}

static void template ()

 throws Exception {

Connection conn = null;

 Statement st = null; 

ResultSet resultset = null;

try {

// 2. establish connection conn = JdbcUtils. getConnection (); 

// 3. create statement st = conn. createStatement ();

 // 4.execute the sentence resultset=st.exe cuteQuery ("select * from user");

 // 5. processing result while (resultset. next () {

System. out. Println (resultset. getObject (1); 

System. out. println (resultset. getObject (2);

 System. out. println (resultset. getObject (3);

 System. out. println (resultset. getObject (4) ;}} 

finally {JdbcUtils. free (resultset, st, conn) ;}}

 public class JdbcUtils {private static String url = "jdbc: mysql:

 // localhost: 3306/jdbc "; 

private static String user = "root"; 

private static String password = "123"; 

private JdbcUtils () {} static {try

 {Class. forName (

"com. mysql. jdbc. driver ");}

 catch (ClassNotFoundException e) {

throw new ExceptionInInitializerError (e) ;}}

 public static Connection getConnection () 

throws SQLException {return DriverManager. getConnection (url, user, password);}

 public static void free (ResultSet resultset, Statement st, Connection conn) {/

/ 6. release resource try {if (resultset! = Null) resultset. close ();} catch (SQLException e) {

// TODO Auto-generated catch blocke. printStackTrace ();} finally {try {if (st! = Null) st. close ();} 

catch (SQLException e) {// TODO Auto-generated catch blocke. printStackTrace ();} finally {if (conn! = Null)

 try {conn. close ();} catch (SQLException e) {// TODO Auto-generated catch blocke. printStackTrace ();}}}}}