java-writing a JDBC operation class

1. By reading the file configuration

 Packagedatabase operation class; /** Db.java Created on August 20, 2007, Morning 8:37*/      ImportJava.io.*; ImportJava.sql.*; Importjava.util.Properties;  Public classDB {PrivateString driver; PrivateString URL; PrivateString User; PrivateString password; PrivateConnection Conn; PrivateStatement stm; PrivateResultSet rs;  PublicDB () { This("Dbconf.properties"); }           PublicDB (String conf) {loadProperties (conf);          Setconn (); }           PublicConnection Getconn () {return  This. Conn; }        //handle the properties file to get the informations for connection        Private voidloadProperties (String conf) {Properties props=NewProperties (); Try{props.load (Newfileinputstream (conf)); } Catch(FileNotFoundException e) {e.printstacktrace (); } Catch(IOException e) {e.printstacktrace (); }               This. Driver = Props.getproperty ("Driver");  This. url = props.getproperty ("url");  This. user = Props.getproperty ("User");  This. Password = props.getproperty ("Password"); }          //Implement the Connection        Private voidSetconn () {Try{class.forname (driver);  This. conn =drivermanager.getconnection (Url,user,password); } Catch(ClassNotFoundException classnotfoundexception) {classnotfoundexception.printstacktrace (); System.err.println ("DB:" +classnotfoundexception.getmessage ()); } Catch(SQLException SQLException) {System.err.println ("Db.getconn ():" +sqlexception.getmessage ()); }          }              Public voidDoinsert (String sql) {Try{Statement Statement=conn.createstatement (); inti =stm.executeupdate (SQL); } Catch(SQLException SQLException) {System.err.println ("Db.executeinset:" +sqlexception.getmessage ()); }          }           Public voiddoDelete (String sql) {Try{STM=conn.createstatement (); inti =stm.executeupdate (SQL); } Catch(SQLException SQLException) {System.err.println ("Db.executedelete:" +sqlexception.getmessage ()); }          }           Public voiddoupdate (String sql) {Try{STM=conn.createstatement (); inti =stm.executeupdate (SQL); } Catch(SQLException SQLException) {System.err.println ("Db.executeupdate:" +sqlexception.getmessage ()); }          }                     PublicResultSet doselect (String sql) {Try{STM=conn.createstatement (java.sql.resultset.type_scroll_insensitive,java.sql.resultset.concur_read_only); RS=stm.executequery (SQL); } Catch(SQLException SQLException) {System.err.println ("Db.executequery:" +sqlexception.getmessage ()); }              returnrs; }           Public Static voidMain (string[] args) {Try{db db=NewDB (); Connection Conn=Db.getconn (); if(Conn! =NULL&&!conn.isclosed ()) {System.out.println ("Success"); ResultSet RS= Db.doselect ("SELECT * from Content");  while(Rs.next ()) {System.out.println (rs.getstring (1) + ":" +rs.getstring (2) + ":" +rs.getstring (3));                      } rs.close ();                  Conn.close (); }              }Catch(SQLException e) {e.printstacktrace (); }          }        }  

java-writing a JDBC operation class