JSP开发模式比较，JSP入门实例——model1VSmodel2

package com.model.javabean; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class DB { private String classname="com.microsoft.sqlserver.jdbc.SQLServerDriver"; private String URL="jdbc:sqlserver://localhost:1433;DatabaseName=db_JSDQ08"; private String username="sa"; private String pwd="1"; private Connection con; private Statement stm; private ResultSet rs; public DB(){ try{ Class.forName(classname); }catch(ClassNotFoundException e){ e.printStackTrace(); System.out.println("加载数据库驱动失败！"); } } private void getCon(){ if(con==null){ try{ con=DriverManager.getConnection(URL,username,pwd); }catch(SQLException e){ con=null; e.printStackTrace(); System.out.println("创建数据库连接失败！"); } } } private void getStm(){ if(stm==null){ try { getCon(); stm=con.createStatement(); } catch (SQLException e) { System.out.println("创建Statement对象失败！"); e.printStackTrace(); } } } private void getStmed(){ if(stm==null){ try { getCon(); stm=con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE ,ResultSet.CONCUR_READ_ONLY); } catch (SQLException e) { e.printStackTrace(); System.out.println("创建用来生成可滚动结果集的Statement对象失败！"); } } } public ResultSet Read(String sql){ if(sql==null)sql=""; System.out.println("sql:"+sql); getStmed(); ResultSet rs=null; try { rs = stm.executeQuery(sql); } catch (SQLException e) { rs=null; e.printStackTrace(); System.out.println("查询数据库失败！"); } return rs; } public int CreateOrUpdate(String sql){ if(sql==null)sql=""; System.out.println("sql:"+sql); getStmed(); int i=0; try { i = stm.executeUpdate(sql); } catch (SQLException e) { i=0; e.printStackTrace(); System.out.println("插入或更新数据失败！"); } return i; } public void closed(){ try{ if(rs!=null){ rs.close(); } if(stm!=null){ stm.close(); } if(con!=null){ con.close(); } }catch(SQLException e){ e.printStackTrace(); System.out.println("关闭数据库失败！"); } } }