jsp常用模块实例（MVC）

package JavaBean; import java.sql.ResultSet; import java.sql.SQLException; import java.util.Vector; import JavaBean.Goods; import JavaBean.DB_Conn; public class DB_goods{ DB_Conn db_conn = new DB_Conn(); //列出网上商城中的所有商品 public Vector list_goods(){ db_conn.ConnectDB(); ResultSet rs = null; try{ String sql = "select * from goods"; sql=new String (sql.getBytes("ISO8859-1"),"GB2312"); rs=db_conn.sm.executeQuery(sql); Goods goods=null; Vector vector =new Vector(); //ResultSet指针最初位于第一行之前，调用next方法使下一行成为当前行 while(rs.next()){ goods=new Goods(); goods.setGoods_id(rs.getInt("goods_id")); goods.setGoods_name(rs.getString("goods_name")); goods.setTypeid(rs.getInt("typeid")); goods.setGoods_price(rs.getFloat("goods_price")); goods.setGoods_discount(rs.getFloat("goods_discount")); goods.setGoods_desc(rs.getString("goods_desc")); goods.setGoods_suppier(rs.getString("goods_suppier")); goods.setQty(rs.getInt("qty")); goods.setIspreferred(rs.getInt("ispreferred")); goods.setGoods_pic(rs.getString("goods_pic")); //想vector矢量中添加对象goods vector.addElement(goods); } return vector; } catch(SQLException sqlE){ sqlE.printStackTrace(); return null; } catch(Exception E){ E.printStackTrace(); return null; } finally{ //关闭数据库连接，释放数据库资源 db_conn.closeDB(); } } //对上述函数实现重载，为了实现通过id获取商品的信息 public Vector list_goods(int id){ db_conn.ConnectDB(); ResultSet rs=null; try{ String sql = "select * from goods where goods_id="+id; sql=new String(sql.getBytes("ISO8859-1"),"GB2312"); rs=db_conn.sm.executeQuery(sql); Goods goods=null; Vector vector =new Vector(); //ResultSet指针最初位于第一行之前，调用next方法使下一行成为当前行 while(rs.next()){ goods=new Goods(); goods.setGoods_id(rs.getInt("goods_id")); goods.setGoods_name(rs.getString("goods_name")); goods.setTypeid(rs.getInt("typeid")); goods.setGoods_price(rs.getFloat("goods_price")); goods.setGoods_discount(rs.getFloat("goods_discount")); goods.setGoods_desc(rs.getString("goods_desc")); goods.setGoods_suppier(rs.getString("goods_suppier")); goods.setQty(rs.getInt("qty")); goods.setIspreferred(rs.getInt("ispreferred")); goods.setGoods_pic(rs.getString("goods_pic")); //想vector矢量中添加对象goods vector.addElement(goods); } return vector; } catch(SQLException sqlE){ sqlE.printStackTrace(); return null; } catch(Exception E){ E.printStackTrace(); return null; } finally{ //关闭数据库连接，释放数据库资源 db_conn.closeDB(); } } public String getStr(String s){ String str = s; try{ byte b[]=str.getBytes("ISO-8859-1"); str=new String(b); return str; } catch(Exception e){ return null; } } //检索出网上商城中商品编号为goods_id的商品 public Goods listgoods(String goods_id){ db_conn.ConnectDB(); ResultSet rs=null; try{ String sql = "select * from goods where goods_id="+goods_id; sql=new String (sql.getBytes("ISO8859-1"),"GB2312"); rs=db_conn.sm.executeQuery(sql); Goods goods=null; while(rs.next()){ goods=new Goods(); goods.setGoods_id(rs.getInt("goods_id")); goods.setGoods_name(rs.getString("goods_name")); goods.setTypeid(rs.getInt("typeid")); goods.setGoods_price(rs.getFloat("goods_price")); goods.setGoods_discount(rs.getFloat("goods_discount")); goods.setGoods_desc(rs.getString("goods_desc")); goods.setGoods_suppier(rs.getString("goods_suppier")); goods.setQty(rs.getInt("qty")); goods.setIspreferred(rs.getInt("ispreferred")); goods.setGoods_pic(rs.getString("goods_pic")); } return goods; } catch(SQLException sqlE){ sqlE.printStackTrace(); return null; } catch(Exception E){ E.printStackTrace(); return null; } finally{ //关闭数据库连接，释放数据库资源 db_conn.closeDB(); } } //列出网上商城的所有商品 public Vector list_goods(String key){ db_conn.ConnectDB(); ResultSet rs=null; Vector vector =new Vector(); try{ String sql = "select * from goods where goods_name like"+"'" +"%"+key+"%"+"'"; rs=db_conn.sm.executeQuery(sql); Goods goods=null; while(rs.next()){ goods=new Goods(); goods.setGoods_id(rs.getInt("goods_id")); goods.setGoods_name(rs.getString("goods_name")); goods.setTypeid(rs.getInt("typeid")); goods.setGoods_price(rs.getFloat("goods_price")); goods.setGoods_discount(rs.getFloat("goods_discount")); goods.setGoods_desc(rs.getString("goods_desc")); goods.setGoods_suppier(rs.getString("goods_suppier")); goods.setQty(rs.getInt("qty")); goods.setIspreferred(rs.getInt("ispreferred")); goods.setGoods_pic(rs.getString("goods_pic")); vector.addElement(goods); } return vector; } catch(SQLException sqlE){ sqlE.printStackTrace(); return null; } catch(Exception E){ E.printStackTrace(); return null; } finally{ //关闭数据库连接，释放数据库资源 db_conn.closeDB(); } } public int goods_count(){ db_conn.ConnectDB(); ResultSet rs=null; try{ String sql="select * from goods"; sql=new String (sql.getBytes("ISO8859-1"),"GB2312"); rs=db_conn.sm.executeQuery(sql); int i=0; //如果next方法返回true,说明ResultRet指针移到下一行是仍然有元素存在，则使i加1 while(rs.next()){ i++; } return i; } catch(SQLException sqlE){ sqlE.printStackTrace(); return -1; } catch(Exception E){ E.printStackTrace(); return -2; } finally{ //关闭数据库连接，释放数据库资源 db_conn.closeDB(); } } //修改商品信息 public int goods_update(Goods goods){ db_conn.ConnectDB(); try{ String sql="update goods set goods_id="+goods.getGoods_id() +",goods_name='"+goods.getGoods_name()+"',typeid=" +goods.getTypeid()+",goods_price=" +goods.getGoods_price()+",goods_discount=" +goods.getGoods_discount()+",goods_desc='" +goods.getGoods_desc()+"',goods_suppier='" +goods.getGoods_suppier()+"',qty="+goods.getQty() +",ispreferred="+goods.getIspreferred()+",goods_pic='" +goods.getGoods_pic()+"'where goods_id=" +goods.getGoods_id(); //sql=new String (sql.getBytes("ISO8859-1"),"GB2312"); System.out.println(sql); int i=db_conn.sm.executeUpdate(sql); return i; } catch(SQLException sqlE){ sqlE.printStackTrace(); return -1; } catch(Exception E){ E.printStackTrace(); return -2; } finally{ //关闭数据库连接，释放数据库资源 db_conn.closeDB(); } } //获取goods中最大标签号，以便产生下一个标签号 public int getMaxid(){ db_conn.ConnectDB(); ResultSet rs=null; try{ String querysql="select max(goods_id) as goods_id from goods"; rs = db_conn.sm.executeQuery(querysql); String max_goods_id=""; rs.next(); max_goods_id=rs.getString("goods_id"); int maxid; //如果库表中存在数据，则在检索的最大标签号的基础上加1产生下一个标签号 //否则以0作为当前标签号 if(max_goods_id != null){ maxid = Integer.parseInt(max_goods_id); maxid = maxid + 1 ; }else{ maxid=0; } return maxid; } catch(SQLException sqlE){ sqlE.printStackTrace(); return -1; } catch(Exception E){ E.printStackTrace(); return -2; } finally { //关闭连接，释放资源 db_conn.closeDB(); } } //插入商品信息 public int goods_insert(Goods goods){ db_conn.ConnectDB(); try{ String sql="insert into goods(goods_id,goods_name,typeid," +"goods_price,goods_discount,goods_desc,goods_suppier," +"qty,ispreferred,goods_pic)values("+"" +goods.getGoods_id()+","+"'" +goods.getGoods_name()+"'"+","+goods.getTypeid() +","+g