jsp+servlet+javabean的注册demo

package cn.hd.utils; import java.lang.reflect.Field; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import org.apache.commons.beanutils.BeanUtils; import cn.hd.model.Student; import cn.hd.utils.DBUtils; public class BaseDao<T> { /** * 增加，删除，修改操作的共用方法 * @param sql SQL语句 * @param params 可变参数 * @return */ public static int CommDBOperate(String sql,Object...params){ PreparedStatement pst=null; Connection conn =null; try { conn = DBUtils.getConn(); //构造SQL语句 //发送SQL语句 pst = conn.prepareStatement(sql); //设置参数 for (int i = 0; i < params.length; i++) { pst.setObject(i+1, params[i]); } //执行SQL语句 int i = pst.executeUpdate(); return i; } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ DBUtils.close(conn, pst); } return -1; } /** * 反射实现共用查询 * @param sql * @param cla * @param params * @return */ public List<T> query(String sql,Class<T> cla,Object...params){ List<T> stuList = new ArrayList<T>(); Connection conn =null; PreparedStatement pst =null; ResultSet rs = null; try { conn = DBUtils.getConn(); pst = conn.prepareStatement(sql); if (params!=null) { for(int i = 0 ; i<params.length;i++){ pst.setObject(i+1, params[i]); } } //执行SQL语句(返回结果集) rs = pst.executeQuery(); //通过元数据得到结果集的数据 ResultSetMetaData rsmt = rs.getMetaData(); int columnCount = rsmt.getColumnCount();//得到数据的列数 while (rs.next()) { T obj = cla.newInstance(); for(int i = 1;i<=columnCount;i++){ Object value = rs.getObject(i);//得到每一列的值 String columName = rsmt.getColumnName(i).toLowerCase();//得到字段名称id stuname sex age classid //根据列名，得到cla中的字段对象 Field field = cla.getDeclaredField(columName); //设置访问权限 field.setAccessible(true); field.set(obj, value);//类似于stu.setId() } stuList.add(obj); } }catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); }finally { DBUtils.close(conn, pst, rs); } return stuList; } /** * 查询多行记录 * @param sql * @param cla * @param params * @return */ public List<T> commQuery(String sql,Class<T> cla,Object...params){ List<T> stuList = new ArrayList<T>(); Connection conn =null; PreparedStatement pst =null; ResultSet rs = null; try { conn = DBUtils.getConn(); pst = conn.prepareStatement(sql); if (params!=null) { for(int i = 0 ; i<params.length;i++){ pst.setObject(i+1, params[i]); } } //执行SQL语句(返回结果集) rs = pst.executeQuery(); ResultSetMetaData rsmt = rs.getMetaData(); int columnCount = rsmt.getColumnCount(); while (rs.next()) { T obj = cla.newInstance(); Map map = new HashMap<>(); for(int i = 1;i<=columnCount;i++){ Object value = rs.getObject(i); String columName = rsmt.getColumnName(i).toLowerCase();//id stuname sex age classid map.put(columName, value); } BeanUtils.populate(obj, map); stuList.add(obj); } return stuList; }catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); }finally { DBUtils.close(conn, pst, rs); } return null; } /** * 查询单条记录 * @param sql * @param cla 对象 * @param params 参数 * @return 单个对象 */ public T findForJavaBean(String sql,Class<T> cla,Object...params){ Connection conn =null; PreparedStatement pst =null; ResultSet rs = null; try { T obj = cla.newInstance(); conn = DBUtils.getConn(); pst = conn.prepareStatement(sql); if (params!=null) { for(int i = 0 ; i<params.length;i++){ pst.setObject(i+1, params[i]); } } //执行SQL语句(返回结果集) rs = pst.executeQuery(); ResultSetMetaData rsmt = rs.getMetaData(); int columnCount = rsmt.getColumnCount(); if (rs.next()) { Map map = new HashMap<>(); for(int i = 1;i<=columnCount;i++){ Object value = rs.getObject(i); String columName = rsmt.getColumnName(i).toLowerCase();//id stuname sex age classid map.put(columName, value); } BeanUtils.populate(obj, map); } return obj; }catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); }finally { DBUtils.close(conn, pst, rs); } return null; } public static Student findForJavaBean(String sql,Object...params){ Connection conn =null; PreparedStatement pst =null; ResultSet rs = null; try { Student obj = new Student(); conn = DBUtils.getConn(); pst = conn.prepareStatement(sql); if (params!=null) { for(int i = 0 ; i<params.length;i++){ pst.setObject(i+1, params[i]); } } //执行SQL语句(返回结果集) rs = pst.executeQuery(); ResultSetMetaData rsmt = rs.getMetaData(); int columnCount = rsmt.getColumnCount(); if (rs.next()) { Map map = new HashMap<>(); for(int i = 1;i<=columnCount;i++){ Object value = rs.getObject(i); String columName = rsmt.getColumnName(i).toLowerCase();//id stuname sex age classid map.put(columName, value); } BeanUtils.populate(obj, map); } return obj; }catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); }finally { DBUtils.close(conn, pst, rs); } return null; } }