JSP+Servlet+JavaBean增删改查实例

package com.bcit.dao; import java.io.Serializable; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; import com.bcit.BaseDao; import com.bcit.DBConnection; import com.bcit.entity.Stu; public class StuDao implements BaseDao<Stu> { DBConnection dbConnection = new DBConnection(); private PreparedStatement pstmt = null; public void add(Stu stu) { String sql = "insert into stu(sname) values(?)"; pstmt = dbConnection.prepareStmt(sql); try { pstmt.setString(1,stu.getSname()); pstmt.executeUpdate(); System.out.println("新加成功！"); } catch (SQLException e) { e.printStackTrace(); }finally{ dbConnection.closePstmt(pstmt); } } /** * 查询列表 */ public List<Stu> query() { List<Stu> list = new ArrayList<Stu>(); String sql = "select * from stu"; ResultSet rs = dbConnection.exeQuery(sql); try { while(rs.next()){ String sname = rs.getString("sname"); String sidStr = rs.getString("sid"); int sid = Integer.parseInt(sidStr); Stu stu = new Stu(); stu.setSname(sname); stu.setSid(sid); list.add(stu); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ dbConnection.closeRs(rs); } return list; } /** * 条件查询 */ public List<Stu> query(Stu g) { int sid = g.getSid(); String sidstr = Integer.toString(sid); String sname = g.getSname(); List<Stu> list = new ArrayList<Stu>(); String sql = "select * from stu where 1=1"; StringBuffer sb = new StringBuffer(sql); if(sidstr!=null&&!"".equals(sidstr)&&!sidstr.equals("0")){ sb.append(" and sid='"+sid+"'"); } if(sname!=null&&!"".equals(sname)){ sb.append(" and sname like '%"+sname+"%'"); } String sql2 = sb.toString(); ResultSet rs = dbConnection.exeQuery(sql2); try { while(rs.next()){ String sidstr2 = rs.getString("sid"); String sname2 = rs.getString("sname"); int sid2 = Integer.valueOf(sidstr2); Stu stu = new Stu(); stu.setSid(sid2); stu.setSname(sname2); list.add(stu); } } catch (SQLException e) { e.printStackTrace(); }finally{ dbConnection.closeRs(rs); } return list; } /** * jdbc 分页查询 */ public void query(int startNo, int maxCount) { String sql = "select * from stu"; PreparedStatement pstmt = dbConnection.prepareStmt(sql); }; public void del(Serializable sid) { String sql = "delete from stu where sid=?"; pstmt = dbConnection.prepareStmt(sql); try { pstmt.setString(1, sid.toString()); pstmt.executeUpdate(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ dbConnection.closePstmt(pstmt); } } public Stu get(Serializable sid) { Stu s = new Stu(); String sql = "select * from stu where sid='"+sid+"'"; ResultSet rs = dbConnection.exeQuery(sql); try { while(rs.next()){ String sidstr = rs.getString("sid"); int sid2 = Integer.valueOf(sidstr); String sname = rs.getString("sname"); s.setSid(sid2); s.setSname(sname); } } catch (SQLException e) { e.printStackTrace(); } return s; } public void mod(Stu stu) { int sid = stu.getSid(); String sname = stu.getSname(); String sql = "update stu set sname=? where sid='"+sid+"'"; pstmt = dbConnection.prepareStmt(sql); try { pstmt.setString(1, sname); pstmt.executeUpdate(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ dbConnection.closePstmt(pstmt); } } }