myeclipse mysql servlet从前端获取数据

package com.jkx.dao; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.sql.Connection; import java.util.ArrayList; import java.util.List; import java.util.Map; import com.jkx.po.User; import com.jkx.util.DBconn; public class UserDao { //데절친駕 public UserDao(){ } public static UserDao userdao=new UserDao(); public static UserDao getIntance() { return userdao; } public boolean saveUser(User user) throws SQLException { boolean flag=false; Connection conn=null; //Statement st=null; PreparedStatement ps=null; try { conn=DBconn.getConnetctio(); String sql ="insert into user(username,password,flag) values(?,?,?)"; ps=conn.prepareStatement(sql); ps.setString(1, user.getUsername()); ps.setString(2, user.getPassword()); ps.setString(3, user.getFlag()); //st=conn.createStatement(); int rows=ps.executeUpdate(); if(rows>0) { flag=true; } System.out.println(sql); } finally { DBconn.Psclose(ps,conn); } return flag; } public boolean deleteUserById(int userid) throws SQLException { boolean boo=false; Connection conn=null; //Statement st=null; PreparedStatement ps=null; try { conn=DBconn.getConnetctio(); String sql ="delete from user where userid=?"; //st=conn.createStatement(); ps=conn.prepareStatement(sql); ps.setInt(1, userid); //int rows=st.executeUpdate(sql); int rows=ps.executeUpdate(); if(rows>0) { boo=true; } } finally { DBconn.Psclose(ps,conn); } return boo; } public boolean updateUserById(Map<String, Object> map) throws SQLException { boolean boo=false; Connection conn=null; Statement st=null; try { conn=DBconn.getConnetctio(); String sql ="update user set username='"+(String)map.get("username")+"' where userid="+(Integer)map.get("userid"); st=conn.createStatement(); int rows=st.executeUpdate(sql); if(rows>0) { boo=true; } } finally { DBconn.close(st,conn); } return boo; } public User getUserByusernameAndPasswoed(String name,String pass) { User user=null; Connection conn=null; PreparedStatement ps=null; conn=DBconn.getConnetctio(); ResultSet rs=null; String sql ="select * from user where username=? and password=?"; try { ps=conn.prepareStatement(sql); ps.setString(1, name); ps.setString(2, pass); rs=ps.executeQuery(); if(rs.next()) { user=new User(); user.setUserid(rs.getInt("userid")); user.setUsername(rs.getString("username")); user.setPassword(rs.getString("password")); user.setFlag(rs.getString("flag")); user.setSex(rs.getInt("sex")); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { DBconn.Rsclose(rs,ps, conn); } return user; } public List<User> getUserList() { List<User> userlist=new ArrayList<User>(); Connection conn=null; PreparedStatement ps=null; conn=DBconn.getConnetctio(); ResultSet rs=null; String sql ="select * from user"; try { ps=conn.prepareStatement(sql); rs=ps.executeQuery(); while(rs.next()) { User user=new User(); user.setUserid(rs.getInt("userid")); user.setUsername(rs.getString("username")); user.setPassword(rs.getString("password")); user.setFlag(rs.getString("flag")); user.setSex(rs.getInt("sex")); userlist.add(user); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { DBconn.Rsclose(rs,ps, conn); } return userlist; } }