mvc用户登录源代码，程序简单逻辑清晰

package jzh.dao; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; import jzh.conn.Conn; import jzh.entity.Login; /* * 用户相关操作实现类 */ public class LoginDao { private Connection conn = null; private PreparedStatement pstmt = null; private ResultSet rs = null; /* * 验证用户登录 */ public Login validLogin(String username, String password) { Login logins = new Login(); String sql = "select * from login where userna = '" + username + "' and userpass = '" + password + "'"; try { conn = Conn.getConnection(); pstmt = conn.prepareStatement(sql); rs = pstmt.executeQuery(); if (rs.next()) { logins.setUserna(username); logins.setUserpass(password); } else { logins = null; } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { Conn.closeAll(rs, pstmt, conn);// 关闭所有链接 } return logins; } /* * 列出所有的用户名单 */ public List selectAlluser() { List list = new ArrayList(); String sql = "select * from login"; conn = Conn.getConnection(); try { pstmt =conn.prepareStatement(sql); rs = pstmt.executeQuery(); while (rs.next()){ Login logins=new Login(); logins.setUserna(rs.getString("userna")); logins.setUserpass(rs.getString("userpass")); list.add(logins); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ Conn.closeAll(rs, pstmt, conn);// 关闭所有链接 } return list; } }