用java编写的登录系统，并且有验证 码登录的功能

package cn.com.zzb.eshopping.db; import java.sql.*; import java.util.Date; public class DBConnect { private Connection conn; private Statement stmt; private ResultSet rst; private void init() { try { Class.forName("com.mysql.jdbc.Driver"); String url="jdbc:mysql://localhost:3306/userinfo"; conn=DriverManager.getConnection(url, "root", "123"); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } public DBConnect() { try { init(); stmt=conn.createStatement(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } public void executeQuery(String s) { try { if(stmt!=null) rst=stmt.executeQuery(s); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } public int executeUpdate(String s) { int status=0; try { if(stmt!=null) status=stmt.executeUpdate(s); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } return status; } public void close() { try { if(conn!=null) conn.close(); if(stmt!=null) stmt.close(); if(rst!=null) rst.close(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } public Boolean next() { try { return rst.next(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); return false; } } public Boolean getBoolean(int i)throws Exception { return rst.getBoolean(i); } public Boolean getBoolean(String s )throws Exception { return rst.getBoolean(s); } public Date geDate(int i)throws Exception { return rst.getDate(i); } public Date geDate(String s)throws Exception { return rst.getDate(s); } public Time geTime(int i)throws Exception { return rst.getTime(i); } public Time geTime(String s)throws Exception { return rst.getTime(s); } public Long geLong(int i)throws Exception { return rst.getLong(i); } public Long geLong(String s)throws Exception { return rst.getLong(s); } public int getInt(int i)throws Exception { return rst.getInt(i); } public int getInt(String s)throws Exception { return rst.getInt(s); } public String getString(String s)throws Exception { return rst.getString(s); } }