好像是这里面读不到数据，改了很久还是改不出来，求助！
package com.ding.dao;
import com.ding.entity.user;
import com.ding.util.DBHelper;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
/**
*
-
@author irin
*/
public class userDao extends DBHelper{public user login(String username, String password){
user u = null;
String sql = "select * from user where username = ? and password=?";
try{
ResultSet rs = this.executeQuery(sql,username,password);
if(rs.next()){
u = new user();
u.setUsername(rs.getString(1));
u.setPassword(rs.getString(2));
}
}catch(Exception e){
e.printStackTrace();
}finally{
this.close();}return u;
}
}
package com.ding.servlet;
import com.ding.dao.userDao;
import com.ding.entity.user;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
*
-
@author irin
*/
public class userServlet extends HttpServlet {@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req,resp);
}
private userDao userdao = new userDao();
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("utf-8");
String username = req.getParameter("user");
String password = req.getParameter("password");user u = new user(); u.setUsername(username); u.setPassword(password); userDao userdao = new userDao(); if(userdao.login(username,password)!=null){ req.setAttribute("user",u ); resp.sendRedirect("welcome.jsp"); } else req.getRequestDispatcher("sorry.jsp").forward(req, resp);}
}
package com.ding.entity;
/**
*
-
@author irin
*/
public class user {
// private int id;
private String username;
private String password;
// private String role;public user() {
}public user(String username, String password) {
this.username = username;
this.password = password;
}public String getUsername() {
return username;
}public void setUsername(String username) {
this.username = username;
}public String getPassword() {
return password;
}public void setPassword(String password) {
this.password = password;
}
}
package com.ding.util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
*
-
@author irin
*/
public class DBHelper {
private Connection conn;
private PreparedStatement ps;
private ResultSet rs;//获得连接
private void getConnection(){
try {
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql://localhost:3306/dormitorymanage?characterEncoding=utf8&useSSL=true";
conn = DriverManager.getConnection(url,"root","Ding1234");
} catch (Exception e) {
e.printStackTrace();
}}
//关闭
public void close(){
if(conn!=null){
try {
conn.close();
} catch (Exception e) {
e.printStackTrace();
}
conn = null;
}if(ps!=null){ try { ps.close(); } catch (Exception e) { e.printStackTrace(); } ps = null; } if(rs!=null){ try { rs.close(); } catch (Exception e) { e.printStackTrace(); } rs = null; }}
//更新--增加、修改、删除
public int executeUpdate(String sql,Object...objects){
try {
this.getConnection();
ps = conn.prepareStatement(sql);
if(objects!=null){
for(int i=0;i<objects.length;i++){
ps.setObject(i+1, objects[i]);
}
}
return ps.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
}finally{
this.close();
}
return -1;
}//查询
public ResultSet executeQuery(String sql,Object...objects){
try {
this.getConnection();
ps = conn.prepareStatement(sql);
if(objects!=null){
for(int i=0;i<objects.length;i++){
ps.setObject(i+1, objects[i]);
}
}
return rs = ps.executeQuery();
} catch (SQLException e) {
e.printStackTrace();
}
return null;
}
}
