系统功能结构图：

数据库结构要素：

            4.0.0    com.mario   smbms   1.0-SNAPSHOT   war   

创建smbss数据库的sql语句代码

pojo下编写对应数据库表的实体类，分类为Bill Role Provider User

Bill

import java.math.BigDecimal;
import java.util.Date;
public class Bill {
   private Integer id;   //id 
   private String billCode; //账单编码 
   private String productName; //商品名称 
   private String productDesc; //商品描述 
   private String productUnit; //商品单位
   private BigDecimal productCount; //商品数量 
   private BigDecimal totalPrice; //总金额
   private Integer isPayment; //是否支付 
   private Integer providerId; //供应商ID 
   private Integer createdBy; //创建者
   private Date creationDate; //创建时间
   private Integer modifyBy; //更新者
   private Date modifyDate;//更新时间
   
   private String providerName;//供应商名称
   
   
   public String getProviderName() {
   	return providerName;
   }
   public void setProviderName(String providerName) {
   	this.providerName = providerName;
   }
   public Integer getId() {
   	return id;
   }
   public void setId(Integer id) {
   	this.id = id;
   }
   public String getBillCode() {
   	return billCode;
   }
   public void setBillCode(String billCode) {
   	this.billCode = billCode;
   }
   public String getProductName() {
   	return productName;
   }
   public void setProductName(String productName) {
   	this.productName = productName;
   }
   public String getProductDesc() {
   	return productDesc;
   }
   public void setProductDesc(String productDesc) {
   	this.productDesc = productDesc;
   }
   public String getProductUnit() {
   	return productUnit;
   }
   public void setProductUnit(String productUnit) {
   	this.productUnit = productUnit;
   }
   public BigDecimal getProductCount() {
   	return productCount;
   }
   public void setProductCount(BigDecimal productCount) {
   	this.productCount = productCount;
   }
   public BigDecimal getTotalPrice() {
   	return totalPrice;
   }
   public void setTotalPrice(BigDecimal totalPrice) {
   	this.totalPrice = totalPrice;
   }
   public Integer getIsPayment() {
   	return isPayment;
   }
   public void setIsPayment(Integer isPayment) {
   	this.isPayment = isPayment;
   }
   
   public Integer getProviderId() {
   	return providerId;
   }
   public void setProviderId(Integer providerId) {
   	this.providerId = providerId;
   }
   public Integer getCreatedBy() {
   	return createdBy;
   }
   public void setCreatedBy(Integer createdBy) {
   	this.createdBy = createdBy;
   }
   public Date getCreationDate() {
   	return creationDate;
   }
   public void setCreationDate(Date creationDate) {
   	this.creationDate = creationDate;
   }
   public Integer getModifyBy() {
   	return modifyBy;
   }
   public void setModifyBy(Integer modifyBy) {
   	this.modifyBy = modifyBy;
   }
   public Date getModifyDate() {
   	return modifyDate;
   }
   public void setModifyDate(Date modifyDate) {
   	this.modifyDate = modifyDate;
   }
}

Role

import java.util.Date;
public class Role {	
   private Integer id;   //id
   private String roleCode; //角色编码
   private String roleName; //角色名称
   private Integer createdBy; //创建者
   private Date creationDate; //创建时间
   private Integer modifyBy; //更新者
   private Date modifyDate;//更新时间
   
   public Integer getId() {
   	return id;
   }
   public void setId(Integer id) {
   	this.id = id;
   }
   public String getRoleCode() {
   	return roleCode;
   }
   public void setRoleCode(String roleCode) {
   	this.roleCode = roleCode;
   }
   public String getRoleName() {
   	return roleName;
   }
   public void setRoleName(String roleName) {
   	this.roleName = roleName;
   }
   public Integer getCreatedBy() {
   	return createdBy;
   }
   public void setCreatedBy(Integer createdBy) {
   	this.createdBy = createdBy;
   }
   public Date getCreationDate() {
   	return creationDate;
   }
   public void setCreationDate(Date creationDate) {
   	this.creationDate = creationDate;
   }
   public Integer getModifyBy() {
   	return modifyBy;
   }
   public void setModifyBy(Integer modifyBy) {
   	this.modifyBy = modifyBy;
   }
   public Date getModifyDate() {
   	return modifyDate;
   }
   public void setModifyDate(Date modifyDate) {
   	this.modifyDate = modifyDate;
   }
}

Provider

import java.util.Date;
public class Provider {
   private Integer id;   //id
   private String proCode; //供应商编码
   private String proName; //供应商名称
   private String proDesc; //供应商描述
   private String proContact; //供应商联系人
   private String proPhone; //供应商电话
   private String proAddress; //供应商地址
   private String proFax; //供应商传真
   private Integer createdBy; //创建者
   private Date creationDate; //创建时间
   private Integer modifyBy; //更新者
   private Date modifyDate;//更新时间

   public Integer getId() {
   	return id;
   }
   public void setId(Integer id) {
   	this.id = id;
   }
   public String getProCode() {
   	return proCode;
   }
   public void setProCode(String proCode) {
   	this.proCode = proCode;
   }
   public String getProName() {
   	return proName;
   }
   public void setProName(String proName) {
   	this.proName = proName;
   }
   public String getProDesc() {
   	return proDesc;
   }
   public void setProDesc(String proDesc) {
   	this.proDesc = proDesc;
   }
   public String getProContact() {
   	return proContact;
   }
   public void setProContact(String proContact) {
   	this.proContact = proContact;
   }
   public String getProPhone() {
   	return proPhone;
   }
   public void setProPhone(String proPhone) {
   	this.proPhone = proPhone;
   }
   public String getProAddress() {
   	return proAddress;
   }
   public void setProAddress(String proAddress) {
   	this.proAddress = proAddress;
   }
   public String getProFax() {
   	return proFax;
   }
   public void setProFax(String proFax) {
   	this.proFax = proFax;
   }
   public Integer getCreatedBy() {
   	return createdBy;
   }
   public void setCreatedBy(Integer createdBy) {
   	this.createdBy = createdBy;
   }
   public Date getCreationDate() {
   	return creationDate;
   }
   public void setCreationDate(Date creationDate) {
   	this.creationDate = creationDate;
   }
   public Integer getModifyBy() {
   	return modifyBy;
   }
   public void setModifyBy(Integer modifyBy) {
   	this.modifyBy = modifyBy;
   }
   public Date getModifyDate() {
   	return modifyDate;
   }
   public void setModifyDate(Date modifyDate) {
   	this.modifyDate = modifyDate;
   }
}

User

import java.util.Date;
public class User {
   private Integer id; //id 
   private String userCode; //用户编码
   private String userName; //用户名称
   private String userPassword; //用户密码
   private Integer gender;  //性别
   private Date birthday;  //出生日期
   private String phone;   //电话
   private String address; //地址
   private Integer userRole;    //用户角色
   private Integer createdBy;   //创建者
   private Date creationDate; //创建时间
   private Integer modifyBy;     //更新者
   private Date modifyDate;   //更新时间
   
   private Integer age;//年龄
   private String userRoleName;    //用户角色名称


   public String getUserRoleName() {
   	return userRoleName;
   }
   public void setUserRoleName(String userRoleName) {
   	this.userRoleName = userRoleName;
   }
   public Integer getAge() {
   	Date date = new Date();
   	Integer age = date.getYear()-birthday.getYear();
   	return age;
   }
   public Integer getId() {
   	return id;
   }
   public void setId(Integer id) {
   	this.id = id;
   }
   public String getUserCode() {
   	return userCode;
   }
   public void setUserCode(String userCode) {
   	this.userCode = userCode;
   }
   public String getUserName() {
   	return userName;
   }
   public void setUserName(String userName) {
   	this.userName = userName;
   }
   public String getUserPassword() {
   	return userPassword;
   }
   public void setUserPassword(String userPassword) {
   	this.userPassword = userPassword;
   }
   public Integer getGender() {
   	return gender;
   }
   public void setGender(Integer gender) {
   	this.gender = gender;
   }
   public Date getBirthday() {
   	return birthday;
   }
   public void setBirthday(Date birthday) {
   	this.birthday = birthday;
   }
   public String getPhone() {
   	return phone;
   }
   public void setPhone(String phone) {
   	this.phone = phone;
   }
   public String getAddress() {
   	return address;
   }
   public void setAddress(String address) {
   	this.address = address;
   }
   public Integer getUserRole() {
   	return userRole;
   }
   public void setUserRole(Integer userRole) {
   	this.userRole = userRole;
   }
   public Integer getCreatedBy() {
   	return createdBy;
   }
   public void setCreatedBy(Integer createdBy) {
   	this.createdBy = createdBy;
   }
   public Date getCreationDate() {
   	return creationDate;
   }
   public void setCreationDate(Date creationDate) {
   	this.creationDate = creationDate;
   }
   public Integer getModifyBy() {
   	return modifyBy;
   }
   public void setModifyBy(Integer modifyBy) {
   	this.modifyBy = modifyBy;
   }
   public Date getModifyDate() {
   	return modifyDate;
   }
   public void setModifyDate(Date modifyDate) {
   	this.modifyDate = modifyDate;
   }

}

resources下新建db.properties文件

      driver=com.mysql.cj.jdbc.Driver
      url=jdbc:mysql://localhost:3306?useUnicode=true&characterEncoding=utf-8
      username=root
      password=123456

在dao下新建BaseDao类用于读取上面的数据库配置文件

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;
//操作数据库的公共类
     public class BaseDao {     
         private static String driver;
         private static String url;
         private static String username;
         private static String password;
     
         //静态代码块，类加载的时候就初始化了
         static {
             Properties properties = new Properties();
             //通过类加载器读取对应的资源
             InputStream is = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");
     
             try {
                 properties.load(is);
             } catch (IOException e) {
                 e.printStackTrace();
             }
     
             driver = properties.getProperty("driver");
             url = properties.getProperty("url");
             username = properties.getProperty("username");
             password = properties.getProperty("password");
         }
     
         //获取数据库的链接
         public static Connection getConnection(){
             Connection connection = null;
             try {
                 Class.forName(driver);
                 connection = DriverManager.getConnection(url, username, password);
             } catch (Exception e) {
                 e.printStackTrace();
             }
             return connection;
         }
     
         //编写查询公共方法
         public static ResultSet execute(Connection connection,String sql,Object[] params,ResultSet resultSet,PreparedStatement preparedStatement) throws SQLException {
             //预编译的sql，在后面直接执行就可以了
             preparedStatement = connection.prepareStatement(sql);
     
             for (int i = 0; i < params.length; i++) {
                 //setObject,占位符从1开始，但是我们的数组是从0开始！
                 preparedStatement.setObject(i+1,params[i]);
             }
     
             resultSet = preparedStatement.executeQuery();
             return resultSet;
         }
     
     
         //编写增删改公共方法
         public static int execute(Connection connection,String sql,Object[] params,PreparedStatement preparedStatement) throws SQLException {
             preparedStatement = connection.prepareStatement(sql);
     
             for (int i = 0; i < params.length; i++) {
                 //setObject,占位符从1开始，但是我们的数组是从0开始！
                 preparedStatement.setObject(i+1,params[i]);
             }
     
             int updateRows = preparedStatement.executeUpdate();
             return updateRows;
         }
     
     
         //释放资源
         public static boolean closeResource(Connection connection,PreparedStatement preparedStatement,ResultSet resultSet){
             boolean flag = true;
     
             if (resultSet!=null){
                 try {
                     resultSet.close();
                     //GC回收
                     resultSet = null;
                 } catch (SQLException e) {
                     e.printStackTrace();
                     flag = false;
                 }
             }
     
             if (preparedStatement!=null){
                 try {
                     preparedStatement.close();
                     //GC回收
                     preparedStatement = null;
                 } catch (SQLException e) {
                     e.printStackTrace();
                     flag = false;
                 }
             }
     
             if (connection!=null){
                 try {
                     connection.close();
                     //GC回收
                     connection = null;
                 } catch (SQLException e) {
                     e.printStackTrace();
                     flag = false;
                 }
             }
             return flag;
         }
     }

import javax.servlet.*;
import java.io.IOException;

public class CharacterEncodingFilter implements Filter {

    public void init(FilterConfig filterConfig) throws ServletException {
    }
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        chain.doFilter(request,response);
    }
    public void destroy() {

    }
}

然后在web.xml中注册

    
        CharacterEncodingFilter
        com.kuang.filter.CharacterEncodingFilter
    
    
        CharacterEncodingFilter
        /*
    

放在webapp目录下

github地址
gitee地址

流程结构

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>



    
    
    
    


    

        

            
超市订单管理系统
        
        

	        

				
${error}
				

                    用户名：
					
				
	
				

                    密码：
                    
                
	
				

					
                    
                    
                
	
			
        
    

在web.xml中加入这段话

    
        login.jsp
    

在dao中建立一个user包，在包中建一个UserDao接口，在接口中写

import com.mario.pojo.User;

import java.sql.Connection;
import java.sql.SQLException;

public interface UserDao {
    public User getLoginUser(Connection connection, String userCode, String userPassword) throws SQLException;

}

import com.mario.dao.BaseDao;
import com.mario.pojo.User;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class UserDaoImpl implements UserDao {
    //得到要登录的用户
    public User getLoginUser(Connection connection, String userCode,String userPassword) throws SQLException {
        PreparedStatement pstm = null;
        ResultSet rs = null;
        User user = null;

        if (connection!=null){
            String sql = "select * from smbms_user where userCode=?";
            Object[] params = {userCode};
            //System.out.println(userPassword);
            rs = BaseDao.execute(connection,sql,params,rs,pstm);
            if (rs.next()){
                user = new User();
                user.setId(rs.getInt("id"));
                user.setUserCode(rs.getString("userCode"));
                user.setUserName(rs.getString("userName"));
                user.setUserPassword(rs.getString("userPassword"));
                user.setGender(rs.getInt("gender"));
                user.setBirthday(rs.getDate("birthday"));
                user.setPhone(rs.getString("phone"));
                user.setAddress(rs.getString("address"));
                user.setUserRole(rs.getInt("userRole"));
                user.setCreatedBy(rs.getInt("createdBy"));
                user.setCreationDate(rs.getTimestamp("creationDate"));
                user.setModifyBy(rs.getInt("modifyBy"));
                user.setModifyDate(rs.getTimestamp("modifyDate"));
            }
            BaseDao.closeResource(null,pstm,rs);
            if (!user.getUserPassword().equals(userPassword))
                user=null;
        }
        return user;
    }
}

在service下建立user包，建立UserService接口

import com.mario.pojo.User;

public interface UserService {
    //用户登录
    public User login(String userCode, String password);
}

在service的user包中建立UserServiceImpl类

import com.mario.dao.BaseDao;
import com.mario.dao.user.UserDao;
import com.mario.dao.user.UserDaoImpl;
import com.mario.pojo.User;
import org.junit.Test;

import java.sql.Connection;
import java.sql.SQLException;

public class UserServiceImpl implements UserService {

    //业务层都会调用dao层，所以我们要引入Dao层；
    private UserDao userDao;
    public UserServiceImpl(){
        userDao = new UserDaoImpl();
    }


    public User login(String userCode, String password) {
        Connection connection = null;
        User user = null;

        try {
            connection = BaseDao.getConnection();
            //通过业务层调用对应的具体的数据库操作
            user = userDao.getLoginUser(connection, userCode,password);
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            BaseDao.closeResource(connection,null,null);
        }
        return user;
    }
//    @Test
//    public void test(){
//        UserServiceImpl userService = new UserServiceImpl();
//        User login = userService.login("test", "111");
//        System.out.println(login.getUserPassword());
//    }

}

在Servlet包中创建user包，在user包中建立LoginServlet类

import com.mario.pojo.User;
import com.mario.service.user.UserService;
import com.mario.service.user.UserServiceImpl;
import com.mario.util.Constants;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class LoginServlet extends HttpServlet {
    //Servlet:控制层，调用业务层代码

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        System.out.println("LoginServlet--start....");
        //获取用户名和密码
        String userCode = req.getParameter("userCode");
        String userPassword = req.getParameter("userPassword");
        //和数据库中的密码进行对比，调用业务层；
        UserService userService = new UserServiceImpl();
        User user = userService.login(userCode, userPassword);  //这里已经把登录的人给查出来了
        System.out.println(userCode);
        System.out.println(userPassword);
        if (user!=null){ //查有此人，可以登录
            //将用户的信息放到Session中;
            req.getSession().setAttribute(Constants.USER_SESSION,user);
            //跳转到主页重定向
            resp.sendRedirect("jsp/frame.jsp");
        }else {//查无此人，无法登录
            //转发回登录页面，顺带提示它，用户名或者密码错误；
            req.setAttribute("error","用户名或者密码不正确");
            req.getRequestDispatcher("login.jsp").forward(req,resp);
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

在web.xml中注册当前的Servlet

    
        login
        com.mario.servlet.user.LoginServlet
    
    
        login
        /login.do
    

移除session，返回登录页面,servlet.user下创建LogoutServlet类

import com.mario.util.Constants;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class LogoutServlet  extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //移除用户的session
        req.getSession().removeAttribute(Constants.USER_SESSION);
        resp.sendRedirect(req.getContextPath()+"/login.jsp");//返回登录页面
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

同理，在web.xml中注册注销servlet

    
        LogoutServlet
        com.mario.servlet.user.LogoutServlet
    
    
        LogoutServlet
        jsp/logout.do
    

在filter下创建SysFilter类

import com.mario.pojo.User;
import com.mario.util.Constants;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class SysFilter implements Filter {
    public void init(FilterConfig filterConfig) throws ServletException {
    }

    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;

        //过滤器，从Session中获取用户，
        User user = (User) request.getSession().getAttribute(Constants.USER_SESSION);

        if (user==null){ //已经被移除或者注销了，或者未登录
            response.sendRedirect("/smbms/error.jsp");
        }else {
            chain.doFilter(req,resp);
        }
    }

    public void destroy() {

    }
}

在web.xml中注册

    
        Sysfilter
        com.mario.filter.SysFilter
    
    
        Sysfilter
        /jsp/*
    

自顶向下设计，自底向上实现

先写基本逻辑，前端在测试后端的路上完善的

• 为了实这个功能需要自底向上逐一实现功能，修改密码需要更新数据库的相关行，所以这就需要dao层去进行增删改查操作数据

• dao层的需要的当前的一些信息，比如用户名，当前的密码，要修改的密码，所以这些就要dao层去从Service层获取这些参数

• service需要获取从Servlet层传过来的数据进行相应的处理，验证，核算，然后将最终的信息传递给dao层

• 而servlet直接与前端接触，返回当前页面上传递而来的用户输入触发的参数，转发到不同的页面，交给不同的service来处理这些请求

  意味着先从dao层开始写，分模块，先写接口，再写接口的实现类，依次写service和servlet，最后注册这个servlet，最后测试并完善前端页面

在dao.user.UserDao的接口下增加updatepwd

    //修改当前用户密码
    //增删改都会影响数据库的变化，所以是返回int类型，说明有几行受到了影响
    public int updatePwd(Connection connection,int id,String userPassword)throws SQLException;

UserDaoImpl下增加

    //修改当前用户密码
    //增删改都会影响数据库的变化，所以是返回int类型，说明有几行受到了影响
    public int updatePwd(Connection connection, int id, String userPassword) throws SQLException {
        int updateRows=0;
        PreparedStatement pstm = null;
        if(connection!=null){
            String Sql="UPDATE `smbms_user` SET `userPassword`=? WHERE `id`=? ";
            Object []params={userPassword,id};
            updateRows=BaseDao.execute(connection,Sql,params,pstm);
        }
        BaseDao.closeResource(null,pstm,null);
        return updateRows;
    }

UserService下增加

    //根据用户id修改密码
    public boolean updatePwd(int id,String password);

UserServiceImpl下增加

    //根据用户id修改密码
    //通过返回的参数flag判断是否修改成功
    public boolean updatePwd(int id, String password) {
        boolean flag = false;
        Connection connection = null;
        try{
            connection = BaseDao.getConnection();
            if(userDao.updatePwd(connection,id,password) > 0)
                flag = true;
        }catch (Exception e) {
            e.printStackTrace();
        }finally{
            BaseDao.closeResource(connection, null, null);
        }
        return flag;
    }

servlet.user 下新增UserServlet类

//实现Servlet复用，实现复用需要提取出方法，然后在doGet函数中调用即可
        String method = req.getParameter("method");
        if(method.equals("savepwd") && method!=null){
            this.updatePwd(req,resp);
        }


//在doGet外写复用方法
 public void updatePwd(HttpServletRequest req, HttpServletResponse resp){
        //从session中获得用户id,这里的attribute包括了用户的所用信息
        Object attribute = req.getSession().getAttribute(Constants.USER_SESSION);
        //获得新密码
        String newpassword = req.getParameter("newpassword");
        boolean flag= false;
        //判断是否有这个用户是否存在，以及新密码不为空
        if(attribute!=null && !StringUtils.isNullOrEmpty(newpassword)){
            UserService userService = new UserServiceImpl();
            flag = userService.updatePwd(((User) attribute).getId(), newpassword);
            if (flag) {
                req.setAttribute(Constants.SYS_MESSAGE,"修改密码成功，请退出后重新登录");
                //密码修改成功后移除当前session
                req.getSession().removeAttribute(Constants.USER_SESSION);
            }else{
                req.setAttribute(Constants.SYS_MESSAGE,"密码修改失败请重新输入");
            }
        }else{
            req.setAttribute(Constants.SYS_MESSAGE,"新密码设置错误请重新输入");
        }
        try {
            req.getRequestDispatcher("pwdmodify.jsp").forward(req,resp);
        } catch (ServletException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    
        UserServlet
        com.mario.servlet.user.UserServlet
    
    
        UserServlet
        /jsp/user.do
    

阿里巴巴的fastjson.jar包

    com.alibaba
    fastjson
    1.2.62

编写验证旧密码的servlet类，还是servlet方法复用

else if(method.equals("pwdmodify") && method!=null){//收到前端发来的请求，根据不同的method值来启动不同的Servlet应对
            this.modifyPwd(req,resp);
        }

//在下面继续写
//验证旧密码，session中可以获得旧密码，不需要重复去数据库中寻找
    public void modifyPwd(HttpServletRequest req, HttpServletResponse resp){
        //从session中获得用户的旧密码,这里的attribute包括了用户的所用信息
        Object attribute = req.getSession().getAttribute(Constants.USER_SESSION);
        //从前端输入的页面中获得输入的旧密码
        String oldpassword = req.getParameter("oldpassword");
        //万能的Map
        Map resultMap = new HashMap();
        if (attribute==null){//取到的session为空，意味着session过期了
            resultMap.put("result","sessionerror");
        }else if (StringUtils.isNullOrEmpty(oldpassword)){//如果输入的旧密码为空
            resultMap.put("result","sessionerror");
        }else{//session不为空，输入的旧密码也不为空，则取出当前旧密码与之比较
            String userPassword = ((User) attribute).getUserPassword();
            if(oldpassword.equals(userPassword)){
                resultMap.put("result","true");
            }else {
                resultMap.put("result","false");
            }
        }
        try {
            resp.setContentType("application/json");
            PrintWriter out = resp.getWriter();
            out.write(JSONArray.toJSONString(resultMap));
            out.flush();
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

结构流程图

静态资源需要导入分页的工具类

页面还需要导入用户列表

按照自底向上的流程，编写顺序

• Dao
• DaoImpl
• Service
• ServiceImpl
• Servlet

首先是UserDao接口添加一个函数

public int getUserCount(Connection connection, String userName, int userRole)throws Exception;

然后UserDaoImpl里实现上面接口里新增的函数

//根据用户输入的名字或者角色id来查询计算用户数量
    public int getUserCount(Connection connection, String userName, int userRole) throws Exception {
        int count=0;
        PreparedStatement pstm = null;
        ResultSet rs=null;
        if (connection!=null) {
            StringBuffer sql=new StringBuffer();
            sql.append("SELECT COUNT(*) AS usernumber FROM `smbms_user` u,`smbms_role` r WHERE u.`userRole`=r.`id`");
            ArrayList