狂神。SMBMS(超市订单管理系统)

SMBMS(超市订单管理系统)

代码:(建议把静态资源和sql拿过来用,其他自己写一遍练手。注意修改相关配置文件。)

链接:https://pan.baidu.com/s/12MmpF9msJVjLT1U77XYfRw
提取码:11fv

狂神。SMBMS(超市订单管理系统)_第1张图片

数据库:

狂神。SMBMS(超市订单管理系统)_第2张图片

项目如何搭建?

考虑是不是用Maven?依赖, jar包.

1.项目搭建准备工作

  1. 搭建一个maven web 项目.
  2. 配置Tomcat.
  3. 测试项目是否能够跑起来.
  4. Pom.xml 中导入项目中需要的jar包.(jsp,Servlet,mysql驱动,jstl,standard…)
<dependencies>
  <dependency>
    <groupId>junitgroupId>
    <artifactId>junitartifactId>
    <version>4.12version>
  dependency>
  
  <dependency>
    <groupId>javax.servletgroupId>
    <artifactId>javax.servlet-apiartifactId>
    <version>4.0.1version>
  dependency>
  
  <dependency>
    <groupId>javax.servlet.jspgroupId>
    <artifactId>javax.servlet.jsp-apiartifactId>
    <version>2.3.3version>
  dependency>
  
  <dependency>
    <groupId>mysqlgroupId>
    <artifactId>mysql-connector-javaartifactId>
    <version>5.1.47version>
  dependency>
  
  <dependency>
    <groupId>javax.servlet.jsp.jstlgroupId>
    <artifactId>jstl-apiartifactId>
    <version>1.2version>
  dependency>
  
  <dependency>
    <groupId>taglibsgroupId>
    <artifactId>standardartifactId>
    <version>1.1.2version>
  dependency>
  
  <dependency>
    <groupId>com.alibabagroupId>
    <artifactId>fastjsonartifactId>
    <version>1.2.80version>
  dependency>
dependencies>
  1. 创建项目包结构.

狂神。SMBMS(超市订单管理系统)_第3张图片

  1. 编写实体类.(pojo)
    ROM映射:表—类映射.

  2. 编写基础公共类.

    1、数据库配置文件:

driver = com.mysql.jdbc.Driver
url = jdbc:mysql://localhost:3306/smbms?useUnicode=true&characterEncoding=utf8&useSSL=true
username = root
password = newpass

​ 2、编写数据库的公共类:

package com.kuang.dao;

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;
    }

  
    //编写查询工具类。
    public static ResultSet execute(Connection connection,PreparedStatement preparedStatement,ResultSet resultSet,String sql,Object[] params) 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开始的。
            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,PreparedStatement preparedStatement,String sql,Object[] params) 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开始的。
            preparedStatement.setObject(i+1,params[i]);
        }
        int updateRows = preparedStatement.executeUpdate();
        return updateRows;
    }

  
    //释放资源。
    public static  boolean closeResourse(Connection connection,PreparedStatement preparedStatement,ResultSet resultSet){
        boolean flag = true;
        if (resultSet != null){
            try {
                resultSet.close();
                //GC回收
                resultSet = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag = false;
            }
        }
        if (preparedStatement != null){
            try {
                preparedStatement.close();
                //GC回收
                preparedStatement = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag = false;
            }
        }
        if (connection != null){
            try {
                connection.close();
                //GC回收
                connection = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag = false;
            }
        }
        return false;
    }

}

​ 3、编写字符编码过滤器(别忘了注册过滤器)

package com.kuang.filter;

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

public class CharacterEncodingFilter implements Filter {//别导错包。

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        servletRequest.setCharacterEncoding("utf-8");
        servletResponse.setCharacterEncoding("utf-8");
        servletResponse.setContentType("text/html");

        filterChain.doFilter(servletRequest,servletResponse);
    }

    @Override
    public void destroy() {

    }
}

<filter>
    <filter-name>CharacterEncodingFilterfilter-name>
    <filter-class>com.kuang.filter.CharacterEncodingFilterfilter-class>
filter>
<filter-mapping>
    <filter-name>CharacterEncodingFilterfilter-name>
    <url-pattern>/*url-pattern>
filter-mapping>
  1. 导入静态资源 (js,css,img,calendar)

2.登录功能实现

狂神。SMBMS(超市订单管理系统)_第4张图片

  1. 编写前端页面(直接拿jsp过来用)
  2. 设置首页

<welcome-file-list>
    <welcome-file>login.jspwelcome-file>
welcome-file-list>
  1. 编写dao层登录用户登录的接口
//通过userCode和userPassword,得到要登陆的用户。
public User getLoginUser(Connection connection,String userCode,String userPassword) throws SQLException;
  1. 编写dao层接口的实现类
//通过userCode和userPassword,得到要登陆的用户。
@Override
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 = ? and userPassword = ?";
        Object[] params = {userCode,userPassword};
        rs = BaseDao.execute(connection,pstm,rs,sql,params);
        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.closeResourse(null,pstm,rs);
    }
    return user;
}
  1. 业务层接口
//用户登录.
public User login(String userCode,String userPassword);
  1. 业务层实现类
//业务层都会调用dao层,所以我们要引入Dao层。
private UserDao userDao;
public UserServiceImpl() {//无参构造器。
    userDao = new UserDaoImpl();
}


//用户登录
@Override
public User login(String userCode, String userPassword) {
    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,userPassword);
    } catch (SQLException throwables) {
        throwables.printStackTrace();
    }finally {
        BaseDao.closeResourse(connection,null,null);
    }
    return user;
}
  1. 编写Servlet
package com.kuang.servlet.user;

import com.kuang.pojo.User;
import com.kuang.service.user.UserServiceImpl;
import com.kuang.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;

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

    @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;
        UserServiceImpl userService = new UserServiceImpl();
        User user = userService.login(userCode, userPassword);//这里已经把登陆的人查出来了。

        if (user!=null){//查有此人,可以登陆。
            //将用户的信息放到Session中;
            req.getSession().setAttribute(Constants.USER_SESSION,user);
            //跳转到主页。
            resp.sendRedirect("jsp/frame.jsp");
        }else {//查无此人,无法登陆。
            //转发回登陆页面,顺带提示它,用户名或者密码错误。
            req.setAttribute("error","用户名或者密码错误!");
            req.getRequestDispatcher("login.jsp").forward(req,resp);
        }
    }

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

<servlet>
    <servlet-name>LoginServletservlet-name>
    <servlet-class>com.kuang.servlet.user.LoginServletservlet-class>
servlet>
<servlet-mapping>
    <servlet-name>LoginServletservlet-name>
    <url-pattern>/login.dourl-pattern>
servlet-mapping>
  1. 测试访问,保证以上功能可以成功

3.登录功能优化

注销功能:

思路:移除session,返回登录页面。

package com.kuang.servlet.user;

import com.kuang.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Constants.USER_SESSION
        req.getSession().removeAttribute(Constants.USER_SESSION);
        resp.sendRedirect(req.getContextPath()+"/login.jsp");//返回登陆页面。
    }

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

注册xml:

<servlet>
    <servlet-name>LogoutServletservlet-name>
    <servlet-class>com.kuang.servlet.user.LogoutServletservlet-class>
servlet>
<servlet-mapping>
    <servlet-name>LogoutServletservlet-name>
    <url-pattern>/jsp/logout.dourl-pattern>
servlet-mapping>

4.登录拦截优化

使用户不能直接进入登陆成功的页面。

编写一个过滤器,并注册.

package com.kuang.filter;

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

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

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

    @Override
    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,或者为登陆。
            response.sendRedirect("/SMBMS/error.jsp");
        }else{
            Chain.doFilter(req,resp);
        }
    }

    @Override
    public void destroy() {}
  
}

注册xml


<filter>
    <filter-name>SysFilterfilter-name>
    <filter-class>com.kuang.filter.SysFilterfilter-class>
filter>
<filter-mapping>
    <filter-name>SysFilterfilter-name>
    <url-pattern>/jsp/*url-pattern>
filter-mapping>

测试,登录,注销,权限,都要保证OK.

5.密码修改

  1. 导入前端素材
  • 密码修改
    1. 写项目,建议从底层向上写

    狂神。SMBMS(超市订单管理系统)_第5张图片

    1. UserDao接口
    //修改当前用户密码。
    public int updatePwd(Connection connection,int id,String password)throws SQLException;
    
    1. UserDao接口实现类
    //修改当前用户密码。
    @Override
    public int updatePwd(Connection connection, int id, String password) throws SQLException {
        PreparedStatement pstm = null;
        int execute = 0;
        if (connection!=null){
            String sql = "update smbms_user set userPassword = ? where id = ?";
            Object params[] = {password,id};
            execute = BaseDao.execute(connection,pstm,sql,params);
            BaseDao.closeResourse(null,pstm,null);
        }
        return execute;
    }
    
    1. UserService层
    //根据用户id修改密码。
    public boolean updatePwd(int id,String password)throws SQLException;
    
    1. UserService实现类
    //根据用户id修改密码。
    @Override
    public boolean updatePwd(int id, String pwd) throws SQLException {
        Connection connection = null;
        boolean flag = false;
        //修改密码。
        try {
            connection = BaseDao.getConnection();
            if (userDao.updatePwd(connection,id,pwd)>0){
                flag = true;
            }
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            BaseDao.closeResourse(connection,null,null);
        }
        return flag;
    }
    
    1. servlet记得实现复用,要提取出方法!
    //实现Servlet复用
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String method = req.getParameter("method");
        if (method.equals("savepwd")){
                this.updatePwd(req,resp);
            }else if (method.equals("pwdmodify")){
                this.pwdModify(req,resp);
            }else if (method.equals("query")){
                this.query(req,resp);
            }else if (method.equals("add")){
                this.add(req,resp);
            }else if (method.equals("modifyexe")){
                this.modify(req,resp);
            }else if (method.equals("deluser")){
                this.delUser(req,resp);
            }else if (method.equals("ucexist")){
                this.userCodeExist(req, resp);
            }else if (method.equals("getrolelist")){
                this.getRoleList(req, resp);
            }else if (method.equals("view")){
                this.getUserById(req,resp,"userview.jsp");
            }else if (method.equals("modify")){
                this.getUserById(req,resp,"usermodify.jsp");
            }
    }
    
    
    //修改密码
    public void updatePwd(HttpServletRequest req, HttpServletResponse resp){
        //从Session里面拿id;
        Object o = req.getSession().getAttribute(Constants.USER_SESSION);
        String newpassword = req.getParameter("newpassword");
    
        boolean flag = false;
    
        if (o!=null && !StringUtils.isNullOrEmpty(newpassword)){
            UserServiceImpl userService = new UserServiceImpl();
    
            try {
                flag = userService.updatePwd(((User)o).getId(),newpassword);
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
    
            if (flag){
                req.setAttribute("message","修改密码成功,请退出,使用新密码登陆!");
                //密码修改成功,移除当前Session。
                req.getSession().removeAttribute(Constants.USER_SESSION);
            }else {
                req.setAttribute("message","密码修改失败。");
            }
        }else {
            req.setAttribute("message","新密码有问题。");
        }
    
        try {
            req.getRequestDispatcher("pwdmodify.jsp").forward(req,resp);
        } catch (ServletException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    

    注册xml

    <servlet>
        <servlet-name>UserServletservlet-name>
        <servlet-class>com.kuang.servlet.user.UserServletservlet-class>
    servlet>
    <servlet-mapping>
        <servlet-name>UserServletservlet-name>
        <url-pattern>/jsp/user.dourl-pattern>
    servlet-mapping>
    
    1. 测试

    6.优化密码修改使用Ajax

    1. 阿里巴巴的fastjson(导入)
    
    <dependency>
      <groupId>com.alibabagroupId>
      <artifactId>fastjsonartifactId>
      <version>1.2.80version>
    dependency>
    
    1. 后台代码修改
    //验证旧密码,session中有用户的密码。
    public void pwdModify(HttpServletRequest req, HttpServletResponse resp){
        //从Session里面拿id;
        Object o = req.getSession().getAttribute(Constants.USER_SESSION);
        String oldpassword = req.getParameter("oldpassword");
    
        //万能的Map:结果集
        Map<String, String> resultMap = new HashMap<String, String>();
    
        if (o==null){//Session失效了,session过期了。
            resultMap.put("result","sessionerror");
        }else if (StringUtils.isNullOrEmpty(oldpassword)){//输入的密码为空。
            resultMap.put("result","error");
        }else {
            String userPassword = ((User)o).getUserPassword();//Session中用户的密码。
            if (oldpassword.equals(userPassword)){
                resultMap.put("result","true");
            }else {
                resultMap.put("result","false");
            }
        }
    
        try {
            resp.setContentType("application/json");
            PrintWriter writer = resp.getWriter();
            //JSONArray 阿里巴巴的JSON工具类,转换格式。
            /*
            resultMap = ["reslut","sessionerror","reslut","error"]
            Json格式 = {key:value}
             */
            writer.write(JSONArray.toJSONString(resultMap));
            writer.flush();
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    1. 测试

    7.用户管理实现

    狂神。SMBMS(超市订单管理系统)_第6张图片

    1. 导入分页的工具类——PageSupport
    2. 用户列表页面导入——userlist.jsp

    1、获取用户数量

    1. UserDao
    //根据用户名或者角色查询用户总数。
    public int getUserCount(Connection connection,String username,int userRole) throws  SQLException;
    
    1. UserDaoImpl
    //根据用户名或者角色查询用户总数。(最难理解的sql)
    @Override
    public int getUserCount(Connection connection,String username,int userRole) throws SQLException {
        PreparedStatement pstm = null;
        ResultSet rs = null;
        int count = 0;
    
        if (connection!=null){
            StringBuffer sql = new StringBuffer();
            sql.append("select count(1) as count from smbms_user u,smbms_role r where u.userRole = r.id");
            ArrayList<Object> list = new ArrayList<Object>();//存放我们的参数。
    
            if (!StringUtils.isNullOrEmpty(username)){
                sql.append(" and u.userName = ?");
                list.add("%"+username+"%");//index:0   模糊查询。
            }
    
            if (userRole>0){
                sql.append(" and u.userRole = ?");
                list.add(userRole);//index:1
            }
    
            //怎么把list转换为数组。
            Object[] params = list.toArray();
    
            System.out.println("getUserCount的sql语句:"+sql.toString());//输出最后完整的sql语句。
            rs = BaseDao.execute(connection, pstm, rs, sql.toString(), params);
    
            if (rs.next()){
                count = rs.getInt("count");//从结果集中获取最终的参数。
            }
            BaseDao.closeResourse(null,pstm,rs);
        }
        return count;
    }
    
    1. UserService
    //查询记录数。
    public int getUserCount(String username,int userRole);
    
    1. UserServiceImpl
    //查询记录数。
    @Override
    public int getUserCount(String username, int userRole) {
        Connection connection = null;
        int count = 0;
        try {
            connection = BaseDao.getConnection();
            count = userDao.getUserCount(connection,username,userRole);
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            BaseDao.closeResourse(connection,null,null);
        }
        return count;
    }
    

    2、获取用户列表

    1. UserDao
    //通过条件查询用户。(分页)
    public List<User> getUserList(Connection connection, String userName, int userRole, int currentPageNo, int pageSize) throws Exception;
    
    1. UserDaoImpl
    //通过条件查询用户。(分页)
    @Override
    public List<User> getUserList(Connection connection, String userName, int userRole, int currentPageNo, int pageSize) throws Exception {
    
        PreparedStatement pstm = null;
        ResultSet rs = null;
        List<User> userList = new ArrayList<User>();
    
        if (connection != null) {
            StringBuffer sql = new StringBuffer();
            sql.append("select u.*,r.roleName as userRoleName from smbms_user u,smbms_role r where u.userRole = r.id");
            List<Object> list = new ArrayList<Object>();
    
            if (!StringUtils.isNullOrEmpty(userName)) {
                sql.append(" and u.userName like ?");
                list.add("%" + userName + "%");
            }
    
            if (userRole > 0) {
                sql.append(" and u.userRole = ?");
                list.add(userRole);
            }
    
            //在mysql数据库中,分页使用 limit startIndex,pageSize ; 总数
            sql.append(" order by creationDate DESC limit ?,?");
            currentPageNo = (currentPageNo - 1) * pageSize;
            list.add(currentPageNo);
            list.add(pageSize);
    
            Object[] params = list.toArray();
            System.out.println("getUserList的sql语句:" + sql.toString());
            rs = BaseDao.execute(connection, pstm, rs, sql.toString(), params);
            while (rs.next()) {
                User _user = new User();
                _user.setId(rs.getInt("id"));
                _user.setUserCode(rs.getString("userCode"));
                _user.setUserName(rs.getString("userName"));
                _user.setGender(rs.getInt("gender"));
                _user.setBirthday(rs.getDate("birthday"));
                _user.setPhone(rs.getString("phone"));
                _user.setUserRole(rs.getInt("userRole"));
                _user.setUserRoleName(rs.getString("userRoleName"));
                userList.add(_user);
            }
            BaseDao.closeResourse(null, pstm, rs);
        }
        return userList;
    }
    
    1. UserService
    //根据条件查询用户列表.
    public List<User> getUserList(String queryUserName, int queryUserRole, int currentPageNo, int pageSize);
    
    1. UserServiceImpl
    //根据条件查询用户列表
    @Override
    public List<User> getUserList(String queryUserName, int queryUserRole, int currentPageNo, int pageSize) {
        Connection connection = null;
        List<User> userList = null;
    
        try {
            connection = BaseDao.getConnection();
            userList = userDao.getUserList(connection, queryUserName, queryUserRole, currentPageNo, pageSize);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            BaseDao.closeResourse(connection, null, null);
        }
        return userList;
    }
    

    3、获取角色操作

    为了我们的职责统一,我们可以把角色的操作单独放在一个包中,和pojo类对应。

    1. RoleDao
    public interface RoleDao {
        //获取角色列表。
        public List<Role> getRoleList(Connection connection)throws SQLException;
    }
    
    1. RoleDaoIpml
    public class RoleDaoImpl implements RoleDao{
      
        //获取角色列表。
        @Override
        public List<Role> getRoleList(Connection connection) throws SQLException {
    
            PreparedStatement pstm = null;
            ResultSet resultSet = null;
            ArrayList<Role> rolelist = new ArrayList<>();
    
            if (connection!=null){
                String sql = "select * from smbms_role";
                Object[] params = {};
                resultSet = BaseDao.execute(connection, pstm, resultSet, sql, params);
    
                while (resultSet.next()){
                    Role role = new Role();
                    role.setId(resultSet.getInt("id"));
                    role.setRoleCode(resultSet.getString("roleCode"));
                    role.setRoleName(resultSet.getString("roleName"));
                    rolelist.add(role);
                }
                BaseDao.closeResourse(null,pstm,resultSet);
            }
            return rolelist;
        }
    }
    
    1. RoleService
    public interface RoleService {
        //获取角色列表。
        public List<Role> getRoleList();
    }
    
    1. RoleServiceIpml
    public class RoleServiceImpl implements RoleService{
    
        //引入Dao。
        private RoleDao roleDao;
        public RoleServiceImpl() {
            roleDao = new RoleDaoImpl();
        }
    
        //获取角色列表。
        @Override
        public List<Role> getRoleList() {
            Connection connection = null;
            List<Role> roleList = null;
    
            try {
                connection = BaseDao.getConnection();
                roleList = roleDao.getRoleList(connection);
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            } finally {
                BaseDao.closeResourse(connection,null,null);
            }
            return roleList;
        }
    
    }
    

    4、用户显示的Servlet

    1. 获取用户前端的数据(查询)。
    2. 判断请求是否需要执行,看参数的值判断。
    3. 为了实现分页,需要计算出当前页面和总页面,页面大小。
    4. 用户列表展示。
    5. 返回前端。
    //查询用户列表(重点,难点)。
    public  void query(HttpServletRequest req, HttpServletResponse resp){
    
        //从前端获取数据:
        String queryUserName = req.getParameter("queryname");
        String temp = req.getParameter("queryUserRole");
        String pageIndex = req.getParameter("pageIndex");//默认为1.
        int queryUserRole = 0;
    
        //获取用户列表
        UserServiceImpl userService = new UserServiceImpl();
        List<User> userList = null;
    
        //第一次走这个请求,一定是第一页,页面大小固定的:
        int pageSize = 5;//可以把这个配置到配置文件中,方便后期修改;
        int currentPageNo = 1;
    
        if (queryUserName==null){
            queryUserName = "";
        }
        if (temp!=null && !temp.equals("")){
            queryUserRole = Integer.parseInt(temp); //给查询赋值!0,1,2,3
        }
        if (pageIndex!=null){
            currentPageNo = Integer.parseInt(pageIndex);
        }
    
        //获取用户的总量(分页:上一页,下一页的情况)
        int totalCount = userService.getUserCount(queryUserName,queryUserRole);
    
        //总页数支持。
        PageSupport pageSupport = new PageSupport();
        pageSupport.setCurrentPageNo(currentPageNo);
        pageSupport.setPageSize(pageSize);
        pageSupport.setTotalCount(totalCount);
        int totalPageCount = pageSupport.getTotalPageCount();//总共有几页。
    
        //控制首页和尾页。
        //如果页面小于1,就显示第一页的东西。
        if (currentPageNo<1){
            currentPageNo = 1;
        }else if (currentPageNo>totalPageCount){//当前页面大于了最后一页。
            currentPageNo = totalPageCount;
        }
    
        //获取用户列表展示。
        userList = userService.getUserList(queryUserName, queryUserRole, currentPageNo, pageSize);
        req.setAttribute("userList",userList);
    
        RoleServiceImpl roleService = new RoleServiceImpl();
        List<Role> roleList = roleService.getRoleList();
        req.setAttribute("roleList",roleList);
        req.setAttribute("totalCount",totalCount);
        req.setAttribute("currentPageNo",currentPageNo);
        req.setAttribute("totalPageCount",totalPageCount);
        req.setAttribute("queryUserName",queryUserName);
        req.setAttribute("queryUserRole",queryUserRole);
    
        //返回前端
        try {
            req.getRequestDispatcher("userlist.jsp").forward(req,resp);
        } catch (ServletException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    

    建议:小黄鸭调试法:自言自语.

    项目原理流程图:

    狂神。SMBMS(超市订单管理系统)_第7张图片

    剩下的两个模块的代码直接CV过来改了改bug加了上去(懒得写了!)

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