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  • SMBMS

    SMBMS(Supermarket Billing Management System )

    1. 项目架构

    graph LR id1[SMBMS] id2[登录注销] id3[用户管理] id4[订单管理] id5[供应商管理] id6[增] id7[删] id8[改] id9[查] id10[ ] id11[数据库] id1 --> id2 id1 --> id3 id1 --> id4 id1 --> id5 id10 --> id6 id10 --> id7 id10 --> id8 id10 --> id9 id3 --> id10 id4 --> id10 id5 --> id10 id6 --> id11 id7 --> id11 id8 --> id11 id9 --> id11

    2. 项目搭建的准备工作

    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. 导入项目中需要用到的Jar包:jsp,Servlet, mysql驱动, jstl, standard

    5. 创建项目包结构

    6. 编写实体类

      ORM映射:表 -- 类映射

    7. 编写基础公共类

      1. 数据库配置文件(db.properties)
      driver = com.mysql.jdbc.Driver
      url = jdbc:mysql://localhost:3306/smbms?useUnicode=true&characterEncoding=utf-8
      username = root
      password = 123456
      
      1. 编写数据库公共类
      package com.wang.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
              //由于getResourceAsStream中调用了private方法,此处必须用反射来读配置文件
              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");
          }
      
          //获取数据库的连接
          public static Connection getConnection() {
              Connection connection = null;
              try {
                  Class.forName(driver);
                  connection = DriverManager.getConnection(url, username, password);
              } catch (Exception e) {
                  e.printStackTrace();
              }
              return connection;
          }
      
          //编写查询公共类
          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,不用传参
              preparedStatement = connection.prepareStatement(sql);
      
              //给预编译的sql传参数
              for (int i = 0; i < params.length; i++) {
                  //setObject方法,占位符从1开始,但是我们的数组是从0开始的,因此下面写 i+1
                  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);
      
              //给预编译的sql传参数
              for (int i = 0; i < params.length; i++) {
                  //setObject方法,占位符从1开始,但是我们的数组是从0开始的,因此下面写 i+1
                  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;
          }
      
      }
      
      1. 编写字符编码过滤器并注册
      package com.wang.filter;
      
      import javax.servlet.*;
      import java.io.IOException;
      
      public class CharacterEncodingFilter implements Filter {
          @Override
          public void init(FilterConfig filterConfig) throws ServletException {
      
          }
      
          @Override
          public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
              request.setCharacterEncoding("utf-8");
              response.setCharacterEncoding("utf-8");
      
              chain.doFilter(request, response);
          }
      
          @Override
          public void destroy() {
      
          }
      }
      
      <!--字符编码过滤器-->
      <filter>
          <filter-name>CharacterEncodingFilter</filter-name>
          <filter-class>com.wang.filter.CharacterEncodingFilter</filter-class>
      </filter>
      <!--所有的url都会被过滤-->
      <filter-mapping>
          <filter-name>CharacterEncodingFilter</filter-name>
          <url-pattern>/*</url-pattern>
      </filter-mapping>
      
    8. 导入静态资源

    3. 登陆功能实现

    graph LR id1[用户] id2[登录界面<br>用户名<br>密码] id3[判断是否登陆成功] id4[失败] id5[成功] id6[后台首页] id7[数据库] id8[Dao] id1 --> id2 id2 --login.dao--> id3 id3 --> id4 id4 --提示登录失败--> id2 id3 --> id5 id5 --跳转到后台首页--> id6 id6 --> id1 id3 --> id8 id8 --> id3 id7 --> id8 id8 --> id7

    1. 编写前端页面

    2. 设置首页

    <!--设置欢迎页面-->
    <welcome-file-list>
        <welcome-file>login.jsp</welcome-file>
    </welcome-file-list>
    

    3. 编写Dao层,用户登录的接口

    package com.wang.dao.user;
    
    import com.wang.pojo.User;
    
    import java.sql.Connection;
    import java.sql.SQLException;
    
    public interface UserDao {
    
        //得到登录的用户
        public User getLoginUser(Connection connection, String userCode) throws SQLException;
    
    }
    

    4. 编写Dao接口的实现类

    package com.wang.dao.user;
    
    import com.wang.dao.BaseDao;
    import com.wang.pojo.User;
    
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    
    public class UserDaoImpl implements UserDao {
        @Override
        public User getLoginUser(Connection connection, String userCode) 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};
    
               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);
    
            }
    
            return user;
    
        }
    }
    

    5. 业务层接口

    package com.wang.service.user;
    
    import com.wang.pojo.User;
    
    public interface UserService {
    
        //用户登录
        public User login(String userCode, String password);
    
    }
    

    6. 业务层实现

    package com.wang.service.user;
    
    import com.wang.dao.BaseDao;
    import com.wang.dao.user.UserDao;
    import com.wang.dao.user.UserDaoImpl;
    import com.wang.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,因此我们要引入dao层
        private UserDao userDao;
        public  UserServiceImpl() {
            userDao = new UserDaoImpl();
        }
    
        @Override
        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);
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            } finally {
                BaseDao.closeResource(connection, null, null);
            }
            return user;
        }
    
        @Test
        public void test() {
            UserServiceImpl userService = new UserServiceImpl();
            User admin = userService.login("admin", "1234567");
            System.out.println(admin.getUserPassword());
        }
    
    }
    

    7. 编写Servlet

    package com.wang.servlet.user;
    
    import com.wang.pojo.User;
    import com.wang.service.user.UserServiceImpl;
    import com.wang.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
            UserServiceImpl userService = new UserServiceImpl();
            //这里已经把登录的人给查出来了
            User user = userService.login(userCode, 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
                resp.sendRedirect("jsp/frame.jsp");
            }else {
                //查无此人,无法登陆
                //转发会登录页面,顺带提示用户名或密码错误
                req.setAttribute("error", "用户名或密码不正确");
                req.getRequestDispatcher("login.jsp").forward(req, resp);
    
            }
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            doGet(req, resp);
        }
    }
    

    8. 注册Servlet

    <!--Servlet-->
    <servlet>
        <servlet-name>LoginServlet</servlet-name>
        <servlet-class>com.wang.servlet.user.LoginServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>LoginServlet</servlet-name>
        <url-pattern>/login.do</url-pattern>
    </servlet-mapping>
    

    9. 测试访问,确保以上功能都能实现

    4. 登录功能优化

    注销功能:

    思路:移除Session,返回登录页面

    package com.wang.servlet.user;
    
    import com.wang.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);
            //返回登录页面
            resp.sendRedirect(req.getContextPath() + "/login.jsp");
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            doGet(req, resp);
        }
    }
    

    注册xml

    <servlet>
        <servlet-name>LogoutServlet</servlet-name>
        <servlet-class>com.wang.servlet.user.LogoutServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>LogoutServlet</servlet-name>
        <url-pattern>/jsp/logout.do</url-pattern>
    </servlet-mapping>
    

    登录拦截优化

    编写过滤器并注册

    package com.wang.filter;
    
    import com.wang.pojo.User;
    import com.wang.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);
    
            //已经被移除或者被注销了,或者未登录
            if (user == null) {
                response.sendRedirect("/smbms/error.jsp");
            }else {
                chain.doFilter(req, resp);
            }
        }
    
        @Override
        public void destroy() {
    
        }
    }
    
    <!--用户登录过滤器-->
    <filter>
        <filter-name>SysFilter</filter-name>
        <filter-class>com.wang.filter.SysFilter</filter-class>
    </filter>
    <!--所有的访问jsp目录下的资源都会被过滤-->
    <filter-mapping>
        <filter-name>SysFilter</filter-name>
        <url-pattern>/jsp/*</url-pattern>
    </filter-mapping>
    

    5. 密码修改

    1. 导入前端素材

    2. 写项目,建议从底层向上写

    3. UserDao接口

    //修改当前用户的密码
    public int updatePwd(Connection connection, int id, int password) throws SQLException;
    

    4. UserDao实现类

    //修改当前用户的密码,返回受影响的行数
    @Override
    public int updatePwd(Connection connection, int id, int 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, sql, params, pstm);
            BaseDao.closeResource(null, pstm, null);
        }
    
        return execute;
    
    }
    

    5. UserService接口

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

    6. UserService实现类

    @Override
    public boolean updatePwd(int id, int pwd) {
        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.closeResource(connection, null, null);
        }
        return flag;
    }
    

    7. 记得实现复用,需要提取出方法!

    package com.wang.servlet.user;
    
    import com.mysql.jdbc.StringUtils;
    import com.wang.pojo.User;
    import com.wang.service.user.UserService;
    import com.wang.service.user.UserServiceImpl;
    import com.wang.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;
    
    //实现Servlet服用
    public class UserServlet extends HttpServlet {
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            String method = req.getParameter("method");
            if (method.equals("savepwd") && method != null) {
                this.updatePwd(req, resp);
            }
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            doGet(req, resp);
        }
    
        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)) {
                UserService userService = new UserServiceImpl();
                flag = userService.updatePwd(((User) o).getId(), newpassword);
                if (flag) {
                    req.setAttribute("message", "修改密码成功,请退出,使用新密码登录");
                    //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();
            }
        }
    }
    

    8. 注册Servlet

    <servlet>
        <servlet-name>UserServlet</servlet-name>
        <servlet-class>com.wang.servlet.user.UserServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>UserServlet</servlet-name>
        <url-pattern>/jsp/user.do</url-pattern>
    </servlet-mapping>
    

    6. 优化密码修改:使用AJAX

    1. 引入阿里巴巴的fastjson

    2. 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<>();
    
        if (o == null) {
            //Session失效了,Session过期了
            resultMap.put("result", "sessionerror");
        } else if (StringUtils.isNullOrEmpty(oldpassword)) {
            resultMap.put("result", "error");
        } else  {
            //Session用户的密码
            String userPassword = ((User) o).getUserPassword();
            if (oldpassword.equals(userPassword)) {
                resultMap.put("result", "true");
            } else {
                resultMap.put("result", "false");
            }
        }
    
        try {
            //限定响应返回的格式为json
            resp.setContentType("application/json");
            PrintWriter writer = resp.getWriter();
            //JSONArray 阿里巴巴的JSON工具类转换格式
            /*
            把resultMap转为JSON格式
             */
            writer.write(JSONArray.toJSONString(resultMap));
            writer.flush();
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    

    7. 用户管理实现

    1. 思路

    graph LR id1[用户] id2[Servlet<br>1.处理请求<br>2.调用业务<br>3.返回页面] id3[用户列表] id4[角色列表] id5[分页<br>pageSize&#40固定的&#41<br>总数&#40从数据库里查&#41] id6[Service] id7[Dao] id8[数据库] id1 --发起请求--> id2 id2 --返回前端页面--> id1 id2 --> id3 id2 --> id4 id2 --> id5 id3 --> id6 id4 --> id6 id5 --> id6 id6 --> id7 id7 --> id8

    2. 导入分页的工具类

    3. 用户列表页导入

    1. userlist.jsp
    2. rollpage.jsp

    4. 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
    @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 as u, smbms_role as r where u.userRole = r.id");
            //存放我们的参数
            ArrayList<Object> list = new ArrayList<>();
    
            if (!StringUtils.isNullOrEmpty(username)) {
                sql.append(" and u.userName like ?");
                list.add("%" + username + "%");     //index = 0
            }
    
            if (userRole > 0) {
                sql.append(" and u.userRole like ?");
                list.add(userRole);     //index = 1
            }
    
            //把list转为数组
            Object[] objects = list.toArray();
    
            rs = BaseDao.execute(connection, sql.toString(), objects, rs, pstm);
    
            if (rs.next()) {
                //从结果集中获得最终的结果
                count = rs.getInt("count");
            }
    
            BaseDao.closeResource(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 userCount = 0;
    
        try {
            connection = BaseDao.getConnection();
            userCount = userDao.getUserCount(connection, username, userRole);
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            BaseDao.closeResource(connection, null, null);
        }
    
        return userCount;
    }
    

    5. 获取用户列表

    1. UserDao
    //通过条件查询-userlist
    public List<User> getUserList(Connection connection, String userName, int userRole, int currentPageNo, int pageSize) throws SQLException;
    
    1. UserDaoImpl
    //通过条件查询-userlist
    @Override
    public List<User> getUserList(Connection connection, String userName, int userRole, int currentPageNo, int pageSize) throws SQLException {
    
        PreparedStatement pstm = null;
        ResultSet rs = null;
        ArrayList<User> userList = new ArrayList<>();
    
        if (connection != null) {
            StringBuffer sql = new StringBuffer();
            sql.append("select u.*, r.roleName userRoleName from smbms_user as u join smbms_role as r on u.userRole = r.id");
            //存放我们的参数
            ArrayList<Object> list = new ArrayList<>();
    
            if (!StringUtils.isNullOrEmpty(userName)) {
                sql.append(" and u.userName like ?");
                list.add("%" + userName + "%");     //index = 0
            }
    
            if (userRole > 0) {
                sql.append(" and u.userRole like ?");
                list.add(userRole);     //index = 1
            }
    
            //在数据库中,分页使用limit   startIndex, pageSize;   总数
            //0,5
            //6,5
            //(当前页-1)*页面大小
    
            sql.append("order by creationDate desc limit ?, ?");
            currentPageNo = (currentPageNo - 1) * pageSize;
            list.add(currentPageNo);
            list.add(pageSize);
    
            Object[] params = list.toArray();
            rs = BaseDao.execute(connection, sql.toString(), params, rs, pstm);
            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.closeResource(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 (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            BaseDao.closeResource(connection, null, null);
        }
    
        return userList;
    
    }
    

    6. 获取角色操作

    为了我们职责统一,可以把角色的操作单独放在一个包中,和POJO类对应

    RoleDao

    public interface RoleDao {
        //获取角色列表
        public List<Role> getRoleList(Connection connection) throws SQLException;
    }
    

    RoleDaoImpl

    package com.wang.dao.role;
    
    import com.wang.dao.BaseDao;
    import com.wang.pojo.Role;
    
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.util.List;
    
    public class RoleDaoImpl implements RoleDao{
        //获取角色列表
        @Override
        public List<Role> getRoleList(Connection connection) throws SQLException {
    
            PreparedStatement pstm = null;
            ResultSet rs = null;
            List<Role> roleList = null;
    
            if (connection != null) {
                String sql = "select * from smbms_role";
                Object[] params = null;
                rs = BaseDao.execute(connection, sql, params, rs, pstm);
    
                while (rs.next()) {
                    Role _role = new Role();
                    _role.setId(rs.getInt("id"));
                    _role.setRoleName(rs.getString("roleName"));
                    _role.setRoleCode(rs.getString("roleCode"));
                    roleList.add(_role);
                }
                BaseDao.closeResource(null, pstm, rs);
            }
            return roleList;
        }
    }
    

    RoleService

    package com.wang.service.role;
    
    import com.wang.pojo.Role;
    
    import java.util.List;
    
    public interface RoleService {
        //获取角色列表
        public List<Role> getRoleList();
    }
    

    RoleServiceImpl

    package com.wang.service.role;
    
    import com.wang.dao.BaseDao;
    import com.wang.dao.role.RoleDao;
    import com.wang.dao.role.RoleDaoImpl;
    import com.wang.pojo.Role;
    
    import java.sql.Connection;
    import java.sql.SQLException;
    import java.util.List;
    
    public class RoleServiceImpl implements RoleService{
    
        //引入Dao
        private RoleDao roleDao;
        public RoleServiceImpl() {
            roleDao = new RoleDaoImpl();
        }
    
        @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.closeResource(connection, null, null);
            }
            return roleList;
        }
    }
    

    7. 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,页面参数

    //重点,难点
    public void query(HttpServletRequest req, HttpServletResponse resp) {
    
        //查询用户列表
    
        //从前端获取数据
        String queryUserName = req.getParameter("queryname");
        String temp = req.getParameter("queryUserRole");
        String pageIndex = req.getParameter("pageIndex");
        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,页面大小是固定的
        //可以把这个写在配置文件中,方便后期修改
        int pageSize = 5;
        int currentPageNo = 1;
    
        if (queryUserName == null) {
            queryUserName = "";
        }
        if (temp != null && !temp.equals("")) {
            queryUserRole = Integer.parseInt(temp);     //给查询赋值
        } if (pageIndex != null) {
            currentPageNo = Integer.parseInt(pageIndex);
        }
    
        //获取用户的总数(分页:上一页,下一页)
        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();
    
        //控制首页和尾页
        //如果页面要小于1了,就显示第一页的东西
        if (totalPageCount < 1) {
            currentPageNo = 1;
        } else if (currentPageNo > totalPageCount){
            //当前页面大于最后一页
            currentPageNo = totalPageCount;
        }
    
        //获取用户列表展示
        userList = userService.getUserList(queryUserName, queryUserRole, currentPageNo, pageSize);
        req.setAttribute("userList", userList);
    
        //展示角色列表
        RoleServiceImpl roleService = new RoleServiceImpl();
        List<Role> roleList = roleService.getRoleList();
        req.setAttribute("roleList", roleList);
        req.setAttribute("queryUserName", queryUserName);
        req.setAttribute("queryUserRole", queryUserRole);
    
        //展示分页
        req.setAttribute("totalCount", totalCount);
        req.setAttribute("currentPageNo", currentPageNo);
        req.setAttribute("totalPageCount", totalPageCount);
    
        //返回前端
        try {
            req.getRequestDispatcher("userlist.jsp").forward(req, resp);
        } catch (ServletException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
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  • 原文地址:https://www.cnblogs.com/wang-sky/p/13560404.html
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