超市管理统SMBMS笔记

作者：@冰山醉酒
本文为作者原创，转载请注明出处：https://www.cnblogs.com/douFrank/p/16117864.html

1|0SMBMS

原理图

数据库：

项目如何搭建？

考虑使用不使用Maven ? 依赖，Jar

2|0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. 导入项目中会遇到的jar包

    sevlet-api，jsp-api，jstl，jstl-api，mysql-connector-java

  5. 构建项目框架

  6. 编写实体类

    ORM：表-类映射

  7. 编写基础公共类

    1. 数据库配置文件 

      diver=com.mysql.jdbc.Driver
 url=jdbc:mysql://localhost:3306/smbms?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8
 username=root
 password=123456

    2. 编写数据库的公共类

       
       
        1 package com.study.dao;
  2  ​
  3  import java.io.IOException;
  4  import java.io.InputStream;
  5  import java.sql.*;
  6  import java.util.Properties;
  7  //操作数据库的公共类
  8  public class BaseDao {
  9      private static String driver;
 10      private static String url;
 11      private static String username;
 12      private static String password;
 13  ​
 14      //静态代码块，类加载的时候就初始化了
 15      static{
 16          Properties properties = new Properties();
 17          //通过类加载器获取对用的资源
 18          InputStream is = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");
 19  ​
 20          try {
 21              properties.load(is);
 22          } catch (IOException e) {
 23              e.printStackTrace();
 24          }
 25  ​
 26          driver = properties.getProperty("driver");
 27          url = properties.getProperty("url");
 28          username = properties.getProperty("username");
 29          password = properties.getProperty("password");
 30      }
 31      //获取数据库的连接
 32      public static Connection getConnection(){
 33          Connection connection = null;
 34          try {
 35              connection = DriverManager.getConnection(url, username, password);
 36          } catch (SQLException e) {
 37              e.printStackTrace();
 38          }
 39          return connection;
 40      }
 41      //编写查询公共类
 42      public static ResultSet excute(Connection connection, String sql, Object[] params, ResultSet resultSet, PreparedStatement preparedStatement) throws SQLException {
 43        //预编译的sql，在后面直接执行就可以了
 44          preparedStatement = connection.prepareStatement(sql);
 45  ​
 46          for (int i = 0; i < params.length; i++) {
 47              //setObject,占位符从1开始，但是我们的数组是从0开始！
 48              preparedStatement.setObject(i+1,params[i]);
 49          }
 50  ​
 51          resultSet = preparedStatement.executeQuery();
 52          return resultSet;
 53      }
 54  ​
 55      //编写增删改公共类
 56      public static int excute(Connection connection,String sql,Object[] params,PreparedStatement preparedStatement) throws SQLException {
 57          preparedStatement = connection.prepareStatement(sql);
 58  ​
 59          for (int i = 0; i < params.length; i++) {
 60              //setObject,占位符从1开始，但是我们的数组是从0开始！
 61              preparedStatement.setObject(i+1,params[i]);
 62          }
 63  ​
 64          int updateRows = preparedStatement.executeUpdate();
 65          return updateRows;
 66      }
 67  ​
 68      //释放资源
 69      public static boolean closeResourse(Connection connection,PreparedStatement preparedStatement,ResultSet resultSet){
 70          boolean flag = true;
 71  ​
 72          if (resultSet!=null){
 73              try {
 74                  resultSet.close();
 75                  //GC回收
 76                  resultSet = null;
 77              } catch (SQLException e) {
 78                  e.printStackTrace();
 79                  flag = false;
 80              }
 81          }
 82  ​
 83          if (preparedStatement!=null){
 84              try {
 85                  preparedStatement.close();
 86                  //GC回收
 87                  preparedStatement = null;
 88              } catch (SQLException e) {
 89                  e.printStackTrace();
 90                  flag = false;
 91              }
 92          }
 93  ​
 94          if (connection!=null){
 95              try {
 96                  connection.close();
 97                  //GC回收
 98                  connection = null;
 99              } catch (SQLException e) {
100                  e.printStackTrace();
101                  flag = false;
102              }
103          }
104          return flag;
105      }
106  }

    3. 编写字符编码过滤器

  8. 导入静态资源

3|0登录功能实现

  1. 设置首页

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

  2. 编写dao层登录用户的接口

     public interface UserDao {
     //得到要登录的用户
     public User getLoginUser(Connection connection, String userCode) throws SQLException;
 }

  3. 编写dao层接口的实现类

     
     
     1 package com.study.dao.user;
 2  ​
 3  import com.study.dao.BaseDao;
 4  import com.study.pojo.User;
 5  ​
 6  import java.sql.Connection;
 7  import java.sql.PreparedStatement;
 8  import java.sql.ResultSet;
 9  import java.sql.SQLException;
10  ​
11  public class UserDaoImpl implements UserDao{
12      //得到要登录的用户
13      public User getLoginUser(Connection connection, String userCode) throws SQLException {
14          PreparedStatement pstm = null;
15          ResultSet rs = null;
16          User user = null;
17  ​
18          if (connection!=null){
19              String sql = "select * from smbms_user where userCode = ?";
20              Object[] params = {userCode};
21  ​
22              rs = BaseDao.excute(connection, pstm, rs, sql, params);
23  ​
24              if(rs.next()){
25                  user = new User();
26                  user.setId(rs.getInt("id"));
27                  user.setUserCode(rs.getString("userCode"));
28                  user.setUserName(rs.getString("userName"));
29                  user.setUserPassword(rs.getString("userPassword"));
30                  user.setGender(rs.getInt("gender"));
31                  user.setBirthday(rs.getDate("birthday"));
32                  user.setPhone(rs.getString("phone"));
33                  user.setAddress(rs.getString("address"));
34                  user.setUserRole(rs.getInt("userRole"));
35                  user.setCreateBy(rs.getInt("createdBy"));
36                  user.setCreationDate(rs.getTimestamp("creationDate"));
37                  user.setModifyBy(rs.getInt("modifyBy"));
38                  user.setModifyDate(rs.getTimestamp("modifyDate"));
39              }
40              BaseDao.closeResourse(null,pstm,rs);//connection不关，业务层可能要用
41          }
42          return user;
43      }
44  }

  4. 业务层接口

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

  5. 业务层实现类

     1  package com.study.service.user;
 2  ​
 3  import com.study.dao.BaseDao;
 4  import com.study.dao.user.UserDao;
 5  import com.study.dao.user.UserDaoImpl;
 6  import com.study.pojo.User;
 7  import org.junit.Test;
 8  ​
 9  import java.sql.Connection;
10  import java.sql.SQLException;
11  ​
12  public class UserServiceImpl implements UserService{
13  ​
14      //业务层都会调用dao层，所以我们要引入Dao层
15      private UserDao userDao;
16      public UserServiceImpl(){
17         userDao = new UserDaoImpl();
18      }
19      public User login(String userCode, String password) {
20          Connection connection = null;
21          User user = null;
22          try {
23              connection = BaseDao.getConnection();
24              //业务层调用对应的具体数据库操作
25              user = userDao.getLoginUser(connection, userCode);
26          } catch (SQLException e) {
27              e.printStackTrace();
28          }finally {
29              BaseDao.closeResourse(connection,null,null);
30          }
31          return user;
32      }
33  ​
34      @Test 
35      public void test(){
36          UserServiceImpl userService = new UserServiceImpl();
37          User admin = userService.login("admin", "dhewfghewe");
38          System.out.println(admin.getUserPassword());
39      }
40  }

  6. 编写Servlet

     1 package com.study.servlet.user;
 2  ​
 3  import com.study.dao.user.UserDaoImpl;
 4  import com.study.pojo.User;
 5  import com.study.service.user.UserService;
 6  import com.study.service.user.UserServiceImpl;
 7  import com.study.util.Constants;
 8  import jakarta.servlet.ServletException;
 9  import jakarta.servlet.http.HttpServlet;
10  import jakarta.servlet.http.HttpServletRequest;
11  import jakarta.servlet.http.HttpServletResponse;
12  ​
13  import java.io.IOException;
14  ​
15  public class LoginServlet extends HttpServlet {
16  ​
17      //Servlet:控制层，调用业务层代码
18      @Override
19      protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
20  ​
21          System.out.println("LoginServlet--start....");
22  ​
23          //获取用户名和密码
24          String userCode = req.getParameter("userCode");
25          String userPassword = req.getParameter("userPassword");
26          
27          //和数据库中的密码进行对比，调用业务层；
28          UserService userService = new UserServiceImpl();
29          User user = userService.login(userCode, userPassword);
30  ​
31          if (user!=null){//查有此人，可以登录
32              //将用户的信息放到Session中；
33              req.getSession().setAttribute(Constants.USER_SESSION,user);
34              //跳转到主页
35              resp.sendRedirect("jsp/frame.jsp");
36          }else{//查无此人，无法登录
37              //转发会登录界面，顺带提示它，用户名或者密码错误；
38              req.setAttribute("error","用户名或者密码不正确");
39              req.getRequestDispatcher("login.jsp").forward(req,resp);
40  ​
41          }
42  ​
43      }
44  ​
45      @Override
46      protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
47          doGet(req, resp);
48      }
49  }

  7. 注册Servlet

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

  8. 测试访问，确保以上能成功

4|0登录功能优化

注销功能：

思路：移除Session,返回登录界面

 
 
 1 package com.study.servlet.user;
 2  ​
 3  import com.study.util.Constants;
 4  import jakarta.servlet.ServletException;
 5  import jakarta.servlet.http.HttpServlet;
 6  import jakarta.servlet.http.HttpServletRequest;
 7  import jakarta.servlet.http.HttpServletResponse;
 8  ​
 9  import java.io.IOException;
10  ​
11  public class LogoutServlet extends HttpServlet {
12      @Override
13      protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
14          //移除用户的Constants.USER_SESSION
15          req.getSession().removeAttribute(Constants.USER_SESSION);
16          resp.sendRedirect(req.getContextPath()+"/login.jsp");//返回登录界面
17      }
18  ​
19      @Override
20      protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
21          doGet(req, resp);
22      }
23  }

注册

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

4|1登录拦击优化

编写一个过滤器，并注册

 
 
package com.study.filter;
 ​
 import com.study.pojo.User;
 import com.study.util.Constants;
 import jakarta.servlet.*;
 import jakarta.servlet.http.HttpServlet;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.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){//已经被一处或者注销了，或者未登录
             response.sendRedirect("/error.jsp");
         }else{
             chain.doFilter(req,resp);
         }
 ​
     }
 ​
     public void destroy() {
 ​
     }
 }
 
 <!-- 用户过滤器 -->
 <filter>
     <filter-name>SysFilter</filter-name>
     <filter-class>com.study.filter.SysFilter</filter-class>
 </filter>
 <filter-mapping>
     <filter-name>SysFilter</filter-name>
     <url-pattern>/jsp/*</url-pattern>
 </filter-mapping>

测试，登录，注销，权限，都要保证OK！

5|0密码修改

  1. 导入前端素材

    <li><a href="${pageContext.request.contextPath }/jsp/pwdmodify.jsp">密码修改</a></li>
 <li><a href="${pageContext.request.contextPath }/jsp/logout.do">退出系统</a></li>

  2. 写项目，建议从底层往上写

     

     

  3. UserDao接口

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

  4. UserDao实现类

    public int updatePwd(Connection connection, int id, int password) throws SQLException {
     PreparedStatement pstm = null;
     int excute = 0;
 ​
 ​
     if (connection!=null){
         String sql = "update smbms_user set userPassword = ? where id = ?";
         Object[] params = {password,id};
         excute = BaseDao.excute(connection, pstm, sql, params);
         BaseDao.closeResourse(null,pstm,null);
     }
     return excute;
 }

  5. UserService层

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

  6. UserService实现类

     1 public boolean updatePwd(int id, int pwd) {
 2      Connection connection = null;
 3      boolean flag = false;
 4  ​
 5      //修改密码
 6      try {
 7          connection = BaseDao.getConnection();
 8          if (userDao.updatePwd(connection, id, pwd) > 0){
 9              flag = true;
10          }
11      } catch (SQLException e) {
12          e.printStackTrace();
13      }finally {
14          BaseDao.closeResourse(connection,null,null);
15      }
16      return flag;
17  }
18  ​
19  //记得注册

  7. 记得实现复用，需要提出方法！ 

    @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);
     }
 }

  8. 测试

5|1优化密码修改使用Ajax

  1. 阿里巴巴的fastjson

    <dependency>
     <groupId>com.alibaba</groupId>
     <artifactId>fastjson</artifactId>
     <version>1.2.80</version>
 </dependency>

  2. 后台代码修改

     1 //修改密码
 2  public void updatePwd(HttpServletRequest req, HttpServletResponse resp){
 3      //从Session里面拿ID；
 4      Object o = req.getSession().getAttribute(Constants.USER_SESSION);
 5      String newpassword = req.getParameter("newpassword");
 6      boolean flag = false;
 7  ​
 8      if(o!=null && !StringUtils.isNullOrEmpty(newpassword)){
 9          UserService userService = new UserServiceImpl();
10          flag = userService.updatePwd(((User)o).getId(), newpassword);
11          if (flag){
12              req.setAttribute("message","修改密码成功，请推出，使用新密码登录");
13              //密码修改成功，移除当前Session
14              req.getSession().removeAttribute(Constants.USER_SESSION);
15          }else{
16              req.setAttribute("message","修改密码失败");
17          }
18      }else {
19          req.setAttribute("message","新密码有问题");
20      }
21  ​
22      try {
23          resp.sendRedirect("pwdmodify.jsp");
24      } catch (IOException e) {
25          e.printStackTrace();
26      }
27  }
28  ​
29  //验证旧密码，session中有用户的密码
30  public void pwdModify(HttpServletRequest req, HttpServletResponse resp){
31      //从Session里面拿ID；
32      Object o = req.getSession().getAttribute(Constants.USER_SESSION);
33      String oldpassword = req.getParameter("oldpassword");
34  ​
35      //万能的Map ： 结果集
36      Map<String, String> resultMap = new HashMap<String, String>();
37  ​
38      if(o==null){//session失效了，session过期了
39          resultMap.put("result","sessionerror");
40      }else if(StringUtils.isNullOrEmpty(oldpassword)){//输入的密码为空
41          resultMap.put("result","error");
42      }else{
43          String userPassword = ((User) o).getUserPassword();//Session中用户的密码
44          if (oldpassword.equals(userPassword)){
45              resultMap.put("result","true");
46          }else{
47              resultMap.put("result","false");
48          }
49      }
50  ​
51      try {
52          resp.setContentType("application/json");
53          PrintWriter writer = null;
54          writer = resp.getWriter();
55          //JSONArray 阿里巴巴的JSON工具类，转换格式
56          /*
57              * resultMap = ["result","sessionerror","result","error"]
58              * JSON格式 = {key:value}
59              * */
60          writer.write(JSONArray.toJSONString(resultMap));
61          writer.flush();
62          writer.close();
63      } catch (IOException e) {
64          e.printStackTrace();
65      }
66  }

  3. 测试

6|0用户管理实现

思路：

  1. 要导入分页的工具类

  2. 用户列表页面导入

    userlist.jsp

    rollpage.jsp

7|0获取用户数量

UserDao

//根据用户名或者角色查询用户数量
public int getUserCount(Connection connection,String username,int userRole)throws SQLException;

UserDaoImpl

 1 //根据用户名或者角色查询用户数量
 2 public int getUserCount(Connection connection, String username, int userRole) throws SQLException {
 3     PreparedStatement pstm = null;
 4     ResultSet rs = null;
 5     int count = 0;
 6 
 7     if (connection!=null){
 8         StringBuffer sql = new StringBuffer();
 9         sql.append("select count(1) as count from smbms_user u,smbms_role r where u.userRole = r.id");
10         ArrayList<Object> list = new ArrayList<Object>();//存放我们的参数
11 
12         if (!StringUtils.isNullOrEmpty(username)){
13             sql.append(" and u.userName like ?");  //and前需要一个空格，否则sql拼接的时候有问题
14             list.add("%"+username+"%");//index:0
15         }
16 
17         if(userRole>0){
18             sql.append(" and u.userRole = ?");
19             list.add(userRole);//index:1
20         }
21 
22         //怎么把list转成数组
23         Object[] params = list.toArray();
24 
25         System.out.println("UserDaoIml-->getUserCount:"+sql.toString());//输出最后完整的代码
26 
27         rs = BaseDao.excute(connection, pstm, rs, sql.toString(), params);
28 
29         if (rs.next()){
30             count = rs.getInt("count");//从结果集中获得最终的数量
31         }
32         BaseDao.closeResourse(null,pstm,rs);
33     }
34     return count;
35 }

UserService

//查询记录数
public int getUserCount(String username,int userRole);

UserServiceImpl

//查询记录数
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 e) {
        e.printStackTrace();
    }finally {
        BaseDao.closeResourse(connection,null,null);
    }
    return count;
}

8|0获取用户列表

UserDao

//根据用户条件获取用户列表
public List<User> getUserList(Connection connection,String userName,int userRole,int currentPageNo,int pageSize)throws Exception;

UserDaoImpl

 1 //根据用户条件获取用户列表
 2 public List<User> getUserList(Connection connection, String userName, int userRole, int currentPageNo, int pageSize) throws Exception {
 3     PreparedStatement pstm = null;
 4     ResultSet rs = null;
 5     List<User> userList = new ArrayList<User>();
 6     if (connection!=null){
 7         StringBuffer sql = new StringBuffer();
 8         sql.append("select u.*,r.roleName as userRoleName from smbms_user u,smbms_role r where u.userRole = r.id");
 9         List<Object> list = new ArrayList<Object>();//存放我们的参数
10 
11         if (!StringUtils.isNullOrEmpty(userName)){
12             sql.append(" and u.userName like ?");  //and前需要一个空格，否则sql拼接的时候有问题
13             list.add("%"+userName+"%");//index:0
14         }
15 
16         if(userRole>0){
17             sql.append(" and u.userRole = ?");
18             list.add(userRole);//index:1
19         }
20         sql.append(" order by creationDate DESC limit ?,?");
21         currentPageNo = (currentPageNo-1)*pageSize;
22         list.add(currentPageNo);
23         list.add(pageSize);
24 
25         Object[] params = list.toArray();
26         System.out.println("sql-->"+sql.toString());
27         rs = BaseDao.excute(connection, pstm, rs, sql.toString(), params);
28         while (rs.next()){
29             User _user = new User();
30             _user.setId(rs.getInt("id"));
31             _user.setUserCode(rs.getString("userCode"));
32             _user.setUserName(rs.getString("userName"));
33             _user.setGender(rs.getInt("gender"));
34             _user.setBirthday(rs.getDate("birthday"));
35             _user.setPhone(rs.getString("phone"));
36             _user.setAddress(rs.getString("address"));
37             _user.setUserRole(rs.getInt("userRole"));
38             _user.setCreateBy(rs.getInt("createdBy"));
39             userList.add(_user);
40         }
41         BaseDao.closeResourse(null,pstm,rs);
42     }
43     return userList;
44 }

UserService

//根据条件查询用户列表
public List<User> getUserList(String queryUserName,int queryUserRole,int currentPageNo,int pageSize);

UserServiceImpl

 1 //根据条件查询用户列表
 2 public List<User> getUserList(String queryUserName, int queryUserRole, int currentPageNo, int pageSize) {
 3     Connection connection = null;
 4     List<User> userList = null;
 5     System.out.println("queryUserName--->"+queryUserName);
 6     System.out.println("queryUserRole--->"+queryUserRole);
 7     System.out.println("currentPageNo--->"+currentPageNo);
 8     System.out.println("pageSize--->"+pageSize);
 9 
10     try {
11         connection = BaseDao.getConnection();
12         userList = userDao.getUserList(connection,queryUserName,queryUserRole,currentPageNo,pageSize);
13     } catch (Exception e) {
14         e.printStackTrace();
15     }finally {
16         BaseDao.closeResourse(connection,null,null);
17     }
18     return userList;
19 }

9|0获取角色列表

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

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

RoleDaoImpl

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

    PreparedStatement pstm = null;
    ResultSet rs = null;
    ArrayList<Role> roleList = new ArrayList<Role>();

    if(connection!=null){
        String sql = "select * from smbms_role";
        Object[] parame = {};
        rs = BaseDao.excute(connection,pstm,rs,sql,parame);

        while(rs.next()){
            Role _role = new Role();
            _role.setId(rs.getInt("id"));
            _role.setRoleCode(rs.getString("roleCode"));
            _role.setRoleName(rs.getString("roleName"));
            roleList.add(_role);
        }
        BaseDao.closeResourse(null,pstm,rs);
    }
    return roleList;
}

RoleService

//获取角色列表
public List<Role> getRoleList();

RoleServiceImpl

package com.study.service.role;

import com.study.dao.BaseDao;
import com.study.dao.role.RoleDao;
import com.study.dao.role.RoleDaoImpl;
import com.study.pojo.Role;

import javax.sql.RowSetInternal;
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();
    }

    //获取角色列表
    public List<Role> getRoleList() {
        Connection connection = null;
        List<Role> roleList = null;

        try {
            connection = BaseDao.getConnection();
            roleList = roleDao.getRoleList(connection);
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            BaseDao.closeResourse(connection,null,null);
        }
        return roleList;
    }
}

10|0用户用于显示的Servlet

  1. 获取用户前端的数据（查询）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，需要极端当前页面合总页数，页面大小……

  4. 用户列表展示

  5. 返回前端

 1 //重点、难点
 2 public void query(HttpServletRequest req, HttpServletResponse resp){
 3 
 4     //查询用户列表
 5 
 6     //从前端端获取数据：
 7     String queryUserName = req.getParameter("queryname");
 8     String temp = req.getParameter("queryUserRole");
 9     String pageIndex = req.getParameter("pageIndex");
10     int queryUserRole = 0;
11 
12     //获取用户列表
13     UserServiceImpl userService = new UserServiceImpl();
14     List<User> userList = null;
15 
16     //第一次走这个请求，一定是第一页，页面大小是固定的：
17     int pageSize = 5;//可以把这个写到配置中，方便否其修改；
18     int currentPageNo = 1;
19 
20     if(queryUserName == null){
21         queryUserName = "";
22     }
23     if (temp!=null&&!temp.equals("")){
24         queryUserRole = Integer.parseInt(temp);//给查询赋值！0，1，2，3
25     }
26     if (pageIndex!=null){
27         currentPageNo = Integer.parseInt(pageIndex);
28     }
29 
30     //获取用户的总数（分页：上一页，下一页的情况）
31     int totalCount = userService.getUserCount(queryUserName, queryUserRole);
32     //总页数支持
33     PageSupport pageSupport = new PageSupport();
34     pageSupport.setCurrentPageNo(currentPageNo);
35     pageSupport.setPageSize(pageSize);
36     pageSupport.setTotalCount(totalCount);
37 
38     int totalPageCount = ((int)(totalCount/pageSize))+1;//总的页数
39 
40     //控制首页和页面
41     //如果页面要小于1，就显示第一页的东西
42     if(currentPageNo<1){
43         currentPageNo = 1;
44     }else if(currentPageNo>totalPageCount){//当前页面大于最后一页
45         currentPageNo = totalPageCount;
46     }
47 
48     //获取用户列表展示
49     userList = userService.getUserList(queryUserName,queryUserRole,currentPageNo,pageSize);
50     req.setAttribute("userList",userList);
51 
52     RoleServiceImpl roleService = new RoleServiceImpl();
53     List<Role> roleList = roleService.getRoleList();
54     req.setAttribute("roleList",roleList);
55     req.setAttribute("totalCount",totalCount);
56     req.setAttribute("currentPageNo",currentPageNo);
57     req.setAttribute("totalPageCount",totalPageCount);
58     req.setAttribute("queryUserName",queryUserName);
59     req.setAttribute("queryUserRole",queryUserRole);
60 
61     //返回前端
62     try {
63         req.getRequestDispatcher("userlist.jsp").forward(req,resp);
64     } catch (ServletException e) {
65         e.printStackTrace();
66     } catch (IOException e) {
67         e.printStackTrace();
68     }
69 }

 


__EOF__

本文作者：冰山醉酒
本文链接：https://www.cnblogs.com/douFrank/p/16117864.html
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