本文共 30834 字，大约阅读时间需要 102 分钟。

三层架构：软件设计架构

1. 界面层(表示层)：用户看的得界面。用户可以通过界面上的组件和服务器进行交互
2. 业务逻辑层：处理业务逻辑的。
3. 数据访问层：操作数据存储文件。

三层架构与MVC相似但有区别

开发前的准备工作

1. 需求：用户信息的增删改查操作2. 设计：	1. 技术选型：Servlet+JSP+MySQL+JDBCTempleat+Duird+BeanUtilS+tomcat	2. 数据库设计：		create database day17; -- 创建数据库		use day17; 			   -- 使用数据库		create table user(   -- 创建表			id int primary key auto_increment,			name varchar(20) not null,			gender varchar(5),			age int,			address varchar(32),			qq	varchar(20),			email varchar(50),			username varchar(32),			password varchar(32)		);3. 开发：	1. 环境搭建		1. 创建数据库环境		2. 创建项目，导入需要的jar包	2. 编码4. 测试5. 部署运维

综合练习：简单功能

1. 列表查询

   

2. 登录

3. 添加

4. 删除 5. 修改

综合练习：复杂功能

1. 删除选中
   
2. 分页查询

复杂条件分页查询

• 分页查询好处：

1. 减轻服务器内存的开销2. 提升用户体验

3. 复杂条件查询

项目工程结构

dao层用来操作数据库 domain文件夹是两个javabean类，含有PageBean和User类 service服务层含一个用户服务的接口和对应实现类 utils文件夹是JDBCUtils工具类便于数据库连接，JDBC工具类 使用Durid连接池 servlet用于接收前端的请求 web文件夹，存放前端的东西，如js，fonts，jsp页面等

项目运行逻辑

1. 首先运行好tomcat服务器，用户来到首页login.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>    
       
       
           
       
       
           
           
   
    
    
管理员登录
    
    
        
     
            
      用户名：            
              
     
        
     
            
      密码：            
              
     
        
     
            
      验证码：            
                  
                                          
     
        
     
        
     
            
              
     
    
    
    
        
    
        
                 ×                
     ${
   login_msg}    
    
   

2. 用户输入用户名，密码，验证码跳转到loginservlet

package cn.itcast.web.servlet;import cn.itcast.domain.User;import cn.itcast.service.UserService;import cn.itcast.service.impl.UserServiceImpl;import org.apache.commons.beanutils.BeanUtils;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import java.io.IOException;import java.lang.reflect.InvocationTargetException;import java.util.Map;@WebServlet("/loginServlet")public class LoginServlet extends HttpServlet {
       protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           //1.设置编码        request.setCharacterEncoding("utf-8");        //2.获取数据        //2.1获取用户填写验证码        String verifycode = request.getParameter("verifycode");        //3.验证码校验        HttpSession session = request.getSession();        String checkcode_server = (String) session.getAttribute("CHECKCODE_SERVER");        session.removeAttribute("CHECKCODE_SERVER");//确保验证码一次性        if(!checkcode_server.equalsIgnoreCase(verifycode)){
               //验证码不正确            //提示信息            request.setAttribute("login_msg","验证码错误！");            //跳转登录页面            request.getRequestDispatcher("/login.jsp").forward(request,response);            return;        }        Map
   
     map = request.getParameterMap();        //4.封装User对象        User user = new User();        try {
               BeanUtils.populate(user,map);        } catch (IllegalAccessException e) {
               e.printStackTrace();        } catch (InvocationTargetException e) {
               e.printStackTrace();        }        //5.调用Service查询        UserService service = new UserServiceImpl();        User loginUser = service.login(user);        //6.判断是否登录成功        if(loginUser != null){
               //登录成功            //将用户存入session            session.setAttribute("user",loginUser);            //跳转页面            response.sendRedirect(request.getContextPath()+"/index.jsp");        }else{
               //登录失败            //提示信息            request.setAttribute("login_msg","用户名或密码错误！");            //跳转登录页面            request.getRequestDispatcher("/login.jsp").forward(request,response);        }    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           this.doPost(request, response);    }}
   

3. 如果用户验证码输入错误，则可以更换验证码，跳转到checkcodeservlet

package cn.itcast.web.servlet;import javax.imageio.ImageIO;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.awt.*;import java.awt.image.BufferedImage;import java.io.IOException;import java.util.Random;/** * 验证码 */@WebServlet("/checkCodeServlet")public class CheckCodeServlet extends HttpServlet {
   	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
   				//服务器通知浏览器不要缓存		response.setHeader("pragma","no-cache");		response.setHeader("cache-control","no-cache");		response.setHeader("expires","0");				//在内存中创建一个长80，宽30的图片，默认黑色背景		//参数一：长		//参数二：宽		//参数三：颜色		int width = 80;		int height = 30;		BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);				//获取画笔		Graphics g = image.getGraphics();		//设置画笔颜色为灰色		g.setColor(Color.GRAY);		//填充图片		g.fillRect(0,0, width,height);				//产生4个随机验证码，12Ey		String checkCode = getCheckCode();		//将验证码放入HttpSession中		request.getSession().setAttribute("CHECKCODE_SERVER",checkCode);				//设置画笔颜色为黄色		g.setColor(Color.YELLOW);		//设置字体的小大		g.setFont(new Font("黑体",Font.BOLD,24));		//向图片上写入验证码		g.drawString(checkCode,15,25);				//将内存中的图片输出到浏览器		//参数一：图片对象		//参数二：图片的格式，如PNG,JPG,GIF		//参数三：图片输出到哪里去		ImageIO.write(image,"PNG",response.getOutputStream());	}	/**	 * 产生4位随机字符串 	 */	private String getCheckCode() {
   		String base = "0123456789ABCDEFGabcdefg";		int size = base.length();		Random r = new Random();		StringBuffer sb = new StringBuffer();		for(int i=1;i<=4;i++){
   			//产生0到size-1的随机值			int index = r.nextInt(size);			//在base字符串中获取下标为index的字符			char c = base.charAt(index);			//将c放入到StringBuffer中去			sb.append(c);		}		return sb.toString();	}	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   		this.doGet(request,response);	}}

4. 登陆成功以后，来到index.jsp，点击查询用户所有信息，跳转到findUserByPageServlet
   index.jsp如下

<%@ page contentType="text/html;charset=UTF-8" language="java" %><%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>  
     
     
       
     
     
       
         
   
    ${
   user.name},欢迎您
   
  
   
    
    查询所有用户信息      
   

findUserByPageServlet如下，将查询的结果转发到list.jsp

package cn.itcast.web.servlet;import cn.itcast.domain.PageBean;import cn.itcast.domain.User;import cn.itcast.service.UserService;import cn.itcast.service.impl.UserServiceImpl;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.util.Map;@WebServlet("/findUserByPageServlet")public class FindUserByPageServlet extends HttpServlet {
       protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           request.setCharacterEncoding("utf-8");        //1.获取参数        String currentPage = request.getParameter("currentPage");//当前页码        String rows = request.getParameter("rows");//每页显示条数        if(currentPage == null || "".equals(currentPage)){
               currentPage = "1";        }        if(rows == null || "".equals(rows)){
               rows = "5";        }                //获取条件查询参数        Map
   
     condition = request.getParameterMap();        //2.调用service查询        UserService service = new UserServiceImpl();        PageBean
    
      pb = service.findUserByPage(currentPage,rows,condition);        System.out.println(pb);        //3.将PageBean存入request        request.setAttribute("pb",pb);        request.setAttribute("condition",condition);//将查询条件存入request        //4.转发到list.jsp        request.getRequestDispatcher("/list.jsp").forward(request,response);    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           this.doPost(request, response);    }}
    
   

6. list.jsp如下，可以看到查询的结果

<%@ page contentType="text/html;charset=UTF-8" language="java" %><%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
       
       
       
       
       
       
       
           
       
       
           
               
   
    
    
用户信息列表
    
    
        
     
            
      
                
       姓名                
                   
      
            
      
                
       籍贯                
                   
      
            
      
                
       邮箱                
                   
      
            
      查询        
     
    
    
    
    
        
     添加联系人        
     删除选中    
    
    
    
        
                 
     
     
              
       
                    
                    
编号
                    
姓名
                    
性别
                    
年龄
                    
籍贯
                    
QQ
                    
邮箱
                    
操作
               
               
                        
                        
${ s.count}
                        
${ user.name}
                        
${ user.gender}
                        
${ user.age}
                        
${ user.address}
                        
${ user.qq}
                        
${ user.email}
                        
修改  删除
                   
                  
     
    
    
    
    
        
         
    
   

7.接着在list.jsp点击删除按钮，可以删除单条记录，跳转deluserservlet如下； deluserservlet

package cn.itcast.web.servlet;import cn.itcast.service.UserService;import cn.itcast.service.impl.UserServiceImpl;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;@WebServlet("/delUserServlet")public class DelUserServlet extends HttpServlet {
       protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           //1.获取id        String id = request.getParameter("id");        //2.调用service删除        UserService service = new UserServiceImpl();        service.deleteUser(id);        //3.跳转到查询所有Servlet        response.sendRedirect(request.getContextPath()+"/userListServlet");    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           this.doPost(request, response);    }}

8而点击删除选中，可以删掉选中的多条记录DelSelectedServlet

package cn.itcast.web.servlet;import cn.itcast.service.UserService;import cn.itcast.service.impl.UserServiceImpl;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;@WebServlet("/delSelectedServlet")public class DelSelectedServlet extends HttpServlet {
       protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           //1.获取所有id        String[] ids = request.getParameterValues("uid");        //2.调用service删除        UserService service = new UserServiceImpl();        service.delSelectedUser(ids);        //3.跳转查询所有Servlet        response.sendRedirect(request.getContextPath()+"/userListServlet");    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           this.doPost(request, response);    }}

8点击修改按钮，跳转到finduserServlet,再将查询到的信息转发回显到update.jsp

finduserServlet

package cn.itcast.web.servlet;import cn.itcast.domain.User;import cn.itcast.service.UserService;import cn.itcast.service.impl.UserServiceImpl;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;@WebServlet("/findUserServlet")public class FindUserServlet extends HttpServlet {
       protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           //1.获取id        String id = request.getParameter("id");        //2.调用Service查询        UserService service = new UserServiceImpl();        User user = service.findUserById(id);        //3.将user存入request        request.setAttribute("user",user);        //4.转发到update.jsp        request.getRequestDispatcher("/update.jsp").forward(request,response);    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           this.doPost(request, response);    }}

update.jsp，在该页面点击跳转updateUserServlet修改联系人生效

<%@ page contentType="text/html;charset=UTF-8" language="java" %><%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
               
           
           
           
                   
                                           
   
        
    
修改联系人
        
    
            
                 
               
     
            
      姓名：            
                
     
          
     
            
      性别：              
                        
       男                  
       女              
                    
                        
       男                  
       女              
                
     
          
     
            
      年龄：            
                
     
          
     
            
      籍贯：             
                                           陕西                    北京                    上海                                                       陕西                     北京                     上海                                                       陕西                     北京                     上海                                       
     
          
     
            
      QQ：            
                
     
          
     
            
      Email：            
                
     
             
     
                
                      
                      
                   
     
        
    
        
   
    

updateUserServlet如下

package cn.itcast.web.servlet;import cn.itcast.domain.User;import cn.itcast.service.UserService;import cn.itcast.service.impl.UserServiceImpl;import org.apache.commons.beanutils.BeanUtils;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.lang.reflect.InvocationTargetException;import java.util.Map;@WebServlet("/updateUserServlet")public class UpdateUserServlet extends HttpServlet {
       protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           //1.设置编码        request.setCharacterEncoding("utf-8");        //2.获取map        Map
   
     map = request.getParameterMap();        //3.封装对象        User user = new User();        try {
               BeanUtils.populate(user,map);        } catch (IllegalAccessException e) {
               e.printStackTrace();        } catch (InvocationTargetException e) {
               e.printStackTrace();        }        //4.调用Service修改        UserService service = new UserServiceImpl();        service.updateUser(user);        //5.跳转到查询所有Servlet        response.sendRedirect(request.getContextPath()+"/userListServlet");    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           this.doPost(request, response);    }}
   

最后是添加联系人功能，点击添加联系人按钮，跳转到add.jsp，在add.jsp页面里面输入添加的信息，然后再跳转到addUserServlet

add.jsp如下：

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
   
       
       
       
       
       
       
       
           
       
       
           
       
   
    
    
     
添加联系人页面
        
    
        
     
            
      姓名：            
              
     
        
     
            
      性别：            
      男            
      女        
     
        
     
            
      年龄：            
              
     
        
     
            
      籍贯：            
                      陕西                北京                上海                    
     
        
     
            
      QQ：            
              
     
        
     
            
      Email：            
              
     
        
     
            
                  
                  
              
     
    
    
   

addUserServlet如下

package cn.itcast.web.servlet;import cn.itcast.domain.User;import cn.itcast.service.UserService;import cn.itcast.service.impl.UserServiceImpl;import org.apache.commons.beanutils.BeanUtils;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.lang.reflect.InvocationTargetException;import java.util.Map;@WebServlet("/addUserServlet")public class AddUserServlet extends HttpServlet {
       protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           //1.设置编码        request.setCharacterEncoding("utf-8");        //2.获取参数        Map
   
     map = request.getParameterMap();        //3.封装对象        User user = new User();        try {
               BeanUtils.populate(user,map);        } catch (IllegalAccessException e) {
               e.printStackTrace();        } catch (InvocationTargetException e) {
               e.printStackTrace();        }        //4.调用Service保存        UserService service = new UserServiceImpl();        service.addUser(user);        //5.跳转到userListServlet        response.sendRedirect(request.getContextPath()+"/userListServlet");    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           this.doPost(request, response);    }}
   

对于dao层有一个接口和对应的实现类

package cn.itcast.dao;import cn.itcast.domain.User;import java.util.List;import java.util.Map;/** * 用户操作的DAO */public interface UserDao {
       public List
   
     findAll();    User findUserByUsernameAndPassword(String username, String password);    void add(User user);    void delete(int id);    User findById(int i);    void update(User user);    /**     * 查询总记录数     * @return     * @param condition     */    int findTotalCount(Map
    
      condition);    /**     * 分页查询每页记录     * @param start     * @param rows     * @param condition     * @return     */    List
     
       findByPage(int start, int rows, Map
      
        condition);}
      
     
    
   

实现类

package cn.itcast.dao.impl;import cn.itcast.dao.UserDao;import cn.itcast.domain.User;import cn.itcast.util.JDBCUtils;import org.springframework.jdbc.core.BeanPropertyRowMapper;import org.springframework.jdbc.core.JdbcTemplate;import java.util.ArrayList;import java.util.List;import java.util.Map;import java.util.Set;public class UserDaoImpl implements UserDao {
       private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());    @Override    public List
   
     findAll() {
           //使用JDBC操作数据库...        //1.定义sql        String sql = "select * from user";        List
    
      users = template.query(sql, new BeanPropertyRowMapper
     
      (User.class));        return users;    }    @Override    public User findUserByUsernameAndPassword(String username, String password) {
           try {
               String sql = "select * from user where username = ? and password = ?";            User user = template.queryForObject(sql, new BeanPropertyRowMapper
      
       (User.class), username, password);            return user;        } catch (Exception e) {
               e.printStackTrace();            return null;        }    }    @Override    public void add(User user) {
           //1.定义sql        String sql = "insert into user values(null,?,?,?,?,?,?,null,null)";        //2.执行sql        template.update(sql, user.getName(), user.getGender(), user.getAge(), user.getAddress(), user.getQq(), user.getEmail());    }    @Override    public void delete(int id) {
           //1.定义sql        String sql = "delete from user where id = ?";        //2.执行sql        template.update(sql, id);    }    @Override    public User findById(int id) {
           String sql = "select * from user where id = ?";        return template.queryForObject(sql, new BeanPropertyRowMapper
       
        (User.class), id);    }    @Override    public void update(User user) {
           String sql = "update user set name = ?,gender = ? ,age = ? , address = ? , qq = ?, email = ? where id = ?";        template.update(sql, user.getName(), user.getGender(), user.getAge(), user.getAddress(), user.getQq(), user.getEmail(), user.getId());    }    @Override    public int findTotalCount(Map
        
          condition) { //1.定义模板初始化sql String sql = "select count(*) from user where 1 = 1 "; StringBuilder sb = new StringBuilder(sql); //2.遍历map Set
         
           keySet = condition.keySet(); //定义参数的集合 List
          
         
        
       
      
     
    
   

domain层的两个实体类，一个是PageBean，一个是User

package cn.itcast.domain;import java.util.List;/** * 分页对象 */public class PageBean
   
     {
       private int totalCount; // 总记录数    private int totalPage ; // 总页码    private List
    
      list ; // 每页的数据    private int currentPage ; //当前页码    private int rows;//每页显示的记录数    public int getTotalCount() {
           return totalCount;    }    public void setTotalCount(int totalCount) {
           this.totalCount = totalCount;    }    public int getTotalPage() {
           return totalPage;    }    public void setTotalPage(int totalPage) {
           this.totalPage = totalPage;    }    public List
     
       getList() {
           return list;    }    public void setList(List
      
        list) {
           this.list = list;    }    public int getCurrentPage() {
           return currentPage;    }    public void setCurrentPage(int currentPage) {
           this.currentPage = currentPage;    }    public int getRows() {
           return rows;    }    public void setRows(int rows) {
           this.rows = rows;    }    @Override    public String toString() {
           return "PageBean{" +                "totalCount=" + totalCount +                ", totalPage=" + totalPage +                ", list=" + list +                ", currentPage=" + currentPage +                ", rows=" + rows +                '}';    }}
      
     
    
   

package cn.itcast.domain;public class User {
       private int id;    private String name;    private String gender;    private int age;    private String address;    private String qq;    private String email;    private String username;    private String password;    public String getUsername() {
           return username;    }    public void setUsername(String username) {
           this.username = username;    }    public String getPassword() {
           return password;    }    public void setPassword(String password) {
           this.password = password;    }    public int getId() {
           return id;    }    public void setId(int id) {
           this.id = id;    }    public String getName() {
           return name;    }    public void setName(String name) {
           this.name = name;    }    public String getGender() {
           return gender;    }    public void setGender(String gender) {
           this.gender = gender;    }    public int getAge() {
           return age;    }    public void setAge(int age) {
           this.age = age;    }    public String getAddress() {
           return address;    }    public void setAddress(String address) {
           this.address = address;    }    public String getQq() {
           return qq;    }    public void setQq(String qq) {
           this.qq = qq;    }    public String getEmail() {
           return email;    }    public void setEmail(String email) {
           this.email = email;    }    @Override    public String toString() {
           return "User{" +                "id=" + id +                ", name='" + name + '\'' +                ", gender='" + gender + '\'' +                ", age=" + age +                ", address='" + address + '\'' +                ", qq='" + qq + '\'' +                ", email='" + email + '\'' +                ", username='" + username + '\'' +                ", password='" + password + '\'' +                '}';    }}

service有一个userService接口，和实现类

package cn.itcast.service;import cn.itcast.domain.PageBean;import cn.itcast.domain.User;import java.util.List;import java.util.Map;/** * 用户管理的业务接口 */public interface UserService {
       /**     * 查询所有用户信息     * @return     */    public List
   
     findAll();    /**     * 登录方法     * @param user     * @return     */    User login(User user);    /**     * 保存User     * @param user     */    void addUser(User user);    /**     * 根据id删除User     * @param id     */    void deleteUser(String id);    /**     * 根据id查询     * @param id     * @return     */    User findUserById(String id);    /**     * 修改用户信息     * @param user     */    void updateUser(User user);    /**     * 批量删除用户     * @param ids     */    void delSelectedUser(String[] ids);    /**     * 分页条件查询     * @param currentPage     * @param rows     * @param condition     * @return     */    PageBean
    
      findUserByPage(String currentPage, String rows, Map
     
       condition);}
     
    
   

userservice实现类如下

package cn.itcast.service.impl;import cn.itcast.dao.UserDao;import cn.itcast.dao.impl.UserDaoImpl;import cn.itcast.domain.PageBean;import cn.itcast.domain.User;import cn.itcast.service.UserService;import java.util.List;import java.util.Map;public class UserServiceImpl implements UserService {
       private UserDao dao = new UserDaoImpl();    @Override    public List
   
     findAll() {
           //调用Dao完成查询        return dao.findAll();    }    @Override    public User login(User user) {
           return dao.findUserByUsernameAndPassword(user.getUsername(),user.getPassword());    }    @Override    public void addUser(User user) {
           dao.add(user);    }    @Override    public void deleteUser(String id) {
           dao.delete(Integer.parseInt(id));    }    @Override    public User findUserById(String id) {
           return dao.findById(Integer.parseInt(id));    }    @Override    public void updateUser(User user) {
           dao.update(user);    }    @Override    public void delSelectedUser(String[] ids) {
           if(ids != null && ids.length > 0){
               //1.遍历数组            for (String id : ids) {
                   //2.调用dao删除                dao.delete(Integer.parseInt(id));            }        }    }    @Override    public PageBean
    
      findUserByPage(String _currentPage, String _rows, Map
     
       condition) {
           int currentPage = Integer.parseInt(_currentPage);        int rows = Integer.parseInt(_rows);        if(currentPage <=0) {
               currentPage = 1;        }        //1.创建空的PageBean对象        PageBean
      
        pb = new PageBean
       
        ();        //2.设置参数        pb.setCurrentPage(currentPage);        pb.setRows(rows);        //3.调用dao查询总记录数        int totalCount = dao.findTotalCount(condition);        pb.setTotalCount(totalCount);        //4.调用dao查询List集合        //计算开始的记录索引        int start = (currentPage - 1) * rows;        List
        
          list = dao.findByPage(start,rows,condition); pb.setList(list); //5.计算总页码 int totalPage = (totalCount % rows) == 0 ? totalCount/rows : (totalCount/rows) + 1; pb.setTotalPage(totalPage); return pb; }}
        
       
      
     
    
   

jdbc工具类代码

package cn.itcast.util;import com.alibaba.druid.pool.DruidDataSourceFactory;import javax.sql.DataSource;import java.io.IOException;import java.io.InputStream;import java.sql.Connection;import java.sql.SQLException;import java.util.Properties;/** * JDBC工具类 使用Durid连接池 */public class JDBCUtils {
       private static DataSource ds ;    static {
           try {
               //1.加载配置文件            Properties pro = new Properties();            //使用ClassLoader加载配置文件，获取字节输入流            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");            pro.load(is);            //2.初始化连接池对象            ds = DruidDataSourceFactory.createDataSource(pro);        } catch (IOException e) {
               e.printStackTrace();        } catch (Exception e) {
               e.printStackTrace();        }    }    /**     * 获取连接池对象     */    public static DataSource getDataSource(){
           return ds;    }    /**     * 获取连接Connection对象     */    public static Connection getConnection() throws SQLException {
           return  ds.getConnection();    }}

druid.properties配置文件定义

遇到问题汇总

1 点击label标签有自动聚焦的功能

2 Bootstrap中文文档，组件之分页

https://v3.bootcss.com/components/#pagination

3 a标签使用js函数方法

https://blog.csdn.net/qq_23994787/article/details/77480049 另外input标签的点击事件也可以触发js函数

4 验证码校验的过程是，在后端的checkservlet中，编写生成验证码，并存入服务器的session，然后前端注册页面输入验证码之后点击注册，将前端传过来的验证码与session进行对比，校验即可

5 JAVA中request.getParameterMap()用法笔记

一个获取提交表单数据的新方法request.getParameterMap。

https://blog.csdn.net/lncsdn_123/article/details/78500328

6 foreach循环中的user对象，如果要到其他地方使用，可在js函数中进行传参

7 Confirm是js里面的警告函数，可以在前端弹出警告提示框

8 组件选中问题，在组件内编写点击事件函数，用this来代指id为“firstCb”的组件

9 前端的表单用submit方法提交，会把选中组件的id的值一并通过请求参数提交到后端