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综合练习

学习目标

  • 能够完成添加联系人案例
  • 能够完成删除联系人案例
  • 能够理解PageBean分页数据的封装
  • 掌握limit关键字的使用
  • 能够完成分页展示联系人案例

案例一-显示所有联系人案例

一，案例需求

Web综合练习 - 图1

  • 查询数据库里面所有的用户, 展示在页面

二,技术分析

  1. 传统方式的开发一个请求对应一个Servlet:这样的话会导致一个模块的Servlet过多,导致整个项目的Servlet都会很多.  能不能做一个处理?让一个**模块**用一个Servlet处理请求.   当前是**联系人模块**, 就创建一个LinkManServlet
  1. @WebServlet("/linkman")
  2. public class LinkManServlet extends HttpServlet {   
  3.     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  4.         doGet(request, response);
  5.     }
  6.     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  7.         //1.获得method请求参数
  8.         String action = request.getParameter("action");
  10.         //2.判断
  11.         if("findAll".equals(action)){
  12.                findAll(request,response);
  13.         }
  14.         if("add".equals(action)){
  15.                add(request,response);
  16.         }
  17.         if("delete".equals(action)){
  18.             delete(request,response);
  19.         }
  20.     }
  22.     //删除联系人
  23.    public void delete(HttpServletRequest request,HttpServletResponse response){
  25.     }
  27.     //查询所有的联系人
  28.    public void findAll(HttpServletRequest request,HttpServletResponse response){
  30.     }
  32.    //添加联系人
  33.    public void add(HttpServletRequest request,HttpServletResponse response){
  35.     }
  36. }

三, 思路分析

Web综合练习 - 图3

四, 代码实现

1.准备工作

  • 数据库的创建
  1. CREATE TABLE linkman (
  2.   id int primary key auto_increment,
  3.   name varchar(50),
  4.   sex varchar(50),
  5.   age int,
  6.   address varchar(50),
  7.   qq varchar(50),
  8.   email varchar(50)
  9. );
  11. INSERT INTO `linkman`  (`id`, `name`, `sex`, `age`, `address`, `qq`, `email`) VALUES
  12. (null, '张三', '男', 11, '广东', '766335435', '766335435@qq.com'),
  13. (null, '李四', '男', 12, '广东', '243424242', '243424242@qq.com'),
  14. (null, '王五', '女', 13, '广东', '474574574', '474574574@qq.com'),
  15. (null, '赵六', '女', 18, '广东', '77777777', '77777777@qq.com'),
  16. (null, '钱七', '女', 15, '湖南', '412132145', '412132145@qq.com'),
  17. (null, '王八', '男', 25, '广西', '412132775', '412132995@qq.com');
  • JavaBean的创建
  1. package com.itheima.pojo;
  3. import java.io.Serializable;
  5. /**
  6.  * 包名:com.itheima.pojo
  7.  *
  8.  * @author Leevi
  9.  * 日期2020-07-18  09:14
  10.  */
  11. public class LinkMan implements Serializable {
  12.     private Integer id;
  13.     private String name;
  14.     private String sex;
  15.     private Integer age;
  16.     private String address;
  17.     private String qq;
  18.     private String email;
  20.     @Override
  21.     public String toString() {
  22.         return "LinkMan{" +
  23.                 "id=" + id +
  24.                 ", name='" + name + '\'' +
  25.                 ", sex='" + sex + '\'' +
  26.                 ", age=" + age +
  27.                 ", address='" + address + '\'' +
  28.                 ", qq='" + qq + '\'' +
  29.                 ", email='" + email + '\'' +
  30.                 '}';
  31.     }
  33.     public Integer getId() {
  34.         return id;
  35.     }
  37.     public void setId(Integer id) {
  38.         this.id = id;
  39.     }
  41.     public String getName() {
  42.         return name;
  43.     }
  45.     public void setName(String name) {
  46.         this.name = name;
  47.     }
  49.     public String getSex() {
  50.         return sex;
  51.     }
  53.     public void setSex(String sex) {
  54.         this.sex = sex;
  55.     }
  57.     public Integer getAge() {
  58.         return age;
  59.     }
  61.     public void setAge(Integer age) {
  62.         this.age = age;
  63.     }
  65.     public String getAddress() {
  66.         return address;
  67.     }
  69.     public void setAddress(String address) {
  70.         this.address = address;
  71.     }
  73.     public String getQq() {
  74.         return qq;
  75.     }
  77.     public void setQq(String qq) {
  78.         this.qq = qq;
  79.     }
  81.     public String getEmail() {
  82.         return email;
  83.     }
  85.     public void setEmail(String email) {
  86.         this.email = email;
  87.     }
  88. }
  • jar包
  • 工具类
  • 解决乱码的过滤器
  • 配置文件
  • 页面

2.代码

  • index.jsp页面
  1. <a href="/linkman?action=findAll">查询所有的联系人</a>
  • LinkManServlet
  1. package com.itheima.web.servlet;
  3. import com.itheima.entry.PageBean;
  4. import com.itheima.pojo.LinkMan;
  5. import com.itheima.service.LinkManService;
  6. import org.apache.commons.beanutils.BeanUtils;
  8. import javax.servlet.ServletException;
  9. import javax.servlet.annotation.WebServlet;
  10. import javax.servlet.http.HttpServlet;
  11. import javax.servlet.http.HttpServletRequest;
  12. import javax.servlet.http.HttpServletResponse;
  13. import java.io.IOException;
  14. import java.lang.reflect.Method;
  15. import java.util.List;
  16. import java.util.Map;
  18. /**
  19.  * 包名:${PACKAGE_NAME}
  20.  *
  21.  * @author Leevi
  22.  * 日期2020-07-18  08:53
  23.  * LinkManServlet负责处理联系人模块的所有请求
  24.  */
  25. @WebServlet("/linkman")
  26. public class LinkManServlet extends HttpServlet {
  27.     private LinkManService linkManService = new LinkManService();
  28.     @Override
  29.     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  30.         doGet(request, response);
  31.     }
  33.     @Override
  34.     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  35.         //1. 获取请求参数action的值
  36.         String action = request.getParameter("action");
  37.         //2. 判断action的值
  38.         if ("findAll".equals(action)) {
  39.             //调用findAll()方法查询所有
  40.             findAll(request,response);
  41.         }
  42.     }
  43.     /**
  44.      * 查询所有联系人
  45.      */
  46.     private void findAll(HttpServletRequest request,HttpServletResponse response) throws IOException {
  47.         try {
  48.             //1. 调用业务层的方法，查询所有联系人
  49.             List<LinkMan> linkManList = linkManService.findAll();
  50.             //2. 将 linkManList存储到request域对象中
  51.             request.setAttribute("list",linkManList);
  52.             //3. 请求转发跳转到list.jsp页面
  53.             request.getRequestDispatcher("/list.jsp").forward(request, response);
  54.         } catch (Exception e) {
  55.             e.printStackTrace();
  56.             //查询失败
  57.             response.getWriter().write("查询所有联系人失败");
  58.         }
  59.     }
  60. }
  • LinkManService
  1. package com.itheima.service;
  3. import com.itheima.dao.LinkManDao;
  4. import com.itheima.entry.PageBean;
  5. import com.itheima.pojo.LinkMan;
  7. import java.sql.SQLException;
  8. import java.util.List;
  10. /**
  11.  * 包名:com.itheima.service
  12.  *
  13.  * @author Leevi
  14.  * 日期2020-07-18  09:17
  15.  */
  16. public class LinkManService {
  17.     private LinkManDao linkManDao = new LinkManDao();
  18.     public List<LinkMan> findAll() throws SQLException {
  19.         return linkManDao.findAll();
  20.     }
  21. }
  • LinkManDao
  1. package com.itheima.dao;
  3. import com.itheima.pojo.LinkMan;
  4. import com.itheima.utils.DruidUtil;
  5. import org.apache.commons.dbutils.QueryRunner;
  6. import org.apache.commons.dbutils.handlers.BeanHandler;
  7. import org.apache.commons.dbutils.handlers.BeanListHandler;
  8. import org.apache.commons.dbutils.handlers.ScalarHandler;
  10. import java.sql.SQLException;
  11. import java.util.List;
  13. /**
  14.  * 包名:com.itheima.dao
  15.  *
  16.  * @author Leevi
  17.  * 日期2020-07-18  09:18
  18.  */
  19. public class LinkManDao {
  20.     private QueryRunner runner = new QueryRunner(DruidUtil.getDataSource());
  21.     public List<LinkMan> findAll() throws SQLException {
  22.         String sql = "select * from linkman";
  23.         List<LinkMan> linkManList = runner.query(sql, new BeanListHandler<>(LinkMan.class));
  24.         return linkManList;
  25.     }
  26. }
  • list.jsp
  1. <%--使用forEach标签遍历--%>
  2. <c:forEach items="${list}" var="linkman" varStatus="vst">
  3.     <tr>
  4.         <td>${vst.count}</td>
  5.         <td>${linkman.name}</td>
  6.         <td>${linkman.sex}</td>
  7.         <td>${linkman.age}</td>
  8.         <td>${linkman.address}</td>
  9.         <td>${linkman.qq}</td>
  10.         <td>${linkman.email}</td>
  11.         <td><a class="btn btn-default btn-sm" href="/linkman?action=findOne&id=${linkman.id}">修改</a>&nbsp;
  12.             <a class="btn btn-default btn-sm" href="javascript:;" onclick="deleteLinkMan('${linkman.name}','${linkman.id}')">删除</a></td>
  13.     </tr>
  14. </c:forEach>

五,小结

  1. 浏览器 请求LinkManServlet, 携带action=findAll
  2. 在LinkManServlet里面创建findAll()方法
  1. //1.调用业务 获得所有的联系人List<LinkMan> list
  2. //2.把list存到request里面, 转发list.jsp
  1. 创建LinkManService
  1. public List<LinkMan> findAll(){
  2.     //1.调用Dao 获得List
  3.     //2.返回List
  4. }
  1. 创建LinkManDao
  1. public List<LinkMan> findAll(){
  2.     //1.使用DBUtils查询所有的联系人(BeanListHandler)
  3. }

案例二:添加联系人

一,案例需求

  1. 点击添加联系人跳转添加联系人页面
    Web综合练习 - 图4

  2. 在添加联系人页面，点击提交按钮,把数据提交到服务器,保存到数据库
    Web综合练习 - 图5

  3. 在添加完成，可以查看到新建的联系人信息
    Web综合练习 - 图6

二,思路分析

Web综合练习 - 图7

三代码实现

  • LinkManServlet
  1. package com.itheima.web.servlet;
  3. import com.itheima.entry.PageBean;
  4. import com.itheima.pojo.LinkMan;
  5. import com.itheima.service.LinkManService;
  6. import org.apache.commons.beanutils.BeanUtils;
  8. import javax.servlet.ServletException;
  9. import javax.servlet.annotation.WebServlet;
  10. import javax.servlet.http.HttpServlet;
  11. import javax.servlet.http.HttpServletRequest;
  12. import javax.servlet.http.HttpServletResponse;
  13. import java.io.IOException;
  14. import java.lang.reflect.Method;
  15. import java.util.List;
  16. import java.util.Map;
  18. /**
  19.  * 包名:${PACKAGE_NAME}
  20.  *
  21.  * @author Leevi
  22.  * 日期2020-07-18  08:53
  23.  * LinkManServlet负责处理联系人模块的所有请求
  24.  */
  25. @WebServlet("/linkman")
  26. public class LinkManServlet extends HttpServlet {
  27.     private LinkManService linkManService = new LinkManService();
  28.     @Override
  29.     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  30.         doGet(request, response);
  31.     }
  33.     @Override
  34.     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  35.         //1. 获取请求参数action的值
  36.         String action = request.getParameter("action");
  37.         //2. 判断action的值
  38.         if ("findAll".equals(action)) {
  39.             //调用findAll()方法查询所有
  40.             findAll(request,response);
  41.         }
  42.         if ("add".equals(action)){
  43.             add(request,response);
  44.         }
  45.     }
  46.     /**
  47.      * 添加联系人
  48.      * @param request
  49.      * @param response
  50.      * @throws IOException
  51.      */
  52.     private void add(HttpServletRequest request,HttpServletResponse response) throws IOException {
  53.         try {
  54.             //1. 获取所有请求参数
  55.             Map<String, String[]> parameterMap = request.getParameterMap();
  56.             //2. 将请求参数封装到LinkMan对象中
  57.             LinkMan linkMan = new LinkMan();
  58.             BeanUtils.populate(linkMan,parameterMap);
  59.             //3. 调用业务层的方法添加联系人
  60.             linkManService.add(linkMan);
  61.             //4. 添加成功
  62.             //跳转到查询所有
  63.             response.sendRedirect("/linkman?action=findAll");
  64.         } catch (Exception e) {
  65.             e.printStackTrace();
  66.             //添加失败
  67.             response.getWriter().write("添加失败");
  68.         }
  69.     }
  70. }
  • LinkManService
  1. package com.itheima.service;
  3. import com.itheima.dao.LinkManDao;
  4. import com.itheima.entry.PageBean;
  5. import com.itheima.pojo.LinkMan;
  7. import java.sql.SQLException;
  8. import java.util.List;
  10. /**
  11.  * 包名:com.itheima.service
  12.  *
  13.  * @author Leevi
  14.  * 日期2020-07-18  09:17
  15.  */
  16. public class LinkManService {
  17.     private LinkManDao linkManDao = new LinkManDao();
  18.     public void add(LinkMan linkMan) throws SQLException {
  19.         //调用dao层的方法，添加联系人
  20.         linkManDao.add(linkMan);
  21.     }
  22. }
  • LinkManDao
  1. package com.itheima.dao;
  3. import com.itheima.pojo.LinkMan;
  4. import com.itheima.utils.DruidUtil;
  5. import org.apache.commons.dbutils.QueryRunner;
  6. import org.apache.commons.dbutils.handlers.BeanHandler;
  7. import org.apache.commons.dbutils.handlers.BeanListHandler;
  8. import org.apache.commons.dbutils.handlers.ScalarHandler;
  10. import java.sql.SQLException;
  11. import java.util.List;
  13. /**
  14.  * 包名:com.itheima.dao
  15.  *
  16.  * @author Leevi
  17.  * 日期2020-07-18  09:18
  18.  */
  19. public class LinkManDao {
  20.     private QueryRunner runner = new QueryRunner(DruidUtil.getDataSource());
  21.     public void add(LinkMan linkMan) throws SQLException {
  22.         String sql = "insert into linkman values (null,?,?,?,?,?,?)";
  23.         runner.update(sql,linkMan.getName(),linkMan.getSex(),linkMan.getAge(),linkMan.getAddress(),linkMan.getQq(),linkMan.getEmail());
  24.     }
  25. }

四,小结

  1. 新增联系人说白了就是向数据库里面插入一条记录

  2. 思路

    • 浏览器 点击提交 把数据提交到LinkManServlet(action=add, 联系人的基本信息)

    • 在LinkManServlet创建add()方法

      1. //1.获得请求参数(联系人的基本信息), 封装成LinkMan对象
      2. //2.调用业务新增联系人
      3. //3.再查询所有展示【建议使用重定向】

    • 在LinkManService创建add()方法

      1. public void add(LinkMan linkMan){
      2. //1.调用Dao 保存
      3. }

    • 在LinkManDao创建save()方法

      1. public void save(LinkMan linkMan){
      2. //1.使用DBUtils保存
      3. }

案例三:删除联系人

一,案例需求

Web综合练习 - 图8

  1. 点击确定删除之后, 再重新查询所有全部展示,

二,思路分析

Web综合练习 - 图9

三,代码实现

  • LinkManServlet
  1. package com.itheima.web.servlet;
  3. import com.itheima.entry.PageBean;
  4. import com.itheima.pojo.LinkMan;
  5. import com.itheima.service.LinkManService;
  6. import org.apache.commons.beanutils.BeanUtils;
  8. import javax.servlet.ServletException;
  9. import javax.servlet.annotation.WebServlet;
  10. import javax.servlet.http.HttpServlet;
  11. import javax.servlet.http.HttpServletRequest;
  12. import javax.servlet.http.HttpServletResponse;
  13. import java.io.IOException;
  14. import java.lang.reflect.Method;
  15. import java.util.List;
  16. import java.util.Map;
  18. /**
  19.  * 包名:${PACKAGE_NAME}
  20.  *
  21.  * @author Leevi
  22.  * 日期2020-07-18  08:53
  23.  * LinkManServlet负责处理联系人模块的所有请求
  24.  */
  25. @WebServlet("/linkman")
  26. public class LinkManServlet extends HttpServlet {
  27.     private LinkManService linkManService = new LinkManService();
  28.     @Override
  29.     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  30.         doGet(request, response);
  31.     }
  33.     @Override
  34.     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  35.         //1. 获取请求参数action的值
  36.         String action = request.getParameter("action");
  37.         //2. 判断action的值
  38.         if ("findAll".equals(action)) {
  39.             //调用findAll()方法查询所有
  40.             findAll(request,response);
  41.         }
  42.         if ("add".equals(action)){
  43.             add(request,response);
  44.         }
  45.         if ("delete".equals(action)){
  46.             delete(request,response);
  47.         }
  48.     }
  49.     /**
  50.      * 删除联系人
  51.      * @param request
  52.      * @param response
  53.      * @throws IOException
  54.      */
  55.     private void delete(HttpServletRequest request,HttpServletResponse response) throws IOException {
  56.         try {
  57.             //1. 获取要删除的联系人的id
  58.             Integer id = Integer.valueOf(request.getParameter("id"));
  59.             //2. 调用业务层的方法，根据id删除联系人
  60.             linkManService.deleteById(id);
  61.             //3. 删除成功，则跳转到查询所有
  62.             response.sendRedirect("/linkman?action=findAll");
  63.         } catch (Exception e) {
  64.             e.printStackTrace();
  65.             response.getWriter().write("删除失败");
  66.         }
  68.     }
  69. }
  • LinkManService
  1. public class linkManService {
  4.     /**
  5.      * 根据id删除联系人
  6.      * @param id
  7.      */
  8.     public void deleteById(Integer id) throws SQLException {
  9.         //调用dao层的方法，根据id删除联系人
  10.         linkManDao.deleteById(id);
  11.     }
  12. }
  • LinkManDao
  1. public void deleteById(Integer id) throws SQLException {
  2.     String sql = "delete from linkman where id=?";
  3.     runner.update(sql,id);
  4. }

四,小结

  1. 点击了确定之后请求服务器删除, 用到location.href请求
  1. Location.href="linkMan?action=delete&id="+id;

  1. 思路

    • 浏览器点击了确定之后, 请求LinkManServlet, 携带action=delete,id

    • 在LinkManServlet里面创建delete()方法

      1. //1.获得请求参数id
      2. //2.调用业务 根据id删除
      3. //3.再查询所有展示

    • 在LinkManService里面创建deleteById()

      1. public void deleteById(int id){
      2. //1.调用Dao 根据id删除
      3. }

    • 在LinkDao里面创建deleteById()

      1. public void deleteById(int id){
      2. //1.使用DBUtils根据id删除
      3. }

案例四:修改联系人

一、案例需求

1. 修改前的数据回显

Web综合练习 - 图10

2. 完成点击提交修改联系人的信息

二、案例流程分析

Web综合练习 - 图11

三、代码实现

1. 数据回显代码实现

list.jsp代码

  1. <td><a class="btn btn-default btn-sm" href="/linkman?action=findOne&id=${linkman.id}">修改</a>&nbsp;
  2.                     <a class="btn btn-default btn-sm" href="javascript:;" onclick="deleteLinkMan('${linkman.name}','${linkman.id}')">删除</a></td>

LinkManServlet代码

  1. package com.itheima.web.servlet;
  3. import com.itheima.entry.PageBean;
  4. import com.itheima.pojo.LinkMan;
  5. import com.itheima.service.LinkManService;
  6. import org.apache.commons.beanutils.BeanUtils;
  8. import javax.servlet.ServletException;
  9. import javax.servlet.annotation.WebServlet;
  10. import javax.servlet.http.HttpServlet;
  11. import javax.servlet.http.HttpServletRequest;
  12. import javax.servlet.http.HttpServletResponse;
  13. import java.io.IOException;
  14. import java.lang.reflect.Method;
  15. import java.util.List;
  16. import java.util.Map;
  18. /**
  19.  * 包名:${PACKAGE_NAME}
  20.  *
  21.  * @author Leevi
  22.  * 日期2020-07-18  08:53
  23.  * LinkManServlet负责处理联系人模块的所有请求
  24.  */
  25. @WebServlet("/linkman")
  26. public class LinkManServlet extends HttpServlet {
  27.     private LinkManService linkManService = new LinkManService();
  28.     @Override
  29.     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  30.         doGet(request, response);
  31.     }
  33.     @Override
  34.     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  35.         //1. 获取请求参数action的值
  36.         String action = request.getParameter("action");
  37.         //2. 判断action的值
  38.         if ("findAll".equals(action)) {
  39.             //调用findAll()方法查询所有
  40.             findAll(request,response);
  41.         }
  42.         if ("add".equals(action)){
  43.             add(request,response);
  44.         }
  45.         if ("delete".equals(action)){
  46.             delete(request,response);
  47.         }
  48.         if("findOne".equals(action)){
  49.             findOne(request,response);
  50.         }
  51.     }
  52.     /**
  53.      * 根据id查询联系人
  54.      * @param request
  55.      * @param response
  56.      */
  57.     private void findOne(HttpServletRequest request, HttpServletResponse response) throws IOException {
  58.         try {
  59.             //1. 获取要查询的联系人的id
  60.             Integer id = Integer.valueOf(request.getParameter("id"));
  61.             //2. 调用业务层的方法，根据id查询联系人
  62.             LinkMan linkMan = linkManService.findById(id);
  63.             //3. 将查询到的linkman对象存储到request域对象中
  64.             request.setAttribute("linkman",linkMan);
  65.             //4. 跳转到update.jsp页面
  66.             request.getRequestDispatcher("/update.jsp").forward(request, response);
  67.         } catch (Exception e) {
  68.             e.printStackTrace();
  69.             response.getWriter().write("数据回显失败");
  70.         }
  72.     }
  73. }

LinkManService代码

  1. package com.itheima.service;
  3. import com.itheima.dao.LinkManDao;
  4. import com.itheima.entry.PageBean;
  5. import com.itheima.pojo.LinkMan;
  7. import java.sql.SQLException;
  8. import java.util.List;
  10. /**
  11.  * 包名:com.itheima.service
  12.  *
  13.  * @author Leevi
  14.  * 日期2020-07-18  09:17
  15.  */
  16. public class LinkManService {
  17.     private LinkManDao linkManDao = new LinkManDao();
  18.     public LinkMan findById(Integer id) throws SQLException {
  19.         //调用dao层的方法，根据id查询联系人
  20.         return linkManDao.findById(id);
  21.     }
  22. }

LinkManDao代码

  1. package com.itheima.dao;
  3. import com.itheima.pojo.LinkMan;
  4. import com.itheima.utils.DruidUtil;
  5. import org.apache.commons.dbutils.QueryRunner;
  6. import org.apache.commons.dbutils.handlers.BeanHandler;
  7. import org.apache.commons.dbutils.handlers.BeanListHandler;
  8. import org.apache.commons.dbutils.handlers.ScalarHandler;
  10. import java.sql.SQLException;
  11. import java.util.List;
  13. /**
  14.  * 包名:com.itheima.dao
  15.  *
  16.  * @author Leevi
  17.  * 日期2020-07-18  09:18
  18.  */
  19. public class LinkManDao {
  20.     private QueryRunner runner = new QueryRunner(DruidUtil.getDataSource());
  21.     public LinkMan findById(Integer id) throws SQLException {
  22.         String sql = "select * from linkman where id=?";
  23.         LinkMan linkMan = runner.query(sql, new BeanHandler<>(LinkMan.class), id);
  24.         return linkMan;
  25.     }
  26. }

update.jsp代码

  1. <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
  2. <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
  3. <%
  4. String path = request.getContextPath();
  5. String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
  6. %>
  7. <!DOCTYPE html>
  8. <!-- 网页使用的语言 -->
  9. <html lang="zh-CN">
  10.     <head>
  11.         <base href="<%=basePath%>"/>
  12.         <!-- 指定字符集 -->
  13.         <meta charset="utf-8">
  14.         <meta http-equiv="X-UA-Compatible" content="IE=edge">
  15.         <meta name="viewport" content="width=device-width, initial-scale=1">
  16.         <title>修改联系人</title>
  18.         <link href="css/bootstrap.min.css" rel="stylesheet">
  19.         <script src="js/jquery-2.1.0.min.js"></script>
  20.         <script src="js/bootstrap.min.js"></script>
  22.     </head>
  23.     <body>
  24.         <div class="container" style="width: 400px;">
  25.         <h3 style="text-align: center;">修改联系人</h3>
  26.         <form action="/linkman" method="post">
  27.             <%--使用隐藏域携带id--%>
  28.             <input type="hidden" name="id" value="${linkman.id}">
  29.             <%--使用隐藏域携带action--%>
  30.             <input type="hidden" name="action" value="update">
  31.       <div class="form-group">
  32.         <label for="name">姓名：</label>
  33.         <input type="text" class="form-control" id="name" name="name"
  34.                value="${linkman.name}" placeholder="请输入姓名" />
  35.       </div>
  37.       <div class="form-group">
  38.         <label>性别：</label>
  39.           <c:if test="${linkman.sex == '男'}">
  40.               <input type="radio" name="sex" value="男"  checked/>男
  41.               <input type="radio" name="sex" value="女"  />女
  42.           </c:if>
  43.           <c:if test="${linkman.sex == '女'}">
  44.               <input type="radio" name="sex" value="男"  />男
  45.               <input type="radio" name="sex" value="女"  checked/>女
  46.           </c:if>
  47.       </div>
  49.       <div class="form-group">
  50.         <label for="age">年龄：</label>
  51.         <input type="text" class="form-control" value="${linkman.age}" id="age"  name="age" placeholder="请输入年龄" />
  52.       </div>
  54.       <div class="form-group">
  55.         <label for="address">籍贯：</label>
  56.          <select name="address" id="address" class="form-control" >
  57.             <c:if test="${linkman.address == '广东'}">
  58.                 <option value="广东" selected>广东</option>
  59.                 <option value="广西">广西</option>
  60.                 <option value="湖南">湖南</option>
  61.             </c:if>
  62.              <c:if test="${linkman.address == '广西'}">
  63.                  <option value="广东">广东</option>
  64.                  <option value="广西" selected>广西</option>
  65.                  <option value="湖南">湖南</option>
  66.              </c:if>
  67.              <c:if test="${linkman.address == '湖南'}">
  68.                  <option value="广东">广东</option>
  69.                  <option value="广西">广西</option>
  70.                  <option value="湖南" selected>湖南</option>
  71.              </c:if>
  72.         </select>
  73.       </div>
  75.       <div class="form-group">
  76.         <label for="qq">QQ：</label>
  77.         <input type="text" id="qq" value="${linkman.qq}" class="form-control" name="qq" placeholder="请输入QQ号码"/>
  78.       </div>
  80.       <div class="form-group">
  81.         <label for="email">Email：</label>
  82.         <input type="text" id="email" value="${linkman.email}" class="form-control" name="email" placeholder="请输入邮箱地址"/>
  83.       </div>
  85.          <div class="form-group" style="text-align: center">
  86.             <input class="btn btn-primary" type="submit" value="提交" />
  87.             <input class="btn btn-default" type="reset" value="重置" />
  88.             <input class="btn btn-default" type="button" value="返回"/>
  89.          </div>
  90.         </form>
  91.         </div>
  92.     </body>
  93. </html>

2. 修改联系人代码实现

LinkManServlet代码

  1. package com.itheima.web.servlet;
  3. import com.itheima.entry.PageBean;
  4. import com.itheima.pojo.LinkMan;
  5. import com.itheima.service.LinkManService;
  6. import org.apache.commons.beanutils.BeanUtils;
  8. import javax.servlet.ServletException;
  9. import javax.servlet.annotation.WebServlet;
  10. import javax.servlet.http.HttpServlet;
  11. import javax.servlet.http.HttpServletRequest;
  12. import javax.servlet.http.HttpServletResponse;
  13. import java.io.IOException;
  14. import java.lang.reflect.Method;
  15. import java.util.List;
  16. import java.util.Map;
  18. /**
  19.  * 包名:${PACKAGE_NAME}
  20.  *
  21.  * @author Leevi
  22.  * 日期2020-07-18  08:53
  23.  * LinkManServlet负责处理联系人模块的所有请求
  24.  */
  25. @WebServlet("/linkman")
  26. public class LinkManServlet extends HttpServlet {
  27.     private LinkManService linkManService = new LinkManService();
  28.     @Override
  29.     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  30.         doGet(request, response);
  31.     }
  33.     @Override
  34.     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  35.         //1. 获取请求参数action的值
  36.         String action = request.getParameter("action");
  37.         //2. 判断action的值
  38.         if ("findAll".equals(action)) {
  39.             //调用findAll()方法查询所有
  40.             findAll(request,response);
  41.         }
  42.         if ("add".equals(action)){
  43.             add(request,response);
  44.         }
  45.         if ("delete".equals(action)){
  46.             delete(request,response);
  47.         }
  48.         if("findOne".equals(action)){
  49.             findOne(request,response);
  50.         }
  51.         if ("update".equals(action)){
  52.             update(request,response);
  53.         }
  54.     }
  55.     /**
  56.      * 修改联系人的方法
  57.      * @param request
  58.      * @param response
  59.      */
  60.     private void update(HttpServletRequest request, HttpServletResponse response) throws IOException {
  61.         try {
  62.             //1. 获取所有请求参数封装到LinkMan对象中
  63.             Map<String, String[]> parameterMap = request.getParameterMap();
  64.             LinkMan linkMan = new LinkMan();
  65.             BeanUtils.populate(linkMan,parameterMap);
  67.             //2. 调用业务层的方法，修改联系人信息
  68.             linkManService.update(linkMan);
  70.             //3. 如果修改成功，则跳转到查询所有
  71.             response.sendRedirect("/linkman?action=findAll");
  72.         } catch (Exception e) {
  73.             e.printStackTrace();
  74.             response.getWriter().write("修改失败");
  75.         }
  76.     }
  77. }

LinkManService代码

  1. package com.itheima.service;
  3. import com.itheima.dao.LinkManDao;
  4. import com.itheima.entry.PageBean;
  5. import com.itheima.pojo.LinkMan;
  7. import java.sql.SQLException;
  8. import java.util.List;
  10. /**
  11.  * 包名:com.itheima.service
  12.  *
  13.  * @author Leevi
  14.  * 日期2020-07-18  09:17
  15.  */
  16. public class LinkManService {
  17.     private LinkManDao linkManDao = new LinkManDao();
  18.     public void update(LinkMan linkMan) throws SQLException {
  19.         //调用dao层的方法，修改联系人信息
  20.         linkManDao.update(linkMan);
  21.     }
  22. }

LinkManDao代码

  1. package com.itheima.dao;
  3. import com.itheima.pojo.LinkMan;
  4. import com.itheima.utils.DruidUtil;
  5. import org.apache.commons.dbutils.QueryRunner;
  6. import org.apache.commons.dbutils.handlers.BeanHandler;
  7. import org.apache.commons.dbutils.handlers.BeanListHandler;
  8. import org.apache.commons.dbutils.handlers.ScalarHandler;
  10. import java.sql.SQLException;
  11. import java.util.List;
  13. /**
  14.  * 包名:com.itheima.dao
  15.  *
  16.  * @author Leevi
  17.  * 日期2020-07-18  09:18
  18.  */
  19. public class LinkManDao {
  20.     private QueryRunner runner = new QueryRunner(DruidUtil.getDataSource());
  21.     public void update(LinkMan linkMan) throws SQLException {
  22.         String sql = "update linkman set name=?,age=?,sex=?,address=?,qq=?,email=? where id=?";   runner.update(sql,linkMan.getName(),linkMan.getAge(),linkMan.getSex(),linkMan.getAddress(),linkMan.getQq(),linkMan.getEmail(),linkMan.getId());
  23.     }
  24. }

案例四:分页展示联系人

一,案例需求

Web综合练习 - 图12

  • 分页查询出联系人信息

二,技术分析

1,数据库操作 limit

  1. SELECT * FROM linkman LIMIT offset,length;
  3. -- 一, 解释limit
  4. -- offset: 跳过多少条数据          【offset=(currentPage-1)*length】
  5. -- length: 查询多少条数据(每页数据条数) 【自定义的】
  7. -- 二, 例子  分页查询联系人, 一页展示5条
  8. -- 第一页  a=0 , b=5;
  9. -- 第二页  a=5 , b=5;
  10. -- 第三页  a=10 , b=5;

2. 分页需要的数据的封装

  1. //封装分页的数据的
  2. public class PageBean{
  3.     //一页显示的联系人的集合  List<linkMan> list
  4.     //当前页码              int curPage;
  5.     //总页数               int sumPage;
  6.     //联系人的总数          int count;
  7.     //一页显示的数量      int curSize;
  8. }
  10. ----------
  11. 一共有10条, 一页显2条,     总页数sumPage = 5
  12. 一共有10条, 一页显3条,     总页数sumPage = 4
  13. 一共有11条, 一页显3条,     总页数sumPage = 4
  15. if(count % curSize == 0){
  16.       sumPage = count/curSize;
  17. }else{
  18.   sumPage = count/curSize+1;
  19. }

三,思路分析

详情请见分页分析图

四,代码实现

  • PageBean
  1. public class PageBean implements Serializable {
  2.     //总条数
  3.     private Long totalSize;
  4.     //总页数
  5.     private Long totalPage;
  6.     //当前页数
  7.     private Long currentPage;
  8.     //每页条数
  9.     private Integer pageSize;
  10.     //当前页的数据集合
  11.     private List<LinkMan> list;
  13.     @Override
  14.     public String toString() {
  15.         return "PageBean{" +
  16.                 "totalSize=" + totalSize +
  17.                 ", totalPage=" + totalPage +
  18.                 ", currentPage=" + currentPage +
  19.                 ", pageSize=" + pageSize +
  20.                 ", list=" + list +
  21.                 '}';
  22.     }
  24.     public Long getTotalSize() {
  25.         return totalSize;
  26.     }
  28.     public void setTotalSize(Long totalSize) {
  29.         this.totalSize = totalSize;
  30.     }
  32.     public Long getTotalPage() {
  33.         return totalPage;
  34.     }
  36.     public void setTotalPage(Long totalPage) {
  37.         this.totalPage = totalPage;
  38.     }
  40.     public Long getCurrentPage() {
  41.         return currentPage;
  42.     }
  44.     public void setCurrentPage(Long currentPage) {
  45.         this.currentPage = currentPage;
  46.     }
  48.     public Integer getPageSize() {
  49.         return pageSize;
  50.     }
  52.     public void setPageSize(Integer pageSize) {
  53.         this.pageSize = pageSize;
  54.     }
  56.     public List<LinkMan> getList() {
  57.         return list;
  58.     }
  60.     public void setList(List<LinkMan> list) {
  61.         this.list = list;
  62.     }
  63. }
  • LinkManServlet
  1. package com.itheima.web.servlet;
  3. import com.itheima.entry.PageBean;
  4. import com.itheima.pojo.LinkMan;
  5. import com.itheima.service.LinkManService;
  6. import org.apache.commons.beanutils.BeanUtils;
  8. import javax.servlet.ServletException;
  9. import javax.servlet.annotation.WebServlet;
  10. import javax.servlet.http.HttpServlet;
  11. import javax.servlet.http.HttpServletRequest;
  12. import javax.servlet.http.HttpServletResponse;
  13. import java.io.IOException;
  14. import java.lang.reflect.Method;
  15. import java.util.List;
  16. import java.util.Map;
  18. /**
  19.  * 包名:${PACKAGE_NAME}
  20.  *
  21.  * @author Leevi
  22.  * 日期2020-07-18  08:53
  23.  * LinkManServlet负责处理联系人模块的所有请求
  24.  */
  25. @WebServlet("/linkman")
  26. public class LinkManServlet extends HttpServlet {
  27.     private LinkManService linkManService = new LinkManService();
  28.     @Override
  29.     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  30.         doGet(request, response);
  31.     }
  33.     @Override
  34.     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  35.         //1. 获取请求参数action的值
  36.         String action = request.getParameter("action");
  37.         //2. 判断action的值
  38.         if ("findAll".equals(action)) {
  39.             //调用findAll()方法查询所有
  40.             findAll(request,response);
  41.         }
  42.         if ("add".equals(action)){
  43.             add(request,response);
  44.         }
  45.         if ("delete".equals(action)){
  46.             delete(request,response);
  47.         }
  48.         if("findOne".equals(action)){
  49.             findOne(request,response);
  50.         }
  51.         if ("update".equals(action)){
  52.             update(request,response);
  53.         }
  54.          if ("findByPage".equals(action)){
  55.             findByPage(request,response);
  56.         }
  57.     }
  59.     private void findByPage(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
  60.         try {
  61.             //1. 获取请求参数currentPage和pageSize的值
  62.             Long currentPage = Long.valueOf(request.getParameter("currentPage"));
  63.             Integer pageSize = Integer.valueOf(request.getParameter("pageSize"));
  65.             //2. 调用业务层的方法，查询当前页的pageBean
  66.             PageBean<LinkMan> pageBean = linkManService.findByPage(currentPage,pageSize);
  68.             //3. 将pageBean对象存储进request域对象
  69.             request.setAttribute("page",pageBean);
  71.             //4. 跳转到list_page.jsp页面
  72.             request.getRequestDispatcher("/list_page.jsp").forward(request, response);
  73.         } catch (Exception e) {
  74.             e.printStackTrace();
  75.             //分页查询失败
  76.             response.getWriter().write("分页查询失败");
  77.         }
  78.     }
  79. }
  • LinkManService
  1. public PageBean findByPage(Long currentPage, Integer pageSize) throws SQLException {
  2.         //1. 创建PageBean对象
  3.         PageBean pageBean = new PageBean();
  4.         //2. 设置pageBean中的五个属性
  5.         //2.1 设置currentPage
  6.         pageBean.setCurrentPage(currentPage);
  7.         //2.2 设置pageSize
  8.         pageBean.setPageSize(pageSize);
  9.         //2.3 设置totalSize 总条数，先要调用dao层的方法，获取联系人的总条数
  10.         Long totalSize = linkManDao.findTotalSize();
  11.         pageBean.setTotalSize(totalSize);
  13.         //2.4 设置totalPage,总页数等于总条数除以每页条数，但是如果除不尽则 +1
  14.         Long totalPage = totalSize % pageSize == 0 ? totalSize / pageSize : (totalSize / pageSize) + 1;
  15.         pageBean.setTotalPage(totalPage);
  17.         //2.5 设置list
  18.         List<LinkMan> list = linkManDao.findPageList(currentPage,pageSize);
  19.         pageBean.setList(list);
  21.         //3. 将pageBean返回
  22.         return pageBean;
  23.     }
  • LinkManDao
  1. public class linkManDao {
  2.   /**
  3.      * 查询总联系人的条数
  4.      * @return
  5.      */
  6.     public Long findTotalSize() throws SQLException {
  7.         String sql = "select count(*) from linkman";
  8.         Long totalSize = (Long) runner.query(sql, new ScalarHandler());
  9.         return totalSize;
  10.     }
  11.     /**
  12.      * 查询当前页的联系人集合
  13.      * @return
  14.      */
  15.     public List<LinkMan> findPageList(Long currentPage, Integer pageSize) throws SQLException {
  16.         String sql = "select * from linkman limit ?,?";
  17.         List<LinkMan> linkManList = runner.query(sql, new BeanListHandler<>(LinkMan.class), (currentPage - 1) * pageSize, pageSize);
  18.         return linkManList;
  19.     }
  21.  }
  • list_page.jsp
  1. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  2. <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
  3. <!DOCTYPE html>
  4. <!-- 网页使用的语言 -->
  5. <html lang="zh-CN">
  6. <head>
  7.     <!-- 指定字符集 -->
  8.     <meta charset="utf-8">
  9.     <!-- 使用Edge最新的浏览器的渲染方式 -->
  10.     <meta http-equiv="X-UA-Compatible" content="IE=edge">
  11.     <!-- viewport视口：网页可以根据设置的宽度自动进行适配，在浏览器的内部虚拟一个容器，容器的宽度与设备的宽度相同。
  12.     width: 默认宽度与设备的宽度相同
  13.     initial-scale: 初始的缩放比，为1:1 -->
  14.     <meta name="viewport" content="width=device-width, initial-scale=1">
  15.     <!-- 上述3个meta标签*必须*放在最前面，任何其他内容都*必须*跟随其后！ -->
  16.     <title>Bootstrap模板</title>
  18.     <!-- 1. 导入CSS的全局样式 -->
  19.     <link href="css/bootstrap.min.css" rel="stylesheet">
  20.     <!-- 2. jQuery导入，建议使用1.9以上的版本 -->
  21.     <script src="js/jquery-2.1.0.min.js"></script>
  22.     <!-- 3. 导入bootstrap的js文件 -->
  23.     <script src="js/bootstrap.min.js"></script>
  24.     <style type="text/css">
  25.         td, th {
  26.             text-align: center;
  27.         }
  28.     </style>
  29. </head>
  30. <body>
  31. <div class="container">
  32.     <h3 style="text-align: center">显示所有联系人</h3>
  33.     <table border="1" class="table table-bordered table-hover">
  34.         <tr class="success">
  35.             <th>编号</th>
  36.             <th>姓名</th>
  37.             <th>性别</th>
  38.             <th>年龄</th>
  39.             <th>籍贯</th>
  40.             <th>QQ</th>
  41.             <th>邮箱</th>
  42.             <th>操作</th>
  43.         </tr>
  44.         <%--遍历当前页的联系人集合--%>
  45.         <c:forEach items="${page.list}" var="linkman" varStatus="vst">
  46.             <tr>
  47.                 <td>${vst.count}</td>
  48.                 <td>${linkman.name}</td>
  49.                 <td>${linkman.sex}</td>
  50.                 <td>${linkman.age}</td>
  51.                 <td>${linkman.address}</td>
  52.                 <td>${linkman.qq}</td>
  53.                 <td>${linkman.email}</td>
  54.                 <td><a class="btn btn-default btn-sm" href="修改联系人.html">修改</a>&nbsp;<a class="btn btn-default btn-sm" href="修改联系人.html">删除</a></td>
  55.             </tr>
  56.         </c:forEach>
  58.         <tr>
  59.             <td colspan="8" align="center">
  60.                 总共有${page.totalPage}页，每页显示${page.pageSize}条
  61.                 <ul class="pagination success">
  62.                     <%--
  63.                         如果当前不是第一页则显示上一页
  64.                     --%>
  65.                     <c:if test="${page.currentPage > 1}">
  66.                         <li><a href="/linkman?action=findByPage&pageSize=${page.pageSize}&currentPage=${page.currentPage-1}" aria-label="Previous">
  67.                             <span aria-hidden="true">&laquo;</span></a>
  68.                         </li>
  69.                     </c:if>
  71.                     <%--总共有多少页，就添加多少个li--%>
  72.                     <c:forEach begin="1" end="${page.totalPage}" var="i">
  73.                         <%--判断i是否是当前页，如果是则高亮显示，如果不是则不高亮--%>
  74.                         <c:if test="${i == page.currentPage}">
  75.                             <li class="active"><a href="javascript:;">${i}</a></li>
  76.                         </c:if>
  79.                         <c:if test="${i != page.currentPage}">
  80.                             <li><a href="/linkman?action=findByPage&pageSize=${page.pageSize}&currentPage=${i}">${i}</a></li>
  81.                         </c:if>
  82.                     </c:forEach>
  83.                     <%--
  84.                         如果当前不是最后一页才显示下一页
  85.                     --%>
  86.                     <c:if test="${page.currentPage != page.totalPage}">
  87.                         <li><a href="/linkman?action=findByPage&pageSize=${page.pageSize}&currentPage=${page.currentPage+1}" aria-label="Next">
  88.                             <span aria-hidden="true">&raquo;</span></a>
  89.                         </li>
  90.                     </c:if>
  91.                 </ul>
  92.             </td>
  93.         </tr>
  94.     </table>
  95. </div>
  96. </body>
  97. </html>

五,小结

扩展

1.PageBean优化

  1. package com.itheima.entry;
  3. import java.io.Serializable;
  4. import java.util.List;
  6. /**
  7.  * 包名:com.itheima.entry
  8.  *
  9.  * @author Leevi
  10.  * 日期2020-07-18  12:03
  11.  */
  12. public class PageBean<T> implements Serializable {
  13.     //总条数
  14.     private Long totalSize;
  15.     //总页数
  16.     private Long totalPage;
  17.     //当前页数
  18.     private Long currentPage;
  19.     //每页条数
  20.     private Integer pageSize;
  21.     //当前页的数据集合
  22.     private List<T> list;
  24.     @Override
  25.     public String toString() {
  26.         return "PageBean{" +
  27.                 "totalSize=" + totalSize +
  28.                 ", totalPage=" + totalPage +
  29.                 ", currentPage=" + currentPage +
  30.                 ", pageSize=" + pageSize +
  31.                 ", list=" + list +
  32.                 '}';
  33.     }
  35.     public Long getTotalSize() {
  36.         return totalSize;
  37.     }
  39.     public void setTotalSize(Long totalSize) {
  40.         this.totalSize = totalSize;
  41.     }
  43.     public Long getTotalPage() {
  44.         return totalPage;
  45.     }
  47.     public void setTotalPage(Long totalPage) {
  48.         this.totalPage = totalPage;
  49.     }
  51.     public Long getCurrentPage() {
  52.         return currentPage;
  53.     }
  55.     public void setCurrentPage(Long currentPage) {
  56.         this.currentPage = currentPage;
  57.     }
  59.     public Integer getPageSize() {
  60.         return pageSize;
  61.     }
  63.     public void setPageSize(Integer pageSize) {
  64.         this.pageSize = pageSize;
  65.     }
  67.     public List<T> getList() {
  68.         return list;
  69.     }
  71.     public void setList(List<T> list) {
  72.         this.list = list;
  73.     }
  74. }

2,模块Servlet优化

  1. 问题:
    Web综合练习 - 图13

    • doGet()方法里面的 if 太多, 可读性很差
    • doGet()方法里面, 每加一个请求, 都需要添加一个if, 维护麻烦

  2. 解决: 反射

    • 一个if都不要

    • 优化之后, 代码就不变了, 不会随着请求的增加而增加if

      1. @WebServlet("/linkMan")
      2. public class LinkManServlet extends HttpServlet {
      4. private LinkManService linkManService = new LinkManService();
      6. @Override
      7. protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      8.    //1. 获取请求参数action的值
      9.    String action = request.getParameter("action");
      10.    //已知方法名，找到并且调用方法,可以使用反射技术
      11.    //获取当前类的字节码对象
      12.    try {
      13.        Class clazz = this.getClass();
      14.        //根据方法名获取方法
      15.        Method method = clazz.getDeclaredMethod(action, HttpServletRequest.class, HttpServletResponse.class);
      16.        //调用方法
      17.        method.invoke(this,request,response);
      18.    } catch (Exception e) {
      19.        e.printStackTrace();
      20.    }
      21. }
      22. }