MyBatis+JSP+Servlet...MySql实现分页/增删改查：代码详细有注释~ |
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MyBatis+JSP+Servlet...MySql实现分页/增删改查：代码详细有注释~
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学习MyBtatis 的第二个星期, 大概已经明白差不多了. 已经可以在 控制台完成 增删改查 了,哈哈哈哈(大佬路过别笑😀)… 感觉还不错呢. 现在也开始学习在 CSDN上写笔记博客, 哈哈以前都是看其它大佬的. 自己平时也记笔记但都是在 OneNote上： **回归主题还是继续今天的代码笔记：**对MyBatis的总结吧：实现基本的增删改查分页… 如果有问题的朋友可以借鉴之前的笔记哦~ 初始MyBatis. MyBatis sql文件映射. MyBatis 动态SQL. MyBatis 实例代码. 这一篇是访问最高的!! 早上起床看到访问量一下子 700多,真的是激动了好一会儿~ 回归主题：当当当~ 惊天的代码~ 正品开始 首先写的分页,分页当然需要的是一个分页类; page.java // 考虑到分页不一定 ，非得是针对 User数据, page类为一个 泛型类; package com.wsm.util; import java.util.List; //泛型类; public class Page { //当前页数默认是 1 private int dye =1; //每页行数 5 private int hang=5; //总行数：数据库查寻 private int zhang; //总页数：根据总行数和每页行数计算而出; private int zye; //每页的呈现数据集合; private List data; //get/set封装; public int getDye() { return dye; } public void setDye(int dye) { this.dye = dye; } public int getHang() { return hang; } public void setHang(int hang) { this.hang = hang; } public int getZhang() { return zhang; } public void setZhang(int zhang) { this.zhang = zhang; this.zye = zhang%hang==0?zhang/hang:zhang/hang+1; //根据总行计算出总页数; } public int getZye() { return zye; } public void setZye(int zye) { this.zye = zye; } public List getData() { return data; } public void setData(List data) { this.data = data; } }UserMapper.java 接口 package com.wsm.dao; import java.util.List; import java.util.Map; import org.apache.ibatis.annotations.Param; import com.wsm.entity.User; public interface UserMapper { //分页 /** * Map需要存储的参数; 多条件分页查看,可能会比较复杂,慢慢理解. * name 姓名 * roleid 部门Id * opdate 生日 开始时间 * cldate 生日结束时间 * dye 当前页 * hang 每页行; * @param uMap * @return */ public List chapage(Map uMap); //查总行,用于获取总页数; public int zhang(Map uMap); //新增 public int add(User u); //修改 public int upd(User u); //修改前,根据id 查询一下要修改的对象及数据; public User updc(int id); //删除 public int del(int id); }UserMapper.xml 实现接口： and `userName` LIKE CONCAT('%',#{name},'%') and `userRole` = #{roleid} and `birthday` BETWEEN #{opdate} AND #{cldate} SELECT su.*,sr.`roleName` FROM `smbms_user` su INNER JOIN `smbms_role` sr ON su.`userRole`=sr.`id` limit #{dye},#{hang} SELECT COUNT(0) FROM `smbms_user` su INNER JOIN `smbms_role` sr ON su.`userRole`=sr.`id` INSERT into `smbms_user` values (null,'userCode',#{userName},111,1,#{birthday},null,#{address},#{userRole},1,'2020-08-18 09:56:31',NULL,NULL); UPDATE `smbms_user` userName = #{userName}, address = #{address}, userRole = #{userRole}, birthday = #{birthday}, where id = #{id} select * from `smbms_user` where id=#{id} DELETE FROM `smbms_user` WHERE `id` =#{id}UserMapper.java 接口 package com.wsm.dao; import java.util.List; import org.apache.ibatis.annotations.Param; import com.wsm.entity.Role; public interface RoleMapper { //查看所有部门信息; 下拉框查询; public List allRole(); }UserMapper.xml 实现接口： select * from smbms_roleService ： 业务逻辑层，用于接受 Servlet 的数据进行对应的操作: 返回至页面显示; RoleService.Java package com.wsm.service; import java.util.List; import org.apache.ibatis.session.SqlSession; import com.wsm.dao.RoleMapper; import com.wsm.entity.Role; import com.wsm.util.MyBatisUtil; //Service 业务逻辑层,处理代码逻辑; public class RoleService { public List allRole(){ //创建SqlSession对象; SqlSession session = MyBatisUtil.createSqlSession(); //获取接口对象; RoleMapper rm = session.getMapper(RoleMapper.class); //面向接口编程...返回部门集合; List roles = rm.allRole(); //关闭sqlSession MyBatisUtil.closeSqlSession(session); return roles; //返回; }; }UserService。Java package com.wsm.service; import java.util.HashMap; import java.util.List; import java.util.Map; import org.apache.ibatis.session.SqlSession; import com.wsm.dao.UserMapper; import com.wsm.entity.User; import com.wsm.util.MyBatisUtil; import com.wsm.util.Page; //Service 业务逻辑层,处理代码逻辑; public class UserService { private MyBatisUtil myba = new MyBatisUtil(); /** * name 姓名 * roleid 部门Id * opdate 生日 开始时间 * cldate 生日结束时间 * dye 当前页 * hang 每页行; */ //业务逻辑层实现,分页操作; public Page chaPage(String name,Integer roleid,String opdate,String cldate,Integer dye,Integer hang){ Page page = new Page(); //包装到map的参数对象 Map umap = new HashMap(); umap.put("name",name); umap.put("roleid",roleid); umap.put("opdate",opdate); umap.put("cldate",cldate); umap.put("dye",(dye-1)*hang); umap.put("hang",hang); //创建连接对象; SqlSession session = MyBatisUtil.createSqlSession(); UserMapper uMapper = session.getMapper(UserMapper.class); List users = uMapper.chapage(umap); //获取当前集合 int zhang = uMapper.zhang(umap); //获取总行; MyBatisUtil.closeSqlSession(session); //封装返回数据 page.setDye(dye); page.setData(users); page.setZhang(zhang); //set方法赋值,同时求出总页数; return page; //返回; }; //新增用户 public int add(User u){ SqlSession session = myba.createSqlSession(); UserMapper um = session.getMapper(UserMapper.class); int han = um.add(u); session.commit(); //提交事务; myba.closeSqlSession(session); return han; } //删除 public int shan(int id){ SqlSession session = myba.createSqlSession(); UserMapper um = session.getMapper(UserMapper.class); int han = um.del(id); session.commit(); //提交事务; myba.closeSqlSession(session); return han; } //修改 public int upd(User u){ SqlSession session = myba.createSqlSession(); UserMapper um = session.getMapper(UserMapper.class); int han = um.upd(u); session.commit(); //提交事务; myba.closeSqlSession(session); return han; } //获取修改对象； public User updc(int id){ SqlSession session = myba.createSqlSession(); UserMapper um = session.getMapper(UserMapper.class); User u = um.updc(id); myba.closeSqlSession(session); return u; } }Servlet 虽然听说现在已经很少用了… …但我现在只会这个哈哈哈… Web项目还需要注意 Web.XML配置信息; 这个是Myelicpse自动生成的…比较重要而且错误致命！cope的话需要注意别漏了; UserServlet; package com.wsm.servlet; import java.io.IOException; import java.io.PrintWriter; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.wsm.entity.Role; import com.wsm.entity.User; import com.wsm.service.RoleService; import com.wsm.service.UserService; import com.wsm.util.Page; public class UserServlet extends HttpServlet { /** * The doGet method of the servlet. * * This method is called when a form has its tag value method equals to get. * * @param request the request send by the client to the server * @param response the response send by the server to the client * @throws ServletException if an error occurred * @throws IOException if an error occurred */ public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); //简便代码就不分开写了。 get/post } /** * The doPost method of the servlet. * * This method is called when a form has its tag value method equals to post. * * @param request the request send by the client to the server * @param response the response send by the server to the client * @throws ServletException if an error occurred * @throws IOException if an error occurred */ public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置编码格式 response.setContentType("text/html;charset=UTF-8"); request.setCharacterEncoding("UTF-8"); PrintWriter out = response.getWriter(); //根据参数,获取当前操作; String op = request.getParameter("op"); //获取业务逻辑层对象; RoleService rs = new RoleService(); UserService us = new UserService(); if("page".equals(op)){ //页面参数的传递 Integer dye = 1; if(request.getParameter("dye")!=null && !"".equals(request.getParameter("dye")) ){ dye = Integer.parseInt(request.getParameter("dye")); } Integer hang = 5; String name = request.getParameter("name"); String opdate = request.getParameter("opdate"); String cldate = request.getParameter("cldate"); Integer roleid = null; if(request.getParameter("role")!=null && !"-1".equals(request.getParameter("role")) ){ roleid = Integer.parseInt(request.getParameter("role")); } //调用对应业务逻辑层获取返回结果; Page page = us.chaPage(name, roleid, opdate, cldate, dye, hang); List roles = rs.allRole(); //需要的数据存在 request中转发——JSP显示 request.setAttribute("roles", roles); request.setAttribute("page",page); //转发 request.getRequestDispatcher("index.jsp").forward(request, response); }else if("roles".equals(op)){ List roles = rs.allRole(); request.setAttribute("roles", roles); request.getRequestDispatcher("add.jsp").forward(request, response); }else if("add".equals(op)){ User u = new User(); u.setAddress(request.getParameter("address")); u.setUserName(request.getParameter("name")); u.setUserRole(Integer.parseInt(request.getParameter("role"))); u.setBirthday(request.getParameter("birthday")); out.print(""); if(us.add(u)==1){ out.print("alert('新增成功');"); out.print("location.href='index.jsp';"); }else{ out.print("alert('新增失败');"); out.print("location.href='add.jsp';"); } out.print(""); }else if("san".equals(op)){ int id = Integer.parseInt(request.getParameter("id")); out.print(""); if(us.shan(id)==1){ out.print("alert('删除成功');"); out.print("location.href='index.jsp';"); }else{ out.print("alert('删除失败');"); out.print("location.href='add.jsp';"); } out.print(""); }else if("updc".equals(op)){ int id = Integer.parseInt(request.getParameter("id")); User u = us.updc(id); request.setAttribute("u",u); List roles = rs.allRole(); request.setAttribute("roles", roles); request.getRequestDispatcher("upd.jsp").forward(request,response); }else if("upd".equals(op)){ User u = new User(); u.setId(Integer.parseInt(request.getParameter("id"))); u.setAddress(request.getParameter("address")); u.setUserName(request.getParameter("name")); u.setUserRole(Integer.parseInt(request.getParameter("role"))); u.setBirthday(request.getParameter("birthday")); out.print(""); if(us.upd(u)==1){ out.print("alert('修改成功');"); out.print("location.href='index.jsp';"); }else{ out.print("alert('修改失败');"); out.print("location.href='add.jsp';"); } out.print(""); } out.flush(); out.close(); } }JSP index.jsp My JSP 'index.jsp' starting page //分页事件; function topage(index){ //给隐藏表单赋值 document.getElementById("dye").value=index; document.forms[0].submit(); //手动提交 第一个表单form ！ } location.href="UserServlet?op=page"; //alert("sas"); 新增员工 名称 部门 请选择 selected="selected" >${r.roleName } 生日 - 编号 名字 生日 地址 部门 操作 ${u.id } ${u.userName } ${u.birthday } ${u.address } ${u.role.roleName } 修改 删除 首页 上一页 下一页 末页add.jsp My JSP 'add.jsp' starting page location.href="UserServlet?op=roles"; 新增员工 姓名 部门 请选择 selected="selected" >${r.roleName } 生日 地址upd.jsp My JSP 'upd.jsp' starting page 新增员工 姓名 部门 请选择 selected="selected" >${r.roleName } 生日 地址终于搞完了, 感谢阅读。有没有路过盆友运行,成功的.有bug 的要加油找哦~ 感谢给各位给出意见~; 说到错误：也遇到了很多补 ：↓↓↓ 常见错误 java.lang.NullPointerException ：空指针,显而易见,对象没new 就调方法对就是这么简单; 我找了一小时…没找到！！；主要是它包的是MyBatisUtil 的因为是复制的很自信没错误; 后面无从下手了 最后的最后才发现是 MyBatis-config.xml 或 sql映射文件 引用失败！ 又或者…反之就是这么坑; 导致, MyBatisUtil 初始化失败… 还有很多写代码还是要耐心… 有时候真的很坑！ 还有要注意：resultMap 需要映射主键,以确保唯一。不然后面查的数据会把前面的覆盖.导致可能每次都是查到一个记录… 最后最后，如果我的代码复制使用后还是存在异常请告诉我。我在进行改正；因为是一直cope的,害怕漏了什么影响效果... |
自己偷偷的写,偷偷的看…哈哈现在在转变ing 加油，奥里给！ 以后有时间也许会想办法吧 笔记都搬到 CSDN上来嘿嘿~ 各位大佬，多多指教；
其中一部分的文件是和 MyBatis 实例代码. 一样的, 就不在这里写了~ database.properties log4j.properties MyBatisUtil mybatis-config.xml MyBatis的核心配置文件应该不会有变化,顶多是引用 映射文件地址不一样~ 这里使用的数据库：也在 MyBatis 实例代码. 两个实体类： Role User 因为这里 java 时间类型date 在页面上展示格式有点混乱是英文格式的 并不是 yyyy-MM-dd的所有我改成String 了; 如果有大佬有解决方法. 麻烦点拨一下~；【本文地址】
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