一、环境搭建
对上一篇的内容优化，将之前写好的frmework包导成jar包
再导入相关jar包
二、导入配置文夹
1.中央控制器xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1"> <display-name>mymvc_crud</display-name> <servlet> <servlet-name>mvc</servlet-name> <servlet-class>com.zking.framework.DispatchServlet</servlet-class> <init-param> <param-name>configurationLocation</param-name> <param-value>/mvc.xml</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>mvc</servlet-name> <url-pattern>*.action</url-pattern> </servlet-mapping> </web-app>
2.增删改配置文件
<?xml version="1.0" encoding="UTF-8"?> <config> <action path="/book" type="com.zking.web.BookAction"> <!-- 查询：BookList.jsp 返回值：list --> <!-- * 增删改确定：book.action?methodName=list 返回值：toList --> <!-- * 增加修改跳转对应界面：bookEdit.jsp 返回值：toEdit --> <forward name="list" path="/bookList.jsp" redirect="false" /> <forward name="toList" path="/book.action?methodName=list" redirect="true" /> <forward name="toEdit" path="/bookEdit.jsp" redirect="false" /> </action> </config>
3.导入工具类
进入此JSP自定义通用分页链接查看分装工具类目录
三、编写后端代码
1. 通用增删改查
package com.zking.util; import java.lang.reflect.Field; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.util.ArrayList; import java.util.List; import com.zking.util.DBAccess; import com.zking.util.PageBean; /** * 所有Dao层的父类 * * @author 云村小威 * * @2023年7月3日 下午10:52:21 */ public class BaseDao<T> { /** * 通用的增删改方法 * * @param book * @throws Exception */ public void executeUpdate(String sql, T t, String[] attrs) throws Exception { Connection con = DBAccess.getConnection(); PreparedStatement pst = con.prepareStatement(sql); /* * 思路： 1.从传进来的t中读取属性值 2.往预定义对象中设置了值 * * t->book f->bid */ for (int i = 0; i < attrs.length; i++) { Field f = t.getClass().getDeclaredField(attrs[i]); f.setAccessible(true); pst.setObject(i + 1, f.get(t)); } pst.executeUpdate(); } /** * 通用分页查询 * * @param sql * @param clz * @return * @throws Exception */ public List<T> executeQuery(String sql, Class<T> clz, PageBean pageBean) throws Exception { List<T> list = new ArrayList<T>(); Connection con = DBAccess.getConnection(); PreparedStatement pst = null; ResultSet rs = null; /* * 是否需要分页？ 无需分页（项目中的下拉框，查询条件教员下拉框，无须分页） 必须分页（项目中列表类需求、订单列表、商品列表、学生列表...） */ if (pageBean != null && pageBean.isPagination()) { // 必须分页（列表需求） String countSQL = getCountSQL(sql); pst = con.prepareStatement(countSQL); rs = pst.executeQuery(); if (rs.next()) { pageBean.setTotal(String.valueOf(rs.getObject(1))); } // 挪动到下面，是因为最后才处理返回的结果集 String pageSQL = getPageSQL(sql, pageBean);// 符合条件的某一页数据 pst = con.prepareStatement(pageSQL); rs = pst.executeQuery(); } else { // 不分页（select需求） pst = con.prepareStatement(sql);// 符合条件的所有数据 rs = pst.executeQuery(); } while (rs.next()) { T t = clz.newInstance(); Field[] fields = clz.getDeclaredFields(); for (Field f : fields) { f.setAccessible(true); f.set(t, rs.getObject(f.getName())); } list.add(t); } return list; } /** * 将原生SQL转换成符合条件的总记录数countSQL * * @param sql * @return */ private String getCountSQL(String sql) { return "select count(1) from (" + sql + ") t"; } /** * 将原生SQL转换成pageSQL * * @param sql * @param pageBean * @return */ private String getPageSQL(String sql, PageBean pageBean) { return sql + " limit " + pageBean.getStartIndex() + "," + pageBean.getRows(); } }
2. BookDao类
package com.zking.dao; import java.util.List; import com.zking.entity.Book; import com.zking.util.BaseDao; import com.zking.util.PageBean; import com.zking.util.StringUtils; /** * bookdao类 * @author 云村小威 * * @2023年7月3日 下午10:51:39 */ public class BookDao extends BaseDao<Book>{ /* * public void add(Book book) throws Exception { String sql = "insert into t_mvc_book values(?,?,?)"; Connection con = DBAccess.getConnection(); PreparedStatement pst = con.prepareStatement(sql); pst.setObject(1, book.getBid()); pst.setObject(2, book.getBname()); pst.setObject(3, book.getPrice()); pst.executeUpdate(); } 增删改查的通用套路 1.建立链接 2.预定义对象PreparedStatement 3.设置占位符的？的值 4.pst.executeUpdate(); 1. */ public void add(Book book) throws Exception { String sql = "insert into t_mvc_book values(?,?,?)"; super.executeUpdate(sql, book, new String[] {"bid","bname","price"}); } public void edit(Book book) throws Exception { String sql = "update t_mvc_book set bname = ?, price = ? where bid = ?"; super.executeUpdate(sql, book, new String[] {"bname","price","bid"}); } public void delete(Book book) throws Exception { String sql = "delete from t_mvc_book where bid = ?"; super.executeUpdate(sql, book, new String[] {"bid"}); } public List<Book> list(Book book,PageBean pageBean) throws Exception { String sql = "select * from t_mvc_book where 1=1 "; String bname = book.getBname(); if(StringUtils.isNotBlank(bname)) { sql += " and bname like '%"+bname+"%'"; } return super.executeQuery(sql, Book.class, pageBean); } }
3. book实现增删改查类
package com.zking.web; import java.util.List; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.zking.dao.BookDao; import com.zking.entity.Book; import com.zking.framework.ActionSupport; import com.zking.framework.ModelDriver; import com.zking.util.PageBean; /** * book工作类 * @author 云村小威 * * @2023年7月3日 下午10:53:52 */ public class BookAction extends ActionSupport implements ModelDriver<Book>{ private Book book = new Book(); private BookDao bookDao = new BookDao(); @Override public Book getModel() { return book; } /* * 增删改最终都要跳回查询界面 * 分析增删改查一共有多少结果集的配置 * 查询：BookList.jsp 返回值：list * 增删改确定：book.action?methodName=list 返回值：toList * 增加修改跳转对应界面：bookEdit.jsp 返回值：toEdit */ public String add(HttpServletRequest req, HttpServletResponse resp) { try { bookDao.add(book); } catch (Exception e) { e.printStackTrace(); } return "toList"; } public String list(HttpServletRequest req, HttpServletResponse resp) { try { PageBean pageBean = new PageBean(); pageBean.setRequest(req); List<Book> list = bookDao.list(book,pageBean); req.setAttribute("books", list); req.setAttribute("pageBean", pageBean); } catch (Exception e) { e.printStackTrace(); } return "list"; } public String delete(HttpServletRequest req, HttpServletResponse resp) { try { bookDao.delete(book); } catch (Exception e) { e.printStackTrace(); } return "toList"; } public String edit(HttpServletRequest req, HttpServletResponse resp) { try { bookDao.edit(book); } catch (Exception e) { e.printStackTrace(); } return "toList"; } /** * 跳转到新增修改页面 * @param req * @param resp * @return */ public String toEdit(HttpServletRequest req, HttpServletResponse resp) { try { /* * 如果是跳转修改页面，那么需要做bid条件的精准查询 */ if(book.getBid() != 0) { List<Book> list = bookDao.list(book, null); req.setAttribute("b", list.get(0)); } } catch (Exception e) { e.printStackTrace(); } return "toEdit"; } }
4. 分页助手类
package com.zking.tag; import com.zking.util.PageBean; import javax.servlet.jsp.JspException; import javax.servlet.jsp.JspWriter; import javax.servlet.jsp.tagext.BodyTagSupport; import java.io.IOException; import java.util.Map; import java.util.Set; /** * Page助手类 * * @author 云村小威 * */ public class PageTag extends BodyTagSupport { private static final long serialVersionUID = 1L; private PageBean pageBean; public PageBean getPageBean() { return pageBean; } public void setPageBean(PageBean pageBean) { this.pageBean = pageBean; } @Override public int doStartTag() throws JspException { // 获取流 JspWriter out = pageContext.getOut(); try { out.print(toHTML()); } catch (IOException e) { e.printStackTrace(); } return SKIP_BODY; } /** * JSP自定义页面内容展示 * * @return */ private String toHTML() { StringBuilder sb = new StringBuilder(); // 这里拼接的是一个上一次发送的请求以及携带的参数，唯一改变的就是页码 sb.append("<form id='pageBeanForm' action='" + pageBean.getUrl() + "' method='post'>"); sb.append("<input type='hidden' name='page'>"); // 重要设置拼接操作，将上一次请求参数携带到下一次 Map<String, String[]> paMap = pageBean.getParameterMap(); if (paMap != null && paMap.size() > 0) { Set<Map.Entry<String, String[]>> entrySet = paMap.entrySet(); for (Map.Entry<String, String[]> entry : entrySet) { for (String val : entry.getValue()) { if (!"page".equals(entry.getKey())) { sb.append("<input type='hidden' name='" + entry.getKey() + "' value='" + val + "'>"); } } } } sb.append("</form>"); /** * 页码数据配置 */ int page = pageBean.getPage(); //当前页码 int max = pageBean.getMaxPage();//最大页码 int before = page > 4 ? 4 : page - 1;//当前页码前面的页码 int after = 10 - 1 - before;//当前页码后面的页码 //如果最大页码没有10页，就显示当前页面后面的所有页码 max - page after = page + after > max ? max - page : after; // 初始页码和结束页码值判断 disabled boolean startFlag = page == 1; boolean endFlag = max == page; // 拼接分页条 sb.append("<ul class='pagination'>"); sb.append("<li class='page-item " + (startFlag ? "disabled" : "") + "'><a class='page-link' href='javascript:gotoPage(1)'>首页</a></li>"); sb.append("<li class='page-item " + (startFlag ? "disabled" : "") + "'><a class='page-link' href='javascript:gotoPage(" + pageBean.getPrevPage() + ")'><</a></li>"); // 代表了当前页的前4页 for (int i = before; i > 0; i--) { sb.append("<li class='page-item'><a class='page-link' href='javascript:gotoPage(" + (page - i) + ")'>" + (page - i) + "</a></li>"); } sb.append("<li class='page-item active'><a class='page-link' href='javascript:gotoPage(" + pageBean.getPage() + ")'>" + pageBean.getPage() + "</a></li>"); // 代表了当前页的后5页 for (int i = 1; i <= after; i++) { sb.append("<li class='page-item'><a class='page-link' href='javascript:gotoPage(" + (page + i) + ")'>" + (page + i) + "</a></li>"); } sb.append("<li class='page-item " + (endFlag ? "disabled" : "") + "'><a class='page-link' href='javascript:gotoPage(" + pageBean.getNextPage() + ")'>></a></li>"); sb.append("<li class='page-item " + (endFlag ? "disabled" : "") + "'><a class='page-link' href='javascript:gotoPage(" + pageBean.getMaxPage() + ")'>尾页</a></li>"); sb.append( "<li class='page-item go-input'><b>到第</b><input class='page-link' type='text' id='skipPage' name='' /><b>页</b></li>"); sb.append("<li class='page-item go'><a class='page-link' href='javascript:skipPage()'>确定</a></li>"); sb.append("<li class='page-item'><b>共" + pageBean.getTotal() + "条</b></li>"); sb.append("</ul>"); // 拼接分页的js代码 sb.append("<script type='text/javascript'>"); sb.append("function gotoPage(page) {"); sb.append("document.getElementById('pageBeanForm').page.value = page;"); sb.append("document.getElementById('pageBeanForm').submit();"); sb.append("}"); sb.append("function skipPage() {"); sb.append("var page = document.getElementById('skipPage').value;"); sb.append("if (!page || isNaN(page) || parseInt(page) < 1 || parseInt(page) > " + max + ") {"); sb.append("alert('请输入1~N的数字');"); sb.append("return;"); sb.append("}"); sb.append("gotoPage(page);"); sb.append("}"); sb.append("</script>"); return sb.toString(); } }
四、编写前端代码
1. 数据显示主界面
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <%@taglib uri="http://jsp.ycxw.cn" prefix="w" %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <link href="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/4.5.0/css/bootstrap.css" rel="stylesheet"> <script src="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/4.5.0/js/bootstrap.js"></script> <title>书籍列表</title> <style type="text/css"> .page-item input { padding: 0; width: 40px; height: 100%; text-align: center; margin: 0 6px; } .page-item input, .page-item b { line-height: 38px; float: left; font-weight: 400; } .page-item.go-input { margin: 0 10px; } </style> </head> <body> <c:if test="${empty books }"> <jsp:forward page="/BookServlet"></jsp:forward> </c:if> <form class="form-inline" action="${pageContext.request.contextPath }/book.action?methodName=list" method="post"> <div class="form-group mb-2"> <input type="text" class="form-control-plaintext" name="bname" placeholder="请输入书籍名称"> <input name="pagination" value="false" type="hidden"> </div> <button type="submit" class="btn btn-primary mb-2">查询</button> <a class="btn btn-primary mb-2" href="${pageContext.request.contextPath }/book.action?methodName=toEdit">新增</a> </form> <table class="table table-striped"> <thead> <tr> <th scope="col">书籍ID</th> <th scope="col">书籍名</th> <th scope="col">价格</th> <th scope="col">操作</th> </tr> </thead> <tbody> <c:forEach var="b" items="${books }"> <tr> <td>${b.bid }</td> <td>${b.bname }</td> <td>${b.price }</td> <td> <a href="${pageContext.request.contextPath }/book.action?methodName=toEdit&bid=${b.bid}">修改</a> <a href="${pageContext.request.contextPath }/book.action?methodName=delete&bid=${b.bid}">删除</a> </td> </tr> </c:forEach> </tbody> </table> <!-- 这一行代码就相当于前面分页需求前端的几十行了 --> <w:page pageBean="${pageBean }"></w:page> </body> </html>
2. 默认运行显示所有数据servlet
package com.zking.web; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet("/BookServlet") public class BookServlet extends HttpServlet { private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.sendRedirect(request.getContextPath()+"/book.action?methodName=list"); } }
3. 新增、修改共用页面
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib uri="http://jsp.ycxw.cn" prefix="z"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <link href="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/4.5.0/css/bootstrap.css" rel="stylesheet"> <script src="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/4.5.0/js/bootstrap.js"></script> <title>书籍新增/修改</title> </head> <body> <form class="form-inline" action="${pageContext.request.contextPath }/book.action?methodName=${empty b ? 'add' : 'edit'}" method="post"> 书籍ID：<input type="text" name="bid" value="${b.bid }"><br> 书籍名称：<input type="text" name="bname" value="${b.bname }"><br> 书籍价格：<input type="text" name="price" value="${b.price }"><br> <input type="submit"> </form> </body> </html>
