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() + ")'>&lt;</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() + ")'>&gt;</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>