自定义MVC框架实现增删改查
目录
一、环境搭建
二、导入配置文夹
1.中央控制器xml
2.增删改配置文件
3.导入工具类
三、编写后端代码
1. 通用增删改查
2. BookDao类
3. book实现增删改查类
4. 分页助手类
四、编写前端代码
1. 数据显示主界面
2. 默认运行显示所有数据servlet
3. 新增、修改共用页面
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
mymvc_crud
mvc
com.zking.framework.DispatchServlet
configurationLocation
/mvc.xml
mvc
*.action
2.增删改配置文件
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 {
/**
* 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 executeQuery(String sql, Class clz, PageBean pageBean) throws Exception {
List list = new ArrayList();
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{
/*
* 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 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{
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 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 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("");
/**
* 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("");
sb.append("- 首页
");
sb.append("- <
");
// 代表了当前页的前4页
for (int i = before; i > 0; i--) {
sb.append("- "
+ (page - i) + "
");
}
sb.append("- " + pageBean.getPage() + "
");
// 代表了当前页的后5页
for (int i = 1; i <= after; i++) {
sb.append("- "
+ (page + i) + "
");
}
sb.append("- >
");
sb.append("- 尾页
");
sb.append(
"- 到第页
");
sb.append("- 确定
");
sb.append("- 共" + pageBean.getTotal() + "条
");
sb.append("
");
// 拼接分页的js代码
sb.append("");
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" %>
书籍列表
书籍ID
书籍名
价格
操作
${b.bid }
${b.bname }
${b.price }
修改
删除
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"%>
书籍新增/修改