自定义MVC框架实现增删改查-阿里云开发者社区

前言

利用自定义MVC框架优化中的代码进行打包，封装成自己的jar包，然后进行使用。

一、环境搭建

将之前写好的MVC导成jar包，方便使用，减少代码冗余，也提高了工作效率

接下来我们将导入我们的mvc.jar与其它相关jar包

将分页标签相关文件、及相关助手类导入

二、配置文件

1.中央控制器.xml

<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>

将其配置在web.xml中

2.mvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<config>
  <!-- 
    在这里每加一个配置，就相当于actions.put("/goods", new GoodsAction());
    这样就解决了代码灵活性的问题
   -->
  <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>

拿到增删改查最终的返回值判断重定向还是转发并进行跳转

三、实体与Dao方法的编写

实体--书类

package com.ctb.entity;
/**
 * 实体--书
 * @author biao
 *
 */
public class Book {
  private int bid;
  private String bname;
  private float price;
  public int getBid() {
    return bid;
  }
  public void setBid(int bid) {
    this.bid = bid;
  }
  public String getBname() {
    return bname;
  }
  public void setBname(String bname) {
    this.bname = bname;
  }
  public float getPrice() {
    return price;
  }
  public void setPrice(float price) {
    this.price = price;
  }
  @Override
  public String toString() {
    return "Book [bid=" + bid + ", bname=" + bname + ", price=" + price + "]";
  }
}

在这，我们先封装一个baseDao，做到通用分页模糊查询以及增删改的通用方法

package com.ctb.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;
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 {
//    String[] attrs = new String[] {"bid", "bname", "price"};
    Connection con = DBAccess.getConnection();
    PreparedStatement pst = con.prepareStatement(sql);
//    pst.setObject(1, book.getBid());
//    pst.setObject(2, book.getBname());
//    pst.setObject(3, book.getPrice());
    for (int i = 0; i < attrs.length; i++) {
      //反射动态获取属性
      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;
    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)));
      }
      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) {
//    -- countSql=select count(1) from (sql) t  符合条件的总记录数
    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) {
//    pageSql=sql limit (page-1)*rows,rows
    return sql + " limit "+ pageBean.getStartIndex() +","+pageBean.getRows();
  }
}

接下来，咱们编写BookDao

package com.ctb.dao;
import java.util.List;
import com.ctb.entity.Book;
import com.ctb.util.BaseDao;
import com.ctb.util.PageBean;
import com.ctb.util.StringUtils;
public class BookDao extends BaseDao<Book>{
  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();
    int bid = book.getBid();
    if(StringUtils.isNotBlank(bname)) {
      sql += " and bname like '%"+bname+"%'";
    }
    if (bid != 0) {
      sql +=" and bid = "+ bid;
    }
    return super.executeQuery(sql, Book.class, pageBean);
  }
}

在BookDao中是不是能看出我们的方法仅需几行就解决了，这大大的提高了我们的效率呢

四、后台代码的编写

下面编写我们的servlet------BookAction

package com.ctb.servlet;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.ctb.dao.BookDao;
import com.ctb.entity.Book;
import com.ctb.util.PageBean;
import com.zking.framework.ActionSupport;
import com.zking.framework.ModelDriver;
/**
 * 
 * @author biao
 *
 * 2023年7月3日:下午6:28:29
 */
public class BookAction extends ActionSupport implements ModelDriver<Book>{
  private Book book = new Book();
  private BookDao bookDao = new BookDao();
  @Override
  public Book getModel() {
    return book;
  }
  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("list", 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";
  }
  public String toEdit(HttpServletRequest req, HttpServletResponse resp) {
    try {
      //拿到id进行查询相应数据再跳转修改页面赋值
      if(book.getBid() != 0) {
        List<Book> list = bookDao.list(book, null);
        req.setAttribute("b", list.get(0));
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
    return "toEdit";
  }
}

在该类中它的返回值需要与我们配置文件中的mvc.xml中的name属性值一致

五、前台代码的编写

主界面

<%@ page language="java" contentType="text/html; charset=UTF-8"
  pageEncoding="UTF-8"%>
<%@ taglib uri="http://com.ctb" prefix="t"%>  
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> 
<!DOCTYPE html>
<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>
  <form class="form-inline"
    action="${pageContext.request.contextPath }/book.action?methodName=list" method="post">
    <div class="form-group mb-2">
      <input type="text" class="form-control-plaintext" name="bname"
        placeholder="请输入书籍名称">
<!-- 不想分页 -->
        <input name="pagination" value="false" type="hidden">
    </div>
    <button type="submit" class="btn btn-primary mb-2">查询</button>
    <a class="btn btn-primary mb-2" href="${pageContext.request.contextPath }/book.action?methodName=toEdit">新增</a>
  </form>
  <table class="table table-striped bg-success">
    <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="${list }">
      <tr>
        <td>${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>
  <t:page pageBean="${pageBean }"></t:page>
</body>
</html>

增加修改界面

<%@ page language="java" contentType="text/html; charset=UTF-8"
  pageEncoding="UTF-8"%>
<%@ taglib uri="http://jsp.veryedu.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>

输出结果：

本篇文章就到这里啦，欢迎大家评论区讨论哦！😊😊

自定义MVC框架实现增删改查

前言

一、环境搭建

二、配置文件

三、实体与Dao方法的编写

四、后台代码的编写

五、前台代码的编写

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