自定义MVC增删改查(CRUD)---超详细讲解-阿里云开发者社区

一，如何导出自定义MVC架包

导出步骤：

1.1 点击想导出的包并右键，点击Export，

1.2 搜索JAR file选中JAR file，点击Next

1.3 找到Browse...并选择你要将架包存储的位置，点击Finish即可

二，导入自定义架包（三步）

2.1 创建一个web项目，将所需要的架包复制到安全目录lib文件架中

2.2 将所需要的工具类导入utils

2.3 将子控制器配置文件导入根目录中

三，通用增删改查

3.1编写BaseDao

3.1.1前言:

优化分页及Dao方法，将之前所写的Dao方法重复的代码进行改善优化

BaseDao代码：

注意：将BaseDao定义成泛型

参数：编写的sql语句，实体，属性

package com.LiuBing.utils;
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;
/**
 * 所有Dao层的父类
 *  ...
 * @author 
 *
 * @param <T>
 */
public class BaseDao<T> {
  /**
   * 通用的增删改方法
   * @param book
   * @return 
   * @throws Exception
   */
  public int executeUpdate(String sql, T t, String[] attrs) throws Exception {
    Connection con = DBAccess.getConnection();
    PreparedStatement pst = con.prepareStatement(sql);
    for (int i = 0; i < attrs.length; i++) {
      Field f = t.getClass().getDeclaredField(attrs[i]);
      f.setAccessible(true);//打开访问权限
      pst.setObject(i+1, f.get(t));
    }
     return 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
//      -- sql=SELECT * FROM t_mvc_book WHERE bname like '%圣墟%'
//      -- pageSql=sql limit (page-1)*rows,rows   对应某一页的数据
//      -- countSql=select count(1) from (sql) t  符合条件的总记录数
      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) {
//    (this.page - 1) * this.rows
//    pageSql=sql limit (page-1)*rows,rows
    return sql + " limit "+ pageBean.getStartIndex() +","+pageBean.getRows();
  }
}

所操作的对象---Book

定义一个Book实体:

package com.LiuBing.entity;
/**
 * 实体类
 * 
 * @author 兵
 *
 */
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;
  }
  public Book(int bid, String bname, float price) {
    super();
    this.bid = bid;
    this.bname = bname;
    this.price = price;
  }
  public Book() {
    super();
  }
  @Override
  public String toString() {
    return "Book [bid=" + bid + ", bname=" + bname + ", price=" + price + "]";
  }
}

将Dao方法继承BaseDao

package com.LiuBing.dao;
import java.util.List;
import com.LiuBing.entity.Book;
import com.LiuBing.utils.BaseDao;
import com.LiuBing.utils.PageBean;
import com.LiuBing.utils.StringUtils;
public class BookDao extends BaseDao<Book>{
    //查询所有
      public List<Book> list(Book book, PageBean pageBean) throws Exception {
       String sql ="select * from t_mvc_book where 1=1";
      String bname = book.getBname();//获取名称
      int bid = book.getBid();//获取id
      //模糊查询 拼接查询所有语句
      if(StringUtils.isNotBlank(bname)) {
        sql+=" and bname like '%"+bname+"%' ";
      }
      //当bid不为0 证明前端已经传来id值
      if(bid!=0) {
        sql += "and bid ="+bid;//拼接
      }
      return super.executeQuery(sql, Book.class, pageBean);
    }
    //增加方法
    public int  add(Book book) throws Exception{
      //编写sql语句
      String sql ="insert into t_mvc_book values(?,?,?)";
      return super.executeUpdate(sql, book,new String[] {"bid","bname","price"});
    }
    //删除方法
    public int  del(Book book) throws Exception{
      //编写sql语句
      String sql ="delete from  t_mvc_book where bid= ?";
    return super.executeUpdate(sql, book,new String[] {"bid"});
    }
    //修改方法
    public int  upd(Book book) throws Exception{
      //编写sql语句
      String sql ="update t_mvc_book set bname=?,price=? where bid=?";
      return super.executeUpdate(sql, book,new String[] {"bname","price","bid"});
    }
}

3.2 编写优化Servlet

前端传增删改查等操作继承ActionSupport(已经导jar) 实现ModelDriver(已导jar)

package com.LiuBing.web;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.LiuBing.dao.BookDao;
import com.LiuBing.entity.Book;
import com.LiuBing.utils.PageBean;
import com.zking.framework.ActionSupport;
import com.zking.framework.ModelDriver;
public class BookAction extends ActionSupport implements ModelDriver<Book> {
private Book book = new Book();
private BookDao bookdao = new BookDao();
PageBean pageBean = new PageBean();
     public String list(HttpServletRequest req ,HttpServletResponse resp) {
       pageBean.setRequest(req);
       try {
      List<Book> list = bookdao.list(book, pageBean);
      req.setAttribute("list", list);
      req.setAttribute("pageBean", pageBean);
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
       return "list";
     }  
      //编辑页面
     public String toEdit(HttpServletRequest req ,HttpServletResponse resp) {
       try {
         if(book.getBid()!=0) {
           List<Book> list = bookdao.list(book, null);
            req.setAttribute("b", list.get(0));
         }
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
       return "toEdit";
     }  
     //增加
     public String add(HttpServletRequest req ,HttpServletResponse resp) {
       try {
         bookdao.add(book);
    } catch (Exception e) {
      e.printStackTrace();
    }
       return "toList";
     }  
     //删除
     public String del(HttpServletRequest req ,HttpServletResponse resp) {
       try {
         bookdao.del(book);
    } catch (Exception e) {
      e.printStackTrace();
    }
       return "toList";
     }  
        //修改
     public String upd(HttpServletRequest req ,HttpServletResponse resp) {
       try {
         bookdao.upd(book);
    } catch (Exception e) {
      e.printStackTrace();
    }
       return "toList";
     }  
  @Override
  public Book getModel() {
    return book;
  }
}

测试Dao方法：

package com.LiuBing.dao;
import static org.junit.Assert.fail;
import java.util.List;
import org.junit.Test;
import com.LiuBing.entity.Book;
import com.LiuBing.utils.PageBean;
public class BookDaoTest {
  private BookDao bookdao = new BookDao();
  //测试增加方法
  @Test
  public void testList() {
    System.out.println("123");
    Book book = new Book();
    PageBean pageBean = new PageBean();
//    book.setBname("圣墟");//模糊查询
//    pageBean.setPage(4);//分页查询
    try {
      List<Book> list = bookdao.list(book, pageBean);
      /*for (int i = 0; i < list.size(); i++) {
        System.out.println(list[i]);
      }*/
      for (Book book2 : list) {
        System.out.println(book2);
      }
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }
  @Test
  public void testAdd() {
//    Book book = new Book(56,"圣墟",520f);
//    try {
//      bookdao.add(book);
//    } catch (Exception e) {
//      // TODO Auto-generated catch block
//      e.printStackTrace();
//    } 
    }
  @Test
  public void testDel() {
//  Book book = new Book();
//  book.setBid(56);
//  
//  try {
//    bookdao.del(book);
//  } catch (Exception e) {
//    // TODO Auto-generated catch block
//    e.printStackTrace();
//  }
  }
  @Test
  public void testUpd() {
    Book book = new Book(56,"圣墟小子",520f);
    try {
      bookdao.upd(book);
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } 
  }
}

3.3 编写PageTag助手类（分页）

3.3.1标签助手类

代码：

package com.LiuBing.tag;
import java.io.IOException;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyTagSupport;
import com.LiuBing.utils.PageBean;
public class PageTag extends BodyTagSupport{
  private PageBean pageBean;// 包含了所有分页相关的元素
  public PageBean getPageBean() {
    return pageBean;
  }
  public void setPageBean(PageBean pageBean) {
    this.pageBean = pageBean;
  }
  @Override
  public int doStartTag() throws JspException {
//    没有标签体，要输出内容
    JspWriter out = pageContext.getOut();
    try {
      out.print(toHTML());
    } catch (IOException e) {
      e.printStackTrace();
    }
    return super.doStartTag();
  }
  private String toHTML() {
    StringBuffer sb = new StringBuffer();
//    隐藏的form表单---这个就是上一次请求下次重新发的奥义所在
//    上一次请求的URL
    sb.append("<form action='"+pageBean.getUrl()+"' id='pageBeanForm' method='post'>");
    sb.append(" <input type='hidden' name='page'>");
//    上一次请求的参数
    Map<String, String[]> paramMap = pageBean.getParamMap();
    if(paramMap != null && paramMap.size() > 0) {
      Set<Entry<String, String[]>> entrySet = paramMap.entrySet();
      for (Entry<String, String[]> entry : entrySet) {
//        参数名
        String key = entry.getKey();
//        参数值
        for (String value : entry.getValue()) {
//          上一次请求的参数，再一次组装成了新的Form表单
//          注意：page参数每次都会提交，我们需要避免
          if(!"page".equals(key)) {
            sb.append(" <input type='hidden' name='"+key+"' value='"+value+"' >");
          }
        }
      }
    }
    sb.append("</form>");
//    分页条
    sb.append("<ul class='pagination justify-content-center'>");
    sb.append(" <li class='page-item "+(pageBean.getPage() == 1 ? "disabled" : "")+"'><a class='page-link'");
    sb.append(" href='javascript:gotoPage(1)'>首页</a></li>");
    sb.append(" <li class='page-item "+(pageBean.getPage() == 1 ? "disabled" : "")+"'><a class='page-link'");
    sb.append(" href='javascript:gotoPage("+pageBean.previousPage()+")'>&lt;</a></li>");// less than 小于号
//    sb.append(" <li class='page-item'><a class='page-link' href='#'>1</a></li>");
//    sb.append(" <li class='page-item'><a class='page-link' href='#'>2</a></li>");
    sb.append(" <li class='page-item active'><a class='page-link' href='#'>"+pageBean.getPage()+"</a></li>");
    sb.append(" <li class='page-item "+(pageBean.getPage() == pageBean.maxPage() ? "disabled" : "")+"'><a class='page-link' href='javascript:gotoPage("+pageBean.nextPage()+")'>&gt;</a></li>");
    sb.append(" <li class='page-item "+(pageBean.getPage() == pageBean.maxPage() ? "disabled" : "")+"'><a class='page-link' href='javascript:gotoPage("+pageBean.maxPage()+")'>尾页</a></li>");
    sb.append(" <li class='page-item go-input'><b>到第</b><input class='page-link'");
    sb.append(" type='text' id='skipPage' name='' /><b>页</b></li>");
    sb.append(" <li class='page-item go'><a class='page-link'");
    sb.append(" href='javascript:skipPage()'>确定</a></li>");
    sb.append(" <li class='page-item'><b>共"+pageBean.getTotal()+"条</b></li>");
    sb.append("</ul>");
//    分页执行的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) > "+pageBean.maxPage()+") {");
    sb.append("     alert('请输入1~"+pageBean.maxPage()+"的数字');");
    sb.append("     return;");
    sb.append("   }");
    sb.append("   gotoPage(page);");
    sb.append(" }");
    sb.append("</script>");
    return sb.toString();
  }
}

3.3.2 自定义PageTag标签进行配置

注意：放置到安全目录下

<?xml version="1.0" encoding="UTF-8" ?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
    version="2.0">
  <description>zking 1.1 core library</description>
  <display-name>zking core</display-name>
  <tlib-version>1.1</tlib-version>
  <short-name>zking</short-name>
  <uri>http://jsp.veryedu.cn</uri>
  <tag>
    <name>page</name>
    <tag-class>com.LiuBing.tag.PageTag</tag-class>
    <body-content>JSP</body-content>
    <attribute>
        <name>pageBean</name>
        <required>true</required>
        <rtexprvalue>true</rtexprvalue>
    </attribute>
  </tag>
</taglib>

3.3.3 jsp页面环境搭建（增删改查）

引入自定义标签库<%@ taglib prefix="z" uri="http://jsp.veryedu.cn"%>

<%@ page language="java" contentType="text/html; charset=UTF-8"
  pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
  <!--导入自定义标签库  -->
<%@ taglib prefix="z" uri="http://jsp.veryedu.cn"%>
<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="${pageContext.request.contextPath }/book.action?methodName=list" method="post">
    <div class="form-group mb-2">
      <input type="text" class="form-control-plaintext" name="bname"
        placeholder="请输入书籍名称">
    </div>
    <button type="submit" class="btn btn-primary mb-2">查询</button>
      <a class="btn btn-primary mb-2" href="${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 items="${list }" var="list"> 
      <tr>
        <td>${list.bid }</td>
        <td>${list.bname }</td>
        <td>${list.price }</td>
        <td>
        <a href="${pageContext.request.contextPath }/book.action?methodName=toEdit$bid=${book.bid }">修改</a>
          <a href="${pageContext.request.contextPath }/book.action?methodName=del$bid=${book.bid }">删除</a>
        </td>
      </tr>
      </c:forEach>
    </tbody>
  </table>
  <!--导入自定义标签库  -->
<z:page pageBean="${pageBean }"></z:page>
</body>
</html>

3.3.4 修改及新增jsp页面

为代码的简化，新增及修改跳的都是同一个页面，在Servlet进行判断，通过返回值点击的是哪个按钮进行不同的页面（一个修改带id值一个增加不要）

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!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">
<title>书记编辑页面</title>
</head>
<body>
<form action="${pageContext.request.contextPath }/book.action?methodName=${not empty b ?'add': 'upd'}" method="post">
     编号：<input type="text" name="bid" value="${b.bid }"><br>
     名称：<input type="text" name="bname" value="${b.bname }"><br>
     价格：<input type="text" name="price" value="${b.price }"><br>
         <input type="submit">
</form>
</body>
</html>

自定义MVC增删改查(CRUD)---超详细讲解

一，如何导出自定义MVC架包

1.1 点击想导出的包并右键，点击Export，

1.2 搜索JAR file选中JAR file，点击Next

1.3 找到Browse...并选择你要将架包存储的位置，点击Finish即可

二，导入自定义架包（三步）

2.1 创建一个web项目，将所需要的架包复制到安全目录lib文件架中

2.2 将所需要的工具类导入utils

2.3 将子控制器配置文件导入根目录中

三，通用增删改查

3.1编写BaseDao

3.1.1前言:

3.2 编写优化Servlet

3.3 编写PageTag助手类（分页）

3.3.1标签助手类

3.3.2 自定义PageTag标签进行配置

3.3.3 jsp页面环境搭建（增删改查）

3.3.4 修改及新增jsp页面

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