自定义mvc----增删改查终极篇

package com.xuyahui.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.xuyahui.util.DBAccess;
import com.xuyahui.util.PageBean;
/**
 *  所有Dao层的父类
 *  BookDao
 *  UserDao
 *  OrderDao
 * @author 86155
 *
 * @param <T>
 */
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);
    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();
  }
  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()) {
      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);
      pst = con.prepareStatement(pageSQL);
      rs = pst.executeQuery();
    }else {
      pst = con.prepareStatement(sql);
      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;
  }
  private String getCountSQL(String sql) {
    return "select count(1) from ("+sql+") t";
  }
  private String getPageSQL(String sql,PageBean pageBean) {
    return sql + " limit "+ pageBean.getStartIndex() +","+pageBean.getRows();
  }
}

package com.xuyahui.dao;
import java.util.List;
import com.xuyahui.entity.Book;
import com.xuyahui.util.BaseDao;
import com.xuyahui.util.PageBean;
import com.xuyahui.util.StringUtils;
public class BookDao extends BaseDao<Book>{
  /*
    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);
  }
  public static void main(String[] args) throws Exception {
    Book b = new Book();
    b.setBid(2323);
    b.setBname("测试www");
    b.setPrice(231f);
    BookDao bookDao = new BookDao();
//    bookDao.delete(b);
//    bookDao.add(b);
    bookDao.edit(b);
  }
}

<?xml version="1.0" encoding="UTF-8"?>
<config>
  <action path="/book" type="com.yinzi.Servlet.BookAction">
    <forward name="list" path="/book.jsp" redirect="false" />
    <forward name="toList" path="/book.action?methodName=list" redirect="true" />
    <forward name="toEdit" path="/BookEdit.jsp" redirect="false" />
  </action>
</config>

<?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>mvc_crud</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <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>

<?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>xuyahui 1.1 core library</description>
  <display-name>xuyahui core</display-name>
  <tlib-version>1.1</tlib-version>
  <short-name>y</short-name>
  <uri>http://xuyahui</uri>
  <tag>
    <name>page</name>
    <tag-class>com.xuyahui.Tag.PageTag</tag-class>
    <body-content>JSP</body-content>
    <attribute>
        <name>pageBean</name>
        <required>true</required>
        <rtexprvalue>true</rtexprvalue>
    </attribute>
  </tag>
</taglib>

<%@ 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="${pageContext.request.contextPath }/book.action?methodName=list" method="post">
    <div class="form-group mb-2">
      <input type="text" class="form-control-plaintext" name="bname"
        placeholder="请输入书籍名称">
<!--      <input name="rows" value="20" type="hidden"> -->
<!-- 不想分页 -->
        <input name="pagination" value="false" type="hidden">
    </div>
    <button type="submit" class="btn btn-primary mb-2">查询</button>
    <a class="btn btn-primary mb-2" href="${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="${books }">
      <tr>
        <td>${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 -->
  <z:page pageBean="${pageBean }"></z:page>
</body>
</html>