[大数据]自定义mvc代码实现

Dao层代码：

?

package com.yq.dao;

import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import com.yq.entity.Student;
import com.zking.unti.PageBean;
import com.zking.unti.StringUtils;

public class StudenDao extends BaseDao<Student>{
	
	public int add(Student stu) {
		 String sql="insert into t_student(sname_pinyin,age,remark) values('"+stu.getSname()+"','"+stu.getSnamePinyin()+"',"+stu.getAge()+",'"+stu.getRemark()+"')";		
		 return this.executeUpdate(sql);
	}
	
	public int update(Student stu) {
		String sql="update t_student set sname='"+stu.getSname()+"',sname_pinyin='"+stu.getSnamePinyin()+"',age="+stu.getAge()+",remark='"+stu.getRemark()+"' where sid="+stu.getSid();
		return this.executeUpdate(sql);
	}
	
	public int del(Student stu) {
		String sql="delete from t_student where sid="+stu.getSid();
		return this.executeUpdate(sql);
	}
	
	/**
	 * 查询所有
	 * @param student
	 * @param pageIndex
	 * @param pageSize
	 * @return
	 */
	public List<Student> list(Student student,PageBean pageBean) throws Exception{
		
		String sql="select * from t_student where 1=1";
		if(StringUtils.isNotBlank(student.getSname())) {
			sql+=" and sname like '%"+student.getSname()+"%'";
		}
		return this.executeQuery(sql, pageBean, new CallBack<Student>() {
			@Override
			public List<Student> forEach(ResultSet rs) throws Exception {
				List<Student> students=new ArrayList<>();
				Student s=null;
				while(rs.next()) {
					s=new Student();
					s.setSid(rs.getInt("sid"));
					s.setSname(rs.getString("sname"));
					s.setAge(rs.getInt("age"));
					s.setRemark(rs.getString("remark"));
					students.add(s);
				}
				return students;
			}
		});
	}
	
}

BaseDao：

package com.yq.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.List;

import com.zking.unti.DBAccess;
import com.zking.unti.PageBean;


public class BaseDao<T> {
	public interface CallBack<T>{
		public List<T> forEach(ResultSet rs) throws Exception;
	}
	
	/**
	 * 1.通用分页两个基本要素
	 *   1.1 需要知道满足条件的条目数
	 *   1.2查询满足条件指定页码的结果
	 * @throws Exception 
	 */
	
	public List<T> executeQuery(String sql,PageBean pageBean,CallBack<T> callBack) throws Exception{
		Connection con=null;
		PreparedStatement ps=null;
		ResultSet rs=null;
		try {
			con=DBAccess.getConnection();
//			如果用户需要分页的话将用户传递过来的sql语句进行转换
			if(null!=pageBean&&pageBean.isPagination()) {
				String countSql = this.countSql(sql);
				ps=con.prepareStatement(countSql);
				rs=ps.executeQuery();
				if(rs.next()) {
					pageBean.setTotal(rs.getInt(1));
				}
				//开始查询结果
				String pageSql = this.pageSql(sql, pageBean);
				ps=con.prepareStatement(pageSql);
			}else {
				//用户不需要分页
				ps=con.prepareStatement(sql);
			}
			rs=ps.executeQuery();
			
		} catch (Exception e) {
			e.printStackTrace();
		}
		return callBack.forEach(rs);
	}

	
	/**
	 * 共用的方法用于执行sql语句实现增删改
	 * 通用编辑
	 * @param sql
	 * @return
	 */
	public int executeUpdate(String sql) {
		Connection con=null;
		PreparedStatement ps=null;
		ResultSet rs=null;
		int n=0;
		try {
			con=DBAccess.getConnection();
			ps=con.prepareStatement(sql);
			n=ps.executeUpdate();
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			DBAccess.close(con, ps, rs);
		}
		return n;
	}
	
	/**
	 * 将用户sql语句修改为查询满足条件的总条目数sql语句
	 * @param sql
	 * @return
	 */
	private String countSql(String sql) {
		String countSql="select count(*) from ("+sql+") a";
		return countSql;
	}
	
	private String pageSql(String sql,PageBean pageBean) {
		String pageSql="select * from ("+sql+")a limit "+pageBean.getStartIndex()+","+pageBean.getRows();
		return pageSql;
	}
}

?子控制器代码：

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package com.yq.web;
import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.yq.dao.StudenDao;
import com.yq.entity.Student;
import com.yq.framework.ActionSupport;
import com.yq.framework.ModelDriver;
import com.zking.unti.PageBean;
public class StudentAction extends ActionSupport implements ModelDriver<Student>{
	private Student s=new Student();
	private StudenDao sd=new StudenDao();
	
	@Override
	public Student getModel() {
		return s;
	}
	
	public String add(HttpServletRequest req, HttpServletResponse resp) {
		sd.add(s);
		return "toList";
	}
	public String delete(HttpServletRequest req, HttpServletResponse resp) {
		sd.del(s);
		return "toList";
	}
	public String edit(HttpServletRequest req, HttpServletResponse resp) {
		sd.update(s);
		return "toList";
	}
	public String list(HttpServletRequest req, HttpServletResponse resp) {
		PageBean pageBean =new PageBean();
		pageBean.setRequest(req);
		try {
			List<Student> list = sd.list(s, pageBean);
			req.setAttribute("books", list);
			req.setAttribute("pageBean", pageBean);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return "list";
	}
	public String toEdit(HttpServletRequest req, HttpServletResponse resp) throws Exception {
//		如果跳转的是新增界面无需查询，如果跳转的是修改界面，需要查询当前bid对应的数据，回显到界面
		if(s.getSid()!=0){
			List<Student> ls = sd.list(s, null);
			req.setAttribute("b", ls.get(0));
		}
		return "toEdit";
	}
	
}

视图层代码：

<%@ 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="${pageContext.request.contextPath }/book.action?methodName=list" method="post">
		<div class="form-group mb-2">
			<input type="text" class="form-control-plaintext" name="sname"
				placeholder="请输入学生名称">
<!-- 			<input name="rows" value="20" type="hidden"> -->
<!-- 不想分页 -->
				<input name="pagination" value="false" type="hidden">
		</div>
		<button type="submit" class="btn btn-primary mb-2">查询</button>
		<a class="btn btn-primary mb-2" href="${pageContext.request.contextPath }/book.action?methodName=toEdit">新增</a>
	</form>

	<table class="table table-striped">
		<thead>
			<tr>
				<th scope="col">学生ID</th>
				<th scope="col">学生名</th>
				<th scope="col">年龄</th>
				<th scope="col">操作</th>
			</tr>
		</thead>
		<tbody>
			<c:forEach  var="b" items="${books }">
			<tr>
				<td>${b.sid }</td>
				<td>${b.sname }</td>
				<td>${b.age }</td>
				<td>
					<a href="${pageContext.request.contextPath }/book.action?methodName=toEdit&sid=${b.sid}">修改</a>
					<a href="${pageContext.request.contextPath }/book.action?methodName=delete&sid=${b.sid}">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>

?运行结果：

查询单个：

修改：?