mvc应用

最新推荐文章于 2024-04-06 20:17:29 发布

原创最新推荐文章于 2024-04-06 20:17:29 发布 · 76 阅读

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#java

web.xml配置

<?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.zw.web.BookAction">
        <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>

开发

Book类：

package com.zw.entity;

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 + "]";
	}
	public Book(int bid, String bname, float price) {
		super();
		this.bid = bid;
		this.bname = bname;
		this.price = price;
	}
	public Book() {
		super();
	}
	
}

BookDao:

public class BookDao extends BaseDao<Book>{
	
	public void add(Book b) throws Exception {
		String sql="insert into t_mvc_book values(?,?,?)";
		super.executeUpdate(sql, b, new String[] {"bid","bname","price"});
	}
	
	public void del(Book b) throws Exception {
		String sql="delete from t_mvc_book where bid=?";
		super.executeUpdate(sql, b, new String[] {"bid"});
	}
	
	public void edit(Book b) throws Exception {
		String sql="update t_mvc_book set bname=?,price=? where bid=?";
		super.executeUpdate(sql, b, new String[] {"bname","price","bid"});
	}
	
	public List<Book> list(Book b,PageBean pageBean) throws Exception {
		String sql="select * from t_mvc_book where 1=1";
		String bname = b.getBname();
		int bid = b.getBid();
		if(StringUtils.isNotBlank(bname)) {
			sql+=" and bname like'%"+bname+"%'";
		}
		if(bid!=0) {
			sql+=" and bid="+bid;
		}
		return super.executeQuery(sql, Book.class, pageBean);
	}

}

BookAaction:

public class BookAction extends ActionSupport implements ModelDriver<Book>{
	
	private Book book=new Book();
	private BookDao bd=new BookDao();
	
	@Override
	public Book getModel() {
		// TODO Auto-generated method stub
		return book;
	}
	
	public String add(HttpServletRequest req, HttpServletResponse resp) {
		try {
			bd.add(book);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "toList";
	}
	
	public String del(HttpServletRequest req, HttpServletResponse resp) {
		try {
			bd.del(book);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "toList";
	}
	
	public String edit(HttpServletRequest req, HttpServletResponse resp) {
		try {
			bd.edit(book);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "toList";
	}
	
	public String toEdit(HttpServletRequest req, HttpServletResponse resp) {
		try {
			if(book.getBid()!=0) {
				List<Book> list=bd.list(book, null);
				req.setAttribute("b", list.get(0));
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "toEdit";
	}
	
	public String list(HttpServletRequest req, HttpServletResponse resp) {
		try {
			PageBean pageBean = new PageBean();
			List<Book> list=bd.list(book, pageBean);
			req.setAttribute("books", list);
			req.setAttribute("pageBean", pageBean);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "list";
	}

}

BaseDao:所有dao层的父类

/**
 * 所有Dao层的父类
 * 	BookDao
 * 	UserDao
 * 	OrderDao
 * 	...
 * @author Administrator
 *
 * @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 {
//		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());
		/*
		 * 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<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();
	}
}

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>博客列表</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">博客ID</th>
				<th scope="col">标题</th>
				<th scope="col">关键字</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="${pageContext.request.contextPath }/book.action?methodName=del&bid=${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>

效果展示：

查询：