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自定义MVC增删改查
2022-08-11 05:35:00 【雨沐笙】
目录
四、BookAction的完成、完成mvc.xml的配置和重复提交表单问题
前言
今日分享的是自定义mvc的增删改，并将其优化成通用的
提示：以下是本篇文章正文内容，下面案例可供参考
一、配置自定义mvc框架环境
1.将我们上次写的框架打成jar包，然后导入新工程，并且把框架的依赖jar包导入进去
①选中我们之前写的framework，右键选中Export...
②输入框中输入java，然后选中 JAR file，点击next
③选择保存地址，然后Finsih即可
④将之前写的分页标签相关文件、及相关助手类导入
⑤将框架的配置文件添加、以及web.xml的配置
注意：要将我们打出来的jar包所需要的包也导入项目中
web.xml配置：
<?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>J2EE_crud</display-name>
<servlet>
<servlet-name>mvc</servlet-name>
<servlet-class>com.mgy.framework.DispatcherServlet</servlet-class>
<init-param>
<param-name>configLocation</param-name>
<param-value>/asd.xml</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>mvc</servlet-name>
<url-pattern>*.action</url-pattern>
</servlet-mapping>
</web-app>二、实体类、以及dao方法的编写和优化
实体类（书籍类）:
package com.mgy.entity;
public class Book {
private int bid;
private String bname;
private float price;
@Override
public String toString() {
return "Book [bid=" + bid + ", bname=" + bname + ", price=" + 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() {
super();
}
public Book(int bid, String bname, float price) {
super();
this.bid = bid;
this.bname = bname;
this.price = price;
}
}
基础的dao方法：
package com.mgy.dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import com.mgy.entity.Book;
import com.mgy.util.BaseDao;
import com.mgy.util.DBAccess;
import com.mgy.util.PageBean;
import com.mgy.util.StringUtils;
public class BookDao extends BaseDao<Book>{
//查询
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+"%'";
}
int bid=book.getBid();
//前台jsp传递到后台，只要传了就有值
if(bid!=0) {
sql+=" and bid="+bid;
}
return super.list(sql, pageBean, rs ->{
List<Book> list=new ArrayList<>();
try {
while(rs.next()) {
list.add(new Book(rs.getInt("bid"), rs.getString("bname"), rs.getFloat("price")));
}
} catch (Exception e) {
e.printStackTrace();
}
return list;
});
}
//增加
public int add(Book book) throws Exception {
Connection con = DBAccess.getConnection();
String sql="insert into t_mvc_book values(?,?,?)";
PreparedStatement ps = con.prepareStatement(sql);
ps.setObject(1, book.getBid());
ps.setObject(2, book.getBname());
ps.setObject(3, book.getPrice());
return ps.executeUpdate();
}
//删
public int del(Book book)throws Exception {
Connection con = DBAccess.getConnection();
String sql = "delete from t_mvc_book where bid=?";
PreparedStatement pst = con.prepareStatement(sql);
pst.setObject(1, book.getBid());
return pst.executeUpdate();
}
//改
public int edit(Book book)throws Exception{
Connection con = DBAccess.getConnection();
String sql = "update t_mvc_book set bname=?,price=? where bid=?";
PreparedStatement pst = con.prepareStatement(sql);
pst.setObject(1, book.getBname());
pst.setObject(2, book.getPrice());
pst.setObject(3, book.getBid());
return pst.executeUpdate();
}
}
我们可以发现增删改中都有重复的代码块，所以我们在BaseDao中添加以下方法
public int executeUpdate(String sql,T t,String[] attrs ) throws Exception{
Connection con = DBAccess.getConnection();
PreparedStatement pst = con.prepareStatement(sql);
//将t的某一个属性对应的值加到pst对象中
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.setObject(1, book.getBid());
// pst.setObject(2, book.getBname());
// pst.setObject(3, book.getPrice());
return pst.executeUpdate();
}通用增删改查：
package com.mgy.dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import com.mgy.entity.Book;
import com.mgy.util.BaseDao;
import com.mgy.util.DBAccess;
import com.mgy.util.PageBean;
import com.mgy.util.StringUtils;
public class BookDao extends BaseDao<Book>{
//查询
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+"%'";
}
int bid=book.getBid();
//前台jsp传递到后台，只要传了就有值
if(bid!=0) {
sql+=" and bid="+bid;
}
return super.list(sql, pageBean, rs ->{
List<Book> list=new ArrayList<>();
try {
while(rs.next()) {
list.add(new Book(rs.getInt("bid"), rs.getString("bname"), rs.getFloat("price")));
}
} catch (Exception e) {
e.printStackTrace();
}
return list;
});
}
//增
public int add(Book book) throws Exception {
String sql="insert into t_mvc_book values(?,?,?)";
return super.executeUpdate(sql, book, new String[] {"bid","bname","price"});
}
//删
public int del(Book book)throws Exception{
String sql="delete from t_mvc_book where bid=?";
return super.executeUpdate(sql, book, new String[] {"bid"});
}
//改
public int edit(Book book) throws Exception {
String sql = "update t_mvc_book set bname=?,price=? where bid=?";
return super.executeUpdate(sql, book, new String[] {"bname","price","bid"});
}
}
三、前台的搭建
主界面：
<%@ 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="css/bootstrap.css" rel="stylesheet">
<script type="text/javascript" src="js/bootstrap.js"></script>
<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>
<!-- ${pageContext.request.contextPath } -->
<body>
<%-- <c:if test="${empty list }">
<jsp:forward page="book/search"></jsp:forward>
</c:if> --%>
<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=preEdit">增加</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="${list }" var="b">
<tr>
<td>${b.bid }</td>
<td>${b.bname }</td>
<td>${b.price }</td>
<td>
<a href="${pageContext.request.contextPath }/book.action?methodName=preEdit&bid=${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>
<z:page pageBean="${pageBean }"></z:page>
</body>
</html>增加界面&修改界面：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action = "${pageContext.request.contextPath }/book.action?methodName=${empty b ? 'add' : 'edit'}" method="post" >
bid:<input type="text" name="bid" value="${b.bid }"><br>
bname:<input type="text" name="bname" value="${b.bname }"><br>
price:<input type="text" name="price" value="${b.price }"><br>
<input type="submit">
</form>
</body>
</html>四、BookAction的完成、完成mvc.xml的配置和重复提交表单问题
mvc.xml：
<?xml version="1.0" encoding="UTF-8"?>
<config>
<action path="/book" type="com.mgy.web.BookAction">
<forward name="list" path="/index.jsp" redirect="false" />
<forward name="toEdit" path="/bookEdit.jsp" redirect="false" />
<forward name="toList" path="/book.action?methodName=list" redirect="true" />
</action>
</config>BookAction：
package com.mgy.web;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.mgy.dao.BookDao;
import com.mgy.entity.Book;
import com.mgy.framework.ActionSupport;
import com.mgy.framework.ModelDriven;
import com.mgy.util.PageBean;
public class BookAction extends ActionSupport implements ModelDriven<Book>{
private Book book = new Book();
private BookDao bookDao = new BookDao();
@Override
public Book getModel() {
return book;
}
//增
public String add(HttpServletRequest request, HttpServletResponse response) {
try {
bookDao.add(book);
} catch (Exception e) {
e.printStackTrace();
}
//toList代表跳到查询页面
return "toList";
}
//删
public String del(HttpServletRequest request, HttpServletResponse response) {
try {
bookDao.del(book);
} catch (Exception e) {
e.printStackTrace();
}
//toList代表跳到查询页面
return "toList";
}
//改
public String edit(HttpServletRequest request, HttpServletResponse response) {
try {
bookDao.edit(book);
} catch (Exception e) {
e.printStackTrace();
}
//toList代表跳到查询页面
return "toList";
}
//查
public String list(HttpServletRequest request, HttpServletResponse response) {
try {
PageBean pageBean = new PageBean();
pageBean.setRequest(request);
List<Book> list = bookDao.list(book,pageBean);
request.setAttribute("list", list);
request.setAttribute("pageBean", pageBean);
} catch (Exception e) {
e.printStackTrace();
}
//执行查询展示
return "list";
}
//跳转到新增/修改界面
public String preEdit(HttpServletRequest request, HttpServletResponse response) {
try {
int bid = book.getBid();
if(bid!=0) {
//传递bid到后台，有且只能查出一条数据，那也就意味着list集合中只要一条
List<Book> list = bookDao.list(book, null);
request.setAttribute("b", list.get(0));
}
} catch (Exception e) {
e.printStackTrace();
}
//toList代表跳到查询页面
return "toEdit";
}
}
五、效果
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