Javaee技术目的总结

青旅半醒 2024-03-17 14:31 92阅读 0赞

## 一.前节回顾 ##

> **在前一节中，我们了解了：**
> 
> **1.将中央控制器中的Action容器，变成可控制!**
> 
> **2.针对于反射调用业务代码，最终页面跳转** 
> 
> **3.jsp页面参数传递后台的代码优化字段太多有影响！**
> 
> ![57936850caed4c4aacc0cd7939a03d43.jpeg][]

--------------------

## 二.项目部署前期准备工作 ##

### 1.项目运行环境配置 ###

#### 1.1.首先新建一个web项目，完成xml构建 ####

> ![04cb8765c6e346f698bd9493badddb7d.png][]
> 
> 然后命名，点击next点到底直到这个出现
> 
> ![56f10484d9094f27a8022139b45db848.png][]
> 
>  **将其勾选，next!**

### 1.2加载jar ###

> 将我们的jar放在web项目的安全目录下
> 
> ![627fdae8fcc745b7b922cb8f4710d243.png][]
> 
> 然后在进行 **add buth将我们的jar加入项目**

### 1.3准备工作结束 ###

> 新建一个utils包，将我们的数据连接驱动，以及过滤器，连接保护文件，分页代码，以及通用的方法basedao加入进utils包中
> 
> ![eebedede767e4a9f8830a6a31f33ca91.png][]

## 三.正式启动项目 ##

### 1.创建实体包 ###

> ![602c3f8446a64c24aae77c717b416bbb.png][]
> 
> 定义需要的属性，提供get,set方法；tostring，，有参，无参数方法

### 2.建立通用查询方法 ###

#### 2.1.继承BaseDao<Book>实现通用查询 ####

public List<Book> list(Book book, PageBean pageBean) throws Exception {
    		String sql = "select *from  t_mvc_book where 1=1 ";
    		String bname = book.getBname();
    		int bid = book.getBid();
    		if (StringUtils.isNotBlank(bname)) {
    			sql += "  and  bname  like  '%" + bname + "%' ";
    		}
    		if (bid != 0) {
    			sql += "  and  bid=" + bid;
    		}
    		return super.executeQuery(sql, Book.class, pageBean);
    	}

### 3.老版本增删改，和新增删改 ###

#### 3.1老版本增删改 ####

// 增加
    	 public int add(Book book) throws Exception {
    	 String sql = "insert into t_mvc_book values(?,?,?)";
    	 Connection conn = DBAccess.getConnection();
    	 PreparedStatement ps = conn.prepareStatement(sql);
    	 ps.setObject(1, book.getBid());
    	 ps.setObject(2, book.getBname());
    	 ps.setObject(3, book.getPrice());
    	
    	 return ps.executeUpdate();
    	 }
    
     //删除
    	 public int del(Book book) throws Exception {
    	 String sql = "delete from t_mvc_book where bid=? ";
    	 Connection conn = DBAccess.getConnection();
    	 PreparedStatement ps = conn.prepareStatement(sql);
    	 ps.setObject(1, book.getBid());
    	 return ps.executeUpdate();
    	 }
    
     public int edit(Book book) throws Exception {
    	 String sql = " update t_mvc_book set bname=?,price=? where bid=?";
    	 Connection conn = DBAccess.getConnection();
    	 PreparedStatement ps = conn.prepareStatement(sql);
    	 ps.setObject(1, book.getBname());
    	 ps.setObject(2, book.getPrice());
    	 ps.setObject(3, book.getBid());
    	 return ps.executeUpdate();
    	 }

> **缺点：**
> 
>  **重复代码:** 
> 
> **Connection conn = DBAccess.getConnection();**
> 
> **PreparedStatement ps =conn.prepareStatement(sql);** 
> 
>  **重复流程:**
> 
> **ps.setObject(1, book.getBid());  
> ps.setObject(2, book.getBname());** 
> 
> **ps.setObject(3, book.getPrice());**

#### 3.2新版本增删改 ####

##### 3.2.1在basedao对于重复代码进行封装 #####

> **通过一个对象集合来存储实体的属性，然后再通过一个for循环其下标其目的是：根据操作来遍历出来所需要的属性，然后通过反射来操作，最后加入设置值**

* 通用的增删改方法
    	 * @param book
    	 * @throws Exception
    	 * sql:sql语句
    	 * T：实体
    	 * attrs：实体属性
    	 */
    	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);
    			pst.setObject(i+1, f.get(t));
    		}
    		 return pst.executeUpdate();
    	}

##### 3.2.2新版本 #####

> **只需要调用那个方法，根据需求编写sql语句，然后在通过return返回，sql语句，实体，集中中的元素**

/**
    	 * 通用增删改
    	 */
    	//增加
    	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"});
    	}
    	//删除
    	public int del(Book book) throws Exception {
    		String sql = "delete from t_mvc_book where bid=?  ";
    		return super.executeUpdate(sql, book, new  String[] {"bid"});
    	}
    	//修改
    	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"});
    	}

### 4.juin测试 ###

> 选择类目,crtl+n 建立一个类Juint test case给代码进行测试
> 
> ![d2cc30ba67f447e092a972890333005c.png][]

#### 4.1方法测试 ####

> 实现思路:
> 
> **1.首先在最外层：调用私有化的dao方法**
> 
> **2.在方法内部实例化实体**
> 
> **3.然后在通过dao.方法名**
> 
> **4.当然具体情况具体分析**

package com.lz.dao;
    
    import static org.junit.Assert.*;
    
    import java.util.List;
    
    import org.junit.Test;
    
    import com.lz.entity.Book;
    import com.lz.utils.PageBean;
    
    public class BookDaoTest {
    	private  BookDao  bk=new  BookDao();
    
    	@Test
    	public void testList() throws Exception {
    		 Book  book=new Book();
    		 book.setBname("圣墟");
    		PageBean  pageBean=new PageBean();
    		//pageBean.setPage(3);
    		pageBean.setPagination(false);
    	        List<Book> list = bk.list(book, pageBean);
    	        for (Book b : list) {
    				System.out.println(b);
    			}
    	}
    
    	@Test
    	public void testAdd() throws Exception {
    		 Book  book=new Book(16,"圣墟嘿嘿嘿",12f);
    		 bk.add(book);
    	}
    
    	@Test
    	public void testDel() throws Exception {
    		 Book  book=new Book();
    		 book.setBid(16);
    		 bk.del(book);
    	}
    
    	@Test
    	public void testEdit() throws Exception {
    		Book  book=new Book(16,"圣墟嘿嘿嘿",12f);
    		 bk.edit(book);
    	}
    
    }

#### 4.2方法调用 ####

> 选择方法
> 
> ![50142d84f7ee4ee39b6052b188834a7c.png][]
> 
>  **当出现绿色时就代表方法没有问题**
> 
> ![5e9eb2c392cb477d92b433feddbde451.png][]

--------------------

### 5.配置xml文件，通过反射来实现一些方法 ###

#### 5.1.配置mvc.xml ####

> ###  ###
> 
> ![bebe7c6e32164061b51366ed9a299cc8.png][]
> 
> name属性为：我们在Bookaction中 return方法的返回值
> 
> ![ff11607e1e4c48228e6af9defc6f4da0.png][]
> 
> path为：跳转路径

#### 5.2配置tid文件 ####

> ![e23218ee742f427d9829811573185f09.png][]
> 
> tag-class属性为：我们配置的分页代码路径

### 6.实现web界面 ###

#### 6.1数据显示界面 ####

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

##### 6.1.2效果图 #####

![11bd02a3171047feb8374c906f34ff39.png][]

#### 6.2增加，修改 ####

##### 6.2.1代码 #####

> **由于增加，修改共用一个jsp界面，当我们传参数时要对于参数进行一个判断，使用三元运算符，如果b为就是增加操作，不然就是修改操作**

##### 6.2.2效果图 #####

![9702fb1ad6d04a99b5c66eed08beeec2.png][]

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