Mvc与三层架构
创建Spring项目
勾选web和mabais框架
配置yml文件,这里创建spring项目默认生成的是propertise文件,但是properties文件的格式看起来没有yml文件一目了然。yml文件配置数据库还有映射mapper层的xml文件以及设置日志级别,比如mapper层的日志级别是debug,而另外两层都是info。
server:port: 8080spring:profiles:active: devmain:allow-circular-references: truedatasource:driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://localhost:3306/elm?useSSL=true&allowPublicKeyRetrieval=true&serverTimezone=UTCusername: yournamepassword: yourpassmybatis:#mapper配置文件mapper-locations: classpath:mapper/*.xmltype-aliases-package: com.zlh.entityconfiguration:#开启驼峰命名map-underscore-to-camel-case: truelogging:level:com:zlh:mapper: debugservice: infocontroller: info
建立如下的包,controller控制器是SpringBoot中负责处理http请求的组件,service是负责处理业务逻辑的组件,mapper是负责数据持久化的组件,由于在SpringMVC中,mapper要么通过xml文件来实现数据持久化,要么通过注解的方式进行,所以只需要一个mapper接口即可。由于需要查询商家及其食品,所以需要用到business和entity两个实体,在SpringBoot中其实使用DTO对象作为不同数据层之间传输对象的模式更为常见,这里由于业务简单,所以所有层之间都是采用的实体本身。Result负责封装返回结果,即在软件开发中所有的返回结果都应该是统一的格式。
Result类,封装所有controller返回的结果,实现Serializable接口,让这个类能够被序列化(自动转换为json格式,http之间能够直接传输)。封装返回结果使用了大量的泛型的思想。方法是静态泛型方法,参数也是泛型参数。极大保证了灵活性。此外,响应码,响应信息,响应数据这个封装格式也是运用的最广泛的封装格式。
import lombok.Data;import java.io.Serializable;/*** this class is used to unify the return result* The Serializable interface is used to mark the class could be Serialized.* */
@Data
public class Result<T> implements Serializable {//the status codeprivate Integer code;//the response messageprivate String msg;//the response dataprivate T data;/*** The generic method can encapsulate the result into the Result class which can be auto serialized.* */public static <T> Result<T> success(){Result<T> result = new Result<>();result.code=1;return result;}/*** The generic method can encapsulate the result into the Result class which can be auto serialized.* @param object could be any object.* */public static <T> Result<T> success(T object){Result<T> result = new Result<>();result.code = 1;result.data = object;return result;}/*** The generic method can encapsulate the result into the Result class which can be auto serialized.* @param msg The error message.* */public static <T> Result<T> error(String msg){Result<T> result = new Result<>();result.msg = msg;result.code=0;return result;}
}//of class Result
Springboot通过启动类来启动项目,第一个注解是将这个类注册为启动类,使用这个注解快速配置Springboot项目,并且启动main方法后,项目就会自动监听配置文件指定的端口。
import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.transaction.annotation.EnableTransactionManagement;@SpringBootApplication
@EnableTransactionManagement //use the annotation of the transaction.
@Slf4j
public class Application {/***The entrance of the program and the* */public static void main(String[] args) {SpringApplication.run(Application.class, args);log.info("server Started");}
}
Controller类,由于项目是前后端分离开发的,所以我们需要解决跨域问题,否则游览器会拦截请求,这里简单的将本机的所有请求全部放行。@RestController注解将这个类标记为SpringMVC控制器的同时指定所有的方法返回值(全部通过序列化转为json格式)直接写入http请求体。@RequestMapping是指定这个控制器中所有方法的前缀名。在SpringBoot中,所有的bean都是通过注入的方式来实例化的,只需要将需要实例化的类或者接口使用@Bean注解或者@Service等注解标记即可。由于查询操作分为根据id查询和根据名称进行查询,而根据名称模糊匹配有可能出现多个商家匹配的情况,所以这里的返回类型是用的泛型。
package com.zlh.controller;import com.zlh.pojo.entity.Business;
import com.zlh.result.Result;
import com.zlh.service.BusinessService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.ArrayList;
import java.util.List;@CrossOrigin(origins = {"http://localhost:8082", "null"})//allow all request from localhost.
@RestController//write the returned object into the http response
@RequestMapping("/business")//map the web request,here is public url of all method of this controller.
@Slf4j//the log of this class
public class businessController {//use this annotation,your class must use the Bean annotation or your implementation class of the//interface must use the used the corresponding annotation.@Autowired//auto-injectionprivate BusinessService businessService;/****/@PostMapping("/query/{param}")public Result<?> query(@PathVariable String param){log.info("查询商家信息,查询参数为:{}",param);Business business = new Business();List<Business> businessesList = new ArrayList<>();try{Integer.parseInt(param);business=businessService.queryById(param);return Result.success(business);}catch (Exception e){businessesList=businessService.queryByName(param);for (Business b:businessesList) System.out.println(b);return Result.success(businessesList);}}//of query/**** */@PostMapping("/insert")public Result insert(@RequestBody Business business){log.info("注册商家信息,注册参数为:{}",business);businessService.insert(business);return Result.success();}//of insert
}//of class businessController
由于没有设计相应的dto和功能都是简单的查找和插入,这里的业务层设计比较简单,直接注入mapper接口然后调用相关方法即可。
import com.zlh.mapper.BusinessMapper;
import com.zlh.pojo.entity.Business;
import com.zlh.service.BusinessService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;import java.util.List;@Service
public class BusinessServiceImpl implements BusinessService {//inject businessMapper@Autowiredprivate BusinessMapper businessMapper;@Overridepublic void insert(Business business) {business.setBusinessImg("图片正在加载中");businessMapper.insert(business);}//of insert@Overridepublic Business queryById(String param) {return businessMapper.queryById(param);}//of queryById@Overridepublic List<Business> queryByName(String param) {return businessMapper.queryByName(param);}//of queryByName
}//of class BusinessServiceImpl
Mapper层
Mapper层负责实现数据持久化,简单的sql语句直接使用相应的注解,复杂语句使用xml文件。这里全部采用的是xml文件(并不是所有语句都很复杂,只是适应写配置文件)。
import com.zlh.pojo.entity.Business;
import org.apache.ibatis.annotations.Mapper;
import java.util.List;@Mapper
public interface BusinessMapper {List<Business> queryByName(String name);Business queryById(String id);void insert(Business business);
}
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.zlh.mapper.BusinessMapper"><resultMap id="BusinessWithFood" type="com.zlh.pojo.entity.Business"><id property="businessId" column="businessId"/><result property="businessName" column="businessName"/><result property="businessAddress" column="businessAddress"/><result property="businessExplain" column="businessExplain"/><result property="businessImg" column="businessImg"/><result property="orderTypeId" column="orderTypeId"/><result property="starPrice" column="starPrice"/><result property="remarks" column="remarks"/><collection property="foods" column="businessId" foreignColumn="businessId" ofType="com.zlh.pojo.entity.Food"select="getFoodByBusinessId"/></resultMap><select id="queryById" resultMap="BusinessWithFood">SELECT * FROM elm.business WHERE businessId = #{id}</select><select id="getFoodByBusinessId" resultType="com.zlh.pojo.entity.Food" parameterType="long">select * FROM elm.food WHERE businessId=#{businessId}</select><select id="queryByName" resultMap="BusinessWithFood">select * from elm.business where businessName like CONCAT('%',#{name},'%')</select><insert id="insert" parameterType="com.zlh.pojo.entity.Business" useGeneratedKeys="true" keyProperty="businessId">insert into elm.business (businessName, businessAddress, businessExplain,businessImg, orderTypeId, starPrice, deliveryPrice)VALUES (#{businessName}, #{businessAddress}, #{businessExplain},#{businessImg},#{orderTypeId},#{starPrice}, #{deliveryPrice})</insert>
</mapper>
查询操作由于要返回商家和食品两个实体的内容。我开始想到的是sql语句里面的连接,但三个连接查询出来的结果全都有问题,后面想到了上课学的association,但是assocaition适应于一对一的关系,这里明显是一对多的关系(一个菜品对应一个店铺,一个店铺对应多个菜品,数据比较极端),所以查资料找到了collection来处理这种一对多的关系。首先要在Business里面加上一个food的列表,泛型指定为Food类型,Food类就对应food这张表。
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;@Data
@NoArgsConstructor
@AllArgsConstructor
public class Food {private long foodId;private String foodName;private String foodExplain;private String foodImg;private float foodPrice;private long businessId;private String remarks;
}
再写一个resultMap,里面对应的是Business这个实体的属性,而collection与food这个列表对应,指定food的外键还有查询food的方法,这个select方法在执行这个resultMap时会自动加载执行。但是在这个方法中要指定resultMap。
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.zlh.mapper.BusinessMapper"><resultMap id="BusinessWithFood" type="com.zlh.pojo.entity.Business"><id property="businessId" column="businessId"/><result property="businessName" column="businessName"/><result property="businessAddress" column="businessAddress"/><result property="businessExplain" column="businessExplain"/><result property="businessImg" column="businessImg"/><result property="orderTypeId" column="orderTypeId"/><result property="starPrice" column="starPrice"/><result property="remarks" column="remarks"/><collection property="foods" column="businessId" foreignColumn="businessId" ofType="com.zlh.pojo.entity.Food"select="getFoodByBusinessId"/></resultMap><select id="queryById" resultMap="BusinessWithFood">SELECT * FROM elm.business WHERE businessId = #{id}</select><select id="getFoodByBusinessId" resultType="com.zlh.pojo.entity.Food" parameterType="long">select * FROM elm.food WHERE businessId=#{businessId}</select><select id="queryByName" resultMap="BusinessWithFood">select * from elm.business where businessName like CONCAT('%',#{name},'%')</select><insert id="insert" parameterType="com.zlh.pojo.entity.Business" useGeneratedKeys="true" keyProperty="businessId">insert into elm.business (businessName, businessAddress, businessExplain,businessImg, orderTypeId, starPrice, deliveryPrice)VALUES (#{businessName}, #{businessAddress}, #{businessExplain},#{businessImg},#{orderTypeId},#{starPrice}, #{deliveryPrice})</insert>
</mapper>
结果图
根据id查询
根据名称模糊查询
插入
htmnl页面,有些功能为了考试修改了一部分,可能会有bug。
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>商家查询与添加</title><script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
</head>
<body><h2>商家查询</h2><input type="text" id="searchInput" placeholder="输入商家ID或名称"><button onclick="queryMerchant()">查询</button><div id="result"></div><h2>商家添加</h2><form id="addForm"><input type="text" name="businessName" placeholder=""><input type="text" name="businessAddress" placeholder="商家地址"><input type="text" name="businessExplain" placeholder="商家描述"><input type="text" name="orderTypeId" placeholder="点餐分类"><button type="button" onclick="addMerchant()">添加</button></form><script>function queryMerchant() { var param = $('#searchInput').val(); $.ajax({ url: 'http://localhost:8080/business/query/' + encodeURIComponent(param), type: 'POST', success: function(data) { var book = Array.isArray(data.data) ? data.data : [data.data]; //将所有商家的信息统一转为数组形式来渲染if(book[0]==null){$('#result').html('没有找到对应的商家信息'); }else{var resultDiv = $('#result'); resultDiv.empty(); // 清空原来的表格$.each(book, function(index, book) { // 商家信息表格 var businessTable = $('<table class="business-table"></table>'); var businessHeader = $('<thead><tr><th>ID</th><th>名称</th><th>价格</th><th>作者</th><th>出版社Id</th></tr></thead>'); var businessBody = $('<tbody><tr><td>' + book.id + '</td><td>' + book.bookName + '</td><td>' + book.price +'</td><td>' + book.author +'</td><td>' + book.press_id +'</td></tr></tbody>'); businessTable.append(businessHeader).append(businessBody); resultDiv.append(businessTable); }); // 如果所有商家都没有foods,则显示提示信息if (resultDiv.find('.foods-table tbody tr').length === 0) { } }}, error: function(jqXHR, textStatus, errorThrown) { // 处理请求失败的情况 $('#result').html('<p>请求失败: ' + textStatus + ', ' + errorThrown + '</p>'); } });
}function addMerchant() {var formData = $('#addForm').serializeArray(); // 序列化表单数据并转换为数组var jsonData = {};for (var i = 0; i < formData.length; i++) {jsonData[formData[i].name] = formData[i].value;}$.ajax({url: 'http://localhost:8080/business/insert',type: 'POST',contentType: 'application/json', data: JSON.stringify(jsonData), success: function(data) {alert('商家添加成功!');},error: function(xhr, status, error) {console.error("添加失败: " + error);}});}</script>
</body>
</html>