Java项目实战-查询用户列表接口服务搭建

概述

这里通过设计一个对用户进行增删改查的接口服务，来练习java项目工程化、Spring框架、Mybatis框架的实际应用

本项目目录

上一节初始化项目，已经controller层了，下方新建包：pojo、mapper、service

pojo:所有的实体类都放这里

mapper:所有的mapper接口都放这里(可以理解为数据访问层)

service:具体的业务逻辑处理写这里(curd)

创建实体类

package com.mxf.monkey.pojo;
import lombok.Data;
import lombok.AllArgsConstructor;
import lombok.NoArgsConstructor;@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
/*
* 定义了一个用户实体类
* 包含getter、setter等构造方法
* */private int user_id;private String user_name;private String user_sex;
}

根据实体类创建和初始化数据

定义一个查询用户列表的mapper接口

package com.mxf.monkey.mapper;import com.mxf.monkey.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Repository;import java.util.List;@Repository
@Mapper
public interface UserMapper {//定义了一个查询用户列表的方法，返回list类型List<User>queryUserList();}

写mapper接口对应的mapper映射文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.mxf.monkey.mapper.UserMapper"><select id="queryUserList" resultType="User">select * from monkey.monkey_user</select>
</mapper>

pom文件中更新mybatis依赖

其他的依赖如sping、mysql等在初始化项目时已经建了

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.7.16</version><relativePath/> <!-- lookup parent from repository --></parent><groupId>com.mxf</groupId><artifactId>monkey</artifactId><version>0.0.1-SNAPSHOT</version><name>monkey</name><description>Demo project for Spring Boot</description><properties><java.version>1.8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-thymeleaf</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-devtools</artifactId><scope>runtime</scope><optional>true</optional></dependency><!--MyBatis-Spring依赖--><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.1.1</version></dependency><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.7</version></dependency><!--数据库连接依赖--><dependency><groupId>com.mysql</groupId><artifactId>mysql-connector-j</artifactId><scope>runtime</scope></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.xmlunit</groupId><artifactId>xmlunit-core</artifactId></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

mybatis映射配置及Spring数据库配置

上边定义了mapper接口和mapper映射文件，那么怎么把2个联系起来，就需要通过在application.yml中进行配置

server:port: 8080
spring:datasource:url: jdbc:mysql://localhost:3306/你的表名?characterEncoding=utf-8&serverTimezone=Asia/Shanghaiusername: 数据库账号password: 数据库密码driver-class-name: com.mysql.cj.jdbc.Driver
mybatis:type-aliases-package: com.mxf.monkey.pojomapper-locations: classpath:mybatis/mapper/*.xml

创建service服务

package com.mxf.monkey.service;import com.mxf.monkey.mapper.UserMapper;
import com.mxf.monkey.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;import java.util.List;@Service
public class UserService {@AutowiredUserMapper userMapper;public List<User> queryUserList(){//导入UserMapper中的queryUserList方法，并调用return userMapper.queryUserList();}}

创建controller对应接口

package com.mxf.monkey.controller;import com.mxf.monkey.pojo.User;
import com.mxf.monkey.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;import java.util.List;@RestController
public class UserController {@AutowiredUserService userService;@GetMapping("/queryUserList")public List<User> queryUserList() {return userService.queryUserList();}
}