springboot项目创建整个完成过程和注意事项

1：application.yml文件配置

server:port: 8088servlet:context-path: /test
spring:datasource:name: text  #????url: jdbc:mysql://localhost:3306/dsdd?serverTimezone=GMT&useUnicode=true&characterEncoding=utf-8&useSSL=trueusername: root  #??password: root  #??#要添加mysql-connector-java依赖driver-class-name: com.mysql.cj.jdbc.Driver  #????com.mysql.jdbc.Drivermybatis-plus:#这个作用是扫描xml文件生效可以和mapper接口文件使用，如果不加这个就是启动类加了@MapperScan#或者在mapper接口添加@Mapper都无法使用xml中的sql语句和默认的BaseMapper的语句mapper-locations: classpath*:com/example/poi/mapper/**/xml/*Mapper.xmlglobal-config:# 关闭MP3.0自带的bannerbanner: falsedb-config:#主键类型id-type: ASSIGN_ID# 默认数据库表下划线命名table-underline: trueconfiguration:# 这个配置会将执行的sql打印出来，在开发或测试的时候可以用log-impl: org.apache.ibatis.logging.stdout.StdOutImpl# 返回类型为Map,显示null对应的字段call-setters-on-nulls: true

2：pom.xml文件依赖管理，web服务必须按以下依赖

<?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>2.2.7.RELEASE</version><relativePath/> <!-- lookup parent from repository --></parent><groupId>com.example</groupId><artifactId>poi</artifactId><version>0.0.1-SNAPSHOT</version><name>poi</name><description>poi</description><properties><java.version>8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.5.1</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.13</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins><resources><resource><directory>src/main/resources</directory><includes><include>**/*.properties</include><include>**/*.yml</include><include>**/*.xml</include></includes><filtering>true</filtering></resource><resource><directory>src/main/java</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>true</filtering></resource></resources></build></project>

注意：1-使用web服务controller访问必须导入以下依赖

        <dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency>

注意：2-使用mybatis必须导入以下依赖

        <dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.5.1</version></dependency>

注意：3-打开项目的target目录，观察里面是否有对应的××Mapper.xml文件，若没有，则在pom.xml文件中加入如下配置

		<resources><resource><directory>src/main/resources</directory><includes><include>**/*.properties</include><include>**/*.yml</include><include>**/*.xml</include></includes><filtering>true</filtering></resource><resource><directory>src/main/java</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>true</filtering></resource></resources>

3：项目结构图

在这里插入图片描述

4：启动类

package com.example.poi;import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
@MapperScan(basePackages = "com.example.poi.mapper")
public class PoiApplication {public static void main(String[] args) {SpringApplication.run(PoiApplication.class, args);}
}

5：controller类

package com.example.poi.controller;import com.example.poi.service.ITest;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;import javax.annotation.Resource;
import javax.servlet.http.HttpServletResponse;/*** @Author xu* @create 2023/7/5 01*/@RestController
@RequestMapping("/customDemo")
public class DemoTwoController {@ResourceITest iTest;@GetMapping("/export")public void exportExcel(HttpServletResponse response) {String age = "20";String phone = iTest.getPhone(age);}
}

6：service和impl类

package com.example.poi.service;import com.baomidou.mybatisplus.extension.service.IService;
import com.example.poi.entity.EntityDemo;/*** @Author xu* @create 2023/7/14 22*/
public interface ITest extends IService<EntityDemo> {String getPhone(String age);}

package com.example.poi.service.impl;import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.example.poi.entity.EntityDemo;
import com.example.poi.mapper.TestMapper;
import com.example.poi.service.ITest;
import org.springframework.stereotype.Service;import javax.annotation.Resource;/*** @Author xu* @create 2023/7/14 22*/
@Service
public class TestImpl extends ServiceImpl<TestMapper, EntityDemo> implements ITest {@ResourceTestMapper testMapper;@Overridepublic String getPhone(String age) {EntityDemo list = testMapper.selectName();this.baseMapper.selectOne(new LambdaQueryWrapper<EntityDemo>().eq(EntityDemo::getAge, age));return "entityDemo.getPhone()";}
}

7：mapper类和xml文件

package com.example.poi.mapper;import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.poi.entity.EntityDemo;/*** @Author xu* @create 2023/7/14 22*/
//@Mapper
public interface TestMapper  extends BaseMapper<EntityDemo> {//@Select("select * from entity_demo where age='20'")EntityDemo selectName();
}

<?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.example.poi.mapper.TestMapper"><select id="selectName" resultType="com.example.poi.entity.EntityDemo">select * from entity_demo where age='20'</select>
</mapper>