SpringBoot3项目-创建及使用

简单的介绍后端SpringBoot3项目，从0到1搭建一个完整项目，给老项目源码升级备用的知识点

一、创建项目

1、打开IDEA，通过New Project创建项目，如下图：

2、选择Spring Initializr，配置好项目信息，点击Next，如下图：

3、选择依赖，点击Create，创建项目成功，如下图：

4、删除一些没啥用的文件及文件夹，只保留源码相关的文件，如下图：

5、最后保留下项目结构是这样的，如下图：

二、使用项目

搭建的项目主体框架是SpringBoot+Mybatis模式

1、修改配置文件格式和pom.xml排版

pom.xml排版如下:

<?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><groupId>com.hz</groupId><artifactId>SpringBoot-Demo</artifactId><version>0.0.1-SNAPSHOT</version><name>${project.artifactId}</name><description>基于 Java 17 + SpringBoot3 创建的Demo项目</description><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>3.4.1</version><relativePath/><!-- lookup parent from repository --></parent><properties><java.version>17</java.version><maven.compiler.source>17</maven.compiler.source><maven.compiler.target>17</maven.compiler.target><hutool.version>5.8.27</hutool.version><mysql.version>8.0.33</mysql.version><mybatis-plus.version>3.5.9</mybatis-plus.version></properties><dependencies><!--lombok 只在编译期间需要--><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><scope>provided</scope></dependency><!--工具类包--><dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId><version>${hutool.version}</version></dependency><!-- mysql数据库连接包--><dependency><groupId>com.mysql</groupId><artifactId>mysql-connector-j</artifactId></dependency><!-- mybatis-plus 见：dependencyManagement下管理 start--><!-- springboot3 --><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-spring-boot3-starter</artifactId></dependency><!-- 分页插件--><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-jsqlparser</artifactId></dependency><!--代码生成器--><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-generator</artifactId></dependency><!-- 代码生成器需要的模版--><dependency><groupId>org.apache.velocity</groupId><artifactId>velocity-engine-core</artifactId><version>2.3</version></dependency><!-- mybatis-plus end --><!-- springboot web包（默认是web服务是tomcat） --><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><!-- springboot test测试包 --><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency></dependencies><dependencyManagement><dependencies><!-- 通过mybatis-plus-bom管理依赖，减少版本号的冲突  --><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-bom</artifactId><version>${mybatis-plus.version}</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

配置文件格式修改，由原始Properties格式：application.properties，修改为YAML格式：application.yml,如下图：

application.yml内容如下：

# web服务配置
server:
port:8080
# 给项目添加前缀，这个可以加也可以不加
servlet:context-path:/demospring:
# 项目名称
application:name:SpringBoot-Demo# 数据库配置
datasource:driver-class-name:com.mysql.cj.jdbc.Driverurl:jdbc:mysql://127.0.0.1:3307/demo?zeroDateTimeBehavior=convertToNull&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai&autoReconnect=true&allowMultiQueries=trueusername:rootpassword:root# mybatis
mybatis-plus:
global-config:db-config:# 主键ID类型id-type:none# 逻辑删除字段名称# logic-delete-field: deleted# 逻辑删除-删除值logic-delete-value:1# 逻辑删除-未删除值logic-not-delete-value:0
configuration:map-underscore-to-camel-case:truecache-enabled:falsecall-setters-on-nulls:truejdbc-type-for-null:'null'# 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

检查项目是否能正常启动，如下图：

以User表进行简单增删改查为例

项目结构，如图：

项目结构
Java三层架构的三个层次：控制层（UserController）,业务逻辑层（UserService 、UserServiceImpl）,数据访问层（UserDao、UserDao.xml）

user表：

CREATE TABLE`user`  (
`id`bigintNOTNULL AUTO_INCREMENT COMMENT'主键',
`username`varchar(100)  NOTNULLCOMMENT'用户名',
`password`varchar(100)  NOTNULLCOMMENT'密码',
`create_time` datetime NULLDEFAULTNULLCOMMENT'创建时间',
`update_time` datetime NULLDEFAULTNULLCOMMENT'更新时间',PRIMARY KEY (`id`) USING BTREE
) COMMENT = '用户表';

User实体类：

/*** <p>* 用户表* </p>**/
@Getter
@Setter
publicclass User implements Serializable {private static final long serialVersionUID = 1L;/*** 主键*/@TableId(value = "id", type = IdType.AUTO)private Long id;/*** 用户名*/private String username;/*** 密码*/private String password;/*** 创建时间*/@TableField(fill = FieldFill.INSERT)@JsonInclude(value = JsonInclude.Include.NON_NULL)@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")private Date createTime;/*** 更新时间*/@TableField(fill = FieldFill.INSERT_UPDATE)@JsonInclude(value = JsonInclude.Include.NON_NULL)@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")private Date updateTime;
}

UserMapper接口类：

/*** <p>* 用户表 Mapper 接口* </p>**/
@Mapper
public interface UserMapper extends BaseMapper<User> {Page<User> listPagedUsers(Page<User> page, UserPageQuery queryParams);
}

UserMapper.xml mybatis写sql语句的位置：

<?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.hz.mapper.UserMapper"><!-- 通用查询映射结果 --><resultMap id="BaseResultMap" type="com.hz.model.User"><id column="id" property="id" /><result column="username" property="username" /><result column="password" property="password" /><result column="create_time" property="createTime" /><result column="update_time" property="updateTime" /></resultMap><!-- 通用查询结果列 --><sql id="Base_Column_List">id, username,password,create_time, update_time</sql><!-- 分页列表 --><select id="listPagedUsers" resultMap="BaseResultMap">SELECT<include refid="Base_Column_List"/>FROMuser<where>1=1<if test="queryParams.username != null">AND username LIKE CONCAT('%',#{queryParams.username},'%')</if></where>ORDER BY create_time DESC</select>
</mapper>

UserService接口类：

/*** <p>* 用户表 服务类* </p>**/
public interface IUserService extends IService<User> {IPage<User> listPagedUsers(UserPageQuery queryParams);boolean saveUser(User formData);User getUserFormData(Long id);boolean updateUser(User formData);boolean deleteUsers(String ids);
}

UserServiceImpl实现类：

/*** <p>* 用户表 服务实现类* </p>**/
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements IUserService {@Overridepublic IPage<User> listPagedUsers(UserPageQuery queryParams) {int pageNum = queryParams.getPageNum();int pageSize = queryParams.getPageSize();Page<User> page = new Page<>(pageNum, pageSize);return this.baseMapper.listPagedUsers(page, queryParams);}@Overridepublic boolean saveUser(User formData) {return this.save(formData);}@Overridepublic User getUserFormData(Long id) {return this.getById(id);}@Overridepublic boolean updateUser(User formData) {return this.updateById(formData);}@Overridepublic boolean deleteUsers(String ids) {Assert.isTrue(StrUtil.isNotBlank(ids), "删除的数据为空");List<Long> idList = Arrays.stream(ids.split(",")).map(Long::parseLong).toList();return this.removeByIds(idList);}
}

UserController控制层：

/*** <p>* 用户表 前端控制器* </p>**/
@RestController
@RequestMapping("/user")
@RequiredArgsConstructor
publicclass UserController {private final IUserService userService;/*** 分页列表*/@GetMapping("/page")public PageResult<User> listPagedUsers(UserPageQuery queryParams ) {IPage<User> result = userService.listPagedUsers(queryParams);return PageResult.success(result);}/*** 新增*/@PostMappingpublic Result saveUser(@RequestBody User formData ) {boolean result = userService.saveUser(formData);return Result.judge(result);}/*** 根据id获取详情*/@GetMapping("/{id}")public Result getUserForm(@PathVariable Long id) {User formData = userService.getUserFormData(id);return Result.success(formData);}/*** 修改*/@PutMapping(value = "/{id}")public Result updateUser(@RequestBody User formData) {boolean result = userService.updateUser(formData);return Result.judge(result);}/*** 删除*/@DeleteMapping("/{ids}")public Result deleteUsers(@PathVariable String ids) {boolean result = userService.deleteUsers(ids);return Result.judge(result);}}

简单流程过程，如下图：

mybatis-plus快速生成代码：

@SpringBootTest
public class CodeGeneratorTest {@Testpublic void codeGenerator() {FastAutoGenerator.create("jdbc:mysql://127.0.0.1:3306/demo", "root", "root").globalConfig(builder -> builder.disableOpenDir().author("hz").dateType(DateType.ONLY_DATE).outputDir(Paths.get(System.getProperty("user.dir")) + "/src/main/java").commentDate("yyyy-MM-dd")).packageConfig(builder -> builder.parent("com.hz").entity("model").mapper("mapper").service("service").serviceImpl("service.impl")//自定义mapper.xml文件输出目录.pathInfo(Collections.singletonMap(OutputFile.xml,Paths.get(System.getProperty("user.dir")) + "/src/main/resources/mapper"))).strategyConfig(builder -> builder.entityBuilder().enableLombok()).execute();}
}