spingboot3 配置文件、整合mybatis

spingboot配置文件

properties配置文件

在官网中： Common Application Properties (spring.io) 提供了许多的配置项

 手动配置启动端口号和虚拟目录

server.port=9090
server.servlet.context-path=/start

 自定义配置实体类信息

yaml配置文件（常用）

文件一般有两种格式：application.yml / application.yaml 

server:
  port: 9191
  servlet:
    context-path: /start2

 相比之下层次清晰，更加关注数据

书写规范:值前边必须有空格，作为分隔符 使用空格作为缩进表示层级关系，相同的层级左侧对齐 

yml配置信息书写与获取 

 1.三方技术配置信息

比如配置整合redis： 

spring:
  data:
    redis:
      host: localhost
      port: 6379
      password: 123456
      connect-timeout: 3000

 2.自定义配置信息

自定义配置实体类信息

 单个实体信息变量多个参数比如数组的形式：使用 - 开头表示

配置信息获取

 把配置文件里的数据封装到实体变量成员变量中：@Value(“${键名}”)

如果成员变量较多且有共同的子层级，就使用 @ConfigurationProperties(prefix=“前缀”)

        实体类的成员变量名与配置文件中的键名保持一致 

spingboot整合mybatis 

实现流程

 项目引入mybatis起步依赖和数据库驱动依赖

        <!-- mybatis -->        
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>3.0.3</version>
        </dependency>

        <!--mysql 驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.26</version>
        </dependency>

 创建演示数据表

create database if not exists mybatis_test;

use mybatis_test;

create table user(
    id int unsigned primary key auto_increment comment 'ID',
    name varchar(100) comment '姓名',
    age tinyint unsigned comment '年龄',
    gender tinyint unsigned comment '性别, 1:男, 2:女',
    phone varchar(11) comment '手机号'
) comment '用户表';

insert into user(id, name, age, gender, phone) VALUES (null,'白眉鹰王',55,'1','18800000000');
insert into user(id, name, age, gender, phone) VALUES (null,'金毛狮王',45,'1','18800000001');
insert into user(id, name, age, gender, phone) VALUES (null,'青翼蝠王',38,'1','18800000002');
insert into user(id, name, age, gender, phone) VALUES (null,'紫衫龙王',42,'2','18800000003');
insert into user(id, name, age, gender, phone) VALUES (null,'光明左使',37,'1','18800000004');
insert into user(id, name, age, gender, phone) VALUES (null,'光明右使',48,'1','18800000005');

 在application.yml配置文件中配置数据源信息

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql:///mybatis_test?useSSL=false
    username: root
    password: root

创建user实体类

public class User {
    
    private Integer id;
    private String name;
    private Short age;
    private Short gender;
    private String phone;

    public User() {
    }

    public User(Integer id, String name, Short age, Short gender, String phone) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.gender = gender;
        this.phone = phone;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Short getAge() {
        return age;
    }

    public void setAge(Short age) {
        this.age = age;
    }

    public Short getGender() {
        return gender;
    }

    public void setGender(Short gender) {
        this.gender = gender;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", gender=" + gender +
                ", phone='" + phone + '\'' +
                '}';
    }
}

 创建UserMapper接口

实现按id查找全都的方法

@Mapper
public interface UserMapper {

    @Select("select * from user where id = #{id}")
    public User selectById(Integer id);
}

创建UserService接口

public User selectById(Integer id);

创建UserService实现类

@Service 
public class UserService implements com.springboot.springboot3_01.service.UserService {

    @Autowired  //依赖注入
    private UserMapper userMapper;

    @Override  //重写方法
    public User selectById(Integer id) {
        return userMapper.selectById(id);
    }
}

创建UserController类

@RestController
public class UserController {

    @Autowired  //注入Service对象
    private UserService userService;

    @RequestMapping("/selectById")
    public User selectById(Integer id){
        return userService.selectById(id);
    }
}

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