SpringBoot 集成 MyBatis/MyBatis-Plus使用示例教程

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/《数据库名称》?useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai
spring.datasource.username=用户名
spring.datasource.password=密码
# 1. 指定 MyBatis 全局配置文件路径（mybatis-config.xml），可配置全局参数（如缓存、插件、驼峰转换等）
mybatis.config-location=classpath:mybatis-config.xml
# 2. 指定 MyBatis Mapper 映射文件（XML）的扫描路径，匹配 classpath 下 mybatis/mapper 目录下的所有 .xml 文件
mybatis.mapper-locations=classpath:mybatis/mapper/*.xml
# 3. 指定实体类包路径，配置后在 XML 中可直接使用实体类名（如 User）代替全类名（com.yugonyun.demo.entity.User），简化 resultType/parameterType 配置
mybatis.type-aliases-package=com.yugonyun.demo.entity

    <settings>
        <setting name="cacheEnabled" value="true"/>
        <setting name="lazyLoadingEnabled" value="true"/>
        <setting name="autoMappingBehavior" value="FULL"/>
    </settings>

public class SysRole {
    private Long id;  //主键ID
    private String code;  //角色编码
    private String roleName;  //角色名称
    private Long createdUserId;  //创建者
    private Date createdTime;  //创建时间
    private Long updatedUserId;  //修改者
    private Date updatedTime;  //修改时间
    //省略get/set...
}

public interface SysRoleMapper {
    /*
    * 查询所有角色信息
    * */
    public List<SysRole> getAll();
}

<?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.ktjiaoyu.mapper.SysRoleMapper">
        <select id="getAll" resultType="com.ktjiaoyu.entity.SysRole">
        select * from sys_role
    </select>
</mapper>

@SpringBootTest
public class SysRoleMapperTest {
    @Autowired
    private SysRoleMapper sysRoleMapper;
    @Test
    public void testSelectAll() {
       List<SysRole> sysRoles = sysRoleMapper.getAll();
       for (SysRole sysRole : sysRoles) {
            System.out.println(sysRole);
        }
    }
}

logging.level.root=warn
logging.level.com.yugonyun.mapper=trace
logging.pattern.console=%p%m%n

<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
</dependency>

// 链式调用（可选）
@Accessors(chain = true)
// 核心简化：getter/setter/toString/equals/hashCode + 无参构造
@Data
// 补充全参构造（@Data 不含全参）
@AllArgsConstructor
// 补充无参构造（若@Data的@RequiredArgsConstructor覆盖了无参，需显式声明）
@NoArgsConstructor
public class User {
    private Long id;
    private String username;
    // 排除toString输出
    @ToString.Exclude
    private String password;
    private Integer age;
}

<!-- MyBatis-Plus SpringBoot 集成包 -->
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.5.3.1</version>
</dependency>

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/ktsms_db?useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai
spring.datasource.username=root
spring.datasource.password=root
logging.level.root=warn
logging.level.com.yugonyun.mapper=trace
logging.pattern.console=%p%m%n

@Data
@NoArgsConstructor
@AllArgsConstructor
// 表名
@TableName("sys_role")
public class SysRole {
    // 主键ID, 自增
    @TableId(type = IdType.AUTO)
    private Long id;  //主键ID
    private String code;  //角色编码
    private String roleName;  //角色名称
    private Long createdUserId;  //创建者
    private Date createdTime;  //创建时间
    private Long updatedUserId;  //修改者
    private Date updatedTime;  //修改时间
}

public interface SysRoleMapper extends BaseMapper<SysRole> {
}

@SpringBootTest
public class SysRoleMapperTest {
    @Autowired
    private SysRoleMapper sysRoleMapper;
    @Test
    public void testSelectAll() {
        List<SysRole> sysRoles = sysRoleMapper.selectList(null);
        for (SysRole sysRole : sysRoles) {
            System.out.println(sysRole);
        }
    }
}

QueryWrapper<User> wrapper = new QueryWrapper<User>()
        .eq("user_name", "张三")
        .gt("age", 18)
        .like("email", "qq.com");
List<User> list = userMapper.selectList(wrapper);

UpdateWrapper<User> wrapper = new UpdateWrapper<User>()
        .eq("user_name", "张三")
        .set("age", 22)
        .setSql("age = age + 1"); // 支持SQL片段
userMapper.update(null, wrapper);

LambdaQueryWrapper<User> wrapper = new LambdaQueryWrapper<User>()
        .eq(User::getUserName, "张三")
        .gt(User::getAge, 18);
List<User> list = userMapper.selectList(wrapper);