Structure

this blog introduce 3 ways using mybatis

• based on annotationed SQL and Query interfaces : suppored by MyBatis framework

• based on Query Wrapper : supported by MyBatis Plus framework

  MyBatis Plus provides a easier way to dynamically set condition and updated fields

• base on Query Condition : combined MyBatis Plus and Kotlin, so called MyBatis++

  MyBatis++ provides a more easier way to build complicated conditions

  and supports update values through an Example bean

MyBatis++ Controller Abilities

this controller present multiple ways to do CURD with MyBatis++

you can choose your favorite ones or those match your current project most comfortably

package x.spring.hello.controllerimport org.springframework.beans.factory.annotation.Autowired
import org.springframework.web.bind.annotation.GetMapping
import org.springframework.web.bind.annotation.RestController
import x.kotlin.commons.serialize.JSON.toJson
import x.kotlin.commons.serialize.JSON.toJsonOrNull
import x.kotlin.commons.string.UUID
import x.spring.hello.model.User
import x.spring.hello.model.UserExample
import x.spring.hello.repository.UserMapper
import x.spring.hello.mybatis.*@RestController
class UserController {@Autowiredprivate lateinit var userMapper: UserMapper@GetMapping("/01")fun selectAll(): String {val userList = userMapper.selectAll()return userList.toJson()}@GetMapping("/02")fun selectByName(): String {val user = userMapper.selectUserByName("Jimmy")return user.toJsonOrNull().orEmpty()}@GetMapping("/03")fun selectByCondition(): String {val condition = condition { it.eq(User::name, "Jimmy") }val users = userMapper.selectList(condition.build())return users.toJson()}@GetMapping("/04")fun insert(): String {val user = User()user.name = UUID.short()userMapper.insert(user)return user.toJson()}@GetMapping("/05")fun insertOrUpdate(): String {val user = User()user.id = "1"user.name = UUID.short()userMapper.insertOrUpdate(user)return user.toJson()}@GetMapping("/06")fun updateByCondition(): String {val cond1 = condition { it.isNotNull(User::id) }val cond2 = condition { it.eq(User::name, "Jimmy") }val cond3 = condition { it.gt(User::age, 15) }val cond4 = condition {it.set(User::name, "Jimmy")it.set(User::age, 18)}val condition = cond1 and cond2 and cond3 attributes cond4val count = userMapper.update(condition.build())return count.toJson()}@GetMapping("/07")fun updateByEntityAndCondition(): String {val entity = User()entity.name = "Updated"entity.age = 36val cond1 = condition { it.isNotNull(User::id) }val cond2 = condition { it.like(User::name, "Jimmy") }val cond3 = condition { it.gt(User::age, 35) }val condition = cond1 and (cond2 or cond3)val count = userMapper.update(entity, condition.build())return count.toJson()}@GetMapping("/08")fun updateByExampleAndCondition(): String {val example = UserExample()example.age = 18val cond1 = condition { it.isNotNull(User::id) }val cond2 = condition { it.like(User::name, "Jimmy") }val cond3 = condition { it.gt(User::age, 35) }val condition = cond1 and (cond2 or cond3) values exampleval count = userMapper.update(condition.build())return count.toJson()}@GetMapping("/09")fun selectCrossTables(): String {val userRoles = userMapper.selectUserRole()return userRoles.toJson()}
}

Configure Plugins and Repositories

pluginManagement {repositories {gradlePluginPortal()google()mavenCentral()}
}dependencyResolutionManagement {repositoriesMode = RepositoriesMode.PREFER_SETTINGSrepositories {gradlePluginPortal()google()mavenCentral()}
}buildscript {repositories {gradlePluginPortal()google()mavenCentral()}
}plugins {id("org.jetbrains.kotlin.jvm") version "2.0.21" apply falseid("org.jetbrains.kotlin.kapt") version "2.0.21" apply falseid("org.jetbrains.kotlin.plugin.spring") version "2.0.21" apply falseid("org.springframework.boot") version "3.4.1" apply false
}include("spring-mybatis")

Apply Plugins and Add Dependencies

plugins {id("org.jetbrains.kotlin.jvm")id("org.jetbrains.kotlin.kapt")id("org.jetbrains.kotlin.plugin.spring")id("org.springframework.boot")
}java {toolchain {languageVersion = JavaLanguageVersion.of(17)}
}dependencies {val springBootVersion = "3.4.1"val springCloudVersion = "4.2.0"val springCloudAlibabaVersion = "2023.0.3.2"// commonsapi("io.github.hellogoogle2000:kotlin-commons:1.0.19")// kotlinapi("org.jetbrains.kotlin:kotlin-reflect:2.0.21")// springapi("org.springframework.boot:spring-boot-starter:$springBootVersion")api("org.springframework.boot:spring-boot-starter-web:$springBootVersion")api("org.springframework.cloud:spring-cloud-starter-bootstrap:$springCloudVersion")// mybatisapi("link.thingscloud:quick-spring-boot-starter-mybatis-plus:2025.01.22")
}

MyBatis++ Spring Properties

# service
server.port=10003
spring.application.name=mybatis
spring.profiles.active=dev
spring.devtools.add-properties=false
# mybatis
spring.datasource.username=root
spring.datasource.password=123456789
spring.datasource.url=jdbc:mysql://localhost:3306/dev?characterEncoding=utf-8&serverTimezone=UTC

MyBatis++ Application

package x.spring.helloimport org.mybatis.spring.annotation.MapperScan
import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication@SpringBootApplication
@MapperScan(basePackages = ["x.spring.hello.repository"])
class MybatisApplicationfun main(args: Array<String>) {runApplication<MybatisApplication>(*args)
}

MyBatis++ Beans

package x.spring.hello.modelimport com.baomidou.mybatisplus.annotation.IdType
import com.baomidou.mybatisplus.annotation.TableIdclass User {@TableId(type = IdType.ASSIGN_UUID)var id = ""var name = ""var age = 0
}

package x.spring.hello.modelclass UserExample {var id: String? = nullvar name: String? = nullvar age: Int? = null
}

package x.spring.hello.modelclass UserRoleQueryResult {var name = ""var role = ""
}

MyBatis++ Mapper

mapper sometimes called interface, service or repository in other projects

package x.spring.hello.repositoryimport link.thingscloud.quick.mybatisplus.base.BaseMapper
import org.apache.ibatis.annotations.Select
import x.spring.hello.model.User
import x.spring.hello.model.UserRoleQueryResultinterface UserMapper : BaseMapper<User> {@Select("select * from user")fun selectAll(): MutableList<User>@Select("select * from user where name = #{name}")fun selectUserByName(name: String): User?@Select("""select user.name as name,role.name as role from user left join roleon user.roleId = role.id""")fun selectUserRole(): List<UserRoleQueryResult>
}

MyBatis++ Query Builder

this is the core component to build query condition and examples

difference between entity and example is :

entity will update all field, while example only update non-null fields

package x.spring.hello.mybatisimport com.baomidou.mybatisplus.extension.kotlin.KtUpdateWrapper
import kotlin.reflect.KClass
import kotlin.reflect.KProperty1
import kotlin.reflect.full.memberPropertiesfun interface ConditionConfigurator<T : Any> {fun configure(wrapper: KtUpdateWrapper<T>)
}data class QueryCondition<T : Any>(val configurator: ConditionConfigurator<T>
)inline fun <reified T : Any> QueryCondition<T>.build(): KtUpdateWrapper<T> {val wrapper = KtUpdateWrapper(T::class.java)configurator.configure(wrapper)return wrapper
}inline fun <reified T : Any> condition(configurator: ConditionConfigurator<T>): QueryCondition<T> {return QueryCondition(configurator)
}infix fun <T : Any> QueryCondition<T>.and(other: QueryCondition<T>): QueryCondition<T> {val configurator = ConditionConfigurator {configurator.configure(it)it.and { other.configurator.configure(it) }}return QueryCondition(configurator)
}infix fun <T : Any> QueryCondition<T>.or(other: QueryCondition<T>): QueryCondition<T> {val configurator = ConditionConfigurator {configurator.configure(it)it.or { other.configurator.configure(it) }}return QueryCondition(configurator)
}infix fun <T : Any> QueryCondition<T>.not(other: QueryCondition<T>): QueryCondition<T> {val configurator = ConditionConfigurator {configurator.configure(it)it.not { other.configurator.configure(it) }}return QueryCondition(configurator)
}infix fun <T : Any> QueryCondition<T>.attributes(other: QueryCondition<T>): QueryCondition<T> {val configurator = ConditionConfigurator {configurator.configure(it)other.configurator.configure(it)}return QueryCondition(configurator)
}inline infix fun <reified T : Any, reified S : Any> QueryCondition<T>.values(example: S): QueryCondition<T> {val configurator = ConditionConfigurator { wrapper ->configurator.configure(wrapper)val properties = S::class.memberPropertiesproperties.forEach { propertyS ->val value = propertyS.get(example)value.takeIf { it != null } ?: return@forEachval property = T::class.findPropertyByName(propertyS.name)property.takeIf { it != null } ?: return@forEachwrapper.set(property, value)}}return QueryCondition(configurator)
}inline fun <reified T : Any> KClass<T>.findPropertyByName(name: String): KProperty1<T, *>? {return memberProperties.firstOrNull { it.name == name }
}