闲来无事，用 Kotlin 写了一个简单的 ORM

目前主要支持单表的 CRUD 和 DML 的 DSL 语法。

package io.github.zhaofanzhe.kom.example import io.github.zhaofanzhe.kom.Database import io.github.zhaofanzhe.kom.connection.ConnectionFactory import io.github.zhaofanzhe.kom.entity.Entity import io.github.zhaofanzhe.kom.express.Table import io.github.zhaofanzhe.kom.toolkit.eq import java.sql.Connection import java.sql.DriverManager fun main() { val database = getDatabase() // 创建表[目前不支持自动迁移] database.createTable(Users()).execute() database.createTable(Addresses()).execute() // 单表 CRUD // 目前插入数据，目前没有做主键的回填 database.create(User(id = 1, username = "张三")) database.create(User(id = 2, username = "李四")) database.create(User(id = 3, username = "王五")) database.create(Address(address = "北京", userId = 1)) database.create(Address(address = "上海", userId = 1)) database.create(Address(address = "广州", userId = 2)) database.create(Address(address = "深圳", userId = 3)) val user = database.fetchOne(Users()) { it.username eq "王五" } // 根据主键更新 user?.let { it.username = "王老五" database.save(it) } // 根据主键删除 user?.let { database.delete(it) } // DSL 查询 val users = Users() val addresses = Addresses() // 子查询 val subQuery = database.selectFrom(users) .where(users.username eq "张三") .subQuery() // 左连接 val express = database.select(users, addresses) .from(subQuery) .leftJoin(addresses).on(addresses.userId eq users.id) // 打印 SQL println(express) // 遍历获取数据 express.fetchAll().forEach { println(it[users]) println(it[addresses]) } // 删除表 database.dropTable(Users()).execute() database.dropTable(Addresses()).execute() } data class User( var id: Int = 0, var username: String = "", ) : Entity<Users>(Users::class) { constructor() : this(id = 0, username = "") } class Users : Table<User>(User::class) { val id = column(User::id).primaryKey().autoIncrement() val username = column(User::username).unique() } data class Address( var id: Int = 0, var address: String = "", var userId: Int = 0, ) : Entity<Addresses>(Addresses::class) { constructor() : this(id = 0, address = "", userId = 0) } class Addresses : Table<Address>(Address::class) { var id = column(Address::id).primaryKey().autoIncrement() var address = column(Address::address) var userId = column(Address::userId) } fun getDatabase(): Database { return Database(object : ConnectionFactory { override fun getConnection(): Connection { return DriverManager.getConnection("{url}", "{user}", "{password}") } }) } 

Github 地址: Kom

另外，求个 star~