[轮子]ormkids

• 2000行代码的Java ORM框架
• 支持分库分表的MySQL单表ORM框架
• 自动创建表
• 支持groupby/having
• 支持事件回调，可用于服务跟踪调试和动态sql改写
• @code https://github.com/pyloque/ormkids (opens new window)
• @doc https://mp.weixin.qq.com/s?__biz=MzI0MzQyMTYzOQ==&mid=22474839... (opens new window)

笔记

• 首先, 开源市场上的Java的ORM框架一个都不好用
• 常用的多表的操作一般都可以使用多条单表操作组合实现
• 不使用外键，专注于sql逻辑

使用示例

• 复杂查询

public class DemoComplexQuery {
    private final static String URI = "jdbc:mysql://localhost:3306/mydrc?user=mydrc&password=mydrc&useUnicode=true&characterEncoding=UTF8";

    public static void main(String[] args) {
        var db = new DemoDB("demo", URI);
        try {
            db.create(Exam.class); // 建表
            var random = new Random();
            for (var i = 0; i < 100; i++) {
                var userId = Math.abs(random.nextLong());
                var exam = new Exam(userId, random.nextInt(100), random.nextInt(100), random.nextInt(100),
                        random.nextInt(100), random.nextInt(100), random.nextInt(100));
                db.insert(exam); // 插入
            }
            System.out.println(db.count(Exam.class)); // 查询总行数
            // math >= 50
            var exams = db.find(Exam.class, Q.ge_("math"), 50); // 条件查询
            System.out.println(exams.size());
            var count = db.count(Exam.class, Q.ge_("math"), 50); // 条件总行数
            System.out.println(count);
            // math > 50 & english >= 50
            exams = db.find(Exam.class, Q.and(Q.gt_("math"), Q.ge_("english")), 50, 50); // 条件查询
            System.out.println(exams.size());
            count = db.count(Exam.class, Q.and(Q.gt_("math"), Q.ge_("english")), 50, 50); // 条件总行数
            System.out.println(count);
            // math > 50 || english >= 50
            exams = db.find(Exam.class, Q.or(Q.gt_("math"), Q.ge_("english")), 50, 50); // 条件查询
            System.out.println(exams.size());
            count = db.count(Exam.class, Q.or(Q.gt_("math"), Q.ge_("english")), 50, 50); // 条件总行数
            System.out.println(count);
            // math > 50 && (english >= 50 || chinese > 60)
            exams = db.find(Exam.class, Q.and(Q.gt_("math"), Q.or(Q.ge_("english"), Q.gt_("chinese"))), 50, 50, 60); // 条件查询
            System.out.println(exams.size());
            count = db.count(Exam.class, Q.and(Q.gt_("math"), Q.or(Q.ge_("english"), Q.gt_("chinese"))), 50, 50, 60); // 条件总行数
            System.out.println(count);
            // math > 50 || physics between 60 and 80 || chemistry < 60
            exams = db.find(Exam.class, Q.or(Q.gt_("math"), Q.between_("physics"), Q.lt_("chemistry")), 50, 60, 80, 60); // 条件查询
            System.out.println(exams.size());
            count = db.count(Exam.class, Q.or(Q.gt_("math"), Q.between_("physics"), Q.lt_("chemistry")), 50, 60, 80,
                    60); // 条件总行数
            System.out.println(count);
            // group by math / 10
            var q = Q.select().field("(math div 10) * 10 as mathx", "count(1)").table("exam").groupBy("mathx")
                    .having(Q.gt_("count(1)")).orderBy("count(1)", "desc"); // 复杂sql构造
            var rank = new LinkedHashMap<Integer, Integer>();
            db.any(Exam.class, q, stmt -> { // 原生sql查询
                stmt.setInt(1, 0);
                ResultSet rs = stmt.executeQuery();
                while (rs.next()) {
                    rank.put(rs.getInt(1), rs.getInt(2));
                }
                return rs;
            });
            rank.forEach((mathx, c) -> {
                System.out.printf("[%d-%d) = %d\n", mathx, mathx + 10, c);
            });
        } finally {
            db.drop(Exam.class);
        }
    }

}

参考