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开源市场上 Java 的 ORM 框架一个都不好用，所以花了几天时间自己撸了一个 OrmKids，欢迎大家下载学习。遇到问题请关注公众号 [码洞] 进群大家一起讨论。

OrmKids

支持分库分表的 MySQL 单表 ORM 框架，暂用于学习，后续会在生产环境进行检验

功能特性

代码简洁，没有任何依赖项，除了使用时需要用到 MySQL driver
易于使用，无须复杂的配置
提供自动创建表功能
支持分库又分表，可以只分库，也可以只分表
支持 groupby/having
支持原生 SQL
支持事件回调，可用于服务跟踪调试和动态 sql 改写

不支持多表关联

多表比较复杂，实现成本高，学习成本也高，容易出错
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
在分库分表的场合，很少使用多表操作
不使用外键，专注于 sql 逻辑

db.withinTx

对于复杂的多表查询和批量数据处理，可以使用该方法。用户可以获得原生的 jdbc 链接，通过编写 jdbc 代码来实现。

Q

用户可以使用 Q 对象构建复杂的 SQL 查询

其它数据库支持

暂时没有

实体接口

/** * 所有的实体类必须实现该接口 */ public interface IEntity { /** * 表名 * @return */ String table(); /** * 分表必须覆盖此方法 * @return */ default String suffix() { return null; } default String tableWithSuffix() { return tableWith(suffix()); } default String tableWith(String suffix) { return Utils.tableWithSuffix(table(), suffix); } /** * 定义表的物理结构属性如 engine=innodb，用于动态创建表 * @return */ TableOptions options(); /** * 定义表的主键和索引信息，用于动态创建表 * @return */ TableIndices indices(); }

单表单主键

@Table public class User implements IEntity { @Column(name = "id", type = "int", autoincrement = true, nullable = false) private Integer id; @Column(name = "name", type = "varchar(255)", nullable = false) private String name; @Column(name = "nick", type = "varchar(255)", nullable = false) private String nick; @Column(name = "passwd", type = "varchar(255)") private String passwd; @Column(name = "created_at", type = "datetime", nullable = false, defaultValue = "now()") private Date createdAt; public User() { } public User(String name, String nick, String passwd) { this.name = name; this.nick = nick; this.passwd = passwd; } public Integer getId() { return id; } public String getName() { return name; } public String getNick() { return nick; } public String getPasswd() { return passwd; } public Date getCreatedAt() { return createdAt; } @Override public TableOptions options() { return new TableOptions().option("engine", "innodb"); } @Override public TableIndices indices() { return new TableIndices().primary("id").unique("name"); } @Override public String table() { return "user"; } }

单表复合主键

@Table public class Member implements IEntity { @Column(name = "user_id", type = "int", nullable = false) private Integer userId; @Column(name = "group_id", type = "int", nullable = false) private Integer groupId; @Column(name = "title", type = "varchar(255)") private String title; @Column(name = "created_at", type = "datetime", nullable = false, defaultValue = "now()") private Date createdAt; public Member() { } public Member(Integer userId, Integer groupId, String title, Date createdAt) { this.userId = userId; this.groupId = groupId; this.title = title; this.createdAt = createdAt; } public Integer getUserId() { return userId; } public Integer getGroupId() { return groupId; } public String getTitle() { return title; } public Date getCreatedAt() { return createdAt; } @Override public TableOptions options() { return new TableOptions().option("engine", "innodb"); } @Override public TableIndices indices() { return new TableIndices().primary("user_id", "group_id"); } @Override public String table() { return "member"; } }

分库接口

public interface IGridable<T extends IEntity> { /** * 根据实体对象选择分库索引 */ int select(int dbs, T t); /** * 根据特定参数选择分库索引 */ int select(int dbs, Object... params); }

分库分表

@Table public class BookShelf implements IEntity { public final static int PARTITIOnS= 4; @Column(name = "user_id", type = "varchar(255)", nullable = false) private String userId; @Column(name = "book_id", type = "varchar(255)", nullable = false) private String bookId; @Column(name = "comment", type = "varchar(255)") private String comment; @Column(name = "created_at", type = "datetime", nullable = false, defaultValue = "now()") private Date createdAt; public BookShelf() { } public BookShelf(String userId, String bookId, String comment, Date createdAt) { this.userId = userId; this.bookId = bookId; this.comment = comment; this.createdAt = createdAt; } public String getUserId() { return userId; } public String getBookId() { return bookId; } public void setComment(String comment) { this.comment = comment; } public String getComment() { return comment; } public Date getCreatedAt() { return createdAt; } @Override public String table() { return "book_shelf"; } @Override public TableOptions options() { return new TableOptions().option("engine", "innodb"); } @Override public TableIndices indices() { return new TableIndices().primary("user_id", "book_id"); } /* * 分表策略 */ @Override public String suffix() { var crc32 = new CRC32(); crc32.update(userId.getBytes(Utils.UTF8)); return String.valueOf(Math.abs(crc32.getValue()) % PARTITIONS); } /** * 分库策略 */ public static class GridStrategy<D extends DB> implements IGridable<BookShelf> { @Override public int select(int dbs, BookShelf t) { return Math.abs(t.getUserId().hashCode()) % dbs; } @Override public int select(int dbs, Object... params) { String userId = (String) params[0]; return Math.abs(userId.hashCode()) % dbs; } } }

定义单个数据库

public class DemoDB extends DB { private DataSource ds; public DemoDB(String name, String uri) { this(name, new HashMap<>(), uri); } public DemoDB(String name, Map<Class<? extends IEntity>, Meta> metas, String uri) { super(name, metas); var ds = new MysqlConnectionPoolDataSource(); // 连接池 ds.setUrl(uri); this.ds = ds; } @Override protected Connection conn() { // 获取链接 try { return ds.getConnection(); } catch (SQLException e) { throw new KidsException(e); } } }

定义网格数据库分库

public class GridDemoDB extends GridDB<DemoDB> { /** * 传进来多个 DB 对象 */ public GridDemoDB(DemoDB[] dbs) { super(dbs); this.registerGridables(); } /* * 注册实体类的分库策略 */ @Override public void registerGridables() { this.gridWith(BookShelf.class, new BookShelf.GridStrategy<DemoDB>()); } }

单表单主键增删改查

public class DemoSimplePk { 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(User.class); // 创建表 var user = new User("test1", "nick1", "passwd1"); db.insert(user); // 插入 System.out.println(user.getId()); user = db.get(User.class, user.getId()); // 主键查询 System.out.printf("%s %s %s %s %s\n", user.getId(), user.getName(), user.getNick(), user.getPasswd(), user.getCreatedAt()) user = new User("test2", "nick2", "passwd2"); db.insert(user); // 再插入 var count = db.count(User.class); // 查询总行数 System.out.println(count); var users = db.find(User.class); // 列出所有行 System.out.println(users.size()); for (var u : users) { System.out.printf("%s %s %s %s %s\n", u.getId(), u.getName(), u.getNick(), u.getPasswd(), u.getCreatedAt()); } users = db.find(User.class, Q.eq_("nick"), "nick2"); // 条件查询 System.out.println(users.size()); var setters = new HashMap<String, Object>(); setters.put("passwd", "whatever"); db.update(User.class, setters, 2); // 修改 users = db.find(User.class); // 再列出所有行 System.out.println(users.size()); for (var u : users) { System.out.printf("%s %s %s %s %s\n", u.getId(), u.getName(), u.getNick(), u.getPasswd(), u.getCreatedAt()); } db.delete(User.class, 1); // 删除 db.delete(User.class, 2); // 再删除 count = db.count(User.class); // 统计所有行 System.out.println(count); } finally { db.drop(User.class); // 删除表 } } }

单表复合主键增删改查

public class DemoCompoundPk { 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(Member.class); // 建表 var member = new Member(1, 2, "boss", null); db.insert(member); // 插入 member = db.get(Member.class, 1, 2); // 主键查询 System.out.println(member.getTitle()); member = new Member(2, 2, "manager", new Date()); db.insert(member); // 再插入 var count = db.count(Member.class); // 获取总行数 System.out.println(count); var members = db.find(Member.class); // 获取全部行 for (var m : members) { System.out.printf("%d %d %s %s\n", m.getUserId(), m.getGroupId(), m.getTitle(), m.getCreatedAt()); } member = new Member(2, 3, "manager", new Date()); db.insert(member); // 再插入 members = db.find(Member.class, Q.eq_("group_id"), 2); // 条件查询 for (var m : members) { System.out.printf("%d %d %s %s\n", m.getUserId(), m.getGroupId(), m.getTitle(), m.getCreatedAt()); } var setters = new HashMap<String, Object>(); setters.put("title", "employee"); db.update(Member.class, setters, 2, 3); // 修改 member = db.get(Member.class, 2, 3); // 主键查询 System.out.println(member.getTitle()); db.delete(Member.class, 1, 2); // 删除 db.delete(Member.class, 2, 2); // 删除 db.delete(Member.class, 2, 3); // 删除 count = db.count(Member.class); // 再获取总行数 System.out.println(count); } finally { db.drop(Member.class); // 删表 } } }

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); } } }

分表

public class DemoPartitioning { 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 { for (int i = 0; i < BookShelf.PARTITIONS; i++) { db.create(BookShelf.class, String.valueOf(i)); // 创建所有分表 } var bss = new ArrayList<BookShelf>(); for (int i = 0; i < 100; i++) { var bs = new BookShelf("user" + i, "book" + i, "comment" + i, new Date()); bss.add(bs); db.insert(bs); // 插入，自动插入相应分表 } for (int i = 0; i < BookShelf.PARTITIONS; i++) { System.out.printf("partition %d count %d\n", i, db.count(BookShelf.class, String.valueOf(i))); } Random random = new Random(); for (var bs : bss) { bs.setComment("comment_update_" + random.nextInt(100)); db.update(bs); // 更新，自动更新相应分表数据 } bss = new ArrayList<BookShelf>(); for (int i = 0; i < BookShelf.PARTITIONS; i++) { bss.addAll(db.find(BookShelf.class, String.valueOf(i))); // 指定分表列出所有行 } for (var bs : bss) { System.out.println(bs.getComment()); } for (var bs : bss) { db.delete(bs); // 挨个删除，自动删除相应分表数据 } } finally { for (int i = 0; i < BookShelf.PARTITIONS; i++) { db.drop(BookShelf.class, String.valueOf(i)); // 删除所有分表 } } } }

分库

public class DemoSharding { private static DemoDB[] dbs = new DemoDB[3]; static { Map<Class<? extends IEntity>, Meta> metas = new HashMap<>(); dbs[0] = new DemoDB("demo-0", metas, "jdbc:mysql://localhost:3306/mydrc?user=mydrc&password=mydrc&useUnicode=true&characterEncoding=UTF8"); dbs[1] = new DemoDB("demo-1", metas, "jdbc:mysql://localhost:3307/mydrc?user=mydrc&password=mydrc&useUnicode=true&characterEncoding=UTF8"); dbs[2] = new DemoDB("demo-2", metas, "jdbc:mysql://localhost:3308/mydrc?user=mydrc&password=mydrc&useUnicode=true&characterEncoding=UTF8"); } public static void main(String[] args) { var grid = new GridDemoDB(dbs); // 构造 Grid 实例 try { for (int k = 0; k < BookShelf.PARTITIONS; k++) { grid.create(BookShelf.class, String.valueOf(k)); // 创建所有分库中的分表 } var bss = new ArrayList<BookShelf>(); for (int i = 0; i < 100; i++) { var bs = new BookShelf("user" + i, "book" + i, "comment" + i, new Date()); bss.add(bs); grid.insert(bs); // 插入，自动分发到相应的分库中的分表 } for (int k = 0; k < grid.size(); k++) { for (int i = 0; i < BookShelf.PARTITIONS; i++) { System.out.printf("db %d partition %d count %d\n", k, i, grid.count(BookShelf.class, k, String.valueOf(i))); // 依次查询出所有分库的分表的行数 } } Random random = new Random(); for (var bs : bss) { bs.setComment("comment_update_" + random.nextInt(100)); grid.update(bs); // 更新，自动分发到相应的分库中的分表 } for (var bs : bss) { bs = grid.get(BookShelf.class, bs.getUserId(), bs.getBookId()); // 主键查询，自动分发到相应的分库中的分表 System.out.println(bs.getComment()); } for (var bs : bss) { grid.delete(bs); // 删除，自动分发到相应的分库中的分表 } for (int k = 0; k < grid.size(); k++) { for (int i = 0; i < BookShelf.PARTITIONS; i++) { System.out.printf("db %d partition %d count %d\n", k, i, grid.count(BookShelf.class, k, String.valueOf(i))); // 依次查询出所有分库的分表的行数 } } } finally { for (int k = 0; k < BookShelf.PARTITIONS; k++) { grid.drop(BookShelf.class, String.valueOf(k)); // 删除所有分库中的分表 } } } }

事件上下文对象

public class Context { private DB db; // 数据库实例 private Connection conn; // 当前的链接 private Class<? extends IEntity> clazz; // 当前的实体类 private Q q; // 查询 sql private Object[] values; // 查询的绑定参数 private boolean before; // before or after private Exception error; // 异常 private long duration; // 耗时 microsecond }

事件回调

public class DemoEvent { 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); db.on(ctx -> { // 全局事件回调 System.out.printf("db=%s sql=%s cost=%dus\n", ctx.db().name(), ctx.q().sql(), ctx.duration()); return true; // 返回 false 会导致事件链终止，后续的 ORM 操作也不会执行 }); try { db.create(User.class); db.scope(ctx -> { // 范围回调，execute 方法内部的所有 ORM 操作都会回调 System.out.printf("db=%s sql=%s cost=%dus\n", ctx.db().name(), ctx.q().sql(), ctx.duration()); return true; }).execute(() -> { db.count(User.class); db.find(User.class); }); } finally { db.drop(User.class); // 删除表 } } }

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