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撸起袖子加油干——自己动手写 ORM 框架

  •  
  •   codehole · 2018-04-28 19:26:09 +08:00 · 1143 次点击
    这是一个创建于 586 天前的主题,其中的信息可能已经有所发展或是发生改变。

    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

    1. 代码简洁,没有任何依赖项,除了使用时需要用到 MySQL driver
    2. 易于使用,无须复杂的配置
    3. 提供自动创建表功能
    4. 支持分库又分表,可以只分库,也可以只分表
    5. 支持 groupby/having
    6. 支持原生 SQL
    7. 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

    1. 多表比较复杂,实现成本高,学习成本也高,容易出错
    2. 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
    3. 在分库分表的场合,很少使用多表操作
    4. 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
    		}
    	}
    
    }
    
        1
    dbpe   2018-04-28 20:45:36 +08:00
    围观大佬...问个事..市面上那些框架至此分库分表呢?
        2
    shellquery   2018-04-28 21:17:35 +08:00 via Android
    去我群里有问吧
        3
    kzzhr   2018-04-28 22:27:44 +08:00 via iPhone
    https://github.com/Kretech/Loulan
    借楼分享,搞了个类似的
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