TiDB 和 Java 的简单 CRUD 应用程序
作者：王琦智
本文将展示如何使用 TiDB 和 Java 来构造一个简单的 CRUD 应用程序。
注意： 推荐使用 Java 8 及以上版本进行 TiDB 的应用程序的编写。
建议： 如果你希望使用 Spring Boot 进行 TiDB 应用程序的编写，可以查看 Build the TiDB Application using Spring Boot。
第 1 步：启动你的 TiDB 集群
本节将介绍 TiDB 集群的启动方法。
使用 TiDB Cloud 免费集群
使用本地集群
此处将简要叙述启动一个测试集群的过程，若需查看正式环境集群部署，或查看更详细的部署内容，请查阅本地启动 TiDB。
部署本地测试集群
适用场景：利用本地 macOS 或者单机 Linux 环境快速部署 TiDB 测试集群，体验 TiDB 集群的基本架构，以及 TiDB、TiKV、PD、监控等基础组件的运行
下载并安装 TiUP。
{{< copyable "shell-regular" >}}
curl --proto '=https' --tlsv1.2 -sSf https://tiup-mirrors.pingcap.com/install.sh | sh声明全局环境变量。
注意：
TiUP 安装完成后会提示对应 profile 文件的绝对路径。在执行以下 source 命令前，需要根据 profile 文件的实际位置修改命令。
{{< copyable "shell-regular" >}}
source .bash_profile在当前 session 执行以下命令启动集群。
直接执行
tiup playground命令会运行最新版本的 TiDB 集群，其中 TiDB、TiKV、PD 和 TiFlash 实例各 1 个：{{< copyable "shell-regular" >}}
tiup playground也可以指定 TiDB 版本以及各组件实例个数，命令类似于：
{{< copyable "shell-regular" >}}
tiup playground v5.4.0 --db 2 --pd 3 --kv 3上述命令会在本地下载并启动某个版本的集群（例如 v5.4.0）。最新版本可以通过执行
tiup list tidb来查看。运行结果将显示集群的访问方式：CLUSTER START SUCCESSFULLY, Enjoy it ^-^
To connect TiDB: mysql --comments --host 127.0.0.1 --port 4001 -u root -p (no password)
To connect TiDB: mysql --comments --host 127.0.0.1 --port 4000 -u root -p (no password)
To view the dashboard: http://127.0.0.1:2379/dashboard
PD client endpoints: [127.0.0.1:2379 127.0.0.1:2382 127.0.0.1:2384]
To view the Prometheus: http://127.0.0.1:9090
To view the Grafana: http://127.0.0.1:3000
注意：
- 支持 v5.2.0 及以上版本的 TiDB 在 Apple M1 芯片的机器上运行
tiup playground。- 以这种方式执行的 playground，在结束部署测试后 TiUP 会清理掉原集群数据，重新执行该命令后会得到一个全新的集群。
- 若希望持久化数据，可以执行 TiUP 的
--tag参数：tiup --tag <your-tag> playground ...，详情参考 TiUP 参考手册。
使用云原生开发环境
基于 Git 的预配置的开发环境: 现在就试试
该环境会自动克隆代码，并通过 TiUP 部署测试集群。
第 2 步：获取代码
git clone https://github.com/pingcap-inc/tidb-example-java.git
- 使用 JDBC
- 使用 Mybatis（推荐）
- 使用 Hibernate（推荐）
进入目录 plain-java-jdbc：
cd plain-java-jdbc
目录结构如下所示：
.
├── Makefile
├── plain-java-jdbc.iml
├── pom.xml
└── src
└── main
├── java
│ └── com
│ └── pingcap
│ └── JDBCExample.java
└── resources
└── dbinit.sql
其中，dbinit.sql 为数据表初始化语句：
USE test;
DROP TABLE IF EXISTS player;
CREATE TABLE player (
`id` VARCHAR(36),
`coins` INTEGER,
`goods` INTEGER,
PRIMARY KEY (`id`)
);
JDBCExample.java 是 plain-java-jdbc 这个示例程序的主体。因为 TiDB 与 MySQL 协议兼容，因此，需要初始化一个 MySQL 协议的数据源 MysqlDataSource，以此连接到 TiDB。并在其后，初始化 PlayerDAO，用来管理数据对象，进行增删改查等操作。
PlayerDAO 是程序用来管理数据对象的类。其中 DAO 是 Data Access Object 的缩写。在其中定义了一系列数据的操作方法，用来对提供数据的写入能力。
PlayerBean 是数据实体类，为数据库表在程序内的映射。PlayerBean 的每个属性都对应着 player 表的一个字段。
package com.pingcap;
import com.mysql.cj.jdbc.MysqlDataSource;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.*;
/**
* Main class for the basic JDBC example.
**/
public class JDBCExample
{
public static class PlayerBean {
private String id;
private Integer coins;
private Integer goods;
public PlayerBean() {
}
public PlayerBean(String id, Integer coins, Integer goods) {
this.id = id;
this.coins = coins;
this.goods = goods;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public Integer getCoins() {
return coins;
}
public void setCoins(Integer coins) {
this.coins = coins;
}
public Integer getGoods() {
return goods;
}
public void setGoods(Integer goods) {
this.goods = goods;
}
@Override
public String toString() {
return String.format(" %-8s => %10s\n %-8s => %10s\n %-8s => %10s\n",
"id", this.id, "coins", this.coins, "goods", this.goods);
}
}
/**
* Data access object used by 'ExampleDataSource'.
* Example for CURD and bulk insert.
*/
public static class PlayerDAO {
private final MysqlDataSource ds;
private final Random rand = new Random();
PlayerDAO(MysqlDataSource ds) {
this.ds = ds;
}
/**
* Create players by passing in a List of PlayerBean.
*
* @param players Will create players list
* @return The number of create accounts
*/
public int createPlayers(List<PlayerBean> players){
int rows = 0;
Connection connection = null;
PreparedStatement preparedStatement = null;
try {
connection = ds.getConnection();
preparedStatement = connection.prepareStatement("INSERT INTO player (id, coins, goods) VALUES (?, ?, ?)");
} catch (SQLException e) {
System.out.printf("[createPlayers] ERROR: { state => %s, cause => %s, message => %s }\n",
e.getSQLState(), e.getCause(), e.getMessage());
e.printStackTrace();
return -1;
}
try {
for (PlayerBean player : players) {
preparedStatement.setString(1, player.getId());
preparedStatement.setInt(2, player.getCoins());
preparedStatement.setInt(3, player.getGoods());
preparedStatement.execute();
rows += preparedStatement.getUpdateCount();
}
} catch (SQLException e) {
System.out.printf("[createPlayers] ERROR: { state => %s, cause => %s, message => %s }\n",
e.getSQLState(), e.getCause(), e.getMessage());
e.printStackTrace();
} finally {
try {
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
System.out.printf("\n[createPlayers]:\n '%s'\n", preparedStatement);
return rows;
}
/**
* Buy goods and transfer funds between one player and another in one transaction.
* @param sellId Sell player id.
* @param buyId Buy player id.
* @param amount Goods amount, if sell player has not enough goods, the trade will break.
* @param price Price should pay, if buy player has not enough coins, the trade will break.
*
* @return The number of effected players.
*/
public int buyGoods(String sellId, String buyId, Integer amount, Integer price) {
int effectPlayers = 0;
Connection connection = null;
try {
connection = ds.getConnection();
} catch (SQLException e) {
System.out.printf("[buyGoods] ERROR: { state => %s, cause => %s, message => %s }\n",
e.getSQLState(), e.getCause(), e.getMessage());
e.printStackTrace();
return effectPlayers;
}
try {
connection.setAutoCommit(false);
PreparedStatement playerQuery = connection.prepareStatement("SELECT * FROM player WHERE id=? OR id=? FOR UPDATE");
playerQuery.setString(1, sellId);
playerQuery.setString(2, buyId);
playerQuery.execute();
PlayerBean sellPlayer = null;
PlayerBean buyPlayer = null;
ResultSet playerQueryResultSet = playerQuery.getResultSet();
while (playerQueryResultSet.next()) {
PlayerBean player = new PlayerBean(
playerQueryResultSet.getString("id"),
playerQueryResultSet.getInt("coins"),
playerQueryResultSet.getInt("goods")
);
System.out.println("\n[buyGoods]:\n 'check goods and coins enough'");
System.out.println(player);
if (sellId.equals(player.getId())) {
sellPlayer = player;
} else {
buyPlayer = player;
}
}
if (sellPlayer == null || buyPlayer == null) {
throw new SQLException("player not exist.");
}
if (sellPlayer.getGoods().compareTo(amount) < 0) {
throw new SQLException(String.format("sell player %s goods not enough.", sellId));
}
if (buyPlayer.getCoins().compareTo(price) < 0) {
throw new SQLException(String.format("buy player %s coins not enough.", buyId));
}
PreparedStatement transfer = connection.prepareStatement("UPDATE player set goods = goods + ?, coins = coins + ? WHERE id=?");
transfer.setInt(1, -amount);
transfer.setInt(2, price);
transfer.setString(3, sellId);
transfer.execute();
effectPlayers += transfer.getUpdateCount();
transfer.setInt(1, amount);
transfer.setInt(2, -price);
transfer.setString(3, buyId);
transfer.execute();
effectPlayers += transfer.getUpdateCount();
connection.commit();
System.out.println("\n[buyGoods]:\n 'trade success'");
} catch (SQLException e) {
System.out.printf("[buyGoods] ERROR: { state => %s, cause => %s, message => %s }\n",
e.getSQLState(), e.getCause(), e.getMessage());
try {
System.out.println("[buyGoods] Rollback");
connection.rollback();
} catch (SQLException ex) {
// do nothing
}
} finally {
try {
connection.close();
} catch (SQLException e) {
// do nothing
}
}
return effectPlayers;
}
/**
* Get the player info by id.
*
* @param id Player id.
* @return The player of this id.
*/
public PlayerBean getPlayer(String id) {
PlayerBean player = null;
try (Connection connection = ds.getConnection()) {
PreparedStatement preparedStatement = connection.prepareStatement("SELECT * FROM player WHERE id = ?");
preparedStatement.setString(1, id);
preparedStatement.execute();
ResultSet res = preparedStatement.executeQuery();
if(!res.next()) {
System.out.printf("No players in the table with id %s", id);
} else {
player = new PlayerBean(res.getString("id"), res.getInt("coins"), res.getInt("goods"));
}
} catch (SQLException e) {
System.out.printf("PlayerDAO.getPlayer ERROR: { state => %s, cause => %s, message => %s }\n",
e.getSQLState(), e.getCause(), e.getMessage());
}
return player;
}
/**
* Insert randomized account data (id, coins, goods) using the JDBC fast path for
* bulk inserts. The fastest way to get data into TiDB is using the
* TiDB Lightning(https://docs.pingcap.com/tidb/stable/tidb-lightning-overview).
* However, if you must bulk insert from the application using INSERT SQL, the best
* option is the method shown here. It will require the following:
*
* Add `rewriteBatchedStatements=true` to your JDBC connection settings.
* Setting rewriteBatchedStatements to true now causes CallableStatements
* with batched arguments to be re-written in the form "CALL (...); CALL (...); ..."
* to send the batch in as few client/server round trips as possible.
* https://dev.mysql.com/doc/relnotes/connector-j/5.1/en/news-5-1-3.html
*
* You can see the `rewriteBatchedStatements` param effect logic at
* implement function: `com.mysql.cj.jdbc.StatementImpl.executeBatchUsingMultiQueries`
*
* @param total Add players amount.
* @param batchSize Bulk insert size for per batch.
*
* @return The number of new accounts inserted.
*/
public int bulkInsertRandomPlayers(Integer total, Integer batchSize) {
int totalNewPlayers = 0;
try (Connection connection = ds.getConnection()) {
// We're managing the commit lifecycle ourselves, so we can
// control the size of our batch inserts.
connection.setAutoCommit(false);
// In this example we are adding 500 rows to the database,
// but it could be any number. What's important is that
// the batch size is 128.
try (PreparedStatement pstmt = connection.prepareStatement("INSERT INTO player (id, coins, goods) VALUES (?, ?, ?)")) {
for (int i=0; i<=(total/batchSize);i++) {
for (int j=0; j<batchSize; j++) {
String id = UUID.randomUUID().toString();
pstmt.setString(1, id);
pstmt.setInt(2, rand.nextInt(10000));
pstmt.setInt(3, rand.nextInt(10000));
pstmt.addBatch();
}
int[] count = pstmt.executeBatch();
totalNewPlayers += count.length;
System.out.printf("\nPlayerDAO.bulkInsertRandomPlayers:\n '%s'\n", pstmt);
System.out.printf(" => %s row(s) updated in this batch\n", count.length);
}
connection.commit();
} catch (SQLException e) {
System.out.printf("PlayerDAO.bulkInsertRandomPlayers ERROR: { state => %s, cause => %s, message => %s }\n",
e.getSQLState(), e.getCause(), e.getMessage());
}
} catch (SQLException e) {
System.out.printf("PlayerDAO.bulkInsertRandomPlayers ERROR: { state => %s, cause => %s, message => %s }\n",
e.getSQLState(), e.getCause(), e.getMessage());
}
return totalNewPlayers;
}
/**
* Print a subset of players from the data store by limit.
*
* @param limit Print max size.
*/
public void printPlayers(Integer limit) {
try (Connection connection = ds.getConnection()) {
PreparedStatement preparedStatement = connection.prepareStatement("SELECT * FROM player LIMIT ?");
preparedStatement.setInt(1, limit);
preparedStatement.execute();
ResultSet res = preparedStatement.executeQuery();
while (!res.next()) {
PlayerBean player = new PlayerBean(res.getString("id"),
res.getInt("coins"), res.getInt("goods"));
System.out.println("\n[printPlayers]:\n" + player);
}
} catch (SQLException e) {
System.out.printf("PlayerDAO.printPlayers ERROR: { state => %s, cause => %s, message => %s }\n",
e.getSQLState(), e.getCause(), e.getMessage());
}
}
/**
* Count players from the data store.
*
* @return All players count
*/
public int countPlayers() {
int count = 0;
try (Connection connection = ds.getConnection()) {
PreparedStatement preparedStatement = connection.prepareStatement("SELECT count(*) FROM player");
preparedStatement.execute();
ResultSet res = preparedStatement.executeQuery();
if(res.next()) {
count = res.getInt(1);
}
} catch (SQLException e) {
System.out.printf("PlayerDAO.countPlayers ERROR: { state => %s, cause => %s, message => %s }\n",
e.getSQLState(), e.getCause(), e.getMessage());
}
return count;
}
}
public static void main(String[] args) {
// 1. Configure the example database connection.
// 1.1 Create a mysql data source instance.
MysqlDataSource mysqlDataSource = new MysqlDataSource();
// 1.2 Set server name, port, database name, username and password.
mysqlDataSource.setServerName("localhost");
mysqlDataSource.setPortNumber(4000);
mysqlDataSource.setDatabaseName("test");
mysqlDataSource.setUser("root");
mysqlDataSource.setPassword("");
// Or you can use jdbc string instead.
// mysqlDataSource.setURL("jdbc:mysql://{host}:{port}/test?user={user}&password={password}");
// 2. And then, create DAO to manager your data.
PlayerDAO dao = new PlayerDAO(mysqlDataSource);
// 3. Run some simple examples.
// Create a player, who has a coin and a goods..
dao.createPlayers(Collections.singletonList(new PlayerBean("test", 1, 1)));
// Get a player.
PlayerBean testPlayer = dao.getPlayer("test");
System.out.printf("PlayerDAO.getPlayer:\n => id: %s\n => coins: %s\n => goods: %s\n",
testPlayer.getId(), testPlayer.getCoins(), testPlayer.getGoods());
// Create players with bulk inserts. Insert 1919 players totally, with 114 players per batch.
int addedCount = dao.bulkInsertRandomPlayers(1919, 114);
System.out.printf("PlayerDAO.bulkInsertRandomPlayers:\n => %d total inserted players\n", addedCount);
// Count players amount.
int count = dao.countPlayers();
System.out.printf("PlayerDAO.countPlayers:\n => %d total players\n", count);
// Print 3 players.
dao.printPlayers(3);
// 4. Explore more.
// Player 1: id is "1", has only 100 coins.
// Player 2: id is "2", has 114514 coins, and 20 goods.
PlayerBean player1 = new PlayerBean("1", 100, 0);
PlayerBean player2 = new PlayerBean("2", 114514, 20);
// Create two players "by hand", using the INSERT statement on the backend.
addedCount = dao.createPlayers(Arrays.asList(player1, player2));
System.out.printf("PlayerDAO.createPlayers:\n => %d total inserted players\n", addedCount);
// Player 1 wants to buy 10 goods from player 2.
// It will cost 500 coins, but player 1 cannot afford it.
System.out.println("\nPlayerDAO.buyGoods:\n => this trade will fail");
int updatedCount = dao.buyGoods(player2.getId(), player1.getId(), 10, 500);
System.out.printf("PlayerDAO.buyGoods:\n => %d total update players\n", updatedCount);
// So player 1 has to reduce the incoming quantity to two.
System.out.println("\nPlayerDAO.buyGoods:\n => this trade will success");
updatedCount = dao.buyGoods(player2.getId(), player1.getId(), 2, 100);
System.out.printf("PlayerDAO.buyGoods:\n => %d total update players\n", updatedCount);
}
}
第 3 步：运行代码
本节将逐步介绍代码的运行方法。
第 3 步第 1 部分：JDBC 表初始化
- 使用 JDBC
- 使用 Mybatis（推荐）
- 使用 Hibernate（推荐）
在 Gitpod Playground 中尝试 JDBC: 现在就试试
使用 JDBC 时，需手动初始化数据库表，若你本地已经安装了 mysql-client，且使用本地集群，可直接在 plain-java-jdbc 目录下运行：
make mysql
或直接执行：
mysql --host 127.0.0.1 --port 4000 -u root<src/main/resources/dbinit.sql
若你不使用本地集群，或未安装 mysql-client，请直接登录你的集群，并运行 src/main/resources/dbinit.sql 文件内的 SQL 语句。
[第 3 步第 2 部分：TiDB Cloud 更改参数](https://tidb.net/blog/2e652000#第 3 步：运行代码 /第 3 步第 2 部分：TiDB Cloud 更改参数 )
- 使用 JDBC
- 使用 Mybatis（推荐）
- 使用 Hibernate（推荐）
若你使用非本地默认集群、TiDB Cloud 或其他远程集群，更改 JDBCExample.java 内关于 Host、Port、User、Password 的参数：
mysqlDataSource.setServerName("localhost");
mysqlDataSource.setPortNumber(4000);
mysqlDataSource.setDatabaseName("test");
mysqlDataSource.setUser("root");
mysqlDataSource.setPassword("");
若你设定的密码为 123456，而且从 TiDB Cloud 得到的连接字符串为：
mysql --connect-timeout 15 -u root -h xxx.tidbcloud.com -P 4000 -p
那么此处应将参数更改为：
mysqlDataSource.setServerName("xxx.tidbcloud.com");
mysqlDataSource.setPortNumber(4000);
mysqlDataSource.setDatabaseName("test");
mysqlDataSource.setUser("root");
mysqlDataSource.setPassword("123456");
第 3 步第 3 部分：运行
- 使用 JDBC
- 使用 Mybatis（推荐）
- 使用 Hibernate（推荐）
运行 make，这是以下两个操作的组合：
- 清理并构建 (make build)：
mvn clean package - 运行 (make run)：
java -jar target/plain-java-jdbc-0.0.1-jar-with-dependencies.jar
你也可以单独运行这两个 make 命令或原生命令。
第 4 步：预期输出
- 使用 JDBC
- 使用 Hibernate（推荐）