通用性：仅依赖一张序列数据表，JDBC支持的数据库均可使用，包括SQLite、MySQL、Oracle、OceanBase等。高性能：本地缓存一个序列区间，缓存使用完之前无DB交互；缓存的区间可设置，区间越大，DB访问越少，性能越高。分布式：受益于集中式的序列数据表，保证了序列全局唯一。
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个人博客-详细介绍了组件的设计思路：https://ntopic.cn/p/2023062101/
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个人博客-详细介绍了Maven托管仓库配置方法：https://ntopic.cn/p/2023062201/
本JAR使用了Gitee和GitHub仓库托管，在项目的根pom.xml中，设置仓库地址：
<repositories>
<repository>
<id>Gitee-obullxl</id>
<url>https://gitee.com/obullxl/maven-repository/raw/master/repository</url>
</repository>
</repositories>或者：
<repositories>
<repository>
<id>GitHub-obullxl</id>
<url>https://raw.githubusercontent.com/obullxl/maven-repository/master/repository</url>
</repository>
</repositories>仅需要依赖本JAR包，无其他JAR包依赖：
<dependency>
<groupId>cn.ntopic</groupId>
<artifactId>sequence-jdbc</artifactId>
<version>1.0.2</version>
</dependency>- 项目根目录有测试的SQLite数据库（
SequenceJDBC.sqlite），可直接用于测试；其他的数据库，可提前创建数据表。 - 序列数据表名可自定义（默认为
nt_sequence），但表的2个字段（name和value）名称不可修改。 可选：默认情况下，序列服务可尝试创建数据表，若当前用户无建表权限，则需要手工创建以下序列数据表：
CREATE TABLE nt_sequence
(
name VARCHAR(64) NOT NULL COMMENT '序列名称',
value bigint NOT NULL COMMENT '序列值',
PRIMARY KEY (name)
) COMMENT='序列数据表'
;// 获取数据源，业务代码提供
DruidDataSource dataSource = new DruidDataSource();
dataSource.setUrl("jdbc:sqlite:./sequence-jdbc/SequenceJDBC.sqlite");
dataSource.setDriverClassName("org.sqlite.JDBC");
dataSource.setPoolPreparedStatements(false);
dataSource.setMaxPoolPreparedStatementPerConnectionSize(-1);
dataSource.setTestOnBorrow(true);
dataSource.setTestOnReturn(false);
dataSource.setTestWhileIdle(true);
dataSource.setValidationQuery("SELECT '1' FROM sqlite_master LIMIT 1");
// 实例化序列
@Bean("ntSequence")
public NTSequence ntSequence(DataSource dataSource) {
NTSequenceImpl impl = new NTSequenceImpl(dataSource);
// 可选：若自定义序列表名，才需要设置
impl.setTableName("nt_sequence"); // 默认为：nt_sequence
// 可选：尝试创建数据表，若当前用户无建表权限，则需要人工创建；若表已经创建，则忽略建表
impl.createTable();
// 可选：以下参数为默认值，若无特殊要求，可无需设置
impl.setRetryTimes(10);
impl.setStep(1000L); // 值越大，访问DB次数越少，性能越好
impl.setMinValue(1L);
impl.setMaxValue(99999999L); // 序列值最大值，当超过该值，则循环从`minValue`开始
// 序列初始化
impl.init();
return impl;
}- 第1种方式：无任何参数，使用默认的序列名称。
- 第2中方式：指定序列名称（如：
USER、ORDER等），每个业务序列独立。
// 获取`DEFAULT`默认序列ID
long newId1 = ntSequence.next();
long newId2 = ntSequence.next();
long newId3 = ntSequence.next();
// 获取`USER`用户ID：
long newUserId1 = ntSequence.next("USER");
long newUserId2 = ntSequence.next("USER");
long newUserId3 = ntSequence.next("USER");
// 获取`ORDER`订单ID：
long newOrderId1 = ntSequence.next("ORDER");
long newOrderId2 = ntSequence.next("ORDER");
long newOrderId3 = ntSequence.next("ORDER");使用本项目根目录SQLite数据库进行测试：
/**
* Author: obullxl@163.com
* Copyright (c) 2020-2023 All Rights Reserved.
*/
package cn.ntopic.sequence;
import cn.ntopic.sequence.impl.NTSequenceImpl;
import com.alibaba.druid.pool.DruidDataSource;
import org.junit.Assert;
import org.junit.Test;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CountDownLatch;
/**
* 分布式序列服务单元测试
*
* @author obullxl 2023年06月22日: 新增
*/
public class NTSequenceTest {
@Test
public void test_next() {
// 1. 创建数据源
DruidDataSource dataSource = new DruidDataSource();
dataSource.setUrl("jdbc:sqlite:./sequence-jdbc/SequenceJDBC.sqlite");
dataSource.setDriverClassName("org.sqlite.JDBC");
dataSource.setPoolPreparedStatements(false);
dataSource.setMaxPoolPreparedStatementPerConnectionSize(-1);
dataSource.setTestOnBorrow(true);
dataSource.setTestOnReturn(false);
dataSource.setTestWhileIdle(true);
dataSource.setValidationQuery("SELECT '1' FROM sqlite_master LIMIT 1");
final String tableName = "nt_sequence";
final String testSeqName = "TEST-" + System.currentTimeMillis() + "-" + System.nanoTime();
try {
// 2. 清理数据
this.deleteSequence(dataSource, tableName, testSeqName);
// 3. 实例化序列服务
NTSequenceImpl ntSequence = new NTSequenceImpl(dataSource);
ntSequence.setTableName(tableName);
ntSequence.createTable();
ntSequence.setStep(5);
ntSequence.init();
// 4. 并发测试
this.multiThreadTest(ntSequence, testSeqName);
// 5. 清理测试数据
this.deleteSequence(dataSource, tableName, testSeqName);
} finally {
dataSource.close();
}
}
private void deleteSequence(DruidDataSource dataSource, String tableName, String sequenceName) {
Connection conn = null;
PreparedStatement stmt = null;
try {
conn = dataSource.getConnection();
String deleteSQL = String.format("DELETE FROM %s WHERE name=?", tableName);
stmt = conn.prepareStatement(deleteSQL);
stmt.setString(1, sequenceName);
stmt.executeUpdate();
} catch (Throwable e) {
// ignore
} finally {
this.closeQuietly(stmt);
this.closeQuietly(conn);
}
}
private void closeQuietly(AutoCloseable closeable) {
if (closeable != null) {
try {
closeable.close();
} catch (Throwable e) {
// ignore
}
}
}
private void multiThreadTest(NTSequence ntSequence, String sequenceName) {
final int threadCount = 3;
final int valueCount = 107;
CountDownLatch countDownLatch = new CountDownLatch(threadCount);
Map<Integer, List<Long>> seqValues = new ConcurrentHashMap<>();
for (int i = 0; i < threadCount; i++) {
List<Long> sequenceValues = new ArrayList<>();
seqValues.put(i, sequenceValues);
new SequenceThread(countDownLatch, valueCount, ntSequence, sequenceName, sequenceValues).start();
}
try {
countDownLatch.await();
} catch (Throwable e) {
e.printStackTrace();
}
// 数据检测
Set<Long> allValues = new HashSet<>();
Assert.assertEquals(threadCount, seqValues.size());
for (int i = 0; i < threadCount; i++) {
allValues.addAll(seqValues.get(i));
Assert.assertEquals(valueCount, seqValues.get(i).size());
}
Assert.assertEquals(threadCount * valueCount, allValues.size());
}
private static class SequenceThread extends Thread {
private final int valueCount;
private final CountDownLatch countDownLatch;
private final NTSequence ntSequence;
private final String sequenceName;
private final List<Long> sequenceValues;
public SequenceThread(CountDownLatch countDownLatch, int valueCount, NTSequence ntSequence, String sequenceName, List<Long> sequenceValues) {
this.countDownLatch = countDownLatch;
this.valueCount = valueCount;
this.ntSequence = ntSequence;
this.sequenceName = sequenceName;
this.sequenceValues = sequenceValues;
}
@Override
public void run() {
try {
for (int i = 0; i < valueCount; i++) {
this.sequenceValues.add(ntSequence.next(this.sequenceName));
}
// 释放信号
this.countDownLatch.countDown();
} catch (Throwable e) {
// ignore
}
}
}
}