java，mysql触发器，redis生成流水号（yyyyMM000）
最近又遇到需要根据日期生成流水号的业务，然后记录了几种生成方法，一个是通过 java 代码，一个是数据库的触发器，还有是通过 redis。下面是代码：
通过 java 生成简易流水：
/**
* 通过日期和生成的流水号拼接
* @param maxCount 已经生成的个数
* @return
*/
public static String recountNew(int maxCount) {
if (maxCount < 0) {
return null;
}
//201707999
String str = LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyyMM"));
String countStr = str + num(maxCount, 3, 3);
System.out.println("合同编号:" + Long.valueOf(countStr));
return countStr;
}
<span class="hljs-comment">/**
* 生成流水号
* <span class="hljs-doctag">@param</span> current 当前生成个数
* <span class="hljs-doctag">@param</span> max 最大整数位
* <span class="hljs-doctag">@param</span> min 最小整数位
* <span class="hljs-doctag">@return</span> 生成的流水号
*/</span>
<span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> String <span class="hljs-title function_">num</span><span class="hljs-params">(<span class="hljs-type">int</span> current, <span class="hljs-type">int</span> max, <span class="hljs-type">int</span> min)</span> {
current++;
<span class="hljs-type">NumberFormat</span> <span class="hljs-variable">numberFormat</span> <span class="hljs-operator">=</span> NumberFormat.getInstance();
<span class="hljs-comment">//设置是否使用分组</span>
numberFormat.setGroupingUsed(<span class="hljs-literal">false</span>);
<span class="hljs-comment">//设置最大整数位数</span>
numberFormat.setMaximumIntegerDigits(max);
<span class="hljs-comment">//设置最小整数位数</span>
numberFormat.setMinimumIntegerDigits(min);
<span class="hljs-keyword">return</span> numberFormat.format(current);
}
通过数据触发器实现：
主要逻辑：以 201906001 为例，根据当前日期 201606 获取流水号最大的一个，保存到 n。然后把流水号加 1，再和当前日期 201906 拼接到一起
CREATE TABLE orders (
orders_id INT (10) PRIMARY KEY,
customer_name VARCHAR (100)
);
<span class="hljs-keyword">DROP</span> <span class="hljs-keyword">TRIGGER</span> tr_orders_id;
<span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">TRIGGER</span> tr_orders_id BEFORE <span class="hljs-keyword">INSERT</span> <span class="hljs-keyword">ON</span> orders <span class="hljs-keyword">FOR</span> <span class="hljs-keyword">EACH</span> <span class="hljs-type">ROW</span>
<span class="hljs-keyword">BEGIN</span>
<span class="hljs-keyword">DECLARE</span>
n <span class="hljs-type">INT</span>;
<span class="hljs-keyword">SELECT</span>
IFNULL(<span class="hljs-built_in">max</span>(<span class="hljs-keyword">RIGHT</span>(orders_id, <span class="hljs-number">3</span>)), <span class="hljs-number">0</span>) <span class="hljs-keyword">INTO</span> n
<span class="hljs-keyword">FROM</span>
orders
<span class="hljs-keyword">WHERE</span>
mid(orders_id, <span class="hljs-number">1</span>, <span class="hljs-number">6</span>) <span class="hljs-operator">=</span> DATE_FORMAT(now(), <span class="hljs-string">'%Y%m'</span>);
<span class="hljs-keyword">SET</span> NEW.orders_id <span class="hljs-operator">=</span> concat(
DATE_FORMAT(now(), <span class="hljs-string">'%Y%m'</span>),
<span class="hljs-keyword">RIGHT</span> (<span class="hljs-number">001</span> <span class="hljs-operator">+</span> n, <span class="hljs-number">3</span>)
);
<span class="hljs-keyword">END</span>;
<span class="hljs-keyword">INSERT</span> <span class="hljs-keyword">INTO</span> orders <span class="hljs-keyword">VALUES</span> (<span class="hljs-number">0</span>, <span class="hljs-string">'jack'</span>);
<span class="hljs-keyword">INSERT</span> <span class="hljs-keyword">INTO</span> orders <span class="hljs-keyword">VALUES</span> (<span class="hljs-number">0</span>, <span class="hljs-string">'jack'</span>);
redis 实现（采用）
主要利用 StringRedisTemplate 来操作 redis，写在业务层，需要使用直接注入就行。这是没有详细的说明配置 StringRedisTemplate，下面代码会有问题，只是知道有这个方法，有用的时候，自己去写一下就好了。
/**
* @version V1.0
* @Authoer CX
* @Since:2019/5/20
*/
public interface NumberGenService {
<span class="hljs-comment">/**
* 根据code生成编号
* 例:NB000001
* <span class="hljs-doctag">@param</span> code 前缀
* <span class="hljs-doctag">@return</span> 编号
*/</span>
<span class="hljs-title class_">String</span> <span class="hljs-title function_">generateNumber</span>(<span class="hljs-title class_">String</span> code);
<span class="hljs-comment">/**
* 根据code及年月生成编号
* 例子:NB201905000001
* <span class="hljs-doctag">@param</span> code 前缀
* <span class="hljs-doctag">@return</span> 编号
*/</span>
<span class="hljs-title class_">String</span> <span class="hljs-title function_">generateNumberByMonth</span>(<span class="hljs-title class_">String</span> code);
<span class="hljs-comment">/**
* 根据code及年月生成编号
* 例子:NB20190508000001
* <span class="hljs-doctag">@param</span> code 前缀
* <span class="hljs-doctag">@return</span> 编号
*/</span>
<span class="hljs-title class_">String</span> generateNumberByDay (<span class="hljs-title class_">String</span> code);
}
import com.cloudkeeper.confinement.main.service.NumberGenService;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import java.text.SimpleDateFormat;
import java.util.Date;
/**
* @version V1.0
* @Authoer CX
* @Since:2019/5/20
*/
@Service
public class NumberGenServiceImpl implements NumberGenService {
@Autowired
private StringRedisTemplate stringRedisTemplate;
private static final int LENGTH = 6;
private static final String MONTH_FORMAT = "yyyyMM";
private static final String DAY_FORMAT = "yyyyMMdd";
public String generateNumber (String code) {
return getNumber(code, "");
}
public String generateNumberByMonth (String code) {
return getNumber(code, new SimpleDateFormat(MONTH_FORMAT).format(new Date()));
}
public String generateNumberByDay (String code) {
return getNumber(code, new SimpleDateFormat(DAY_FORMAT).format(new Date()));
}
private String getNumber(String code, String month) {
code += month;
Long number = stringRedisTemplate.opsForValue().increment("" + ":" + code);
return code + StringUtils.leftPad(number.toString(), LENGTH, '0');
}
}
总结
以上是总结的几种实现方式，公司采用的是通过 redis 的自增来实现的，可以避免并发时生成相同编号的问题。通过 java 生成，在保存时会出现相同编号的问题。