springboot推荐算法springboot项⽬通过雪花算法⽣成19位数字id
建议：
雪花算法可以⽤来⽣成id也可以⽤来⽣成订单号。但是不常使⽤的表可以使⽤⾃增，常⽤的表使⽤雪花算法⽣成id。这样效果更好数据库表Id类型设置为bigint  （否则下⾯的代码也会报错）
⾸先⽣成雪花id，这样虽然可以直接调⽤也就是通过new这个类的对象来⽣成，但是因为使⽤了spring框架，交给容器管理更好，所以下⾯就通过配置来实现将类注⼊到容器中
import java.security.SecureRandom;
public class SnowflakeManager {
private static final long EPOCH_STAMP = 1262275200000L;
private static final long SEQUENCE_BIT = 12L;
private static final long MACHINE_BIT = 5L;
private static final long DATA_CENTER_BIT = 5L;
private static final long MAX_SEQUENCE_NUM = -1L ^ (-1L << SEQUENCE_BIT);
private static final long MAX_MACHINE_NUM = -1L ^ (-1L << MACHINE_BIT);
private static final long MAX_DATA_CENTER_NUM = -1L ^ (-1L << DATA_CENTER_BIT);
private static final long MACHINE_LEFT = SEQUENCE_BIT;
private static final long DATA_CENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT;
private static final long TIMESTAMP_LEFT = SEQUENCE_BIT + MACHINE_BIT + DATA_CENTER_BIT;
private final long machineId;
private final long dataCenterId;
private long sequence = 0L;
private long lastTimestamp = -1L;
public SnowflakeManager(long machineId, long dataCenterId) {
if (machineId > MAX_MACHINE_NUM || machineId < 0) {
throw new IllegalArgumentException(String.format("machine id can't be greater than %d or less than 0", MAX_MACHINE_NUM));
}
if (dataCenterId > MAX_DATA_CENTER_NUM || dataCenterId < 0) {
throw new IllegalArgumentException(String.format("data center id can't be greater than %d or less than 0", MAX_DATA_CENTER_NUM));
}
this.machineId = machineId;
this.dataCenterId = dataCenterId;
}
public synchronized long nextValue() throws Exception {
String os = Property("os.name");
SecureRandom secureRandom;
if (os.toLowerCase().startsWith("win")) {
// windows机器⽤
secureRandom = InstanceStrong();
} else {
// linux机器⽤
secureRandom = Instance("NativePRNGNonBlocking");
}
//SecureRandom secureRandom = InstanceStrong();
long currentTimeMillis = this.currentTimeMillis();
if(currentTimeMillis < this.lastTimestamp) {
throw new Exception(String.format("Clock moved backwards. Refusing to generate id for %d milliseconds", (this.lastTimestamp-currentTimeMillis)));
}
if(this.lastTimestamp == currentTimeMillis) {
this.sequence = (this.sequence+1) & MAX_SEQUENCE_NUM;
if (this.sequence == 0) {
this.sequence = Int(Long.valueOf(SEQUENCE_BIT).intValue());
currentTimeMillis = this.tilNextMillis(this.lastTimestamp);
}
} else {
this.sequence = Int(Long.valueOf(SEQUENCE_BIT).intValue());
}
this.lastTimestamp = currentTimeMillis;
// 64 Bit ID (42(Millis)+5(Data Center ID)+5(Machine ID)+12(Repeat Sequence Summation))
long nextId = ((currentTimeMillis-EPOCH_STAMP) << TIMESTAMP_LEFT)
| (this.dataCenterId << DATA_CENTER_LEFT)
| (this.machineId << MACHINE_LEFT)
| this.sequence;
return nextId;
}
private long tilNextMillis(long lastTimestamp) {
long currentTimeMillis = this.currentTimeMillis();
while (currentTimeMillis <= lastTimestamp) {
currentTimeMillis = this.currentTimeMillis();
}
return currentTimeMillis;
}
private long currentTimeMillis() {
return System.currentTimeMillis();
}
public static void main(String[] args) throws Exception {
SnowflakeManager snowflakeManager = new SnowflakeManager(0L,0L);
long l = Value();
System.out.println(l);
}
}
View Code
1、因为⽣成雪花id时要传⼊两个long型的参数，所以将这两个参数提到配置⽂件中来
com:
linshan:
demo1:
snowflake:
machine-id: 1
data-center-id: 1
我的包结构如下：（可以⾃⼰适当调整）
2、创建⼀个类 TestProperties ，来获取配置⽂件中的信息，⼀个类 SnowflakeProperties 来存需要传⼊的两个参数。
TestProperties
import com.ity.SnowflakeProperties;
import lombok.Data;
import org.t.properties.ConfigurationProperties;
@Data
//包名更改成⾃⼰的
@ConfigurationProperties(prefix = "com.linshan.demo1")
public class TestProperties {
private SnowflakeProperties snowflake;
}
SnowflakeProperties
import lombok.Getter;
import lombok.Setter;
@Getter
@Setter
public class SnowflakeProperties {
private long machineId;
private long dataCenterId;
}
3、创建BossAutoConfiguration类
这⾥注意的是@EnableConfigurationProperties注解的作⽤是：使使⽤ @ConfigurationProperties 注解的类⽣效。import com.ity.SnowflakeManager;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.dition.ConditionalOnMissingBean;
import org.t.properties.EnableConfigurationProperties;
import t.annotation.Bean;
import t.annotation.Configuration;
@Configuration
@EnableConfigurationProperties(TestProperties.class)
public class BossAutoConfiguration {
@Autowired
private TestProperties properties;
@Bean
@ConditionalOnMissingBean
public SnowflakeManager snowflakeManager() {
return new SnowflakeManager(Snowflake().getMachineId(), Snowflake().getDataCenterId());
}
}
4、最后就是直接在需要使⽤的类中注⼊即可