一.雪花算法
1.为什么使用
- 当一个表的数据量非常大的时候 肯定要分库分表 此时id如果是自增长 分开之后就会出现id相同的情况
2.工具类
import java.lang.management.ManagementFactory;
import .InetAddress;
import .NetworkInterface;
/**
* <p>名称：IdWorker.java</p>
* <p>描述：分布式自增长ID</p>
* <pre>
* Twitter的 Snowflake JAVA实现方案
* </pre>
* 核心代码为其IdWorker这个类实现，其原理结构如下，我分别用一个0表示一位，用—分割开部分的作用：
* 1||0---0000000000 0000000000 0000000000 0000000000 0 --- 00000 ---00000 ---000000000000
* 在上面的字符串中，第一位为未使用（实际上也可作为long的符号位），接下来的41位为毫秒级时间，
* 然后5位datacenter标识位，5位机器ID（并不算标识符，实际是为线程标识），
* 然后12位该毫秒内的当前毫秒内的计数，加起来刚好64位，为一个Long型。
* 这样的好处是，整体上按照时间自增排序，并且整个分布式系统内不会产生ID碰撞（由datacenter和机器ID作区分），
* 并且效率较高，经测试，snowflake每秒能够产生26万ID左右，完全满足需要。
* <p>
* 64位ID (42(毫秒)+5(机器ID)+5(业务编码)+12(重复累加))
*
* @author Polim
*/
public class IdWorker {
// 时间起始标记点，作为基准，一般取系统的最近时间（一旦确定不能变动）
private final static long twepoch = 1288834974657L;
// 机器标识位数
private final static long workerIdBits = 5L;
// 数据中心标识位数
private final static long datacenterIdBits = 5L;
// 机器ID最大值
private final static long maxWorkerId = -1L ^ (-1L << workerIdBits);
// 数据中心ID最大值
private final static long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);
// 毫秒内自增位
private final static long sequenceBits = 12L;
// 机器ID偏左移12位
private final static long workerIdShift = sequenceBits;
// 数据中心ID左移17位
private final static long datacenterIdShift = sequenceBits + workerIdBits;
// 时间毫秒左移22位
private final static long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
private final static long sequenceMask = -1L ^ (-1L << sequenceBits);
/* 上次生产id时间戳 */
private static long lastTimestamp = -1L;
// 0，并发控制
private long sequence = 0L;
private final long workerId;
// 数据标识id部分
private final long datacenterId;
public IdWorker(){
this.datacenterId = getDatacenterId(maxDatacenterId);
this.workerId = getMaxWorkerId(datacenterId, maxWorkerId);
}
/**
* @param workerId
* 工作机器ID
* @param datacenterId
* 序列号
*/
public IdWorker(long workerId, long datacenterId) {
if (workerId > maxWorkerId || workerId < 0) {
throw new IllegalArgumentException(String.format("worker Id can't be greater than %d or less than 0", maxWorkerId));
}
if (datacenterId > maxDatacenterId || datacenterId < 0) {
throw new IllegalArgumentException(String.format("datacenter Id can't be greater than %d or less than 0", maxDatacenterId));
}
this.workerId = workerId;
this.datacenterId = datacenterId;
}
/**
* 获取下一个ID
*
* @return
*/
public synchronized long nextId() {
long timestamp = timeGen();
if (timestamp < lastTimestamp) {
throw new RuntimeException(String.format("Clock moved backwards. Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
}
if (lastTimestamp == timestamp) {
// 当前毫秒内，则+1
sequence = (sequence + 1) & sequenceMask;
if (sequence == 0) {
// 当前毫秒内计数满了，则等待下一秒
timestamp = tilNextMillis(lastTimestamp);
}
} else {
sequence = 0L;
}
lastTimestamp = timestamp;
// ID偏移组合生成最终的ID，并返回ID
long nextId = ((timestamp - twepoch) << timestampLeftShift)
| (datacenterId << datacenterIdShift)
| (workerId << workerIdShift) | sequence;
return nextId;
}
private long tilNextMillis(final long lastTimestamp) {
long timestamp = this.timeGen();
while (timestamp <= lastTimestamp) {
timestamp = this.timeGen();
}
return timestamp;
}
private long timeGen() {
return System.currentTimeMillis();
}
/**
* <p>
* 获取 maxWorkerId
* </p>
*/
protected static long getMaxWorkerId(long datacenterId, long maxWorkerId) {
StringBuffer mpid = new StringBuffer();
mpid.append(datacenterId);
String name = ManagementFactory.getRuntimeMXBean().getName();
if (!name.isEmpty()) {
/*
* GET jvmPid
*/
mpid.append(name.split("@")[0]);
}
/*
* MAC + PID 的 hashcode 获取16个低位
*/
return (mpid.toString().hashCode() & 0xffff) % (maxWorkerId + 1);
}
/**
* <p>
* 数据标识id部分
* </p>
*/
protected static long getDatacenterId(long maxDatacenterId) {
long id = 0L;
try {
InetAddress ip = InetAddress.getLocalHost();
NetworkInterface network = NetworkInterface.getByInetAddress(ip);
if (network == null) {
id = 1L;
} else {
byte[] mac = network.getHardwareAddress();
id = ((0x000000FF & (long) mac[mac.length - 1])
| (0x0000FF00 & (((long) mac[mac.length - 2]) << 8))) >> 6;
id = id % (maxDatacenterId + 1);
}
} catch (Exception e) {
System.out.println(" getDatacenterId: " + e.getMessage());
}
return id;
}
}2.使用
- 在配置文件写入
yzx: #项目名
worker:
workerId: 1 #工作机器ID
datacenterId: 1 #序列号- 将配置文件读成实体类
@ConfigurationProperties(prefix = "yzx.worker")
public class IdWorkerProperties {
private long workerId;// 当前机器id
private long datacenterId;// 序列号
public long getWorkerId() {
return workerId;
}
public void setWorkerId(long workerId) {
this.workerId = workerId;
}
public long getDatacenterId() {
return datacenterId;
}
public void setDatacenterId(long datacenterId) {
this.datacenterId = datacenterId;
}
}- 给Spring注入配置好的IdWorker
@Configuration
@EnableConfigurationProperties(IdWorkerProperties.class)
public class IdWorkerConfig {
@Bean
public IdWorker idWorker(IdWorkerProperties prop) {
return new IdWorker(prop.getWorkerId(), prop.getDatacenterId());
}
}- 调用注入的IdWorker 生成id
@Service
public class TestService {
@Autowired
private IdWorker idWorker;
public void test() {
// 生成orderId
long id = idWorker.nextId();
}
}二.几个工具类
1.JsonUtils
- 序列化和反序列化json
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.lang.Nullable;
import java.io.IOException;
import java.util.List;
import java.util.Map;
public class JsonUtils {
public static final ObjectMapper mapper = new ObjectMapper();
private static final Logger logger = LoggerFactory.getLogger(JsonUtils.class);
@Nullable
public static String serialize(Object obj) {
if (obj == null) {
return null;
}
if (obj.getClass() == String.class) {
return (String) obj;
}
try {
return mapper.writeValueAsString(obj);
} catch (JsonProcessingException e) {
logger.error("json序列化出错：" + obj, e);
return null;
}
}
@Nullable
public static <T> T parse(String json, Class<T> tClass) {
try {
return mapper.readValue(json, tClass);
} catch (IOException e) {
logger.error("json解析出错：" + json, e);
return null;
}
}
@Nullable
public static <E> List<E> parseList(String json, Class<E> eClass) {
try {
return mapper.readValue(json, mapper.getTypeFactory().constructCollectionType(List.class, eClass));
} catch (IOException e) {
logger.error("json解析出错：" + json, e);
return null;
}
}
@Nullable
public static <K, V> Map<K, V> parseMap(String json, Class<K> kClass, Class<V> vClass) {
try {
return mapper.readValue(json, mapper.getTypeFactory().constructMapType(Map.class, kClass, vClass));
} catch (IOException e) {
logger.error("json解析出错：" + json, e);
return null;
}
}
@Nullable
public static <T> T nativeRead(String json, TypeReference<T> type) {
try {
return mapper.readValue(json, type);
} catch (IOException e) {
logger.error("json解析出错：" + json, e);
return null;
}
}
}2.ObjectUtils
- 解析object类型的对象
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
</dependency>import org.apache.commons.lang3.StringUtils;
/**
* Object类型转换为具体类型可能出现空指针，
* 这个工具类进行了一些转换
*/
public class ObjectUtils {
public static String toString(Object obj) {
if (obj == null) {
return null;
}
return obj.toString();
}
public static Long toLong(Object obj) {
if (obj == null) {
return 0L;
}
if (obj instanceof Double || obj instanceof Float) {
return Long.valueOf(StringUtils.substringBefore(obj.toString(), "."));
}
if (obj instanceof Number) {
return Long.valueOf(obj.toString());
}
if (obj instanceof String) {
return Long.valueOf(obj.toString());
} else {
return 0L;
}
}
public static Integer toInt(Object obj) {
return toLong(obj).intValue();
}
}3.CodecUtils
- 加密算法
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>1.11</version>
</dependency>import org.apache.commons.codec.digest.DigestUtils;
import org.apache.commons.lang3.StringUtils;
import java.util.UUID;
public class CodecUtils {
/*
* md5加密
* data：要加密的字符串
* salt：盐
*/
public static String md5Hex(String data,String salt) {
if (StringUtils.isBlank(salt)) {
salt = data.hashCode() + "";
}
return DigestUtils.md5Hex(salt + DigestUtils.md5Hex(data));
}
/*
* sha加密
* data：要加密的字符串
* salt：盐
*/
public static String shaHex(String data, String salt) {
if (StringUtils.isBlank(salt)) {
salt = data.hashCode() + "";
}
return DigestUtils.sha512Hex(salt + DigestUtils.sha512Hex(data));
}
/*
* 生成盐
*/
public static String generateSalt(){
return StringUtils.replace(UUID.randomUUID().toString(), "-", "");
}
}4.NumberUtils
- 数字相关的工具类
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.regex.MatchResult;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class NumberUtils {
public static boolean isInt(Double num) {
return num.intValue() == num;
}
/**
* 判断字符串是否是数值格式
* @param str
* @return
*/
public static boolean isDigit(String str){
if(str == null || str.trim().equals("")){
return false;
}
return str.matches("^\\d+$");
}
/**
* 将一个小数精确到指定位数
* @param num
* @param scale
* @return
*/
public static double scale(double num, int scale) {
BigDecimal bd = new BigDecimal(num);
return bd.setScale(scale, RoundingMode.HALF_UP).doubleValue();
}
// 从字符串中根据正则表达式寻找，返回找到的数字数组
public static Double[] searchNumber(String value, String regex){
List<Double> doubles = new ArrayList<>();
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(value);
if(matcher.find()) {
MatchResult result = matcher.toMatchResult();
for (int i = 1; i <= result.groupCount(); i++) {
doubles.add(Double.valueOf(result.group(i)));
}
}
return doubles.toArray(new Double[doubles.size()]);
}
/**
* 生成指定位数的随机数字
* @param len
* @return
*/
public static String generateCode(int len){
len = Math.min(len, 8);
int min = Double.valueOf(Math.pow(10, len - 1)).intValue();
int num = new Random().nextInt(Double.valueOf(Math.pow(10, len + 1)).intValue() - 1) + min;
return String.valueOf(num).substring(0,len);
}
}5.BeanUtils
- 从上下文中获得bean
public class BeanUtils {
public static <T> T getBean(Class<T> clazz, HttpServletRequest request){
WebApplicationContext applicationContext = WebApplicationContextUtils.getRequiredWebApplicationContext(request.getServletContext());
return applicationContext.getBean(clazz);
}
}
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