UUID或者UNID或者UID,是一個統一唯一辨別,可以用來标記文檔、資料或其它需要唯一辨別的東西。Java 5.0内置UUID的實作,見java.util.UUID. 下面代碼是找到的2種實作方式,随手測了一下,兩者時間效率居然出奇的相似,在10000000次循環中,均在660秒左右。
Java代碼
![](https://img.laitimes.com/img/__Qf2AjLwojIjJCLyojI0JCLicmbw5iNyImMwQzNxQzM3YWO1MTOhljNmVDMhVTNjVmMzYjZi9CX0JXZ252bj91Ztl2Lc52YucWbp5GZzNmLn9Gbi1yZtl2Lc9CX6MHc0RHaiojIsJye.png)
import java.math.BigInteger;
import java.util.Random;
import java.util.UUID;
public class UUIDTest {
private static UUID uid = null;
private static final Random RANDOM = new Random();
public static String getUUID() {
uid = UUID.randomUUID();
String idstr = uid.toString().replace("-", "");
return idstr.toUpperCase();
}
public static String generateGUID(){
return new BigInteger(165, RANDOM).toString(36).toUpperCase();
}
public static void main(String[] args) {
int cycles = 100000000;
long start = System.currentTimeMillis();
for (int i = 0; i
//System.out.println(getUUID());
getUUID();
}
long end = System.currentTimeMillis();
String msg = "Time(ms) of getUUID() " + cycles + " times: " ;
System.out.println (msg + (end - start));
long start1 = System.currentTimeMillis();
for (int i = 0; i
//System.out.println(generateGUID());
generateGUID();
}
long end1 = System.currentTimeMillis();
msg = "Time(ms) of generateGUID() " + cycles + " times: " ;
System.out.println (msg + (end1 - start1));
}
}
2者所生成ID字串如下:
引用
FB0F88715B564691A85F28DBFDD57D90
E50999DA27624D7E81B89C47DF02DA92
E601B3C99AC4490E97EA0174860EEFDF
839DF94E497E45D09D5D7F34C531511F
54459B4DACF94097962A1C6017A35882
6A6CAF5667F74C24A28141CD287C44BE
7DF3E7F386934C4E9842E980E9E4C652
3370A0549E3C4C5EA3A5EFC53E5DC9B6
563F56BA980F43D3A07DF58B9F95F2EC
0968563C99E046B9944DFDD36CDDF5E2
GV9VQMTJC4NDFV5IB7N5IDWABQWF8M4M
LD0U9UKFPGG9LKKYHEWJSJ40OC57JHIQ
J9KTPM0Y9676256UNQTO7HFQG0G0CBDK
H0B4IVYNO99N918YIJ12PKA4T0R6P394
CTYE9DTF9IBUXXOR1SYCJYCRXD9H6KO9
2ZQ1CH3MGP5M3AOTFH1VJ3ZQ8M0CH2I5
MDGHQLHQ34A0Q9JNJ7S6WFAN8YV0M652
HVC2R84PT2ZKABL2FSSR84K9N5IG98WP
MGZ3NZJ5RS51KCL12KHLGURXCHZK8YNK
129RZPH0UPQO8SMCZZJFTY37G47T19KL
時間測試結果:
引用
Time(ms) of getUUID() 100000000 times: 669516
Time(ms) of generateGUID() 100000000 times: 663656