如何在Java中创建唯一Id

这是一个 UUID ,“用于识别计算机系统中信息的128位数字”。

在其规范文本表示中,UUID的十六个八位字节表示为32个十六进制(以16为基数)数字,以8-4-4-4-12的形式显示,共36个字符(32个字母数字字符和四个连字符)。例如:

123e4567-e89b-12d3-a456-426655440000
xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx

// Create a random UUID:
UUID uuid1 = UUID.randomUUID();
System.out.println(uuid1);

// Create a fixed UUID:
String uuidString = "D00077B4-EBFB-4BD8-9E3F-1F3943CBCE35";
UUID uuid2 = UUID.fromString(uuidString);
System.out.println(uuid2);

// Get string from UUID:
UUID uuid = ...
String s = uuid.toString();
System.out.println(s);

这是GUID或UUID,您可以在此处阅读更多内容:

https://en.wikipedia.org/wiki/Universally_unique_identifier

http://docs.oracle.com/javase/7/docs/api/java/util/UUID.html

import java.util.UUID;

public class RandomStringUUID {
    public static void main(String[] args) {
        // Creating a random UUID (Universally unique identifier).
        UUID uuid = UUID.randomUUID();
        String randomUUIDString = uuid.toString();

        System.out.println("Random UUID String = " + randomUUIDString);
        System.out.println("UUID version       = " + uuid.version());
        System.out.println("UUID variant       = " + uuid.variant());
    }
}