What is UUID? How to generate UUID in Java

What this article brings to you is about what is UUID? The method of generating UUID in Java has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

UUID introduction:

UUID (Universally Unique Identifier) ​​globally unique identifier refers to a number generated on one machine, which is guaranteed to be unique to all machines in the same time and space. Calculations based on standards set by the Open Software Foundation (OSF) use the Ethernet card address, nanosecond time, chip ID and many possible numbers. It is a combination of the following parts: the current date and time (the first part of the UUID is related to the time, if you generate a UUID after a few seconds, the first part is different and the rest are the same), clock Sequence, a globally unique IEEE machine identification number (if there is a network card, it is obtained from the network card, if there is no network card, it is obtained in other ways). The only flaw of UUID is that the generated result string will be relatively long.

UUID function:

We usually use int as the primary key of the database, which can be easily used for auto-increment, but the data range of using int is limited. If there is a large amount of data, the value range of int may be exceeded. So we can use uuid as primary key.

The details of their advantages and disadvantages can be found online

The class java.Util.UUID in java

(It is best to generate the UUID in the java program and then put the data Insert into the database, there is no need to modify the code that generates UUID if you change the database)

jdk1.5 adds the class java.Util.UUID to facilitate the generation of UUID.

Code:

/**
 * @author hh
 * @Date 2018/9/12 */public class UUIDUtil {    
 /**
     * 获取UUID 32位
     * @return
     */
    public static String createUUID(){
        String uuid= UUID.randomUUID().toString();        
        return  uuid.replace("-","");
    }
}

Run:

The storage type of UUID in the database

Take mySql database as an example

select replace(uuid(),'-','') from dual;

Run:

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