uuid

问题 I'd like to use a UUID for database records but if I'm using it for the URL I'd like it to be 5 to 8 characters. I know I need to use SecureRandom and base64 , but how do I specify the length I need? 回答1: You can't get a real UUID down to 5-8 characters, as another answer points out, but you can shorten them somewhat. UUIDs are 128-bit integers which works out to 32 hex digits. You can easily store 6 bits per character and cut the length down to 22 characters, which is what base 64 encoding

问题 I have following problem: When my headset is turned on before my phone bluetooth is on, it will not connect to my phone. It will only connect to my phone when phone bluetooth is on and my headset is turned on second. I found out that I can still connect to my headset when bluetooth is turned on second (1. case), by going into androids bluetooth menu where my paired devices are listed and select my headset (although my headset is listed as 'connected'). This will connect my headset and my

问题 This question already has an answer here : CoreBluetooth: What is the lifetime of unique UUIDs (1 answer) Closed 5 years ago . I've been playing with Corebluetooth and I've learnt that besides going through the tedious process of scanning for a peripheral every time I want to connect, I can also store the peripheral's UUID and use it with retrievePeripheralsWithIdentifiers and connectPeripheral for further reconnections. Turns out that it only works for a certain amount of time, apparently

问题 So, I have been battling a problem with nested UUID's in mongoose that is outlined in the following stack overflow post Mongoose and array of ref UUID's does not convert However, after some more testing and research, I found that this breaks another part of my code for updates to documents that I use to apply to the system. Since this code is complex, I will provide an simpler example that creates this same condition. Upon installing the following nodejs packages "mongoose": "^5.6.10",

问题 could anyone tell me the difference between android unique id i.e UUID and phonegap device id UUID? Are they same or different values? If these values different,then is there any unique property value that is same in both.? 回答1: Update The values obtain from above two parameters are different.Don't match with each other. android UUID: TelephonyManager manager=(TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE); String uuid=manager.getDeviceId(); android phonegap UUID --Returns a

问题 The app I have found online works flawlessly except when clicking onto the Send Button, after typing something into the textbox, the printer runs, and stops in the middle of the process of printing, program doesn't crash however. I'm just curious if I'm using the wrong UUID, in fact I don't even know what it is. I have this following class, which is the only class needed to run the app, the rest are XML, with all three bluetooth permissions; package com.example.bluetoothprinter; import

问题 Have following CF: create column family gr_ip2 with column_type = 'Standard' and comparator = 'TimeUUIDType(reversed=true)' ...; then do following code: $uuid1 = phpcassa\UUID::uuid1(null, $time); $cf->insert("$key" , array($uuid1 => $url) ); it works without exceptions, but CF at the end is empty. 回答1: $uuid1 is not string, but an object. When we do $cf->insert("$key" , array($uuid1 => $url) ); the object is converted to string, and insert fails. phpcassa does not give exeption, but insert

问题 I have a distributed application that sends and receives data from a specific service on the Internet. When a node receives data, sometimes it needs to validate that that data is correlated with data it or another node previously sent. The value also needs to be unique enough so that I can practically expect never to generate identical values within 24 hours. In the current implementation I have been using a custom header containing a value of uuid.uuid1() . I can easily validate that that

问题 What is the smallest way to store a UUID that is human readable and widely database compatible? I am thinking a char array of some sort using hex values? 回答1: As common approach, i think that encoding the binary data (16 bytes) as Base64 could be what you want. 回答2: Use Base-85 encoding to store the UUID as 20 US-ASCII characters. 回答3: You might find the latest podcast relevant: http://itc.conversationsnetwork.org/shows/detail4087.html Database-wide unique-yet-simple identifiers in SQL Server

问题 I am looking at a piece of code, and i can see that the following code has been written which generates a string, and that string has been set as the primary key of the table. return new BigInteger(UUID.randomUUID().toString().replaceAll("-", ""), 16).toString(36); Till now, there are lots of records and they seem to be unique as the primary key constraint is not violated. I understand that the number will be random but will it be unique? thanks Tuco 回答1: There is no guarantee that the