uuid | 易学教程

How to create a GUID/UUID using iOS

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I want to be able to create a GUID/UUID on the iPhone and iPad. The intention is to be able to create keys for distributed data that are all unique. Is there a way to do this with the iOS SDK? Stephan Burlot [[UIDevice currentDevice] uniqueIdentifier] Returns the Unique ID of your iPhone. EDIT: -[UIDevice uniqueIdentifier] is now deprecated and apps are being rejected from the App Store for using it. The method below is now the preferred approach. If you need to create several UUID, just use this method (with ARC): + (NSString *)GetUUID { CFUUIDRef theUUID = CFUUIDCreate(NULL); CFStringRef

Generating 8-character only UUIDs

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问题 UUID libraries generate 32-character UUIDs. I want to generate 8-character only UUIDs, is it possible? 回答1: It is not possible since a UUID is a 16-byte number per definition. But of course, you can generate 8-character long unique strings (see the other answers). Also be careful with generating longer UUIDs and substring-ing them, since some parts of the ID may contain fixed bytes (e.g. this is the case with MAC, DCE and MD5 UUIDs). 回答2: You can try RandomStringUtils class from apache

When are you truly forced to use UUID as part of the design?

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问题 I don\'t really see the point of UUID. I know the probability of a collision is effectively nil , but effectively nil is not even close to impossible. Can somebody give an example where you have no choice but to use UUID? From all the uses I\'ve seen, I can see an alternative design without UUID. Sure the design might be slightly more complicated, but at least it doesn\'t have a non-zero probability of failure. UUID smells like global variables to me. There are many ways global variables make

Differences between UDID and UUID [duplicate]

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问题 This question already has an answer here: iPhone/iPad unique identifier BESIDES UUID/UDID? 6 answers Some people say UDID (Unique Device IDentifier) and some say UUID (Universally Unique IDentifier) . Are they are the same or not? What are the differences between them? 回答1: UUID (Universally Unique IDentifier) Is on a per-app basis. identifies an app on a device. As long as the user doesn’t completely delete the app, then this identifier will persist between app launches, and at least let you

UUID performance in MySQL?

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问题 We\'re considering using UUID values as primary keys for our MySQL database. The data being inserted is generated from dozens, hundreds, or even thousands of remote computers and being inserted at a rate of 100-40,000 inserts per second, and we\'ll never do any updates. The database itself will typically get to around 50M records before we start to cull data, so not a massive database, but not tiny either. We\'re also planing to run on InnoDB, though we are open to changing that if there is a

How can I get the UUID of my Android phone in an application?

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问题 I\'m looking for help to get the UUID of my Android phone. I have searched the net and found one potential solution but it is not working in the emulator. Here is the code: Class<?> c; try { c = Class.forName(\"android.os.SystemProperties\"); Method get = c.getMethod(\"get\", String.class); serial = (String) get.invoke(c, \"ro.serialno\"); Log.d(\"ANDROID UUID\",serial); } catch (Exception e) { e.printStackTrace(); } Does anybody know why it isn\'t working, or have a better solution? 回答1:

How to set cookies for uuid

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问题 I have a website which generates a uuid every time the page is loaded/refreshed. I want to make it so that a certain value remains the same for a period of time using cookies. Does anyone know of a script which can help me? 回答1: Not sure why you are asking for a script, or what the problem here is. To set a cookie, just use: if (empty($_COOKIE["uuid"])) { $uuid = uniqid(); // or use a real UUID setcookie("uuid", $uuid, time()+30*24*60*60, "/"); } else { $uuid = $_COOKIE["uuid"]; } Actually

Is Secure.ANDROID_ID unique for each device?

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问题 I am using this call: Secure.getString(getApplicationContext().getContentResolver(), Secure.ANDROID_ID); To get a UID for the device. I think I am getting the same ID from multiple devices though. Should this be possible? The ID in question is: 9774d56d682e549c and apparently there is an issue with several devices returning this ID http://code.google.com/p/android/issues/list?cursor=10603&updated=10603&ts=1295993403 回答1: Check into this thread,. However you should be careful as it's

Android: How do bluetooth UUIDs work?

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问题 I don\'t understand what a bluetooth UUID denotes. Do UUIDs denote protocols (e.g. RFCOMM)? If so, why do the createRfcommSocketToServiceRecord() methods require UUIDs, when they specify rfcomm right in their names? Why does the BluetoothChat sample code have a seemingly arbitrary, hardcoded UUID? My question arises because, as per this question, I\'m getting a null pointer exception when devices running 4.0.4 try to connect (to an external, non-android device) using reflection. However, the

How to store uuid as number?

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问题 Based on the answer of question, UUID performance in MySQL, the person who answers suggest to store UUID as a number and not as a string. I\'m not so sure how it can be done. Anyone could suggest me something? How my ruby code deal with that? 回答1: If I understand correctly, you're using UUIDs in your primary column? People will say that a regular (integer) primary key will be faster , but there's another way using MySQL's dark side. In fact, MySQL is faster using binary than anything else